February 9, 2010

-page 47-

The natural aw tradition may either assume a stranger form, in which it is claimed that various fact’s entails of primary and secondary qualities, any of which is claimed that various facts entail values, reason by itself is capable of discerning moral requirements. As in the ethics of Knt, these requirements are supposed binding on all human beings, regardless of their desires.


The supposed natural or innate abilities of the mind to know the first principle of ethics and moral reasoning, wherein, those expressions are assigned and related to those that distinctions are which make in terms contribution to the function of the whole, as completed definitions of them, their phraseological impression is termed ‘synderesis’ (or, syntetesis) although traced to Aristotle, the phrase came to the modern era through St Jerome, whose scintilla conscientiae (gleam of conscience) wads a popular concept in early scholasticism. Nonetheless, it is mainly associated in Aquinas as an infallible natural, simple and immediate that the obtainable achieve makes certain upon which our receding of first moral principles. Conscience, by contrast, is, more concerned with or unitary modules that evolved with the addition of separate modules that were eventually wired together on some neutral circuit board.

While the brain that evolved this capacity was obviously a product of Darwinian evolution, the most critical precondition for the evolution of this brain cannot be simply explained in these terms. Darwinian evolution can explain why the creation of stone tools altered conditions for survival in a new ecological niche in which group living, pair bonding, and more complex social structures were critical to survival. And Darwinian evolution can also explain why selective pressures in this new ecological niche favoured pre-adaptive changes required for symbolic communication. All the same, this communication resulted directly through its passing an increasingly atypically structural complex and intensively condensed behaviour. Social evolution began to take precedence over physical evolution in the sense that mutations resulting in enhanced social behaviour particular instances of right and wrong, and can be in error, under which the assertion that is taken as fundamental, at least for the purposes of the branch of enquiry in hand.

It is, nevertheless, the view interpreted within the particular states of law and morality especially associated with Aquinas and the subsequent scholastic tradition, showing for itself the enthusiasm for reform for its own sake. Or for ‘rational’ schemes thought up by managers and theorists, is therefore entirely misplaced. Major o exponent s of this theme include the British absolute idealist Herbert Francis Bradley (1846-1924) and Austrian economist and philosopher Friedrich Hayek. The notably the idealism of Bradley, there ids the same doctrine that change is contradictory and consequently unreal: The Absolute is changeless. A way of sympathizing a little with his idea is to reflect that any scientific explanation of change will proceed by finding an unchanging law operating, or an unchanging quantity conserved in the change, so that explanation of change always proceeds by finding that which is unchanged. The metaphysical problem of change is to shake off the idea that each moment is created afresh, and to obtain a conception of events or processes as having a genuinely historical reality, Really extended and unfolding in time, as opposed to being composites of discrete temporal atoms. A step toward this end may be to see time itself not as an infinite container within which discrete events are located, bu as a kind of logical construction from the flux of events. This relational view of time was advocated by Leibniz and a subject of the debate between him and Newton’s Absolutist pupil, Clarke.

Generally, nature is an indefinitely mutable term, changing as our scientific conception of the world changes, and often best seen as signifying a contrast with something considered not part of nature. The term applies both to individual species (it is the nature of gold to be dense or of dogs to be friendly), and also to the natural world as a whole. The sense in which it applies between to species is quickly linked with ethical and aesthetic ideals: A thing ought to realize its nature, what is natural is what it is good for a thing to become, it is natural for humans to be healthy or two-legged, and departure from this is a misfortune or deformity. The associations of what is natural with what it is good to become is visible in Plato, and is the central idea of Aristotle’s philosophy of nature. Unfortunately, the pinnacle of nature in this sense is the mature adult male citizen, with the rest of what we would call the natural world, including women, slaves, children and other species, not quite making it.

Nature in general can, however, function as a foil to any idea inasmuch as a source of ideals: In this sense fallen nature is contrasted with a supposed celestial realization of the ‘forms’. The theory of ‘forms’ is probably the most characteristic, and most contested of the doctrines of Plato. In the background ie the Pythagorean conception of form as the key to physical nature, bu also the sceptical doctrine associated with the Greek philosopher Cratylus, and is sometimes thought to have been a teacher of Plato before Socrates. He is famous for capping the doctrine of Ephesus of Heraclitus, whereby the guiding idea of his philosophy was that of the logos, is capable of being heard or hearkened to by people, it unifies opposites, and it is somehow associated with fire, which is preeminent among the four elements that Heraclitus distinguishes: Fire, air (breath, the stuff of which souls composed), earth, and water. Although he is principally remembered for the doctrine of the ‘flux’ of all things, and the famous statement that you cannot step into the same river twice, for new waters are ever flowing in upon you. The more extreme implication of the doctrine of flux, e.g., the impossibility of categorizing things truly, do not seem consistent with his general epistemology and views of meaning, and were to his follower Cratylus, although the proper conclusion of his views was that the flux cannot be captured in words. According to Aristotle, he eventually held that since ‘regarding that which everywhere in every respect is changing nothing ids just to stay silent and wag one’s finger. Plato ‘s theory of forms can be seen in part as an action against the impasse to which Cratylus was driven.

The Galilean world view might have been expected to drain nature of its ethical content, however, the term seldom loses its normative force, and the belief in universal natural laws provided its own set of ideals. In the 18th century for example, a painter or writer could be praised as natural, where the qualities expected would include normal (universal) topics treated with simplicity, economy, regularity and harmony. Later on, nature becomes an equally potent emblem of irregularity, wildness, and fertile diversity, but also associated with progress of human history, its incurring definition that has been taken to fit many things as well as transformation, including ordinary human self-consciousness. Nature, being in contrast within integrated phenomenon may include (1) that which is deformed or grotesque or fails to achieve its proper form or function or just the statistically uncommon or unfamiliar, (2) the supernatural, or the world of gods and invisible agencies, (3) the world of rationality and unintelligence, conceived of as distinct from the biological and physical order, or the product of human intervention, and (5) related to that, the world of convention and artifice.

Different conceptualized traits as founded within the nature's continuous overtures that play ethically, for example, the conception of ‘nature red in tooth and claw’ often provides a justification for aggressive personal and political relations, or the idea that it is women’s nature to be one thing or another is taken to be a justification for differential social expectations. The term functions as a fig-leaf for a particular set of stereotypes, and is a proper target of much feminist writings. Feminist epistemology has asked whether different ways of knowing for instance with different criteria of justification, and different emphases on logic and imagination, characterize male and female attempts to understand the world. Such concerns include awareness of the ‘masculine’ self-image, itself a social variable and potentially distorting picture of what thought and action should be. Again, there is a spectrum of concerns from highly theoretical hypnotises, that only approve to theoretical proportionalities, as our attributive contributions are as yet, to be functionally dynamic in purpose and rationally vivid, as associated and intertwined by relativistic accounts. In this latter area particular attention is given to the institutional biases that stand in the way of equal opportunities in science and other academic pursuits, or the ideologies that stand in the way of women seeing themselves as leading contributors to various disciplines. However, to more radical feminists such concerns merely exhibit women wanting for themselves the same power and rights over others that men have claimed, and failing to confront the real problem, which is how to live without such symmetrical powers and rights.

In biological determinism, not only influences but constraints and makes inevitable our development as persons with a variety of traits. At its silliest the view postulates such entities as a gene predisposing people to poverty, and it is the particular enemy of thinkers stressing the parental, social, and political determinants of the way we are.

The philosophy of social science is more heavily intertwined with actual social science than in the case of other subjects such as physics or mathematics, since its question is centrally whether there can be such a thing as sociology. The idea of a ‘science of man’, devoted to uncovering scientific laws determining the basic dynamic s of human interactions was a cherished ideal of the Enlightenment and reached its heyday with the positivism of writers such as the French philosopher and social theorist Auguste Comte (1798-1957), and the historical materialism of Marx and his followers. Sceptics point out that what happens in society is determined by peoples’ own ideas of what should happen, and like fashions those ideas change in unpredictable ways as self-consciousness is susceptible to change by any number of external event s: Unlike the solar system of celestial mechanics a society is not at all a closed system evolving in accordance with a purely internal dynamic, but constantly responsive to shocks from outside.

The sociological approach to human behaviour is based on the premise that all social behaviour has a biological basis, and seeks to understand that basis in terms of genetic encoding for features that are then selected for through evolutionary history. The philosophical problem is essentially one of methodology, however, this philosophical feature for identifying represents that it can usefully be explained as for finding measures for assessing various genetic stories that might provide useful explanations.

Among the features that are proposed for this kind o f explanations are such things as male dominance, male promiscuity versus female fidelity, propensities to sympathy and other emotions, and the limited altruism characteristic of human beings. The strategy has proved unnecessarily controversial, with proponents accused of ignoring the influence of environmental and social factors in moulding people’s characteristics, e.g., at the limit of silliness, by postulating a ‘gene for poverty’, however, there is no need for the approach to commit such errors, since the feature explained sociobiological may be indexed to environment: For instance, it may be a propensity to develop some feature in some other environments (for even a propensity to develop propensities . . .) The main problem is to separate genuine explanation from speculative, just so stories which may or may not identify as really selective mechanisms.

Subsequently, in the 19th century attempts were made to base ethical reasoning on the presumed facts about evolution. The movement is particularly associated with the English philosopher of evolution Herbert Spencer (1820-1903), His first major work was the book Social Statics (1851), which advocated an extreme political libertarianism. The Principles of Psychology was published in 1855, and his very influential Education advocating natural development of intelligence, the creation of pleasurable interest, and the importance of science in the curriculum, appeared in 1861. His First Principles (1862) was followed over the succeeding years by volumes on the Principles of biology and psychology, sociology and ethics. Although he attracted a large public following and attained the stature of a sage, his speculative work has not lasted well, and in his own time there was dissident voices. T.H. Huxley said that Spencer’s definition of a tragedy was a deduction killed by a fact. Writer and social prophet Thomas Carlyle (1795-1881) called him a perfect vacuum, and the American psychologist and philosopher William James (1842-1910) wondered why half of England wanted to bury him in Westminister Abbey, and talked of the ‘hurdy-gurdy’ monotony of him, his whole system woodland, as if knocked together out of cracked hemlock.

The premises regarded by a later elements in an evolutionary path are better than earlier ones, the application of this principle then requires seeing western society, laissez-faire capitalism, or some other object of approval, as more evolved than more ‘primitive’ social forms. Neither the principle nor the applications command much respect. The version of evolutionary ethics called ‘social Darwinism’ emphasizes the struggle for natural selection, and drawn the conclusion that we should glorify such struggle, usually by enhancing competitive and aggressive relations between people in society or between societies themselves. More recently the relation between evolution and ethics has been rethought in the light of biological discoveries concerning altruism and kin-selection.

In that, the study of the say in which a variety of higher mental function may be adaptively implicated such that it becomes applicable of a psychology of evolution, formed in response to selection pressures on human populations through evolutionary time. Candidates for such theorizing include material and paternal motivations, capabilities for love and friendship, the development of language as a signalling system, cooperative and aggressive tendencies, our emotional repertoires, our moral reaction, including the disposition to direct and punish those who cheat on an agreement? Or who free-ride’s on the work of others, our cognitive structure and many others. Evolutionary psychology goes hand-in-hand with neurophysiological evidence about the underlying circuitry in the brain which subserves the psychological mechanisms it claims to identify.

For all that, an essential part of the British absolute idealist Herbert Bradley (1846-1924) was largely on the ground s that the self-sufficiency individualized through community and oneself is to contribute to social and other ideals. However, truth as formulated in language is always partial, and dependent upon categories that they are inadequate to the harmonious whole. Nevertheless, these self-contradictory elements somehow contribute to the harmonious whole, or Absolute, lying beyond categorization. Although absolute idealism maintains few adherents today, Bradley’s general dissent from empiricism, his holism, and the brilliance and style of his writing continue to make him the most interesting of the late 19th century writers influenced by the German philosopher Friedrich Hegel (1770-1831).

Understandably, something less than the fragmented division that belonging of Bradley’s case has a preference, voiced much earlier by the German philosopher, mathematician and polymath was Gottfried Leibniz (1646-1716), for categorical monadic properties over relations. He was particularly troubled by the relation between that which its known and the more that knows it. In philosophy, the Romantics took from the German philosopher and founder of critical philosophy Immanuel Kant (1724-1804) both the emphasis on free-will and the doctrine that reality is ultimately spiritual, with nature itself a mirror of the human soul. To fix upon one among alternatives as the one to be taken, Friedrich Schelling (1775-1854) foregathers nature of becoming a creative spirit whose aspiration is ever further and more to completed self-realization. Although a movement of more generalized naturalization was imperative, still, Romanticism drew on the same intellectual and emotional resources as German idealism was increasingly culminating in the philosophy of Hegel (1770-1831) and of absolute idealism.

Being such in comparison with nature may include (1) that which is deformed or grotesque, or fails to achieve its proper form or function, or just the statistically uncommon or unfamiliar, (2) the supernatural, or th world of gods and invisible agencies, (3) the world of rationality and intelligence, conceived of as distinct from the biological and physical order, (4) that which is manufactured and artefactual, or the product of human invention, and (5) related to it, the world of convention and artifice.

Different conceptions of nature continue to have ethical overtones, for example, the conception of ‘nature red in tooth and claw’ often provide a justification for aggressive personal and political relations, or the idea that it is a women’s nature to be one thing or another, as taken to be a justification for differential social expectations. The term functions as a fig-leaf for a particular set of stereotype, and is a proper target of much ‘feminist’ writing.

This brings to question, that most of all ethics are contributively distributed as an understanding for which a dynamic function in and among the problems that are affiliated with human desire and needs the achievements of happiness, or the distribution of goods. The central problem specific to thinking about the environment is the independent value to place on ‘such-things’ as preservation of species, or protection of the wilderness. Such protection can be supported as a mans to ordinary human ends, for instance, when animals are regarded as future sources of medicines or other benefits. Nonetheless, many would want to claim a non-utilitarian, absolute value for the existence of wild things and wild places. It is in their value that thing consist. They put u in our proper place, and failure to appreciate this value is not only an aesthetic failure but one of due humility and reverence, a moral disability. The problem is one of expressing this value, and mobilizing it against utilitarian agents for developing natural areas and exterminating species, more or less at will.

Many concerns and disputed cluster around the idea associated with the term ‘substance’. The substance of a thing may be considered in: (1) Its essence, or that which makes it what it is. This will ensure that the substance of a thing is that which remains through change in properties. Again, in Aristotle, this essence becomes more than just the matter, but a unity of matter and form. (2) That which can exist by itself, or does not need a subject for existence, in the way that properties need objects, hence (3) that which bears properties, as a substance is then the subject of predication, that about which things are said as opposed to the things said about it. Substance in the last two senses stands opposed to modifications such as quantity, quality, relations, etc. it is hard to keep this set of ideas distinct from the doubtful notion of a substratum, something distinct from any of its properties, and hence, as an incapable characterization. The notion of substances tend to vanquish into an empiricist thought, in which has fewer of the sensible questions of things with the notion of that in which they infer of giving way to an empirical notion of their regular occurrence. However, this is in turn is problematic, since it only makes sense to talk of the occurrence of instance of qualities, not of quantities themselves. So the problem of what it is for a value quality to be the instance that remains.

Metaphysics inspired by modern science tends to reject the concept of substance in favour of concepts such as that of a field or a process, each of which may seem to provide a better example of a fundamental physical category.

It must be spoken of a concept that is deeply embedded in 18th century aesthetics, but deriving from the 1st century rhetorical treatise On the Sublime, by Longinus. The sublime is great, fearful, noble, calculated to arouse sentiments of pride and majesty, as well as awe and sometimes terror. According to Alexander Gerard’s writing in 1759, ‘When a large object is presented, the mind expands itself to the extent of that objects, and is filled with one grand sensation, which totally possessing it, composes it into a solemn sedateness and strikes it with deep silent wonder, and administration’: It finds such a difficulty in spreading itself to the dimensions of its object, as enliven and invigorates which this occasions, it sometimes images itself present in every part of the sense which it contemplates, and from the sense of this immensity, feels a noble pride, and entertains a lofty conception of its own capacity.

In Kant’s aesthetic theory the sublime ‘raises the soul above the height of vulgar complacency’. We experience the vast spectacles of nature as ‘absolutely great’ and of irresistible might and power. This perception is fearful, but by conquering this fear, and by regarding as small ‘those things of which we are wont to be solicitous’ we quicken our sense of moral freedom. So we turn the experience of frailty and impotence into one of our true, inward moral freedom as the mind triumphs over nature, and it is this triumph of reason that is truly sublime. Kant thus paradoxically places our sense of the sublime in an awareness of ourselves as transcending nature, than in an awareness of ourselves as a frail and insignificant part of it.

Nevertheless, the doctrine that all relations are internal was a cardinal thesis of absolute idealism, and a central point of attack by the British philosopher’s George Edward Moore (1873-1958) and Bertrand Russell (1872-1970). It is a kind of ‘essentialism’, stating that if two things stand in some relationship, then they could not be what they are, did they not do so, if, for instance, I am wearing a hat mow, then when we imagine a possible situation that we would be got to describe as my not wearing the hat now, we would strictly not be imaging as one and the hat, but only some different individual.

The countering partitions a doctrine that bears some resemblance to the metaphysically based view of the German philosopher and mathematician Gottfried Leibniz (1646-1716) that if a person had any other attributes that the ones he has, he would not have been the AME person. Leibniz thought that when asked hat would have happened if Peter had not denied Christ. That being that if I am asking what had happened if Peter had not been Peter, denying Christ is contained in the complete notion of Peter. But he allowed that by the name ‘Peter’ might be understood as ‘what is involved in those attributes [of Peter] from which the denial does not follow’. In order that we are held accountable to allow of external relations, in that these being relations which individuals could have or not depending upon contingent circumstances. The relations of ideas is used by the Scottish philosopher David Hume (1711-76) in the First Enquiry of Theoretical Knowledge. All the objects of human reason or enquiring naturally, be divided into two kinds: To unit all the, ‘relations of ideas’ and ‘matter of fact ‘ (Enquiry Concerning Human Understanding) the terms reflect the belief that any thing that can be known dependently must be internal to the mind, and hence transparent to us.

In Hume, objects of knowledge are divided into matter of fact (roughly empirical things known by means of impressions) and the relation of ideas. The contrast, also called “Hume’s Fork’, is a version of the speculative deductivity distinction, but reflects the 17th and early 18th centauries behind that the deductivity is established by chains of infinite certainty as comparable to ideas. It is extremely important that in the period between Descartes and J.S. Mill that a demonstration is not, but only a chain of ‘intuitive’ comparable ideas, whereby a principle or maxim can be established by reason alone. In this sense, that the English philosopher John Locke (1632-1704) who believed that theological and moral principles are capable of demonstration, and Hume denies that they are, and also denies that scientific enquiries proceed in demonstrating its results.

A mathematical proof is formally inferred as to an argument that is used to show the truth of a mathematical assertion. In modern mathematics, a proof begins with one or more statements called premises and demonstrates, using the rules of logic, that if the premises are true then a particular conclusion must also be true.

The accepted methods and strategies used to construct a convincing mathematical argument have evolved since ancient times and continue to change. Consider the Pythagorean theorem, named after the 5th century Bc Greek mathematician and philosopher Pythagoras, which states that in a right-angled triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides. Many early civilizations considered this theorem true because it agreed with their observations in practical situations. But the early Greeks, among others, realized that observation and commonly held opinion do not guarantee mathematical truth. For example, before the 5th century Bc it was widely believed that all lengths could be expressed as the ratio of two whole numbers. But an unknown Greek mathematician proved that this was not true by showing that the length of the diagonal of a square with an area of 1 is the irrational number Ã.

The Greek mathematician Euclid laid down some of the conventions central to modern mathematical proofs. His book The Elements, written about 300 Bc, contains many proofs in the fields of geometry and algebra. This book illustrates the Greek practice of writing mathematical proofs by first clearly identifying the initial assumptions and then reasoning from them in a logical way in order to obtain a desired conclusion. As part of such an argument, Euclid used results that had already been shown to be true, called theorems, or statements that were explicitly acknowledged to be self-evident, called axioms; this practice continues today.

In the 20th century, proofs have been written that are so complex that no one person understands every argument used in them. In 1976, a computer was used to complete the proof of the four-colour theorem. This theorem states that four colours are sufficient to colour any map in such a way that regions with a common boundary line have different colours. The use of a computer in this proof inspired considerable debate in the mathematical community. At issue was whether a theorem can be considered proven if human beings have not actually checked every detail of the proof.

The study of the relations of deductibility among sentences in a logical calculus which benefits the prof theory. Deductibility is defined purely syntactically, that is, without reference to the intended interpretation of the calculus. The subject was founded by the mathematician David Hilbert (1862-1943) in the hope that strictly finitary methods would provide a way of proving the consistency of classical mathematics, but the ambition was torpedoed by Gödel’s second incompleteness theorem.

What is more, the use of a model to test for consistencies in an ‘axiomatized system’ which is older than modern logic. Descartes’ algebraic interpretation of Euclidean geometry provides a way of showing that if the theory of real numbers is consistent, so is the geometry. Similar representation had been used by mathematicians in the 19th century, for example to show that if Euclidean geometry is consistent, so are various non-Euclidean geometries. Model theory is the general study of this kind of procedure: The ‘proof theory’ studies relations of deductibility between formulae of a system, but once the notion of an interpretation is in place we can ask whether a formal system meets certain conditions. In particular, can it lead us from sentences that are true under some interpretation? And if a sentence is true under all interpretations, is it also a theorem of the system? We can define a notion of validity (a formula is valid if it is true in all interpret rations) and semantic consequence (a formula ‘B’ is a semantic consequence of a set of formulae, written {A1 . . . An} ⊨B, if it is true in all interpretations in which they are true) Then the central questions for a calculus will be whether all and only its theorems are valid, and whether {A1 . . . An} ⊨ B if and only if {A1 . . . An} ⊢B. There are the questions of the soundness and completeness of a formal system. For the propositional calculus this turns into the question of whether the proof theory delivers as theorems all and only ‘tautologies’. There are many axiomatizations of the propositional calculus that are consistent and complete. The mathematical logician Kurt Gödel (1906-78) proved in 1929 that the first-order predicate under every interpretation is a theorem of the calculus.

The Euclidean geometry is the greatest example of the pure ‘axiomatic method’, and as such had incalculable philosophical influence as a paradigm of rational certainty. It had no competition until the 19th century when it was realized that the fifth axiom of his system (parallel lines never meet) could be denied without inconsistency, leading to Riemannian spherical geometry. The significance of Riemannian geometry lies in its use and extension of both Euclidean geometry and the geometry of surfaces, leading to a number of generalized differential geometries. Its most important effect was that it made a geometrical application possible for some major abstractions of tensor analysis, leading to the pattern and concepts for general relativity later used by Albert Einstein in developing his theory of relativity. Riemannian geometry is also necessary for treating electricity and magnetism in the framework of general relativity. The fifth chapter of Euclid’s Elements, is attributed to the mathematician Eudoxus, and contains a precise development of the real number, work which remained unappreciated until rediscovered in the 19th century.

The Axiom, in logic and mathematics, is a basic principle that is assumed to be true without proof. The use of axioms in mathematics stems from the ancient Greeks, most probably during the 5th century Bc, and represents the beginnings of pure mathematics as it is known today. Examples of axioms are the following: 'No sentence can be true and false at the same time' (the principle of contradiction); 'If equals are added to equals, the sums are equal'. 'The whole is greater than any of its parts'. Logic and pure mathematics begin with such unproved assumptions from which other propositions (theorems) are derived. This procedure is necessary to avoid circularity, or an infinite regression in reasoning. The axioms of any system must be consistent with one another, that is, they should not lead to contradictions. They should be independent in the sense that they cannot be derived from one another. They should also be few in number. Axioms have sometimes been interpreted as self-evident truths. The present tendency is to avoid this claim and simply to assert that an axiom is assumed to be true without proof in the system of which it is a part.

The terms 'axiom' and 'postulate' are often used synonymously. Sometimes the word axiom is used to refer to basic principles that are assumed by every deductive system, and the term postulate is used to refer to first principles peculiar to a particular system, such as Euclidean geometry. Infrequently, the word axiom is used to refer to first principles in logic, and the term postulate is used to refer to first principles in mathematics.

The applications of game theory are wide-ranging and account for steadily growing interest in the subject. Von Neumann and Morgenstern indicated the immediate utility of their work on mathematical game theory by linking it with economic behaviour. Models can be developed, in fact, for markets of various commodities with differing numbers of buyers and sellers, fluctuating values of supply and demand, and seasonal and cyclical variations, as well as significant structural differences in the economies concerned. Here game theory is especially relevant to the analysis of conflicts of interest in maximizing profits and promoting the widest distribution of goods and services. Equitable division of property and of inheritance is another area of legal and economic concern that can be studied with the techniques of game theory.

In the social sciences, n-person game theory has interesting uses in studying, for example, the distribution of power in legislative procedures. This problem can be interpreted as a three-person game at the congressional level involving vetoes of the president and votes of representatives and senators, analysed in terms of successful or failed coalitions to pass a given bill. Problems of majority rule and individual decision making are also amenable to such study.

Sociologists have developed an entire branch of game theory devoted to the study of issues involving group decision making. Epidemiologists also make use of game theory, especially with respect to immunization procedures and methods of testing a vaccine or other medication. Military strategists turn to game theory to study conflicts of interest resolved through 'battles' where the outcome or payoff of a given war game is either victory or defeat. Usually, such games are not examples of zero-sum games, for what one player loses in terms of lives and injuries is not won by the victor. Some uses of game theory in analyses of political and military events have been criticized as a dehumanizing and potentially dangerous oversimplification of necessarily complicating factors. Analysis of economic situations is also usually more complicated than zero-sum games because of the production of goods and services within the play of a given 'game'.

All is the same in the classical theory of the syllogism, a term in a categorical proposition is distributed if the proposition entails any proposition obtained from it by substituting a term denoted by the original. For example, in ‘all dogs bark’ the term ‘dogs’ is distributed, since it entails ‘all terriers’ bark’, which is obtained from it by a substitution. In ‘Not all dogs bark’, the same term is not distributed, since it may be true while ‘not all terriers’ bark’ is false.

When a representation of one system by another is usually more familiar, in and for itself, that those extended in representation that their workings are supposed analogous to that of the first. This one might model the behaviour of a sound wave upon that of waves in water, or the behaviour of a gas upon that to a volume containing moving billiard balls. While nobody doubts that models have a useful ‘heuristic’ role in science, there has been intense debate over whether a good model, or whether an organized structure of laws from which it can be deduced and suffices for scientific explanation. As such, the debate of topic was inaugurated by the French physicist Pierre Marie Maurice Duhem (1861-1916), in ‘The Aim and Structure of Physical Theory’ (1954) by which Duhem’s conception of science is that it is simply a device for calculating as science provides deductive system that is systematic, economical, and predictive, but not that represents the deep underlying nature of reality. Steadfast and holding of its contributive thesis that in isolation, and since other auxiliary hypotheses will always be needed to draw empirical consequences from it. The Duhem thesis implies that refutation is a more complex matter than might appear. It is sometimes framed as the view that a single hypothesis may be retained in the face of any adverse empirical evidence, if we prepared to make modifications elsewhere in our system, although strictly speaking this is a stronger thesis, since it may be psychologically impossible to make consistent revisions in a belief system to accommodate, say, the hypothesis that there is a hippopotamus in the room when visibly there is not.

Primary and secondary qualities are the division associated with the 17th-century rise of modern science, wit h its recognition that the fundamental explanatory properties of things that are not the qualities that perception most immediately concerns. They’re later are the secondary qualities, or immediate sensory qualities, including colour, taste, smell, felt warmth or texture, and sound. The primary properties are less tied than their deliverance of one particular sense, and include the size, shape, and motion of objects. In Robert Boyle (1627-92) and John Locke (1632-1704) the primary qualities are scientifically tractable, objective qualities essential to anything material, are of a minimal listing of size, shape, and mobility, i.e., the state of being at rest or moving. Locke sometimes adds number, solidity, texture (where this is thought of as the structure of a substance, or way in which it is made out of atoms). The secondary qualities are the powers to excite particular sensory modifications in observers. Once, again, that Locke himself thought in terms of identifying these powers with the texture of objects that, according to corpuscularian science of the time, were the basis of an object’s causal capacities. The ideas of secondary qualities are sharply different from these powers, and afford us no accurate impression of them. For Renè Descartes (1596-1650), this is the basis for rejecting any attempt to think of knowledge of external objects as provided by the senses. But in Locke our ideas of primary qualities do afford us an accurate notion of what shape, size. And mobility are. In English-speaking philosophy the first major discontent with the division was voiced by the Irish idealist George Berkeley (1685-1753), who probably took for a basis of his attack from Pierre Bayle (1647-1706), who in turn cites the French critic Simon Foucher (1644-96). Modern thought continues to wrestle with the difficulties of thinking of colour, taste, smell, warmth, and sound as real or objective properties to things independent of us.

Continuing as such, is the doctrine advocated by the American philosopher David Lewis (1941-2002), in that different possible worlds are to be thought of as existing exactly as this one does. Thinking in terms of possibilities is thinking of real worlds where things are different. The view has been charged with making it impossible to see why it is good to save the child from drowning, since there is still a possible world in which she (or her counterpart) drowned, and from the standpoint of the universe it should make no difference which world is actual. Critics also charge that the notion fails to fit either with a coherent theory lf how we know about possible worlds, or with a coherent theory of why we are interested in them, but Lewis denied that any other way of interpreting modal statements is tenable.

The proposal set forth that characterizes the ‘modality’ of a proposition as the notion for which it is true or false. The most important division is between propositions true of necessity, and those true as things are: Necessary as opposed to contingent propositions. Other qualifiers sometimes called ‘modal’ include the tense indicators, ‘it will be the case that ‘p’, or ‘it was the case that ‘p’, and there are affinities between the ‘deontic’ indicators, ‘it ought to be the case that ‘p’, or ‘it is permissible that ‘p’, and the of necessity and possibility.

The aim of a logic is to make explicit the rules by which inferences may be drawn, than to study the actual reasoning processes that people use, which may or may not conform to those rules. In the case of deductive logic, if we ask why we need to obey the rules, the most general form of answer is that if we do not we contradict ourselves (or, strictly speaking, we stand ready to contradict ourselves. Someone failing to draw a conclusion that follows from a set of premises need not be contradicting him or herself, but only failing to notice something. However, he or she is not defended against adding the contradictory conclusion to his or fer set of beliefs.) There is no equally simple answer in the case of inductive logic, which is in general a less robust subject, but the aim will be to find reasoning such hat anyone failing to conform to it will have improbable beliefs. Traditional logic dominated the subject until the 19th century, and has become increasingly recognized in the 20th century, in that finer work that were done within that tradition, but syllogistic reasoning is now generally regarded as a limited special case of the form of reasoning that can be reprehend within the promotion and predated values, these form the heart of modern logic, as their central notions or qualifiers, variables, and functions were the creation of the German mathematician Gottlob Frége, who is recognized as the father of modern logic, although his treatment of a logical system as an abreact mathematical structure, or algebraic, has been heralded by the English mathematician and logician George Boole (1815-64), his pamphlet The Mathematical Analysis of Logic (1847) pioneered the algebra of classes. The work was made of in An Investigation of the Laws of Thought (1854). Boole also published many works in our mathematics, and on the theory of probability. His name is remembered in the title of Boolean algebra, and the algebraic operations he investigated are denoted by Boolean operations.

The syllogistic, or categorical syllogism is the inference of one proposition from two premises. For example is, ‘all horses have tails, and things with tails are four legged, so all horses are four legged. Each premise has one term in common with the other premises. The term that ds not occur in the conclusion is called the middle term. The major premise of the syllogism is the premise containing the predicate of the contraction (the major term). And the minor premise contains its subject (the minor term). So the first premise of the example in the minor premise the second the major term. So the first premise of the example is the minor premise, the second the major premise and ‘having a tail’ is the middle term. This enable syllogisms that there of a classification, that according to the form of the premises and the conclusions. The other classification is by figure, or way in which the middle term is placed or way in within the middle term is placed in the premise.

Although the theory of the syllogism dominated logic until the 19th century, it remained a piecemeal affair, able to deal with only relations valid forms of valid forms of argument. There have subsequently been rearguing actions attempting, but in general it has been eclipsed by the modern theory of quantification, the predicate calculus is the heart of modern logic, having proved capable of formalizing the calculus rationing processes of modern mathematics and science. In a first-order predicate calculus the variables range over objects: In a higher-order calculus the may range over predicate and functions themselves. The fist-order predicated calculus with identity includes ‘=’ as primitive (undefined) expression: In a higher-order calculus I t may be defined by law that χ= y iff (∀F)(Fχ↔Fy), which gives grater expressive power for less complexity.

Modal logic was of great importance historically, particularly in the light of the deity, but was not a central topic of modern logic in its gold period as the beginning of the 20th century. It was, however, revived by the American logician and philosopher Irving Lewis (1883-1964), although he wrote extensively on most central philosophical topis, he is remembered principally as a critic of the intentional nature of modern logic, and as the founding father of modal logic. His two independent proofs showing that from a contradiction anything follows a relevance logic, using a notion of entailment stronger than that of strict implication.

The imparting information has been conduced or carried out of the prescribed procedures, as impeding of something that tajes place in the chancing encounter out to be to enter ons’s mind may from time to time occasion of various doctrines concerning th necessary properties, least of mention, by adding to a prepositional or predicated calculus two operator, □and ◊(sometimes written ‘N’ and ‘M’), meaning necessarily and possible, respectfully. These like ‘p ➞◊p and □p ➞p will be wanted. Controversial these include □p ➞□□p (if a proposition is necessary. It is necessarily, characteristic of a system known as S4) and ◊p ➞□◊p (if as preposition is possible, it’s necessarily possible, characteristic of the system known as S5). The classical modal theory for modal logic, due to the American logician and philosopher (1940-) and the Swedish logician Sig Kanger, involves valuing prepositions not true or false simpiciter, but as true or false at possible worlds with necessity then corresponding to truth in all worlds, and possibility to truth in some world. Various different systems of modal logic result from adjusting the accessibility relation between worlds.

In Saul Kripke, gives the classical modern treatment of the topic of reference, both clarifying the distinction between names and definite description, and opening te door to many subsequent attempts to understand the notion of reference in terms of a causal link between the use of a term and an original episode of attaching a name to the subject.

One of the three branches into which ‘semiotic’ is usually divided, the study of semantical meaning of words, and the relation of signs to the degree to which the designs are applicable. In that, in formal studies, a semantics is provided for a formal language when an interpretation of ‘model’ is specified. However, a natural language comes ready interpreted, and the semantic problem is not that of specification but of understanding the relationship between terms of various categories (names, descriptions, predicate, adverbs . . . ) and their meaning. An influential proposal by attempting to provide a truth definition for the language, which will involve giving a full structure of different kinds have on the truth conditions of sentences containing them.

Holding that the basic casse of reference is the relation between a name and the persons or object which it names. The philosophical problems include trying to elucidate that relation, to understand whether other semantic relations, such s that between a predicate and the property it expresses, or that between a description an what it describes, or that between myself and the word ‘I’, are examples of the same relation or of very different ones. A great deal of modern work on this was stimulated by the American logician Saul Kripke’s, Naming and Necessity (1970). It would also be desirable to know whether we can refer to such things as objects and how to conduct the debate about each and issue. A popular approach, following Gottlob Frége, is to argue that the fundamental unit of analysis should be the whole sentence. The reference of a term becomes a derivative notion it is whatever it is that defines the term’s contribution to the trued condition of the whole sentence. There need be nothing further to say about it, given that we have a way of understanding the attribution of meaning or truth-condition to sentences. Other approach, searching for a more substantive possibly that causality or psychological or social constituents are pronounced between words and things.

However, following Ramsey and the Italian mathematician G. Peano (1858-1932), it has been customary to distinguish logical paradoxes that depend upon a notion of reference or truth (semantic notions) such as those of the ‘Liar family, Berry, Richard, etc. form the purely logical paradoxes in which no such notions are involved, such as Russell’s paradox, or those of Canto and Burali-Forti. Paradoxes of the fist type seem to depend upon an element of self-reference, in which a sentence is about itself, or in which a phrase refers to something about itself, or in which a phrase refers to something defined by a set of phrases of which it is itself one. It is to feel that this element is responsible for the contradictions, although self-reference itself is often benign (for instance, the sentence ‘All English sentences should have a verb’, includes itself happily in the domain of sentences it is talking about), so the difficulty lies in forming a condition that existence only pathological self-reference. Paradoxes of the second kind then need a different treatment. Whilst the distinction is convenient in allowing set theory to proceed by circumventing the latter paradoxes by technical mans, even when there is no solution to the semantic paradoxes, it may be a way of ignoring the similarities between the two families. There is still th possibility that while there is no agreed solution to the semantic paradoxes, our understand of Russell’s paradox may be imperfect as well.

Truth and falsity are two classical truth-values that a statement, proposition or sentence can take, as it is supposed in classical (two-valued) logic, that each statement has one of these values, and non has both. A statement is then false if and only if it is not true. The basis of this scheme is that to each statement there corresponds a determinate truth condition, or way the world must be for it to be true: If this condition obtains the statement is true, and otherwise false. Statements may indeed be felicitous or infelicitous in other dimensions (polite, misleading, apposite, witty, etc.) but truth is the central normative notion governing assertion. Considerations of vagueness may introduce greys into this black-and-white scheme. For the issue to be true, any suppressed premise or background framework of thought necessary makes an agreement valid, or valued as equally positional, in that, for reasons that tenably purport of a proposition whose truth is necessary for either the truth or the falsity of another statement. Thus if ‘p’ presupposes ‘q’, ‘q’ must be true for ‘p’ to be either true or false. In the theory of knowledge, the English philologer and historian George Collingwood (1889-1943), announces hat any proposition capable of truth or falsity stand on bed of ‘absolute presuppositions’ which are not properly capable of truth or falsity, since a system of thought will contain no way of approaching such a question (a similar idea later voiced by Wittgenstein in his work On Certainty). The introduction of presupposition therefore mans that either another of a truth value is fond, ‘intermediate’ between truth and falsity, or the classical logic is preserved, but it is impossible to tell whether a particular sentence empresses a preposition that is a candidate for truth and falsity, without knowing more than the formation rules of the language. Each suggestion carries coss, and there is some consensus that at least who where definite descriptions are involved, examples equally given by regarding the overall sentence as false as the existence claim fails, and explaining the data that the English philosopher Frederick Strawson (1919-) relied upon as the effects of ‘implicature’.

Views about the meaning of terms will often depend on classifying the implicature of sayings involving the terms as implicatures or as genuine logical implications of what is said. Implicatures may be divided into two kinds: Conversational implicatures of the two kinds and the more subtle category of conventional implicatures. A term may as a matter of convention carry an implicature, thus one of the relations between ‘he is poor and honest’ and ‘he is poor but honest’ is that they have the same content (are true in just the same conditional) but the second has implicatures (that the combination is surprising or significant) that the first lacks.

It is, nonetheless, that we find in classical logic a proposition that may be true or false. In that, if the former, it is said to take the truth-value true, and if the latter the truth-value false. The idea behind the terminological phrases is the analogues between assigning a propositional variable one or other of these values, as is done in providing an interpretation for a formula of the propositional calculus, and assigning an object as the value of any other variable. Logics with intermediate value are called ‘many-valued logics’.

Nevertheless, an existing definition of the predicate’ . . . is true’ for a language that satisfies convention ‘T’, the material adequately condition laid down by Alfred Tarski, born Alfred Teitelbaum (1901-83), whereby his methods of ‘recursive’ definition, enabling us to say for each sentence what it is that its truth consists in, but giving no verbal definition of truth itself. The recursive definition or the truth predicate of a language is always provided in a ‘metalanguage’, Tarski is thus committed to a hierarchy of languages, each with it’s associated, but different truth-predicate. Whist this enables the approach to avoid the contradictions of paradoxical contemplations, it conflicts with the idea that a language should be able to do everything that there is to say, and other approaches have become increasingly important.

So, that the truth condition of a statement is the condition for which the world must meet if the statement is to be true. To know this condition is equivalent to knowing the meaning of the statement. Although this sounds as if it gives a solid anchorage for meaning, some of the securities disappear when it turns out that the truth condition can only be defined by repeating the very same statement: The truth condition of ‘now is white’ is that ‘snow is white’, the truth condition of ‘Britain would have capitulated had Hitler invaded’, is that ‘Britain would have capitulated had Hitler invaded’. It is disputed whether this element of running-on-the-spot disqualifies truth conditions from playing the central role in a substantives theory of meaning. Truth-conditional theories of meaning are sometimes opposed by the view that to know the meaning of a statement is to be able to use it in a network of inferences.

Taken to be the view, inferential semantics take on the role of sentence in inference give a more important key to their meaning than this ‘external’ relations to things in the world. The meaning of a sentence becomes its place in a network of inferences that it legitimates. Also known as functional role semantics, procedural semantics, or conception to the coherence theory of truth, and suffers from the same suspicion that it divorces meaning from any clar association with things in the world.

Moreover, a theory of semantic truth be that of the view if language is provided with a truth definition, there is a sufficient characterization of its concept of truth, as there is no further philosophical chapter to write about truth: There is no further philosophical chapter to write about truth itself or truth as shared across different languages. The view is similar to the disquotational theory.

The redundancy theory, or also known as the ‘deflationary view of truth’ fathered by Gottlob Frége and the Cambridge mathematician and philosopher Frank Ramsey (1903-30), who showed how the distinction between the semantic paradoses, such as that of the Liar, and Russell’s paradox, made unnecessary the ramified type theory of Principia Mathematica, and the resulting axiom of reducibility. By taking all the sentences affirmed in a scientific theory that use some terms, e.g., quark, and to a considerable degree of replacing the term by a variable instead of saying that quarks have such-and-such properties, the Ramsey sentence says that there is something that has those properties. If the process is repeated for all of a group of the theoretical terms, the sentence gives ‘topic-neutral’ structure of the theory, but removes any implication that we know what the terms so treated denote. It leaves open the possibility of identifying the theoretical item with whatever. It is that best fits the description provided. However, it was pointed out by the Cambridge mathematician Newman, that if the process is carried out for all except the logical bones of a theory, then by the Löwenheim-Skolem theorem, the result will be interpretable, and the content of the theory may reasonably be felt to have been lost.

All the while, both Frége and Ramsey are agreeing that the essential claim is that the predicate’ . . . is true’ does not have a sense, i.e., expresses no substantive or profound or explanatory concept that ought to be the topic of philosophical enquiry. The approach admits of different versions, but centres on the points (1) that ‘it is true that ‘p’ says no more nor less than ‘p’ (hence, redundancy): (2) that in less direct contexts, such as ‘everything he said was true’, or ‘all logical consequences of true propositions are true’, the predicate functions as a device enabling us to generalize than as an adjective or predicate describing the things he said, or the kinds of propositions that follow from true preposition. For example, the second may translate as ‘(∀p, q)(p & p ➞q ➞q)’ where there is no use of a notion of truth.

There are technical problems in interpreting all uses of the notion of truth in such ways, nevertheless, they are not generally felt to be insurmountable. The approach needs to explain away apparently substantive uses of the notion, such as ‘science aims at the truth’, or ‘truth is a norm governing discourse’. Postmodern writing frequently advocates that we must abandon such norms. Along with a discredited ‘objective’ conception of truth. Perhaps, we can have the norms even when objectivity is problematic, since they can be framed without mention of truth: Science wants it to be so that whatever science holds that ‘p’, then ‘p’. Discourse is to be regulated by the principle that it is wrong to assert ‘p’, when ‘not-p’.

Something that tends of something in addition of content, or coming by way to justify such a position can very well be more that in addition to several reasons, as to bring in or join of something might that there be more so as to a larger combination for us to consider the simplest formulation, is that the claim that expression of the form ‘S is true’ mean the same as expression of the form ‘S’. Some philosophers dislike the ideas of sameness of meaning, and if this I disallowed, then the claim is that the two forms are equivalent in any sense of equivalence that matters. This is, it makes no difference whether people say ‘Dogs bark’ id Tue, or whether they say, ‘dogs bark’. In the former representation of what they say of the sentence ‘Dogs bark’ is mentioned, but in the later it appears to be used, of the claim that the two are equivalent and needs careful formulation and defence. On the face of it someone might know that ‘Dogs bark’ is true without knowing what it means (for instance, if he kids in a list of acknowledged truths, although he does not understand English), and tis is different from knowing that dogs bark. Disquotational theories are usually presented as versions of the ‘redundancy theory of truth’.

The relationship between a set of premises and a conclusion when the conclusion follows from the premise. Many philosophers identify this with it being logically impossible that the premises should all be true, yet the conclusion false. Others are sufficiently impressed by the paradoxes of strict implication to look for a stranger relation, which would distinguish between valid and invalid arguments within the sphere of necessary propositions. The seraph for a strange notion is the field of relevance logic.

From a systematic theoretical point of view, we may imagine the process of evolution of an empirical science to be a continuous process of induction. Theories are evolved and are expressed in short compass as statements of as large number of individual observations in the form of empirical laws, from which the general laws can be ascertained by comparison. Regarded in this way, the development of a science bears some resemblance to the compilation of a classified catalogue. It is, a it were, a purely empirical enterprise.

But this point of view by no means embraces the whole of the actual process, for it slurs over the important part played by intuition and deductive thought in the development of an exact science. As soon as a science has emerged from its initial stages, theoretical advances are no longer achieved merely by a process of arrangement. Guided by empirical data, the investigators rather develops a system of thought which, in general, it is built up logically from a small number of fundamental assumptions, the so-called axioms. We call such a system of thought a ‘theory’. The theory finds the justification for its existence in the fact that it correlates a large number of single observations, and is just here that the ‘truth’ of the theory lies.

Corresponding to the same complex of empirical data, there may be several theories, which differ from one another to a considerable extent. But as regards the deductions from the theories which are capable of being tested, the agreement between the theories may be so complete, that it becomes difficult to find any deductions in which the theories differ from each other. As an example, a case of general interest is available in the province of biology, in the Darwinian theory of the development of species by selection in the struggle for existence, and in the theory of development which is based on the hypophysis of the hereditary transmission of acquired characters. THE Origin of Species was principally successful in marshalling the evidence for evolution, than providing a convincing mechanisms for genetic change. And Darwin himself remained open to the search for additional mechanisms, while also remaining convinced that natural selection was at the hart of it. It was only with the later discovery of the gene as the unit of inheritance that the synthesis known as ‘neo-Darwinism’ became the orthodox theory of evolution in the life sciences.

In the 19th century the attempt to base ethical reasoning o the presumed facts about evolution, the movement is particularly associated with the English philosopher of evolution Herbert Spencer (1820-1903). The premise is that later elements in an evolutionary path are better than earlier ones: The application of this principle then requires seeing western society, laissez-faire capitalism, or some other object of approval, as more evolved than more ‘primitive’ social forms. Neither the principle nor the applications command much respect. The version of evolutionary ethics called ‘social Darwinism’ emphasises the struggle for natural selection, and draws the conclusion that we should glorify and assist such struggle, usually by enhancing competition and aggressive relations between people in society or between evolution and ethics has been rethought in the light of biological discoveries concerning altruism and kin-selection.

Once again, the psychology proven attempts are founded to evolutionary principles, in which a variety of higher mental functions may be adaptations, forced in response to selection pressures on the human populations through evolutionary time. Candidates for such theorizing include material and paternal motivations, capacities for love and friendship, the development of language as a signalling system cooperative and aggressive, our emotional repertoire, our moral and reactions, including the disposition to detect and punish those who cheat on agreements or who ‘free-ride’ on =the work of others, our cognitive structures, nd many others. Evolutionary psychology goes hand-in-hand with neurophysiological evidence about the underlying circuitry in the brain which subserves the psychological mechanisms it claims to identify. The approach was foreshadowed by Darwin himself, and William James, as well as the sociology of E.O. Wilson. The term of use are applied, more or less aggressively, especially to explanations offered in Sociobiology and evolutionary psychology.

Another assumption that is frequently used to legitimate the real existence of forces associated with the invisible hand in neoclassical economics derives from Darwin’s view of natural selection as a warlike competing between atomized organisms in the struggle for survival. In natural selection as we now understand it, cooperation appears to exist in complementary relation to competition. It is complementary relationships between such results that are emergent self-regulating properties that are greater than the sum of parts and that serve to perpetuate the existence of the whole.

According to E.O Wilson, the ‘human mind evolved to believe in the gods’ and people ‘need a sacred narrative’ to have a sense of higher purpose. Yet it id also clear that the ‘gods’ in his view are merely human constructs and, therefore, there is no basis for dialogue between the world-view of science and religion. ‘Science for its part’, said Wilson, ‘will test relentlessly every assumption about the human condition and in time uncover the bedrock of the moral an religious sentiments. The eventual result of the competition between the other, will be the secularization of the human epic and of religion itself.

Man has come to the threshold of a state of consciousness, regarding his nature and his relationship to te Cosmos, in terms that reflect ‘reality’. By using the processes of nature as metaphor, to describe the forces by which it operates upon and within Man, we come as close to describing ‘reality’ as we can within the limits of our comprehension. Men will be very uneven in their capacity for such understanding, which, naturally, differs for different ages and cultures, and develops and changes over the course of time. For these reasons it will always be necessary to use metaphor and myth to provide ‘comprehensible’ guides to living. In thus way. Man’s imagination and intellect play vital roles on his survival and evolution.

Since so much of life both inside and outside the study is concerned with finding explanations of things, it would be desirable to have a concept of what counts as a good explanation from bad. Under the influence of ‘logical positivist’ approaches to the structure of science, it was felt that the criterion ought to be found in a definite logical relationship between the ‘exlanans’ (that which does the explaining) and the explanandum (that which is to be explained). The approach culminated in the covering law model of explanation, or the view that an event is explained when it is subsumed under a law of nature, that is, its occurrence is deducible from the law plus a set of initial conditions. A law would itself be explained by being deduced from a higher-order or covering law, in the way that Johannes Kepler(or Keppler, 1571-1630), was by way of planetary motion that the laws were deducible from Newton’s laws of motion. The covering law model may be adapted to include explanation by showing that something is probable, given a statistical law. Questions for the covering law model include querying for the covering law are necessary to explanation (we explain whether everyday events without overtly citing laws): Querying whether they are sufficient (it ma y not explain an event just to say that it is an example of the kind of thing that always happens). And querying whether a purely logical relationship is adapted to capturing the requirements, we make of explanations. These may include, for instance, that we have a ‘feel’ for what is happening, or that the explanation proceeds in terms of things that are familiar to us or unsurprising, or that we can give a model of what is going on, and none of these notions is captured in a purely logical approach. Recent work, therefore, has tended to stress the contextual and pragmatic elements in requirements for explanation, so that what counts as good explanation given one set of concerns may not do so given another.

The argument to the best explanation is the view that once we can select the best of any in something in explanations of an event, then we are justified in accepting it, or even believing it. The principle needs qualification, since something it is unwise to ignore the antecedent improbability of a hypothesis which would explain the data better than others, e.g., the best explanation of a coin falling heads 530 times in 1,000 tosses might be that it is biassed to give a probability of heads of 0.53 but it might be more sensible to suppose that it is fair, or to suspend judgement.

In a philosophy of language is considered as the general attempt to understand the components of a working language, the relationship th understanding speaker has to its elements, and the relationship they bear to the world. The subject therefore embraces the traditional division of semiotic into syntax, semantics, an d pragmatics. The philosophy of language thus mingles with the philosophy of mind, since it needs an account of what it is in our understanding that enables us to use language. It so mingles with the metaphysics of truth and the relationship between sign and object. Much as much is that the philosophy in the 20th century, has been informed by the belief that philosophy of language is the fundamental basis of all philosophical problems, in that language is the distinctive exercise of mind, and the distinctive way in which we give shape to metaphysical beliefs. Particular topics will include the problems of logical form. And the basis of the division between syntax and semantics, as well as problems of understanding the number and nature of specifically semantic relationships such as meaning, reference, predication, and quantification. Pragmatics include that of speech acts, while problems of rule following and the indeterminacy of translation infect philosophies of both pragmatics and semantics.

On this conception, to understand a sentence is to know its truth-conditions, and, yet, in a distinctive way the conception has remained central that those who offer opposing theories characteristically define their position by reference to it. The Concepcion of meaning s truth-conditions need not and should not be advanced for being in itself as complete account of meaning. For instance, one who understands a language must have some idea of the range of speech acts contextually performed by the various types of sentence in the language, and must have some idea of the insufficiencies of various kinds of speech act. The claim of the theorist of truth-conditions should rather be targeted on the notion of content: If indicative sentence differ in what they strictly and literally say, then this difference is fully accounted for by the difference in the truth-conditions.

The meaning of a complex expression is a function of the meaning of its constituent. This is just as a sentence of what it is for an expression to be semantically complex. It is one of th initial attractions of the conception of meaning truth-conditions tat it permits a smooth and satisfying account of th way in which the meaning of s complex expression is a function of the meaning of its constituents. On the truth-conditional conception, to give the meaning of an expression is to state the contribution it makes to the truth-conditions of sentences in which it occurs. For singular terms-proper names, indexical, and certain pronouns-this is done by stating the reference of the terms in question. For predicates, it is done either by stating the conditions under which the predicate is true of arbitrary objects, or by stating th conditions under which arbitrary atomic sentences containing it are true. The meaning of a sentence-forming operator is given by stating its contribution to the truth-conditions of as complex sentence, as a function of the semantic values of the sentences on which it operates.

The theorist of truth conditions should insist that not every true statement about the reference of an expression is fit to be an axiom in a meaning-giving theory of truth for a language, such is the axiom: ‘London’ refers to the city in which there was a huge fire in 1666, is a true statement about the reference of ‘London’. It is a consequent of a theory which substitutes this axiom for no different a term than of our simple truth theory that ‘London is beautiful’ is true if and only if the city in which there was a huge fire in 1666 is beautiful. Since a subject can understand the name ‘London’ without knowing that last-mentioned truth condition, this replacement axiom is not fit to be an axiom in a meaning-specifying truth theory. It is, of course, incumbent on a theorised meaning of truth conditions, to state in a way which does not presuppose any previous, non-truth conditional conception of meaning

Among the many challenges facing the theorist of truth conditions, two are particularly salient and fundamental. First, the theorist has to answer the charge of triviality or vacuity, second, the theorist must offer an account of what it is for a person’s language to be truly describable by as semantic theory containing a given semantic axiom.

Since the content of a claim that the sentence ‘Paris is beautiful’ is true amounts to no more than the claim that Paris is beautiful, we can trivially describers understanding a sentence, if we wish, as knowing its truth-conditions, but this gives us no substantive account of understanding whatsoever. Something other than grasp of truth conditions must provide the substantive account. The charge rests upon what has been called the redundancy theory of truth, the theory which, somewhat more discriminatingly. Horwich calls the minimal theory of truth. It’s conceptual representation that the concept of truth is exhausted by the fact that it conforms to the equivalence principle, the principle that for any proposition ‘p’, it is true that ‘p’ if and only if ‘p’. Many different philosophical theories of truth will, with suitable qualifications, accept that equivalence principle. The distinguishing feature of the minimal theory is its claim that the equivalence principle exhausts the notion of truth. It is now widely accepted, both by opponents and supporters of truth conditional theories of meaning, that it is inconsistent to accept both minimal theory of ruth and a truth conditional account of meaning. If the claim that the sentence ‘Paris is beautiful’ is true is exhausted by its equivalence to the claim that Paris is beautiful, it is circular to try of its truth conditions. The minimal theory of truth has been endorsed by the Cambridge mathematician and philosopher Plumpton Ramsey (1903-30), and the English philosopher Jules Ayer, the later Wittgenstein, Quine, Strawson. Horwich and-confusing and inconsistently if this article is correct-Frége himself. but is the minimal theory correct?

The minimal theory treats instances of the equivalence principle as definitional of truth for a given sentence, but in fact, it seems that each instance of the equivalence principle can itself be explained. The truths from which such an instance as: ‘London is beautiful’ is true if and only if London is beautiful. This would be a pseudo-explanation if the fact that ‘London’ refers to London consists in part in the fact that ‘London is beautiful’ has the truth-condition it does. But it is very implausible, it is, after all, possible to understand the name ‘London’ without understanding the predicate ‘is beautiful’.

Sometimes, however, the counterfactual conditional is known as subjunctive conditionals, insofar as a counterfactual conditional is a conditional of the form ‘if p were to happen q would’, or ‘if p were to have happened q would have happened’, where the supposition of ‘p’ is contrary to the known fact that ‘not-p’. Such assertions are nevertheless, use=ful ‘if you broken the bone, the X-ray would have looked different’, or ‘if the reactor were to fail, this mechanism wold click in’ are important truths, even when we know that the bone is not broken or are certain that the reactor will not fail. It is arguably distinctive of laws of nature that yield counterfactuals (‘if the metal were to be heated, it would expand’), whereas accidentally true generalizations may not. It is clear that counterfactuals cannot be represented by the material implication of the propositional calculus, since that conditionals comes out true whenever ‘p’ is false, so there would be no division between true and false counterfactuals.

Although the subjunctive form indicates a counterfactual, in many contexts it does not seem to matter whether we use a subjunctive form, or a simple conditional form: ‘If you run out of water, you will be in trouble’ seems equivalent to ‘if you were to run out of water, you would be in trouble’, in other contexts there is a big difference: ‘If Oswald did not kill Kennedy, someone else did’ is clearly true, whereas ‘if Oswald had not killed Kennedy, someone would have’ is most probably false.

The best-known modern treatment of counterfactuals is that of David Lewis, which evaluates them as true or false according to whether ‘q’ is true in the ‘most similar’ possible worlds to ours in which ‘p’ is true. The similarity-ranking this approach needs has proved controversial, particularly since it may need to presuppose some notion of the same laws of nature, whereas art of the interest in counterfactuals is that they promise to illuminate that notion. There is a growing awareness tat the classification of conditionals is an extremely tricky business, and categorizing them as counterfactuals or not be of limited use.

The pronouncing of any conditional is proportionate of the form ‘if p then q’. The condition hypothesizes, ‘p’. It’s called the antecedent of the conditional, and ‘q’ the consequent. Various kinds of conditional have been distinguished. The weaken in that of material implication, merely telling us that with not-p. or q. stronger conditionals include elements of modality, corresponding to the thought that ‘if p is true then q must be true’. Ordinary language is very flexible in its use of the conditional form, and there is controversy whether, yielding different kinds of conditionals with different meanings, or pragmatically, in which case there should be one basic meaning which case there should be one basic meaning, with surface differences arising from other implicatures.

Passively, there are many forms of Reliabilism. Just as there are many forms of ‘Foundationalism’ and ‘coherence’. How is Reliabilism related to these other two theories of justification? We usually regard it as a rival, and this is aptly so, in as far as Foundationalism and Coherentism traditionally focussed on purely evidential relations than psychological processes, but we might also offer Reliabilism as a deeper-level theory, subsuming some precepts of either Foundationalism or Coherentism. Foundationalism says that there are ‘basic’ beliefs, which acquire justification without dependence on inference, Reliabilism might rationalize this indicating that reliable non-inferential processes have formed the basic beliefs. Coherence stresses the primary of systematicity in all doxastic decision-making. Reliabilism might rationalize this by pointing to increases in reliability that accrue from systematicity consequently, Reliabilism could complement Foundationalism and coherence than completed with them.

These examples make it seem likely that, if there is a criterion for what makes an alternate situation relevant that will save Goldman’s claim about local reliability and knowledge. Will did not be simple. The interesting thesis that counts as a causal theory of justification, in the making of ‘causal theory’ intended for the belief as it is justified in case it was produced by a type of process that is ‘globally’ reliable, that is, its propensity to produce true beliefs that can be defined, to an acceptable approximation, as the proportion of the beliefs it produces, or would produce where it used as much as opportunity allows, that is true is sufficiently relializable. We have advanced variations of this view for both knowledge and justified belief, its first formulation of a reliability account of knowing appeared in the notation from F.P.Ramsey (1903-30). The theory of probability, he was the first to show how a ‘personalists theory’ may as a feature in the probability of things that can be constructively impressed and firmly based on a precise behavioural notion of preference and expectation. In the philosophy of language, much of Ramsey’s work was directed at saving classical mathematics from ‘intuitionism’, or what he called the ‘Bolshevik menace of Brouwer and Weyl. In the theory of probability he was the first to show how we could develop some personalists theory, based on precise behavioural notation of preference and expectation. In the philosophy of language, Ramsey was one of the first thankers, which he combined with radical views of the function of many kinds of a proposition. Neither generalizations, nor causal propositions, nor those treating probability or ethics, describe facts, but each has a different specific function in our intellectual economy. Ramsey was one of the earliest commentators on the early work of Wittgenstein, and his continuing friendship that led to Wittgenstein’s return to Cambridge and to philosophy in 1929.

Ramsey’s sentence theory is the sentence generated by taking all the sentences affirmed in a scientific theory that use some term, e.g., ‘quark’. Replacing the term by a variable, and existentially quantifying into the result, instead of saying that quarks have such-and-such properties, the Ramsey sentence says that there is something that has those properties. If we repeat the process for all of a group of the theoretical terms, the sentence gives the ‘topic-neutral’ structure of the theory, but removes any implication that we know what the term so treated prove competent. It leaves open the possibility of identifying the theoretical item with whatever, but it is that best fits the description provided. Just about, all theories of knowledge are, of course, shared by an externalist component in requiring truth as a condition for known in. Reliabilism goes further, however, in trying to capture additional conditions for knowledge by ways of a nomic, counterfactual or similar ‘external’ relations between belief and truth. Closely allied to the nomic sufficiency account of knowledge, primarily due to Dretshe (1971, 1981), A. I. Goldman (1976, 1986) and R. Nozick (1981), whereby, the main core of this approach is that X’s belief that ‘p’ qualifies as knowledge just in case ‘X’ believes ‘p’, because of reasons that would not obtain unless ‘p’s’ being true, or because of a process or method that would not yield belief in ‘p’ if ‘p’ were not true. An enemy example, ‘X’ would not have its current reasons for believing there is a telephone before it. Or, for any reason, that any pursuant influence is much depictive to conditions backed by circumstance. This coming to the surface through which attentions would be quickened to indorse the negative value for things unknowingly improper. In this belief, and in this way, it does, however, an encounter upon a result of counterfactuals that seem reliably fortified by a guarantor of the belief’s being true. Determined to and the facts of counterfactual approach say that ‘X’ knows that ‘p’ only if there is no ‘relevant alternative’ situation in which ‘p’ is false but ‘X’ would still believe that a proposition ‘p’; must be sufficient to eliminate all the alternatives too ‘p’ where an alternative to a proposition ‘p’ is a proposition incompatible with ‘p?’. That I, one’s justification or evidence for ‘p’ must be sufficient for one to know that every alternative too ‘p’ is false. This element of our evolving thinking, sceptical arguments have exploited about which knowledge. These arguments call our attentions to alternatives that our evidence sustains itself with no elimination. The sceptic inquires to how we know that we are not seeing a cleverly disguised mule. While we do have some evidence against the likelihood of such as deception, intuitively knowing that we are not so deceived is not strong enough for ‘us’. By pointing out alternate but hidden points of nature, in that we cannot eliminate, and others with more general application, as dreams, hallucinations, etc. , The sceptic appears to show that every alternative is seldom. If ever, satisfied.

All the same, and without a problem, is noted by the distinction between the ‘in itself’ and the; for itself’ originated in the Kantian logical and epistemological distinction between a thing as it is in itself, and that thing as an appearance, or as it is for us. For Kant, the thing in itself is the thing as it is intrinsically, that is, the character of the thing apart from any relations in which it happens to stand. The thing for which, or as an appearance, is the thing in so far as it stands in relation to our cognitive faculties and other objects. ‘Now a thing in itself cannot be known through mere relations: and we may therefore conclude that since outer sense gives us nothing but mere relations, this sense can contain in its representation only the relation of an object to the subject, and not the inner properties of the object in itself’. Kant applies this same distinction to the subject’s cognition of itself. Since the subject can know itself only in so far as it can intuit itself, and it can intuit itself only in terms of temporal relations, and thus as it is related to its own-self, it represents either ‘in’ or ‘for’ itself, as it appears to itself, not as it is. Thus, the distinction between what the subject is in itself and hat it is for itself arises in Kant in so far as the distinction between what an object is in itself and what it is for a Knower is applied to the subject’s own knowledge of itself.

Hegel (1770-1831) begins the transition of the epistemological distinct ion between what the subject is in itself and what it is for itself into an ontological distinction. Since, for Hegel, what is, s it is in fact ir in itself, necessarily involves relation, the Kantian distinction must be transformed. Taking his cue from the fact that, even for Kant, what the subject is in fact ir in itself involves a relation to itself, or seif-consciousness. Hegel suggests that the cognition of an entity in terms of such relations or self-relations do not preclude knowledge of the thing itself. Rather, what an entity is intrinsically, or in itself, is best understood in terms of the potentiality of that thing to enter specific explicit relations with itself. And, just as for consciousness to be explicitly itself is for it to be for itself by being in relation to itself, i.e., to be explicitly self-conscious, for-itself of any entity is that entity in so far as it is actually related to itself. The distinction between the entity in itself and the entity for itself is thus taken t o apply to every entity, and not only to the subject. For example, the seed of a plant is that plant in itself or implicitly, while the mature plant which involves actual relation among the plant’s various organs is the plant ‘for itself’. In Hegel, then, the in itself/for itself distinction becomes universalized, in is applied to all entities, and not merely to conscious entities. In addition, the distinction takes on an ontological dimension. While the seed and the mature plant are one and the same entity, being in itself of the plan, or the plant as potential adult, in that an ontologically distinct commonality is in for itself on the plant, or the actually existing mature organism. At the same time, the distinction retains an epistemological dimension in Hegel, although its import is quite different from that of the Kantian distinction. To know a thing it is necessary to know both the actual, explicit self-relations which mark the thing (the being for itself of the thing) and the inherent simpler principle of these relations, or the being in itself of the thing. Real knowledge, for Hegel, thus consists in a knowledge of the thing as it is in and for itself.

Sartre’s distinction between being in itself and being for itself, which is an entirely ontological distinction with minimal epistemological import, is descended from the Hegelian distinction. Sartre distinguishes between what it is for consciousness to be, i.e., being for itself, and the being of the transcendent being which is intended by consciousness, i.e., being in itself. What is it for consciousness to be, being for itself, is marked by self relation? Sartre posits a ‘pre-reflective Cogito’, such that every consciousness of ‘χ’ necessarily involves a ‘non-positional’ consciousness of the consciousness of χ. While in Kant every subject is both in itself, i.e., as it is apart from its relations, and for itself in so far as it is related to itself, and for itself in so far as it is related to itself by appearing to itself, and in Hegel every entity can be considered as it is both in itself and for itself, in Sartre, to be selfly related or for itself is the distinctive ontological mark of consciousness, while to lack relations or to be in itself is the distinctive e ontological mark of non-conscious entities.

This conclusion conflicts with another strand in our thinking about knowledge, in that we know many things. Thus, there is a tension in our ordinary thinking about knowledge ~. We believe that knowledge is, in the sense indicated, an absolute concept and yet, we also believe that there are many instances of that concept.

If one finds absoluteness to be too central a component of our concept of knowledge to be relinquished, one could argue from the absolute character of knowledge to a sceptical conclusion (Unger, 1975). Most philosophers, however, have taken the other course, choosing to respond to the conflict by giving up, perhaps reluctantly, the absolute criterion. This latter response holds as sacrosanct our commonsense belief that we know many things (Pollock, 1979 and Chisholm, 1977). Each approach is subject to the criticism that it preserves one aspect of our ordinary thinking about knowledge at the expense of denying another. We can view the theory of relevant alternatives as an attempt to provide a more satisfactory response to this tension in our thinking about knowledge. It attempts to characterize knowledge in a way that preserves both our belief that knowledge is an absolute concept and our belief that we have knowledge.

Having to its recourse of knowledge, its cental questions include the origin of knowledge, the place of experience in generating knowledge, and the place of reason in doing so, the relationship between knowledge and certainty, and between knowledge and the impossibility of error, the possibility of universal scepticism, and the changing forms of knowledge that arise from new conceptualizations of the world. All these issues link with other central concerns of philosophy, such as the nature of truth and the natures of experience and meaning. Seeing epistemology is possible as dominated by two rival metaphors. One is that of a building or pyramid, built on foundations. In this conception it is the job of the philosopher to describe especially secure foundations, and to identify secure modes of construction, s that the resulting edifice can be shown to be sound. This metaphor of knowledge, and in turn of a rationally defensible theory of confirmation and inference as a method of construction, equally that knowledge must be regarded as a structure arisen upon secure, certain foundations. These are found in some formidable combinations of experience and reason, with different schools (empiricism, rationalism) emphasizing the role of one over that of the others. Foundationalism was associated with the ancient Stoics, and in the modern era with Descartes (1596-1650). Who discovered his foundations in the ‘clear and distinct’ ideas of reason? Its main opponent is Coherentism, or the view that a body of propositions mas be known without a foundation in certainty, but by their interlocking strength, than as a crossword puzzle may be known to have been solved correctly even if each answer, taken individually, admits of uncertainty. Difficulties at this point led the logical passivists to abandon the notion of an epistemological foundation, and justly philander with the coherence theory of truth. It is widely accepted that trying to make the connection between thought and experience through basic sentences depends on an untenable ‘myth of the given’.

Still, of the other metaphor, is that of a boat or fuselage, that has no foundation but owes its strength to the stability given by its interlocking parts. This rejects the idea of a basis in the ‘given’, favours ideas of coherence and holism, but finds it harder to ward off scepticism. In spite of these concerns, the problem, least of mention, is of defining knowledge in terms of true beliefs plus some favoured relations between the believer and the facts that began with Plato’s view in the “Theaetetus” that knowledge is true belief, and some logos.` This, unrelenting causality that, in this case, lays’ into accountable grounds through some formalities existing to or descendable with natural epistemology, the enterprising of studying the actual formation of knowledge by human beings, without aspiring to make evidently those processes as rational, or proof against ‘scepticism’ or even apt to yield the truth. Natural epistemology would therefore blend into the psychology of learning and the study of episodes in the history of science. The scope for ‘external’ or philosophical reflection of the kind that might result in scepticism or its refutation is markedly diminished. Nonetheless, the terms are modern, they however distinguish exponents of the approach that include Aristotle, Hume, and J. S. Mills.

The task of the philosopher of a discipline would then be to reveal the correct method and to unmask counterfeits. Although this belief lay behind much positivist philosophy of science, few philosophers at present, subscribe to it. It places too well a confidence in the possibility of a purely a prior ‘first philosophy’, or standpoint beyond that of the working practitioners, from which they can measure their best efforts as good or bad. This point of view now seems that many philosophers are acquainted with the affordance of fantasy. The more modest of tasks that we actually adopt at various historical stages of investigation into different areas with the aim not so much of criticizing but more of systematization, in the presuppositions of a particular field at a particular tie. There is still a role for local methodological disputes within the community investigators of some phenomenon, with one approach charging that another is unsound or unscientific, but logic and philosophy will not, on the modern view, provide an independent arsenal of weapons for such battles, which indeed often come to seem more like political bids for ascendancy within a discipline.

This is an approach to the theory of knowledge that sees an important connection between the growth of knowledge and biological evolution. An evolutionary epistemologist claims that the development of human knowledge processed through some natural selection process, the best example of which is Darwin’s theory of biological natural selection. There is a widespread misconception that evolution proceeds according to some plan or direct, put it has neither, and the role of chance ensures that its future course will be unpredictable. Random variations in individual organisms create tiny differences in their Darwinian fitness. Some individuals have more offsprings than others, and the characteristics that increased their fitness thereby become more prevalent in future generations. Once upon a time, at least a mutation occurred in a human population in tropical Africa that changed the haemoglobin molecule in a way that provided resistance to malaria. This enormous advantage caused the new gene to spread, with the unfortunate consequence that sickle-cell anaemia came to exist.

Chance can influence the outcome at each stage: First, in the creation of genetic mutation, second, in whether the bearer lives long enough to show its effects, thirdly, in chance events that influence the individual’s actual reproductive success, and fourth, in wether a gene even if favoured in one generation, is, happenstance, eliminated in the next, and finally in the many unpredictable environmental changes that will undoubtedly occur in the history of any group of organisms. As Harvard biologist Stephen Jay Gould has so vividly expressed that process over again, the outcome would surely be different. Not only might there not be humans, there might not even be anything like mammals.

We will often emphasis the elegance of traits shaped by natural selection, but the common idea that nature creates perfection needs to be analysed carefully. The extent to which evolution achieves perfection depends on exactly what you mean. If you mean “Does natural selections always take the best path for the long-term welfare of a species?” The answer is no. That would require adaption by group selection, and this is, unlikely. If you mean “Does natural selection creates every adaption that would be valuable?” The answer again, is no. For instance, some kinds of South American monkeys can grasp branches with their tails. The trick would surely also be useful to some African species, but, simply because of bad luck, none have it. Some combination of circumstances started some ancestral South American monkeys using their tails in ways that ultimately led to an ability to grab onto branches, while no such development took place in Africa. Mere usefulness of a trait does not necessitate it mean that will evolve.

This is an approach to the theory of knowledge that sees an important connection between the growth of knowledge and biological evolution. An evolutionary epistemologist claims that the development of human knowledge proceeds through some natural selection process, the best example of which is Darwin’s theory of biological natural selection. The three major components of the model of natural selection are variation selection and retention. According to Darwin’s theory of natural selection, variations are not pre-designed to perform certain functions. Rather, these variations that perform useful functions are selected. While those that suffice on doing nothing are not selected as such, the selection is responsible for the appearance that specific variations built upon intentionally do really occur. In the modern theory of evolution, genetic mutations provide the blind variations ( blind in the sense that variations are not influenced by the effects they would have,-the likelihood of a mutation is not correlated with the benefits or liabilities that mutation would confer on the organism), the environment provides the filter of selection, and reproduction provides the retention. It is achieved because those organisms with features that make them less adapted for survival do not survive about other organisms in the environment that have features that are better adapted. Evolutionary epistemology applies this blind variation and selective retention model to the growth of scientific knowledge and to human thought processes in general.

The parallel between biological evolution and conceptual or we can see ‘epistemic’ evolution as either literal or analogical. The literal version of evolutionary epistemology bestows upon biological evolution the main cause of the growth of knowledge. On this view, called the ‘evolution of cognitive mechanic programs’, by Bradie (1986) and the ‘Darwinian approach to epistemology’ by Ruse (1986), that growth of knowledge occurs through blind variation and selective retention because biological natural selection itself is the cause of epistemic variation and selection. The most plausible version of the literal view does not hold that all human beliefs are innate but rather than the mental mechanisms that guide the acquisition of non-innate beliefs are themselves innately and the result of biological natural selection. Ruses ( 1986) repossess on the demands of an interlingual rendition of literal evolutionary epistemology that he links to sociology (Rescher, 1990).

Determining the value upon innate ideas can take the path to consider as these have been variously defined by philosophers either as ideas consciously present to the mind priori to sense experience (the non-dispositional sense), or as ideas which we have an innate disposition to form (though we need to be actually aware of them at a particular r time, e.g., as babies-the dispositional sense. Understood in either way they were invoked to account for our recognition of certain verification, such as those of mathematics, or to justify certain moral and religious clams which were held to b capable of being know by introspection of our innate ideas. Examples of such supposed truths might include ‘murder is wrong’ or ‘God exists’.

One difficulty with the doctrine is that it is sometimes formulated as one about concepts or ideas which are held to be innate and at other times one about a source of propositional knowledge, in so far as concepts are taken to be innate the doctrine reflates primarily to claims about meaning: our idea of God, for example, is taken as a source for the meaning of the word God. When innate ideas are understood prepositionally, their supposed innateness is taken an evidence for the truth. This latter thesis clearly rests on the assumption that innate propositions have an unimpeachable source, usually taken to be God, but then any appeal to innate ideas to justify the existence of God is circular. Despite such difficulties the doctrine of innate ideas had a long and influential history until the eighteenth century and the concept has in recent decades been revitalized through its employment in Noam Chomsky’s influential account of the mind’s linguistic capacities.

The attraction of the theory has been felt strongly by those philosophers who has been unable to give an alternative account of our capacity to recognize that some propositions are certainly true where that recognition cannot be justified solely o the basis of an appeal to sense experiences. Thus Plato argued that, for example, recognition of mathematical truths could only be explained on the assumption of some form of recollection, in Plato, the recollection of knowledge, possibly obtained in a previous stat e of existence e draws its topic as most famously broached in the dialogue Meno, and the doctrine is one attempt oi account for the ‘innate’ unlearned character of knowledge of first principles. Since there was no plausible post-natal source the recollection must refer to a perinatal acquisition of knowledge. Thus understood, the doctrine of innate ideas supported the views that there were importantly gradatorially innate in human beings and it was the sense which hindered their proper apprehension.

The ascetic implications of the doctrine were important in Christian philosophy throughout the Middle Ages and scholastic teaching until its displacement by Locke’ philosophy in the eighteenth century. It had in the meantime acquired modern expression in the philosophy of Descartes who argued that we can come to know certain important truths before we have any empirical knowledge at all. Our idea of God must necessarily exist, is Descartes held, logically independent of sense experience. In England the Cambridge Plantonists such as Henry Moore and Ralph Cudworth added considerable support.

Locke’s rejection of innate ideas and his alternative empiricist account was powerful enough to displace the doctrine from philosophy almost totally. Leibniz, in his critique of Locke, attempted to defend it with a sophisticated disposition version of theory, but it attracted few followers.

The empiricist alternative to innate ideas as an explanation of the certainty of propositions in the direction of construing with necessary truths as analytic. Kant’s refinement of the classification of propositions with the fourfold distentions was to imply much as much involved by analytic/synthetic and deductive/inductive, least of mention, he did nothing to encourage a return to their innate idea’s doctrine, which slipped from view. The doctrine may fruitfully be understood as the genesis of confusion between explaining the genesis of ideas or concepts and the basis for regarding some propositions as necessarily true.

Chomsky’s revival of the term in connection with his account of the spoken exchange acquisition has once more made the issue topical. He claims that the principles of language and ‘natural logic’ are known unconsciously and are a precondition for language acquisition. But for his purposes innate ideas must be taken in a strong dispositional sense-so strong that it is far from clear that Chomsky’s claims are as in conflict with empiricist accounts as some (including Chomsky) have supposed. Quine, for example, sees no clash with his own version of empirical behaviourism, in which old talk of ideas is eschewing in favour of dispositions to observable behaviors.

Locke’ accounts of analytic propositions was, that everything that a succinct account of analyticity should be (Locke, 1924). He distinguishes two kinds of analytic propositions, identity propositions in which ‘we affirm the said term of itself’, e.g., ‘Roses are roses’ and predicative propositions in which ‘a part of the complex idea is predicated of the name of the whole’, e.g., ‘Roses are flowers’. Locke calls such sentences ‘trifling’ because a speaker who uses them ‘trifling with words’. A synthetic sentence, in contrast, such as a mathematical theorem, states ‘a real truth and conveys, and with it parallels really instructive knowledge’, and correspondingly, Locke distinguishes two kinds of ‘necessary consequences’, analytic entailments where validity depends on the literal containment of the conclusion in the premiss and synthetic entailment where it does not. (Locke did not originate this concept-containment notion of analyticity. It is discussed by Arnaud and Nicole, and it is safe to say that it has been around for a very long time (Arnaud, 1964).

All the same, the analogical version of evolutionary epistemology, called the ‘evolution of theory’s program’, by Bradie (1986). The ‘Spenserians approach’ (after the nineteenth century philosopher Herbert Spencer) by Ruse (1986), a process analogous to biological natural selection has governed the development of human knowledge, rather than by an instance of the mechanism itself. This version of evolutionary epistemology, introduced and elaborated by Donald Campbell (1974) and Karl Popper, sees the [partial] fit between theories and the world as explained by a mental process of trial and error known as epistemic natural selection.

We have usually taken both versions of evolutionary epistemology to be types of naturalized epistemology, because both take some empirical facts as a starting point for their epistemological project. The literal version of evolutionary epistemology begins by accepting evolutionary theory and a materialist approach to the mind and, from these, constructs an account of knowledge and its developments. In contrast, the analogical; the version does not require the truth of biological evolution: It simply draws on biological evolution as a source for the model of natural selection. For this version of evolutionary epistemology to be true, the model of natural selection need only apply to the growth of knowledge, not to the origin and development of species. Savagery put, evolutionary epistemology of the analogical sort could still be true even if creationism is the correct theory of the origin of species.

Although they do not begin by assuming evolutionary theory, most analogical evolutionary epistemologists are naturalized epistemologists as well, their empirical assumptions, least of mention, implicitly come from psychology and cognitive science, not evolutionary theory. Sometimes, however, evolutionary epistemology is characterized in a seemingly non-naturalistic fashion. (Campbell 1974) says that ‘if one is expanding knowledge beyond what one knows, one has no choice but to explore without the benefit of wisdom’, i.e., blindly. This, Campbell admits, makes evolutionary epistemology close to being a tautology (and so not naturalistic). Evolutionary epistemology does assert the analytic claim that when expanding one’s knowledge beyond what one knows, one must precessed to something that is already known, but, more interestingly, it also makes the synthetic claim that when expanding one’s knowledge beyond what one knows, one must proceed by blind variation and selective retention. This claim is synthetic because we can empirically falsify it. The central claim of evolutionary epistemology is synthetic, not analytic. If the central contradictory, which they are not. Campbell is right that evolutionary epistemology does have the analytic feature he mentions, but he is wrong to think that this is a distinguishing feature, since any plausible epistemology has the same analytic feature (Skagestad, 1978).

Two extra-ordinary issues lie to awaken the literature that involves questions about ‘realism’, i.e., What metaphysical commitment does an evolutionary epistemologist have to make? . (Progress, i.e., according to evolutionary epistemology, does knowledge develop toward a goal?) With respect to realism, many evolutionary epistemologists endorse that is called ‘hypothetical realism’, a view that combines a version of epistemological ‘scepticism’ and tentative acceptance of metaphysical realism. With respect to progress, the problem is that biological evolution is not goal-directed, but the growth of human knowledge is. Campbell (1974) worries about the potential dis-analogy here but is willing to bite the stone of conscience and admit that epistemic evolution progress toward a goal (truth) while biological evolution does not. Some have argued that evolutionary epistemologists must give up the ‘truth-topic’ sense of progress because a natural selection model is in non-teleological in essence alternatively, following Kuhn (1970), and embraced along with evolutionary epistemology.

Among the most frequent and serious criticisms levelled against evolutionary epistemology is that the analogical version of the view is false because epistemic variation is not blind (Skagestad, 1978 and Ruse, 1986), Stein and Lipton (1990) have argued, however, that this objection fails because, while epistemic variation is not random, its constraints come from heuristics that, for the most part, are selective retention. Further, Stein and Lipton argue that lunatics are analogous to biological pre-adaptions, evolutionary pre-biological pre-adaptions, evolutionary cursors, such as a half-wing, a precursor to a wing, which have some function other than the function of their descendable structures: The function of descentable structures, the function of their descendable character embodied to its structural foundations, is that of the guidelines of epistemic variation is, on this view, not the source of disanalogy, but the source of a more articulated account of the analogy.

Many evolutionary epistemologists try to combine the literal and the analogical versions (Bradie, 1986, and Stein and Lipton, 1990), saying that those beliefs and cognitive mechanisms, which are innate results from natural selection of the biological sort and those that are innate results from natural selection of the epistemic sort. This is reasonable as long as the two parts of this hybrid view are kept distinct. An analogical version of evolutionary epistemology with biological variation as its only source of blindeness would be a null theory: This would be the case if all our beliefs are innate or if our non-innate beliefs are not the result of blind variation. An appeal to the legitimate way to produce a hybrid version of evolutionary epistemology since doing so trivializes the theory. For similar reasons, such an appeal will not save an analogical version of evolutionary epistemology from arguments to the effect that epistemic variation is blind (Stein and Lipton, 1990).

Although it is a new approach to theory of knowledge, evolutionary epistemology has attracted much attention, primarily because it represents a serious attempt to flesh out a naturalized epistemology by drawing on several disciplines. In science is used for understanding the nature and development of knowledge, then evolutionary theory is among the disciplines worth a look. Insofar as evolutionary epistemology looks there, it is an interesting and potentially fruitful epistemological programme.

What makes a belief justified and what makes a true belief knowledge? Thinking that whether a belief deserves one of these appraisals is natural depends on what caused such subjectivity to have the belief. In recent decades many epistemologists have pursued this plausible idea with a variety of specific proposals. Some causal theories of knowledge have it that a true belief that ‘p’ is knowledge just in case it has the right causal connection to the fact that ‘p’. They can apply such a criterion only to cases where the fact that ‘p’ is a sort that can enter inti causal relations, as this seems to exclude mathematically and other necessary facts and perhaps any fact expressed by a universal generalization, and proponents of this sort of criterion have usually supposed that it is limited to perceptual representations where knowledge of particular facts about subjects’ environments.

For example, Armstrong (1973) proposed that a belief of the form ‘This [perceived] object is F’ is [non-inferential] knowledge if and only if the belief is a completely reliable sign that the perceived object is ‘F’, that is, the fact that the object is ‘F’ contributed to causing the belief and its doing so depended on properties of the believer such that the laws of nature dictated that, for any subject ‘χ’ and perceived object ‘y’, if ‘χ’ has those properties and believed that ‘y’ is ‘F’, then ‘y’ is ‘F’. (Dretske (1981) offers a rather similar account, in terms of the belief’s being caused by a signal received by the perceiver that carries the information that the object is ‘F’.

This sort of condition fails, however, to be sufficiently for non-inferential perceptivity, for knowledge is accountable for its compatibility with the belief’s being unjustified, and an unjustified belief cannot be knowledge. For example, suppose that your organism for sensory data of colour as perceived, is working well, but you have been given good reason to think otherwise, to think, say, that the sensory data of things look chartreuse to say, that chartreuse things look magenta, if you fail to heed these reasons you have for thinking that your colour perception is awry and believe of a thing that looks magenta to you that it is magenta, your belief will fail top be justified and will therefore fail to be knowledge, although it is caused by the thing’s being withing the grasp of sensory perceptivity, in a way that is a completely reliable sign, or to carry the information that the thing is sufficiently to organize all sensory data as perceived in and of the World, or Holistic view.

The view that a belief acquires favourable epistemic status by having some kind of reliable linkage to the truth. Variations of this view have been advanced for both knowledge and justified belief. The first formulation of a reliable account of knowing notably appeared as marked and noted and accredited to F. P. Ramsey (1903-30), whereby much of Ramsey’s work was directed at saving classical mathematics from ‘intuitionism’, or what he called the ‘Bolshevik menace of Brouwer and Weyl’. In the theory of probability he was the first to develop, based on precise behavioural nations of preference and expectation. In the philosophy of language, Ramsey was one of the first thinkers to accept a ‘redundancy theory of truth’, which he combined with radical views of the function of many kinds of propositions. Neither generalizations, nor causal positions, nor those treating probability or ethics, described facts, but each has a different specific function in our intellectual economy. Additionally, Ramsey, who said that an impression of belief was knowledge if it were true, certain and obtained by a reliable process. P. Unger (1968) suggested that ‘S’ knows that ‘p’ just in case it is of at all accidental that ‘S’ is right about its being the case that D.M. Armstrong (1973) drew an analogy between a thermometer that reliably indicates the temperature and a belief interaction of reliability that indicates the truth. Armstrong said that a non-inferential belief qualified as knowledge if the belief has properties that are nominally sufficient for its truth, i.e., guarantee its truth via laws of nature.

Closely allied to the nomic sufficiency account of knowledge, primarily due to F.I. Dretske (1971, 1981), A.I. Goldman (1976, 1986) and R. Nozick (1981). The core of this approach is that ‘S’s’ belief that ‘p’ qualifies as knowledge just in case ‘S’ believes ‘p’ because of reasons that would not obtain unless ‘p’s’ being true, or because of a process or method that would not yield belief in ‘p’ if ‘p’ were not true. For example, ‘S’ would not have his current reasons for believing there is a telephone before him, or would not come to believe this in the way he does, unless there was a telephone before him. Thus, there is a counterfactual reliable guarantee of the belief’s being true. A variant of the counterfactual approach says that ‘S’ knows that ‘p’ only if there is no ‘relevant alternative’ situation in which ‘p’ is false but ‘S’ would still believe that ‘p’ must be sufficient to eliminate all the other situational alternatives of ‘p’, where an alternative to a proposition ‘p’ is a proposition incompatible with ‘p’, that is, one’s justification or evidence fort ‘p’ must be sufficient for one to know that every subsidiary situation is ‘p’ is false.

They standardly classify Reliabilism as an ‘externaturalist’ theory because it invokes some truth-linked factor, and truth is ‘eternal’ to the believer the main argument for externalism derives from the philosophy of language, more specifically, from the various phenomena pertaining to natural kind terms, indexicals, etc., that motivate the views that have come to be known as direct reference’ theories. Such phenomena seem, at least to show that the belief or thought content that can be properly attributed to a person is dependent on facts about his environment, i.e., whether he is on Earth or Twin Earth, what in fact he is pointing at, the classificatory criteria employed by the experts in his social group, etc. ~. Not just on what is going on internally in his mind or brain (Putnam, 175 and Burge, 1979.) Virtually all theories of knowledge, of course, share an externalist component in requiring truth as a condition for knowing. Reliabilism goes further, however, in trying to capture additional conditions for knowledge by means of a nomic, counterfactual or other such ‘external’ relations between ‘belief’ and ‘truth’.

The most influential counterexample to Reliabilism is the demon-world and the clairvoyance examples. The demon-world example challenges the necessity of the reliability requirement, in that a possible world in which an evil demon creates deceptive visual experience, the process of vision is not reliable. Still, the visually formed beliefs in this world are intuitively justified. The clairvoyance example challenges the sufficiency of reliability. Suppose a cognitive agent possesses a reliable clairvoyance power, but has no evidence for or against his possessing such a power. Intuitively, his clairvoyantly formed beliefs are unjustifiably unreasoned, but Reliabilism declares them justified.

Another form of Reliabilism, ‘normal worlds’, Reliabilism (Goldman, 1986), answers the range problem differently, and treats the demon-world problem in the same stroke. Permit a ‘normal world’ be one that is consistent with our general beliefs about the actual world. Normal-worlds Reliabilism says that a belief, in any possible world is justified just in case its generating processes have high truth ratios in normal worlds. This resolves the demon-world problem because the relevant truth ratio of the visual process is not its truth ratio in the demon world itself, but its ratio in normal worlds. Since this ratio is presumably high, visually formed beliefs in the demon world turn out to be justified.

Yet, a different version of Reliabilism attempts to meet the demon-world and clairvoyance problems without recourse to the questionable notion of ‘normal worlds’. Consider Sosa’s (1992) suggestion that justified beliefs is belief acquired through ‘intellectual virtues’, and not through intellectual ‘vices’, whereby virtues are reliable cognitive faculties or processes. The task is to explain how epistemic evaluators have used the notion of indelible virtues, and vices, to arrive at their judgements, especially in the problematic cases. Goldman (1992) proposes a two-stage reconstruction of an evaluator’s activity. The first stage is a reliability-based acquisition of a ‘list’ of virtues and vices. The second stage is application of this list to queried cases. Determining has executed the second stage whether processes in the queried cases resemble virtues or vices. We have classified visual beliefs in the demon world as justified because visual belief formation is one of the virtues. Clairvoyance formed, beliefs are classified as unjustified because clairvoyance resembles scientifically suspect processes that the evaluator represents as vices, e.g., mental telepathy, ESP, and so forth

We now turn to a philosophy of meaning and truth, for which it is especially associated with the American philosopher of science and of language (1839-1914), and the American psychologist philosopher William James (1842-1910), wherefore the study in Pragmatism is given to various formulations by both writers, but the core is the belief that the meaning of a doctrine is the same as the practical effects of adapting it. Peirce interpreted of theocratical sentences ids only that of a corresponding practical maxim (telling us what to do in some circumstance). In James the position issues in a theory of truth, notoriously allowing that belief, including for the example, belief in God, is the widest sense of the works satisfactorily in the widest sense of the word. On James’s view almost any belief might be respectable, and even rue, provided it works (but working is no s simple matter for James). The apparent subjectivist consequences of tis were wildly assailed by Russell (1872-1970), Moore (1873-1958), and others in the early years of the 20th century. This led to a division within pragmatism between those such as the American educator John Dewey (1859-1952), whose humanistic conception of practice remains inspired by science, and the more idealistic route that especially by the English writer F.C.S. Schiller (1864-1937), embracing the doctrine that our cognitive efforts and human needs actually transform the reality that we seek to describe. James often writes as if he sympathizes with this development. For instance, in The Meaning of Truth (1909), he considers the hypothesis that other people have no minds (dramatized in the sexist idea of an ‘automatic sweetheart’ or female zombie) and remarks’ hat the hypothesis would not work because it would not satisfy our egoistic craving for the recognition and admiration of others. The implying inclinations that depict of those that distortion may as it is, make it true, at least are those that the other persons have minds in the disturbing parts.

Modern pragmatists such as the American philosopher and critic Richard Rorty (1931-) and some writings of the philosopher Hilary Putnam (1925-) who has usually trued to dispense with an account of truth and concentrate, as perhaps James should have done, upon the nature of belief and its relations with human attitude, emotion, and need. The driving motivation of pragmatism is the idea that belief in the truth on te one hand must have a close connection with success in action on the other. One way of cementing the connection is found in the idea that natural selection must have adapted us to be cognitive creatures because beliefs have effects, as they work. Pragmatism can be found in Kant’s doctrine of the primary of practical over pure reason, and continued to play an influential role in the theory of meaning and of truth.

In case of fact, the philosophy of mind is the modern successor to behaviourism, as do the functionalism that its early advocates were Putnam (1926-) and Sellars (1912-89), and its guiding principle is that we can define mental states by a triplet of relations they have on other mental stares, what effects they have on behaviour. The definition need not take the form of a simple analysis, but if w could write down the totality of axioms, or postdate, or platitudes that govern our theories about what things of other mental states, and our theories about what things are apt to cause (for example), a belief state, what effects it would have on a variety of other mental states, and, of its gross effect, it is likely to have on behavioural conduct, then we would have done all that is needed to make the state acquitting of a proper theoretical notion. It could be implicitly defied by these theses. Functionalism is often compared with descriptions of a computer, since according to mental descriptions correspond to a description of a machine in terms of software, that remains silent about the underlaying hardware or ‘realization’ of the program the machine is running. The principal advantages of functionalism include its fitness with the ways we know of mental states both of ourselves and of others, which is via their effect on behaviour and other mental events as characterized by other alternative states. As with behaviourism, critics charge that structurally complex items that do not bear mental states might nevertheless, imitate the functions that are cited. According to this criticism functionalism is too generous and would count too many things as having minds. It is also queried whether functionalism is too paradoxical, able to see mental similarities only when there is causal similarity, or when our actual situational practices of analytic interpretations enable us to ascertain the thoughts and desires to differentiate from our own. It may then seem as though beliefs and desires can or ought be ‘variably realized’, only when its causative architecture, just as much as they can be in different neurophysiological states.

The philosophical movement of Pragmatism had a major impact on American culture from the late 19th century to the present. Pragmatism calls for ideas and theories to be tested in practice, by assessing whether acting upon the idea or theory produces desirable or undesirable results. According to pragmatists, all claims about truth, knowledge, morality, and politics must be tested in this way. Pragmatism has been critical of traditional Western philosophy, especially the notions that there are absolute truths and absolute values. Although pragmatism was popular for a time in France, England, and Italy, most observers believe that it encapsulates an American faith in know-how and practicality and an equally American distrust of abstract theories and ideologies.

In mentioning the American psychologist and philosopher we find William James, who helped to popularize the philosophy of pragmatism with his book Pragmatism: A New Name for Old Ways of Thinking (1907). Influenced by a theory of meaning and verification developed for scientific hypotheses by American philosopher C.S. Peirce, James held that truths are what works, or has good experimental results. In a related theory, James argued the existence of God is partly verifiable because many people derive benefits from believing.

Pragmatists regard all theories and institutions as tentative hypotheses and solutions. For this reason they believed that efforts to improve society, through such means as education or politics, must be geared toward problem solving and must be ongoing. Through their emphasis on connecting theory to practice, pragmatist thinkers attempted to transform all areas of philosophy, from metaphysics to ethics and political philosophy.

Pragmatism sought a middle ground between traditional ideas about the nature of reality and radical theories of nihilism and irrationalism, which had become popular in Europe in the late 19th century. Traditional metaphysics assumed that the world has a fixed, intelligible structure and that human beings can know absolute or objective truths about the world and about what constitutes moral behaviour. Nihilism and irrationalism, on the other hand, denied those very assumptions and their certitude. Pragmatists today still try to steer a middle course between contemporary offshoots of these two extremes.

The ideas of the pragmatists were considered revolutionary when they first appeared. To some critics, pragmatism’s refusal to affirm any absolutes carried negative implications for society. For example, pragmatists do not believe that a single absolute idea of goodness or justice exists, but rather than these concepts are changeable and depend on the context in which they are being discussed. The absence of these absolutes, critics feared, could result in a decline in moral standards. The pragmatists’ denial of absolutes, moreover, challenged the foundations of religion, government, and schools of thought. As a result, pragmatism influenced developments in psychology, sociology, education, semiotics (the study of signs and symbols), and scientific method, as well as philosophy, cultural criticism, and social reform movements. Various political groups have also drawn on the assumptions of pragmatism, from the progressive movements of the early 20th century to later experiments in social reform.

Pragmatism is best understood in its historical and cultural context. It arose during the late 19th century, a period of rapid scientific advancement typified by the theories of British biologist Charles Darwin, whose theories suggested too many thinkers that humanity and society are in a perpetual state of progress. During this same period a decline in traditional religious beliefs and values accompanied the industrialization and material progress of the time. In consequence it became necessary to rethink fundamental ideas about values, religion, science, community, and individuality.

The three most important pragmatists are American philosophers’ Charles Sanders Peirce, William James, and John Dewey. Peirce was primarily interested in scientific method and mathematics; his objective was to infuse scientific thinking into philosophy and society, and he believed that human comprehension of reality was becoming ever greater and that human communities were becoming increasingly progressive. Peirce developed pragmatism as a theory of meaning-in particular, the meaning of concepts used in science. The meaning of the concept 'brittle', for example, is given by the observed consequences or properties that objects called 'brittle' exhibit. For Peirce, the only rational way to increase knowledge was to form mental habits that would test ideas through observation, experimentation, or what he called inquiry. Many philosophers known as logical positivists, a group of philosophers who have been influenced by Peirce, believed that our evolving species was fated to get ever closer to Truth. Logical positivists emphasize the importance of scientific verification, rejecting the assertion of positivism that personal experience is the basis of true knowledge.

James moved pragmatism in directions that Peirce strongly disliked. He generalized Peirce’s doctrines to encompass all concepts, beliefs, and actions; he also applied pragmatist ideas to truth as well as to meaning. James was primarily interested in showing how systems of morality, religion, and faith could be defended in a scientific civilization. He argued that sentiment, as well as logic, is crucial to rationality and that the great issues of life-morality and religious belief, for example-are leaps of faith. As such, they depend upon what he called 'the will to believe' and not merely on scientific evidence, which can never tell us what to do or what is worthwhile. Critics charged James with relativism (the belief that values depend on specific situations) and with crass expediency for proposing that if an idea or action works the way one intends, it must be right. But James can more accurately be described as a pluralist-someone who believes the world to be far too complex for any one philosophy to explain everything.

Dewey’s philosophy can be described as a version of philosophical naturalism, which regards human experience, intelligence, and communities as ever-evolving mechanisms. Using their experience and intelligence, Dewey believed, human beings can solve problems, including social problems, through inquiry. For Dewey, naturalism led to the idea of a democratic society that allows all members to acquire social intelligence and progress both as individuals and as communities. Dewey held that traditional ideas about knowledge, truth, and values, in which absolutes are assumed, are incompatible with a broadly Darwinian world-view in which individuals and societies are progressing. In consequence, he felt that these traditional ideas must be discarded or revised. Indeed, for pragmatists, everything people know and do depend on a historical context and are thus tentative rather than absolute.

Many followers and critics of Dewey believe he advocated elitism and social engineering in his philosophical stance. Others think of him as a kind of romantic humanist. Both tendencies are evident in Dewey’s writings, although he aspired to synthesize the two realms.

The pragmatist’s tradition was revitalized in the 1980s by American philosopher Richard Rorty, who has faced similar charges of elitism for his belief in the relativism of values and his emphasis on the role of the individual in attaining knowledge. Interest has renewed in the classic pragmatists-Pierce, James, and Dewey-have an alternative to Rorty’s interpretation of the tradition.

One of the earliest versions of a correspondence theory was put forward in the 4th century Bc Greek philosopher Plato, who sought to understand the meaning of knowledge and how it is acquired. Plato wished to distinguish between true belief and false belief. He proposed a theory based on intuitive recognition that true statements correspond to the facts-that is, agree with reality-while false statements do not. In Plato’s example, the sentence “Theaetetus flies” can be true only if the world contains the fact that Theaetetus flies. However, Plato—and much later, 20th-century British philosopher Bertrand Russell—recognized this theory as unsatisfactory because it did not allow for false belief. Both Plato and Russell reasoned that if a belief is false because there is no fact to which it corresponds, it would then be a belief about nothing and so not a belief at all. Each then speculated that the grammar of a sentence could offer a way around this problem. A sentence can be about something (the person Theaetetus), yet false (flying is not true of Theaetetus). But how, they asked, are the parts of a sentence related to reality? One suggestion, proposed by 20th-century philosopher Ludwig Wittgenstein, is that the parts of a sentence relate to the objects they describe in much the same way that the parts of a picture relate to the objects pictured. Once again, however, false sentences pose a problem: If a false sentence pictures nothing, there can be no meaning in the sentence.

In the late 19th-century American philosopher Charles S. Peirce offered another answer to the question “What is truth?” He asserted that truth is that which experts will agree upon when their investigations are final. Many pragmatists such as Peirce claim that the truth of our ideas must be tested through practice. Some pragmatists have gone so far as to question the usefulness of the idea of truth, arguing that in evaluating our beliefs we should rather pay attention to the consequences that our beliefs may have. However, critics of the pragmatic theory are concerned that we would have no knowledge because we do not know which set of beliefs will ultimately be agreed upon; nor are there sets of beliefs that are useful in every context.

A third theory of truth, the coherence theory, also concerns the meaning of knowledge. Coherence theorists have claimed that a set of beliefs is true if the beliefs are comprehensive-that is, they cover everything-and do not contradict each other.

Other philosophers dismiss the question “What is truth?” with the observation that attaching the claim “it is true that” to a sentence adds no meaning. However, these theorists, who have proposed what are known as deflationary theories of truth, do not dismiss such talk about truth as useless. They agree that there are contexts in which a sentence such as “it is true that the book is blue” can have a different impact than the shorter statement “the book is blue.” What is more important, use of the word true is essential when making a general claim about everything, nothing, or something, as in the statement “most of what he says is true?”

Nevertheless, in the study of neuroscience it reveals that the human brain is a massively parallel system in which language processing is widely distributed. Computers generated images of human brains engaged in language processing reveals a hierarchical organization consisting of complicated clusters of brain areas that process different component functions in controlled time sequences. Stand-alone or unitary modules have clearly not accomplished language processing that evolved with the addition of separate modules that were eventually incorporated systematically upon some neural communications channel board.

Similarly, we have continued individual linguistic symbols as given to clusters of distributed brain areas and are not in a particular area. We may produce the specific sound patterns of words in dedicated regions. We have generated all the same, the symbolic and referential relationships between words through a convergence of neural codes from different and independent brain regions. The processes of words comprehension and retrieval result from combinations simpler associative processes in several separate brain fields of forces that command stimulation from other regions. The symbolic meaning of words, like the grammar that is essential for the construction of meaningful relationships between stings of words, is an emergent property from the complex interaction of several brain parts.

While the brain that evolved this capacity was obviously a product of Darwinian evolution, we cannot simply explain the most critical precondition for the evolution of brain in these terms. Darwinian evolution can explain why the creation of stone tools altered condition for survival in a ne ecological niche in which group living, pair bonding, and more complex social structures were critical to survival. Darwinian evolution can also explain why selective pressure in this new ecological niche favoured pre-adaptive changes required for symbolic commonisation. Nevertheless, as this communication resulted in increasingly more complex behaviour evolution began to take precedence of physical evolution in the sense that mutations resulting in enhanced social behaviour became selectively advantageously within the context of the social behaviour of hominids.

Although male and female hominids favoured pair bonding and created more complex social organizations in the interests of survival, the interplay between social evolution and biological evolution changed the terms of survival radically. The enhanced ability to use symbolic communication to construct of social interaction eventually made this communication the largest determinant of survival. Since this communication was based on a symbolic vocalization that requires the evolution of neural mechanisms and processes that did not evolve in any other species, this marked the emergence of a mental realm that would increasingly appear as separate nd distinct from the external material realm.

Nonetheless, if we could, for example, define all of the neural mechanisms involved in generating a particular word symbol, this would reveal nothing about the active experience of the world symbol as an idea in human consciousness. Conversely, the experience of the word symbol as an idea would reveal nothing about the neuronal processes involved. While one mode of understanding the situation necessarily displaces the other, we require both to achieve a complete understanding of the situation.

Most experts agree that our ancestries became knowledgeably articulated in the spoken exchange as based on complex grammar and syntax between two hundred thousand and some hundred thousand years ago. The mechanisms in the human brain that allowed for this great achievement clearly evolved, however, over great spans of time. In biology textbooks, the lists of prior adaptations that enhanced the ability of our ancestors to use communication normally include those that are inclining to inclinations to increase intelligence. As to approach a significant alteration of oral and auditory abilities, in that separation or localization of functional representations are well founded on two sides of the brain. The evolution of some innate or hard wired grammar, however, when we look at how our ability to use language could have really evolved over the entire course of hominid evolution. The process seems more basic and more counterintuitive than we had previously imagined.

Although we share some aspects of vocalization with our primate cousins, the mechanisms of human vocalization are quite different and have evolved over great spans of time. Incremental increases in hominid brain size over the last 2.5 million years enhanced cortical control over the larynx, which originally evolved to prevent food and other particles from entering the windpipe or trachea; This eventually contributed to the use of vocal symbolization. Humans have more voluntary motor control over sound produced in the larynx than any other vocal species, and this control are associated with higher brain systems involved in skeletal muscle control as opposed to just visceral control. As a result, humans have direct cortical motor control over phonation and oral movement while chimps do not.

We position the larynx in modern humans in a comparatively low position to the throat and significantly increase the range and flexibility of sound production. The low position of the larynx allows greater changes in the volume to the resonant chamber formed by the mouth and pharynx and makes it easier to shift sounds to the mouth and away from the nasal cavity. Formidable conclusions are those of the sounds that comprise vowel components of speeches that become much more variable, including extremes in resonance combinations such as the “ee” sound in “tree” and the “aw” sound in “flaw.” Equally important, the repositioning of the larynx dramatically increases the ability of the mouth and tongue to modify vocal sounds. This shift in the larynx also makes it more likely that food and water passing over the larynx will enter the trachea, and this explains why humans are more inclined to experience choking. Yet this disadvantage, which could have caused the shift to e selected against, was clearly out-weighed by the advantage of being able to produce all the sounds used in modern language systems.

Some have argued that this removal of constraints on vocalization suggests that spoken language based on complex symbol systems emerged quite suddenly in modern humans only about one hundred thousand years ago. It is, however, far more likely that language use began with very primitive symbolic systems and evolved over time to increasingly complex systems. The first symbolic systems were not full-blown language systems, and they were probably not as flexible and complex as the vocal calls and gestural displays of modern primates. The first users of primitive symbolic systems probably coordinated most of their social comminations with call and display behavioural attitudes alike those of the modern ape and monkeys.

Critically important to the evolution of enhanced language skills are that behavioural adaptive adjustments that serve to precede and situate biological changes. This represents a reversal of the usual course of evolution where biological change precedes behavioural adaption. When the first hominids began to use stone tools, they probably rendered of a very haphazard fashion, by drawing upon their flexible ape-like learning abilities, however, the use of this technology over time opened a new ecological niche where selective pressures occasioned new adaptions. A tool use became more indispensable for obtaining food and organized social behaviours, mutations that enhanced the use of tools probably functioned as a principal source of selection for both bodied and brains.

The first stone choppers appear in the fossil remnant fragments remaining about 2.5 million years ago, and they appear to have been fabricated with a few sharp blows of stone on stone. If these primitive tools are reasonable, which were hand-held and probably used to cut flesh and to chip bone to expose the marrow, were created by Homo habilis-the first large-brained hominid. Stone making is obviously a skill passed on from one generation to the next by learning as opposed to a physical trait passed on genetically. After these tools became critical to survival, this introduced selection for learning abilities that did not exist for other species. Although the early tool maskers may have had brains roughly comparable to those of modern apes, they were already confronting the processes for being adapted for symbol learning.

The first symbolic representations were probably associated with social adaptations that were quite fragile, and any support that could reinforce these adaptions in the interest of survival would have been favoured by evolution. The expansion of the forebrain in Homo habilis, particularly the prefrontal cortex, was on of the core adaptations. Increased connectivity enhanced this adaption over time to brain regions involved in language processing.

Imagining why incremental improvements in symbolic representations provided a selective advantage is easy. Symbolic communication probably enhanced cooperation in the relationship of mothers to infants, allowed forgoing techniques to be more easily learned, served as the basis for better coordinating scavenging and hunting activities, and generally improved the prospect of attracting a mate. As the list of domains in which symbolic communication was introduced became longer over time, this probably resulted in new selective pressures that served to make this communication more elaborate. After more functions became dependent on this communication, those who failed in symbol learning or could only use symbols awkwardly were less likely to pass on their genes to subsequent generations.

We must have considerably gestured the crude language of the earliest users of symbolics and nonsymbiotic vocalizations. Their spoken language probably became reactively independent and a closed cooperative system. Only after the emergence of hominids were to use symbolic communication evolved, symbolic forms progressively took over functions served by non-anecdotical symbolic forms. We reflect this in modern languages. The structure of syntax in these languages often reveals its origins in pointing gestures, in the manipulation and exchange of objects, and in more primitive constructions of spatial and temporal relationships. We still use nonverbal vocalizations and gestures to complement meaning in spoken language.

The encompassing intentionality to its thought is mightily effective, least of mention, the relevance of spatiality to self-consciousness comes about not merely because the world is spatial but also because the self-conscious subject is a spatial element of the world. One cannot be self-conscious without being aware that one is a spatial element of the world, and one cannot be ware that one is a spatial element of the world without a grasp of the spatial nature of the world. Face to face, the idea of a perceivable, objective spatial world that causes ideas too subjectively becoming to denote in the wold. During which time, his perceptions as they have of changing position within the world and to the essentially stable way the world is. The idea that there is an objective world and the idea that the subject is somewhere, and where what he can perceive gives it apart.

Research, however distant, are those that neuroscience reveals in that the human brain is a massive parallel system which language processing is widely distributed. Computers generated images of human brains engaged in language processing reveals a hierarchal organization consisting of complicated clusters of brain areas that process different component functions in controlled time sequences. Stand-alone or unitary modules that evolved with the addition of separate modules have clearly not accomplished language processing that were incorporated on some neutral circuit board.

While the brain that evolved this capacity was obviously a product of Darwinian evolution, he realized that the different chances of survival of different endowed offsprings could account for the natural evolution of species. Nature “selects” those members of some spacies best adapted to the environment in which they are themselves, just as human animal breeders may select for desirable traits for their livestock, and by that control the evolution of the kind of animal they wish. In the phase of Spencer, nature guarantees the “survival of the fittest.” The Origin of Species was principally successful in marshalling the evidence for evolution, than providing a convincing mechanism for genetic change, and Darwin himself remained open to the search for additional mechanisms, also reaming convinced that natural selection was at the heat of it. It was only with the later discovery of the “gene” as the unit of inheritance that the syntheses known as “neo-Darwinism” became the orthodox theory of evolution.

The solutions to the mysterious evolution by natural selection can shape sophisticated mechanisms are to found in the working of natural section, in that for the sake of some purpose, namely, some action, the body as a whole must evidently exist for the sake of some complex action: Having possession of simplistically actualized cognition, finding to its process one might look on as through the fundamentals, this may still be the recourse value in proceeding functionally as made simple just as natural selection occurs whenever genetic influence’s vary among individual effects as implicates its drama by the survival and reproduction? If a gene codes for characteristics that result in fewer viable offspring in future generations, governing evolutionary principles have gradually eliminated that gene. For instance, genetic mutation that an increase vulnerability to infection, or cause foolish risk taking or lack of interest in sex, will never become common. On the other hand, genes that cause resistance that causes infection, appropriate risk taking and success in choosing fertile mates are likely to spread in the gene pool even if they have substantial costs.

A classical example is the spread of a gene for dark wing colour in a British moth population living downward form major source of air pollution. Pale moths were conspicuous on smoke-darkened trees and easily caught by birds, while a rare mutant form of a moth whose colour closely matched that of the bark escaped the predator beaks. As the tree trucks became darkened, the mutant gene spread rapidly and largely displaced the gene for pale wing colour. That is all on that point to say is that natural selection insole no plan, no goal, and no direction-just genes increasing and decreasing in frequency depending on whether individuals with these genes have, compared with order individuals, greater of lesser reproductive success.

Many misconceptions have obscured the simplicity of natural selection. For instance, they have widely thought Herbert Spencer’s nineteenth-century catch phrase “survival of the fittest” to summarize the process, but an abstractive actuality openly provides a given forwarding to several misunderstandings. First, survival is of no consequence by itself. This is why natural selection has created some organisms, such as salmon and annual plants, that reproduces only once, the die. Survival increases fitness only as far as it increases later reproduction. Genes that increase lifetime reproduction will be selected for even if they result in a reduced longevity. Conversely, a gene that deceases selection will obviously eliminate total lifetime reproduction even if it increases an individual’s survival.

Considerable confusion arises from the ambiguous meaning of “fittest.” The fittest individuals in the biological scene, is not necessarily the healthiest, stronger, or fastest. In today’s world, and many of those of the past, individuals of outstanding athletic accomplishment need not be the ones who produce the most grandchildren, a measure that should be roughly correlated with fattiness. To someone who understands natural selection, it is no surprise that the parents who are not concerned about their children;’s reproduction.

We cannot call a gene or an individual “fit” in isolation but only concerning some particular spacies in a particular environment. Even in a single environment, every gene involves compromise. Consider a gene that makes rabbits more fearful and thereby helps to keep then from the jaws of foxes. Imagine that half the rabbits in a field have this gene. Because they do more hiding and less eating, these timid rabbits might be, on average, some bitless well fed than their bolder companions. Of, a hundred down-bounded in the March swamps awaiting for spring, two thirds of them starve to death while this is the fate of only one-third of the rabbits who lack the gene for fearfulness, it has been selected against. It might be nearly eliminated by a few harsh winters. Milder winters or an increased number of foxes could have the opposite effect, but it all depends on the current environment.

The version of an evolutionary ethic called “social Darwinism” emphasizes the struggle for natural selection, and draws the conclusion that we should glorify the assists each struggle, usually by enhancing competitive and aggressive relations between people in society, or better societies themselves. More recently we have rethought the reaction between evolution and ethics in the light of biological discoveries concerning altruism and kin-selection.

We cannot simply explain the most critical precondition for the evolution of this brain in these terms. Darwinian evolution can explain why the creation of stone tools altered conditions for survival in a new ecological niche in which group living, pair bonding, and more complex social structures were critical to survival. Darwinian evolution can also explain why selective pressures in this new ecological niche favoured pre-adaptive changes required for symbolic communication. All the same, this communication resulted directly through its passing an increasingly atypically structural complex and intensively condensed behaviour. Social evolution began to take precedence over physical evolution in the sense that mutations resulting in enhanced social behaviour became selectively advantageously within the context of the social behaviour of hominids.

Because this communication was based on symbolic vocalization that required the evolution of neural mechanisms and processes that did not evolve in any other species. As this marked the emergence of a mental realm that would increasingly appear as separate and distinct from the external material realm.

If they cannot reduce to, or entirely explain the emergent reality in this mental realm as for, the sum of its parts, concluding that this reality is greater than the sum of its parts seems reasonable. For example, a complete proceeding of the manner in which light in particular wave lengths has ben advancing by the human brain to generate a particular colour says nothing about the experience of colour. In other words, a complete scientific description of all the mechanisms involved in processing the colour blue does not correspond with the colour blue as perceived in human consciousness. No scientific description of the physical substrate of a thought or feeling, no matter how accomplish it can but be accounted for in actualized experience, especially of a thought or feeling, as an emergent aspect of global brain function.

If we could, for example, define all of the neural mechanisms involved in generating a particular word symbol, this would reveal nothing about the experience of the word symbol as an idea in human consciousness. Conversely, the experience of the word symbol as an idea would reveal nothing about the neuronal processes involved. While one mode of understanding the situation necessarily displaces the other, they require both to achieve a complete understanding of the situation.

Even if we are to include two aspects of biological reality, finding to a more complex order in biological reality is associated with the emergence of new wholes that are greater than the orbital parts. Yet, the entire biosphere is of a whole that displays self-regulating behaviour that is greater than the sum of its parts. Seemingly, that our visionary skills could view the emergence of a symbolic universe based on a complex language system as another stage in the evolution of more complicated and complex systems. As marked and noted by the appearance of a new profound complementarity in relationships between parts and wholes. This does not allow us to assume that human consciousness was in any sense preordained or predestined by natural process. Even so, it does make it possible, in philosophical terms at least, to argue that this consciousness is an emergent aspect of the self-organizing properties of biological life.

If we also concede that an indivisible whole contains, by definition, no separate parts and that in belief alone one can assume that a phenomenon was “real” only when it is “observed” phenomenon, have sparked advance the given processes for us to more interesting conclusions. The indivisible whole whose existence we have inferred in the results of the aspectual experiments that cannot in principal is itself the subject of scientific investigation. In that respect, no simple reason of why this is the case. Science can claim knowledge of physical reality only when experiment has validated the predictions of a physical theory. Since, invisualizability has restricted our view we cannot measure or observe the indivisible whole, we encounter by engaging the “eventful horizon” or knowledge where science can say nothing about the actual character of this reality. Why this is so, is a property of the entire universe, then we must also conclude that undivided wholeness exists on the most primary and basic level in all aspects of physical reality. What we are dealing within science per se, however, are manifestations of tis reality, which are invoked or “actualized” in making acts of observation or measurement. Since the reality that exists between the space-like separated regions is a whole whose existence can only be inferred in experience. As opposed to proven experiment, the correlations between the particles, and the sum of these parts, do not constitute the “indivisible” whole. Physical theory allows us to understand why the correlations occur. Nevertheless, it cannot in principal impart or describe the actualized character of the indivisible whole.

The scientific implications to this extraordinary relationship between parts ( in that, to know what it is like to have an experience is to know its qualia) and indivisible whole (the universe) are quite staggering. Our primary concern, however, is a new view of the relationship between mind and world that carries even larger implications in human terms. When factors into our understanding of the relationship between parts and wholes in physics and biology, then mind, or human consciousness, must be viewed as an emergent phenomenon in a seamlessly interconnected whole called the cosmos.

All that is required to embrace the alternative view of the relationship between mind and world that are consistent with our most advanced scientific knowledge is a commitment to metaphysical and epistemological realism and a willingness to follow arguments to their logical conclusions. Metaphysical realism assumes that physical reality or has an actual existence independent of human observers or any act of observation, epistemological realism assumes that progress in science requires strict adherence to scientific mythology, or to the rules and procedures for doing science. If one can accept these assumptions, most of the conclusions drawn should appear self-evident in logical and philosophical terms. Attributing any extra-scientific properties to the whole to understand is also not necessary and embrace the new relationship between part and whole and the alternative view of human consciousness that is consistent with this relationship. This is, in this that our distinguishing character between what can be “proven” in scientific terms and what can with reason be realized and “inferred” as a philosophical basis through which grounds can be assimilated as some indirect scientific evidence.

Moreover, advances in scientific knowledge rapidly became the basis for the creation of a host of new technologies. Yet are those responsible for evaluating the benefits and risks associated with the use of these technologies, much less their potential impact on human needs and values, normally have expertise on only one side of a two-culture divide. Perhaps, more important, many potential threats to the human future-such as, to, environmental pollution, arms development, overpopulation, and spread of infectious diseases, poverty, and starvation-can be effectively solved only by integrating scientific knowledge with knowledge from the social sciences and humanities. We have not done so for a simple reason-the implications of the amazing new fact of nature named for by non-locality, and cannot be properly understood without some familiarity with the actual history of scientific thought. The less resultant quantity is to suggest that what be most important about this background can be understood in its absence. Those who do not wish to struggle with the small and perhaps, fewer resultant quantities by which measure has substantiated the strengthening background implications with that should feel free to ignore it. Yet this material will be no more challenging as such, that the hope is that from those of which will find a common ground for understanding and that will meet again on this commonly functions as addressed to the relinquishing clasp of closure, and unswervingly close of its circle, resolve in the equations of eternity and complete of the universe of its obtainable gains for which its unification holds all that should be.

Another aspect of the evolution of a brain that allowed us to construct symbolic universes based on complex language system that is particularly relevant for our purposes concerns consciousness of self. Consciousness of self as an independent agency or actor is predicted on a fundamental distinction or dichotomy between this self and the other selves. Self, as it is constructed in human subjective reality, is perceived as having an independent existence and a self-referential character in a mental realm separately distinct from the material realm. It was, the assumed separation between these realms that led Descartes to posit his famous dualism in understanding the nature of consciousness in the mechanistic classical universe.

In a thought experiment, instead of bringing a course of events, as in a normal experiment, we are invited to imagine one. We may tenably be able to “see” that some result’s following, or that by some description is appropriate, or our inability to describe the situation may itself have some consequential consequence. Thought experiments played a major role in the development of physics: For example, Galileo probably never dropped two balls of unequal weight from the leaning Tower of Pisa, to refute the Aristotelean view that a heavy body falls faster than a lighter one. He merely asked used to imagine a heavy body made into the shape of a dumbbell, and then connecting rod gradually thinner, until it is finally severed. The thing is one heavy body until the last moment and he n two light ones, but it is incredible that this final snip alters the velocity dramatically. Other famous examples include the Einstein-Podolsky-Rosen thought experiment. In the philosophy of personal identity, our apparent capacity to imagine ourselves surviving drastic changes of body, brain, and mind is a permanent source of difficulty. On that point, no consensus on the legitimate place of thought experiments, to substitute either for real experiment, or as a reliable device for discerning possibilities. Though experiments with and one dislike is sometimes called intuition pumps.

For overfamiliar reasons, of hypothesizing that people are characterized by their rationality is common, and the most evident display of our rationality is our capacity to think. This is the rehearsal in the mind of what to say, or what to do. Not all thinking is verbal, since chess players, composers and painters all think, and in that respect no deductive reason that their deliberations should take any more verbal a form than this action. It is permanently tempting to conceive of this activity as for the presence inbounded in the mind of elements of some language, or other medium that represents aspects of the world. In whatever manner, the model has been attacked, notably by Wittgenstein, as insufficient, since no such presence could carry a guarantee that the right use would be made of it. Such that of an inner present seems unnecessary, since an intelligent outcome might arouse of some principal measure from it.

In the philosophy of mind and ethics the treatment of animals exposes major problems if other animals differ from human beings, how is the difference to be characterized: Do animals think and reason, or have thoughts and beliefs? In philosophers as different as Aristotle and Kant the possession of reason separates humans from animals, and alone allows entry to the moral community.

For Descartes, animals are mere machines and ee lack consciousness or feelings. In the ancient world the rationality of animals is defended with the example of Chrysippus’ dog. This animal, tracking prey, comes to a cross-roads with three exits, and without pausing to pick-up the scent, reasoning, according to Sextus Empiricus. The animal went either by this road, or by this road, or by that, or by the other. However, it did not go by this or that. Therefore, he went the other way. The ‘syllogism of the dog’ was discussed by many writers, since in Stoic cosmology animals should occupy a place on the great chain of being to an exceeding degree below human beings, the only terrestrial rational agents: Philo Judaeus wrote a dialogue attempting to show again Alexander of Aphrodisias that the dog’s behaviour does no t exhibit rationality, but simply shows it following the scent, by way of response Alexander has the animal jump down a shaft (where the scent would not have lingered). Plutah sides with Philo, Aquinas discusses the dog and scholastic thought in general was quite favourable to brute intelligence (being made to stand trail for various offences in medieval times was common for animals). In the modern era Montaigne uses the dog to remind us of the frailties of human reason: Rorarious undertook to show not only that beasts are rational, but that they make better use of reason than people do. James, the first of England defends the syllogising dog, and Henry More and Gassendi both takes issue with Descartes on that matter. Hume is an outspoken defender of animal cognition, but with their use of the view that language is the essential manifestation of mentality, animals’ silence began to count heavily against them, and they are completely denied thoughts by, for instance Davidson.

Dogs are frequently shown in pictures of philosophers, as their assiduity and fidelity are some symbols

It is, nonetheless, that Decanters’s first work, the Regulae ad Directionem Ingenii (1628/9), was never complected, yet in Holland between 1628 and 1649, Descartes first wrote, and then cautiously suppressed, Le Monde (1934), and in 1637 produced the Discours de la méthode as a preface to the treatise on mathematics and physics in which he introduced the notion of Cartesian co-ordinates. His best-known philosophical work, the Meditationes de Prima Philosophiia (Meditations on First Philosophy), together with objections by distinguished contemporaries and replies by Descartes (The Objections and Replies), appeared in 1641. The authors of the Objections were First set, for which is Hobbes, fourth set. Arnauld, fifth set, Gassendi and the sixth set, Mersenne. The second edition (1642) of the Meditations included a seventh se t by the Jesuit Pierre Bourdin. Descartes’s penultimate work, the Principia Pilosophiae (Principles of the Soul), published in 1644 was designed partly for use as a theological textbook. His last work was Les Passions de l´ame (The Passions of the Soul) published in 1649. When in Sweden, where he contracted pneumonia, allegedly through being required to break his normal habit of late rising in order to give lessons at 5:00 a.m. His last words are supposed to have been “Ça, mon âme, il faut partir” (so, my soul, it is time to part).

All the same, Descartes’s theory of knowledge starts with the quest for certainty, for an indubitable starting-point or foundation on the bassi alone of which progress is possible.

The Cartesian doubt is the method of investigating how much knowledge and its basis in reason or experience as used by Descartes in the first two Medications. It attempted to put knowledge upon secure foundation by first inviting us to suspend judgements on any proportion whose truth can be doubted, even as a bare possibility. The standards of acceptance are gradually raised as we are asked to doubt the deliverance of memory, the senses, and eve n reason, all of which are principally capable of letting us down. This is eventually found in the celebrated “Cogito ergo sum”: I think, therefore I am. By locating the point of certainty in my awareness of my own self, Descartes gives a first-person twist to the theory of knowledge that dominated the following centuries in spite of a various counter attack on behalf of social and public starting-points. The metaphysics associated with this priority are the Cartesian dualism, or separation of mind and matter into two different but interacting substances. Descartes rigorously and rightly to ascertain that it takes divine dispensation to certify any relationship between the two realms thus divided, and to prove the reliability of the senses invokes a “clear and distinct perception” of highly dubious proofs of the existence of a benevolent deity. This has not met general acceptance: A Hume drily puts it, “to have recourse to the veracity of the supreme Being, in order to prove the veracity of our senses, is surely making a very unexpected circuit.”

By dissimilarity, Descartes’s notorious denial that non-human animals are conscious is a stark illustration of dissimulation. In his conception of matter Descartes also gives preference to rational cogitation over anything from the senses. Since we can conceive of the matter of a ball of wax, surviving changes to its sensible qualities, matter is not an empirical concept, but eventually an entirely geometrical one, with extension and motion as its only physical nature.

Although the structure of Descartes’s epistemology, theory of mind and theory of matter have been rejected many times, their relentless exposure of the hardest issues, their exemplary clarity and even their initial plausibility, all contrives to make him the central point of reference for modern philosophy.

The term instinct (Lat., instinctus, impulse or urge) implies innately determined behaviour, flexible to change in circumstance outside the control of deliberation and reason. The view that animals accomplish even complex tasks not by reason was common to Aristotle and the Stoics, and the inflexibility of their outline was used in defence of this position as early as Avicennia. A continuity between animal and human reason was proposed by Hume, and followed by sensationalist such as the naturalist Erasmus Darwin (1731-1802). The theory of evolution prompted various views of the emergence of stereotypical behaviour, and the idea that innate determinants of behaviour are fostered by specific environments is a guiding principle of ethology. In this sense that being social may be instinctive in human beings, and for that matter too reasoned on what we now know about the evolution of human language abilities, however, our real or actualized self is clearly not imprisoned in our minds.

It is implicitly a part of the larger whole of biological life, human observers its existence from embedded relations to this whole, and constructs its reality as based on evolved mechanisms that exist in all human brains. This suggests that any sense of the “otherness” of self and world be is an illusion, in that disguises of its own actualization are to find all its relations between the part that are of their own characterization. Its self as related to the temporality of being whole is that of a biological reality. It can be viewed, of course, that a proper definition of this whole must not include the evolution of the larger indivisible whole. Yet, the cosmos and unbroken evolution of all life, by that of the first self-replication molecule that was the ancestor of DNA. It should include the complex interactions that have proven that among all the parts in biological reality that any resultant of emerging is self-regulating. This, of course, is responsible to properties owing to the whole of what might be to sustain the existence of the parts.

Founded on complications and complex coordinate systems in ordinary language may be conditioned as to establish some developments have been descriptively made by its physical reality and metaphysical concerns. That is, that it is in the history of mathematics and that the exchanges between the mega-narratives and frame tales of religion and science were critical factors in the minds of those who contributed. The first scientific revolution of the seventeenth century, allowed scientists to better them in the understudy of how the classical paradigm in physical reality has marked results in the stark Cartesian division between mind and world that became one of the most characteristic features of Western thought. This is not, however, another strident and ill-mannered diatribe against our misunderstandings, but drawn upon equivalent self realization and undivided wholeness or predicted characterlogic principles of physical reality and the epistemological foundations of physical theory.

The subjectivity of our mind affects our perceptions of the world held to be objective by natural science. Create both aspects of mind and matter as individualized forms that belong to the same underlying reality.

Our everyday experience confirms the apparent fact that there is a dual-valued world as subject and objects. We as having consciousness, as personality and as experiencing beings are the subjects, whereas for everything for which we can come up with a name or designation, seems to be the object, that which is opposed to us as a subject. Physical objects are only part of the object-world. In that respect are mental objects, objects of our emotions, abstract objects, religious objects etc. language objectifies our experience. Experiences per se are purely sensational experienced that do not make a distinction between object and subject. Only verbalized thought reifies the sensations by conceptualizing them and pigeonholing them into the given entities of language.

Some thinkers maintain, that subject and object are only different aspects of experience. I can experience myself as subject, and in the act of self-reflection. The fallacy of this argument is obvious: Being a subject implies having an object. We cannot experience something consciously without the mediation of understanding and mind. Our experience is already conceptualized at the time it comes into our consciousness. Our experience is negative insofar as it destroys the original pure experience. In a dialectical process of synthesis, the original pure experience becomes an object for us. The common state of our mind is only capable of apperceiving objects. Objects are reified negative experience. The same is true for the objective aspect of this theory: by objectifying myself I do not dispense with the subject, but the subject is causally and apodeictically linked to the object. When I make an object of anything, I have to realize, that it is the subject, which objectifies something. It is only the subject who can do that. Without the subject at that place are no objects, and without objects there is no subject. This interdependence, however, is not to be understood for a dualism, so that the object and the subject are really independent substances. Since the object is only created by the activity of the subject, and the subject is not a physical entity, but a mental one, we have to conclude then, that the subject-object dualism is purely mentalistic.

The Cartesian dualism posits the subject and the object as separate, independent and real substances, both of which have their ground and origin in the highest substance of God. Cartesian dualism, however, contradicts itself: The very fact, which Descartes posits the "I,” that is the subject, as the only certainty, he defied materialism, and thus the concept of some "res extensa.” The physical thing is only probable in its existence, whereas the mental thing is absolutely and necessarily certain. The subject is superior to the object. The object is only derived, but the subject is the original. This makes the object not only inferior in its substantive quality and in its essence, but relegates it to a level of dependence on the subject. The subject recognizes that the object is a "res’ extensa" and this means, that the object cannot have essence or existence without the acknowledgment through the subject. The subject posits the world in the first place and the subject is posited by God. Apart from the problem of interaction between these two different substances, Cartesian dualism is not eligible for explaining and understanding the subject-object relation.

By denying Cartesian dualism and resorting to monistic theories such as extreme idealism, materialism or positivism, the problem is not resolved either. What the positivists did, was just verbalizing the subject-object relation by linguistic forms. It was no longer a metaphysical problem, but only a linguistic problem. Our language has formed this object-subject dualism. These thinkers are very superficial and shallow thinkers, because they do not see that in the very act of their analysis they inevitably think in the mind-set of subject and object. By relativizing the object and subject for language and analytical philosophy, they avoid the elusive and problematical oppure of subject-object, since which has been the fundamental question in philosophy ever. Shunning these metaphysical questions is no solution. Excluding something, by reducing it to a more material and verifiable level, is not only pseudo-philosophy but a depreciation and decadence of the great philosophical ideas of mankind.

Therefore, we have to come to grips with idea of subject-object in a new manner. We experience this dualism as a fact in our everyday lives. Every experience is subject to this dualistic pattern. The question, however, is, whether this underlying pattern of subject-object dualism is real or only mental. Science assumes it to be real. This assumption does not prove the reality of our experience, but only that with this method science is most successful in explaining our empirical facts. Mysticism, on the other hand, believes that on that point is an original unity of subject and objects. To attain this unity is the goal of religion and mysticism. Man has fallen from this unity by disgrace and by sinful behaviour. Now the task of man is to get back on track again and strive toward this highest fulfilment. Again, are we not, on the conclusion made above, forced to admit, that also the mystic way of thinking is only a pattern of the mind and, as the scientists, that they have their own frame of reference and methodology to explain the supra-sensible facts most successfully?

If we assume mind to be the originator of the subject-object dualism, then we cannot confer more reality on the physical or the mental aspect, and we cannot deny the one as to the other.

Fortunately or not, history has made its play, and, in so doing, we must have considerably gestured the crude language of the earliest users of symbolics and nonsymbiotic vocalizations. Their spoken language probably became reactively independent and a closed cooperative system. Only after the emergence of hominids were to use symbolic communication evolved, symbolic forms progressively took over functions served by non-vocal symbolic forms. The earliest of Jutes, Saxons and Jesuits have reflected this in the modern mixtures of the English-speaking language. The structure of syntax in these languages often reveals its origins in pointing gestures, in the manipulation and exchange of objects, and in more primitive constructions of spatial and temporal relationships. We still use nonverbal vocalizations and gestures to complement meaning in spoken language.

Language involves specialized cortical regions in a complex interaction that allows the brain to comprehend and communicate abstract ideas. The motor cortex initiates impulses that travel through the brain stem to produce audible sounds. Neighbouring regions of motor cortex, called the supplemental motor cortex, are involved in sequencing and coordinating sounds. Broca's area of the frontal lobe is responsible for the sequencing of language elements for output. The comprehension of language is dependent upon Wernicke's area of the temporal lobe. Other cortical circuits connect these areas.

Memory is usually considered a diffusely stored associative process—that is, it puts together information from many different sources. Although research has failed to identify specific sites in the brain as locations of individual memories, certain brain areas are critical for memory to function. Immediate recall—the ability to repeat short series of words or numbers immediately after hearing them-is thought to be located in the auditory associative cortex. Short-term memory-the ability to retain a limited amount of information for up to an hour-is located in the deep temporal lobe. Long-term memory probably involves exchanges between the medial temporal lobe, various cortical regions, and the midbrain.

The autonomic nervous system regulates the life support systems of the body reflexively—that is, without conscious direction. It automatically controls the muscles of the heart, digestive system, and lungs; certain glands; and homeostasis—that is, the equilibrium of the internal environment of the body. The autonomic nervous system itself is controlled by nerve canters in the spinal cord and brain stem and is fine-tuned by regions higher in the brain, such as the midbrain and cortex. Reactions such as blushing indicate that cognitive, or thinking, canters of the brain are also involved in autonomic responses.

The brain is guarded by several highly developed protective mechanisms. The bony cranium, the surrounding meninges, and the cerebrospinal fluid all contribute to the mechanical protection of the brain. In addition, a filtration system called the blood-brain barrier protects the brain from exposure to potentially harmful substances carried in the bloodstream. Brain disorders have a wide range of causes, including head injury, stroke, bacterial diseases, complex chemical imbalances, and changes associated with aging.

Head injury can initiate a cascade of damaging events. After a blow to the head, a person may be stunned or may become unconscious for a moment. This injury, called a concussion, usually leaves no permanent damage. If the blow is more severe and haemorrhage (excessive bleeding) and swelling occurs, however, severe headache, dizziness, paralysis, a convulsion, or temporary blindness may result, depending on the area of the brain affected. Damage to the cerebrum can also result in profound personality changes.

Damage to Broca's area in the frontal lobe causes difficulty in speaking and writing, a problem known as Broca's aphasia. Injury to Wernicke's area in the left temporal lobe results in an inability to comprehend spoken language, called Wernicke's aphasia.

An injury or disturbance to a part of the hypothalamus may cause a variety of different symptoms, such as loss of appetite with an extreme drop in body weight; increase in appetite leading to obesity; extraordinary thirst with excessive urination (diabetes insipidus); failure in body-temperature control, resulting in either low temperature (hypothermia) or high temperature (fever); excessive emotionality; and uncontrolled anger or aggression. If the relationship between the hypothalamus and the pituitary gland is damaged, other vital bodily functions may be disturbed, such as sexual function, metabolism, and cardiovascular activity.

Injury to the brain stem is even more serious because it houses the nerve canters that control breathing and heart action. Damage to the medulla oblongata usually results in immediate death.

To the brain due to an interruption in blood flow. The interruption may be caused by a blood clot: constriction of a blood vessel, or rupture of a vessel accompanied by bleeding. A pouch-like expansion of the wall of a blood vessel, called an aneurysm, may weaken and burst, for example, because of high blood pressure.

Sufficient quantities of glucose and oxygen, transported through the bloodstream, are needed to keep nerve cells alive. When the blood supply to a small part of the brain is interrupted, the cells in that area die and the function of the area is lost. A massive stroke can cause a one-sided paralysis (hemiplegia) and sensory loss on the side of the body opposite the hemisphere damaged by the stroke.

Epilepsy is a broad term for a variety of brain disorders characterized by seizures, or convulsions. Epilepsy can result from a direct injury to the brain at birth or from a metabolic disturbance in the brain at any time later in life.

Some brain diseases, such as multiple sclerosis and Parkinson disease, are progressive, becoming worse over time. Multiple sclerosis damages the myelin sheath around axons in the brain and spinal cord. As a result, the affected axons cannot transmit nerve impulses properly. Parkinson disease destroys the cells of the substantia nigra in the midbrain, resulting in a deficiency in the neurotransmitter dopamine that affects motor functions.

Cerebral palsy is a broad term for brain damage sustained close to birth that permanently affects motor function. The damage may take place either in the developing fetus, during birth, or just after birth and is the result of the faulty development or breaking down of motor pathways. Cerebral palsy is nonprogressive—that is, it does not worsen with time.

A bacterial infection in the cerebrum or in the coverings of the brain swelling of the brain, or an abnormal growth of healthy brain tissue can all cause an increase in intracranial pressure and result in serious damage to the brain.

Scientists are finding that certain brain chemical imbalances are associated with mental disorders such as schizophrenia and depression. Such findings have changed scientific understanding of mental health and have resulted in new treatments that chemically correct these imbalances.

During childhood development, the brain is particularly susceptible to damage because of the rapid growth and reorganization of nerve connections. Problems that originate in the immature brain can appear as epilepsy or other brain-function problems in adulthood.

Several neurological problems are common in aging. Alzheimer's disease damages many areas of the brain, including the frontal, temporal, and parietal lobes. The brain tissue of people with Alzheimer's disease shows characteristic patterns of damaged neurons, known as plaques and tangles. Alzheimer's disease produces a progressive dementia, characterized by symptoms such as failing attention and memory, loss of mathematical ability, irritability, and poor orientation in space and time.

Several commonly used diagnostic methods give images of the brain without invading the skull. Some portray anatomy, that is, the structure of the brain—whereas others measures brain function. Two or more methods may be used to complement each other, together providing a more complete picture than would be possible by one method alone.

Magnetic resonance imaging (MRI), introduced in the early 1980s, beams high-frequency radio waves into the brain in a highly magnetized field that causes the protons that form the nuclei of hydrogen atoms in the brain to remit the radio waves. The re-emitted radio waves are analysed by computer to create thin cross-sectional images of the brain. MRI provides the most detailed images of the brain and is safer than imaging methods that use X rays. However, MRI is a lengthy process and also cannot be used with people who have pacemakers or metal implants, both of which are adversely affected by the magnetic field.

Computed tomography (CT), also known as CT scans, developed in the early 1970s. This imaging method X-rays the brain from many different angles, feeding the information into a computer that produces a series of cross-sectional images. CT is particularly useful for diagnosing blood clots and brain tumours. It is a much quicker process than magnetic resonance imaging and is therefore advantageous in certain situations—for example, with people who are extremely ill.

Changes in brain function due to brain disorders can be visualized in several ways. Magnetic resonance spectroscopy measures the concentration of specific chemical compounds in the brain that may change during specific behaviours. Functional magnetic resonance imaging (fMRI) maps changes in oxygen concentration that correspond to nerve cell activity.

Positron emission tomography (PET), developed in the mid-1970s, uses computed tomography to visualize radioactive tracers radioactive substances introduced into the brain intravenously or by inhalation. PET can measure such brain functions as cerebral metabolism, blood flow and volume, oxygen use, and the formation of neurotransmitters. Single photon emission computed tomography (SPECT), developed in the 1950s and 1960s, used radioactive tracers to visualize the circulation and volume of blood in the brain.

Brain-imaging studies have provided new insights into sensory, motor, language, and memory processes, as well as brain disorders such as epilepsy cerebrovascular disease; Alzheimer's, Parkinson, and Huntington's diseases: And nd various mental disorders, such as schizophrenia.

In lower vertebrates, such as fish and reptiles, the brain is often tubular and bears a striking resemblance to the early embryonic stages of the brains of more highly evolved animals. In all vertebrates, the brain is divided into three regions: the forebrain (prosencephalon), the midbrain (mesencephalon), and the hindbrain (rhombencephalon). These three regions further subdivide into different structures, systems, nuclei, and layers.

The more highly evolved the animal, the more complex is the brain structure. Human beings have the most complex brains of all animals. Evolutionary forces have also resulted in a progressive increase in the size of the brain. In vertebrates lower than mammals, the brain is small. In meat-eating animals, particularly primates, the brain increases dramatically in size.

The cerebrum and cerebellum of higher mammals are highly convoluted in order to fit the most gray matter surface within the confines of the cranium. Such highly convoluted brains are called gyrencephalic. Many lower mammals have a smooth, or lissencephalic (“smooth head”), cortical surface.

There is also evidence of evolutionary adaption of the brain. For example, many birds depend on an advanced visual system to identify food at great distances while in flight. Consequently, their optic lobes and cerebellum are well developed, giving them keen sight and outstanding motor coordination in flight. Rodents, on the other hand, as nocturnal animals, do not have a well-developed visual system. Instead, they rely more heavily on other sensory systems, such as a highly-developed sense of smell and facial whiskers.

Recent research in brain function suggests that there may be sexual differences in both brain anatomy and brain function. One study indicated that man’s nd women may use their brains differently while thinking. Researchers used functional magnetic resonance imaging to observe which parts of the brain were activated as groups of men and women tried to determine whether sets of nonsense words rhymed. Men used only Broca's area in this task, whereas women used Broca's area plus an area on the right side of the brain.

Both Analytic and Linguistic philosophy, are 20th-century philosophical movements, and dominated most of Britain and the United States since World War II, that aims to clarify language and analyze the concepts expressed in it. The movement has been given a variety of designations, including linguistic analysis, logical empiricism, logical positivism, Cambridge analysis, and “Oxford philosophy.” The last two labels are derived from the universities in England where this philosophical method has been particularly influential. Although no specific doctrines or tenets are accepted by the movement as a whole, analytic and linguistic philosophers agree that the proper activity of philosophy is clarifying language, or, as some prefer, clarifying concepts. The aim of this activity is to settle philosophical disputes and resolve philosophical problems, which, it is argued, originates in linguistic confusion.

A considerable diversity of views exists among analytic and linguistic philosophers regarding the nature of conceptual or linguistic analysis. Some have been primarily concerned with clarifying the meaning of specific words or phrases as an essential step in making philosophical assertions clear and unambiguous. Others have been more concerned with determining the general conditions that must be met for any linguistic utterance to be meaningful; their intent is to establish a criterion that will distinguish between meaningful and nonsensical sentences. Still other analysts have been interested in creating formal, symbolic languages that are mathematical in nature. Their claim is that philosophical problems can be more effectively dealt with once they are formulated in a rigorous logical language.

By contrast, many philosophers associated with the movement have focussed on the analysis of ordinary, or natural, language. Difficulties arise when concepts such as time and freedom, for example, are considered apart from the linguistic context in which they normally appear. Attention to language as it is ordinarily used for the key it is argued, to resolving many philosophical puzzles.

Many experts believe that philosophy as an intellectual discipline originated with the work of Plato, one of the most celebrated philosophers in history. The Greek thinker had an immeasurable influence on Western thought. However, Plato’s expression of ideas in the form of dialogues—the dialectical method, used most famously by his teacher Socrates—has led to difficulties in interpreting some of the finer points of his thoughts. The issue of what exactly Plato meant to say is addressed in the following excerpt by author R. M. Hare.

Linguistic analysis as a method of philosophy is as old as the Greeks. Several of the dialogues of Plato, for example, are specifically concerned with clarifying terms and concepts. Nevertheless, this style of philosophizing has received dramatically renewed emphasis in the 20th century. Influenced by the earlier British empirical tradition of John Locke, George Berkeley, David Hume, and John Stuart Mill and by the writings of the German mathematician and philosopher Gottlob Frigg, the 20th-century English philosopher’s G. E. Moore and Bertrand Russell became the founders of this contemporary analytic and linguistic trend. As students together at the University of Cambridge, Moore and Russell rejected Hegelian idealism, particularly as it was reflected in the work of the English metaphysician F. H. Bradley, who held that nothing is completely real except the Absolute. In their opposition to idealism and in their commitment to the view that careful attention to language is crucial in philosophical inquiry. They set the mood and style of philosophizing for much of the 20th century English-speaking world.

For Moore, philosophy was first and foremost analysis. The philosophical task involves clarifying puzzling propositions or concepts by indicating less puzzling propositions or concepts to which the originals are held to be logically equivalent. Once this task has been completed, the truth or falsity of problematic philosophical assertions can be determined more adequately. Moore was noted for his careful analyses of such puzzling philosophical claims as “time is unreal,” analyses that then aided in determining the truth of such assertions.

Russell, strongly influenced by the precision of mathematics, was concerned with developing an ideal logical language that would accurately reflect the nature of the world. Complex propositions, Russell maintained, can be resolved into their simplest components, which he called atomic propositions. These propositions refer to atomic facts, the ultimate constituents of the universe. The metaphysical views based on this logical analysis of language and the insistence that meaningful propositions must correspond to facts constitute what Russell called logical atomism. His interest in the structure of language also led him to distinguish between the grammatical form of a proposition and its logical form. The statements “John is good” and “John is tall” have the same grammatical form but different logical forms. Failure to recognize this would lead one to treat the property “goodness” as if it were a characteristic of John in the same way that the property “tallness” is a characteristic of John. Such failure results in philosophical confusion.

Austrian-born philosopher Ludwig Wittgenstein was one of the most influential thinkers of the 20th century. With his fundamental work, Tractatus Logico-philosophicus, published in 1921, he became a central figure in the movement known as analytic and linguistic philosophy.

Russell’s work in mathematics attracted to Cambridge the Austrian philosopher Ludwig Wittgenstein, who became a central figure in the analytic and linguistic movement. In his first major work, Tractatus Logico-Philosophicus (1921; trans. 1922), in which he first presented his theory of language, Wittgenstein argued that “all philosophy is a ‘critique of language’” and that “philosophy aims at the logical clarification of thoughts.” The results of Wittgenstein’s analysis resembled Russell’s logical atomism. The world, he argued, is ultimately composed of simple facts, which it is the purpose of language to picture. To be meaningful, statements about the world must be reducible to linguistic utterances that have a structure similar to the simple facts pictured. In this early Wittgensteinian analysis, only propositions that picture facts—the propositions of science-are considered factually meaningful. Metaphysical, theological, and ethical sentences were judged to be factually meaningless.

Influenced by Russell, Wittgenstein, Ernst Mach, and others, a group of philosophers and mathematicians in Vienna in the 1920s initiated the movement known as logical positivism: Led by Moritz Schlick and Rudolf Carnap, the Vienna Circle initiated one of the most important chapters in the history of analytic and linguistic philosophy. According to the positivists, the task of philosophy is the clarification of meaning, not the discovery of new facts (the job of the scientists) or the construction of comprehensive accounts of reality (the misguided pursuit of traditional metaphysics).

The positivists divided all meaningful assertions into two classes: analytic propositions and empirically verifiable ones. Analytic propositions, which include the propositions of logic and mathematics, are statements the truth or falsity of which depend altogether on the meanings of the terms constituting the statement. An example would be the proposition “two plus two equals four.” The second class of meaningful propositions includes all statements about the world that can be verified, at least in principle, by sense experience. Indeed, the meaning of such propositions is identified with the empirical method of their verification. This verifiability theory of meaning, the positivists concluded, would demonstrate that scientific statements are legitimate factual claims and that metaphysical, religious, and ethical sentences are factually empties. The ideas of logical positivism were made popular in England by the publication of A. J. Ayer’s Language, Truth and Logic in 1936.

The positivists’ verifiability theory of meaning came under intense criticism by philosophers such as the Austrian-born British philosopher Karl Popper. Eventually this narrow theory of meaning yielded to a broader understanding of the nature of language. Again, an influential figure was Wittgenstein. Repudiating many of his earlier conclusions in the Tractatus, he initiated a new line of thought culminating in his posthumously published Philosophical Investigations (1953; trans. 1953). In this work, Wittgenstein argued that once attention is directed to the way language is actually used in ordinary discourse, the variety and flexibility of language become clear. Propositions do much more than simply picture facts.

This recognition led to Wittgenstein’s influential concept of language games. The scientist, the poet, and the theologian, for example, are involved in different language games. Moreover, the meaning of a proposition must be understood in its context, that is, in terms of the rules of the language game of which that proposition is a part. Philosophy, concluded Wittgenstein, is an attempt to resolve problems that arise as the result of linguistic confusion, and the key to the resolution of such problems is ordinary language analysis and the proper use of language.

Additional contributions within the analytic and linguistic movement include the work of the British philosopher’s Gilbert Ryle, John Austin, and P. F. Strawson and the American philosopher W. V. Quine. According to Ryle, the task of philosophy is to restate “systematically misleading expressions” in forms that are logically more accurate. He was particularly concerned with statements the grammatical form of which suggests the existence of nonexistent objects. For example, Ryle is best known for his analysis of mentalistic language, language that misleadingly suggests that the mind is an entity in the same way as the body.

Austin maintained that one of the most fruitful starting points for philosophical inquiry is attention to the extremely fine distinctions drawn in ordinary language. His analysis of language eventually led to a general theory of speech acts, that is, to a description of the variety of activities that an individual may be performing when something is uttered.

Strawson is known for his analysis of the relationship between formal logic and ordinary language. The complexity of the latter, he argued, is inadequately represented by formal logic. A variety of analytic tools, therefore, are needed in addition to logic in analysing ordinary language.

Quine discussed the relationship between language and ontology. He argued that language systems tend to commit their users to the existence of certain things. For Quine, the justification for speaking one way rather than another is a thoroughly pragmatic one.

The commitment to language analysis as a way of pursuing philosophy has continued as a significant contemporary dimension in philosophy. A division also continues to exist between those who prefer to work with the precision and rigour of symbolic logical systems and those who prefer to analyze ordinary language. Although few contemporary philosophers maintain that all philosophical problems are linguistic, the view continues to be widely held that attention to the logical structure of language and to how language is used in everyday discourse can often aid in resolving philosophical problems.

A loose title for various philosophies that emphasize certain common themes, the individual, the experience of choice, and if the absence of rational understanding of the universe, with a consequent dread or sense of ‘absurdity human life’ however, existentialism is a philosophical movement or tendency, emphasizing individual existence, freedom, and choice, that influenced many diverse writers in the 19th and 20th centuries.

Because of the diversity of positions associated with existentialism, the term is impossible to define precisely. Certain themes common to virtually all existentialist writers can, however, be identified. The term itself suggests one major theme: the stress on concrete individual existence and, consequently, on subjectivity, individual freedom, and choice.

Most philosophers since Plato have held that the highest ethical good are the same for everyone; insofar as one approaches moral perfection, one resembles other morally perfect individuals. The 19th-century Danish philosopher Søren Kierkegaard, who was the first writer to call himself existential, reacted against this tradition by insisting that the highest good for the individual are to find his or her own unique vocation. As he wrote in his journal, “I must find a truth that is true for me . . . the idea for which I can live or die.” Other existentialist writers have echoed Kierkegaard's belief that one must choose one's own way without the aid of universal, objective standards. Against the traditional view that moral choice involves an objective judgment of right and wrong, Existentialists have argued that no objective, rational basis can be found for moral decisions. The 19th-century German philosopher Friedrich Nietzsche further contended that the individual must decide which situations are to count as moral situations.

All Existentialists have followed Kierkegaard in stressing the importance of passionate individual action in deciding questions of both morality and truth. They have insisted, accordingly, that personal experience and acting on one's own convictions are essential in arriving at the truth. Thus, the understanding of a situation by someone involved in that situation is superior to that of a detached, objective observer. This emphasis on the perspective of the individual agent has also made Existentialists suspicious of systematic reasoning. Kierkegaard, Nietzsche, and other existentialist writers have been deliberately unsystematic in the exposition of their philosophies, preferring to express themselves in aphorisms, dialogues, parables, and other literary forms. Despite their antirationalist position, however, most Existentialists cannot be said to be irrationalists in the sense of denying all validity to rational thought. They have held that rational clarity is desirable wherever possible, but that the most important questions in life are not accessible to reason or science. Furthermore, they have argued that even science is not as rational as is commonly supposed. Nietzsche, for instance, asserted that the scientific assumption of an orderly universe is for the most part a useful fiction.

Perhaps the most prominent theme in existentialist writing is that of choice. Humanity's primary distinction, in the view of most Existentialists, is the freedom to choose. Existentialists have held that human beings do not have a fixed nature, or essence, as other animals and plants do; each human being makes choices that create his or her own nature. In the formulation of the 20th-century French philosopher Jean-Paul Sartre, existence precedes essence. Choice is therefore central to human existence, and it is inescapable; even the refusal to choose is a choice. Freedom of choice entails commitment and responsibility. Because individuals are free to choose their own path, Existentialists have argued, they must accept the risk and responsibility of following their commitment wherever it leads.

Kierkegaard held that it is spiritually crucial to recognize that one experiences not only a fear of specific objects but also a feeling of general apprehension, which he called dread. He interpreted it as God's way of calling each individual to make a commitment to a personally valid way of life. The word anxiety (German Angst) has a similarly crucial role in the work of the 20th-century German philosopher Martin Heidegger; anxiety leads to the individual's confrontation with nothingness and with the impossibility of finding ultimate justification for the choices he or she must make. In the philosophy of Sartre, the word nausea is used for the individual's recognition of the pure contingency of the universe, and the word anguish is used for the recognition of the total freedom of choice that confronts the individual at every moment.

Existentialism as a distinct philosophical and literary movement belongs to the 19th and 20th centuries, but elements of existentialism can be found in the thought (and life) of Socrates, in the Bible, and in the work of many premodern philosophers and writers.

The first to anticipate the major concerns of modern existentialism was the 17th-century French philosopher Blaise Pascal. Pascal rejected the rigorous rationalism of his contemporary René Descartes, asserting, in his Pensées (1670), that a systematic philosophy that presumes to explain God and humanity is a form of pride. Like later existentialist writers, he saw human life in terms of paradoxes: The human self, which combines mind and body, is itself a paradox and contradiction.

Kierkegaard, generally regarded as the founder of modern existentialism, reacted against the systematic absolute idealism of the 19th-century German philosopher Georg Wilhelm Friedrich Hegel, who claimed to have worked out a total rational understanding of humanity and history. Kierkegaard, on the contrary, stressed the ambiguity and absurdity of the human situation. The individual's response to this situation must be to live a totally committed life, and this commitment can only be understood by the individual who has made it. The individual therefore must always be prepared to defy the norms of society for the sake of the higher authority of a personally valid way of life. Kierkegaard ultimately advocated a “leap of faith” into a Christian way of life, which, although incomprehensible and full of risk, was the only commitment he believed could save the individual from despair.

Danish religious philosopher Søren Kierkegaard rejected the all-encompassing, analytical philosophical systems of such 19th-century thinkers as German philosopher G. W. F. Hegel. Instead, Kierkegaard focussed on the choices the individual must make in all aspects of his or her life, especially the choice to maintain religious faith. In Fear and Trembling (1846; trans. 1941), Kierkegaard explored the concept of faith through an examination of the biblical story of Abraham and Isaac, in which God demanded that Abraham demonstrate his faith by sacrificing his son.

One of the most controversial works of 19th-century philosophy, Thus Spake Zarathustra (1883-1885) articulated German philosopher Friedrich Nietzsche’s theory of the Übermensch, a term translated as “Superman” or “Overman.” The Superman was an individual who overcame what Nietzsche termed the “slave morality” of traditional values, and lived according to his own morality. Nietzsche also advanced his idea that “God is dead,” or that traditional morality was no longer relevant in people’s lives. In this passage, the sage Zarathustra came down from the mountain where he had spent the last ten years alone to preach to the people.

Nietzsche, who was not acquainted with the work of Kierkegaard, influenced subsequent existentialist thought through his criticism of traditional metaphysical and moral assumptions and through his espousal of tragic pessimism and the life-affirming individual will that opposes itself to the moral conformity of the majority. In contrast to Kierkegaard, whose attack on conventional morality led him to advocate a radically individualistic Christianity, Nietzsche proclaimed the “death of God” and went on to reject the entire Judeo-Christian moral tradition in favor of a heroic pagan ideal.

The modern philosophy movements of phenomenology and existentialism have been greatly influenced by the thought of German philosopher Martin Heidegger. According to Heidegger, humankind has fallen into a crisis by taking a narrow, technological approach to the world and by ignoring the larger question of existence. People, if they wish to live authentically, must broaden their perspectives. Instead of taking their existence for granted, people should view themselves as part of Being (Heidegger's term for that which underlies all existence).

Heidegger, like Pascal and Kierkegaard, reacted against an attempt to put philosophy on a conclusive rationalistic basis—in this case the phenomenology of the 20th-century German philosopher Edmund Husserl. Heidegger argued that humanity finds itself in an incomprehensible, indifferent world. Human beings can never hope to understand why they are here; instead, each individual must choose a goal and follow it with passionate conviction, aware of the certainty of death and the ultimate meaninglessness of one's life. Heidegger contributed to existentialist thought an original emphasis on being and ontology (see Metaphysics) as well as on language.

Twentieth-century French intellectual Jean-Paul Sartre helped to develop existential philosophy through his writings, novels, and plays. A large portion of Sartre’s work focus on the dilemma of choice faced by free individuals and on the challenge of creating meaning by acting responsibly in an indifferent world. In stating that “man is condemned to be free,” Sartre reminds us of the responsibility that accompanies human decisions.

Sartre first gave the term existentialism general currency by using it for his own philosophy and by becoming the leading figure of a distinct movement in France that became internationally influential after World War II. Sartre's philosophy is explicitly atheistic and pessimistic; he declared that human beings require a rational basis for their lives but are unable to achieve one, and thus human life is a “futile passion.” Sartre nevertheless insisted that his existentialism is a form of humanism, and he strongly emphasized human freedom, choice, and responsibility. He eventually tried to reconcile these existentialist concepts with a Marxist analysis of society and history.

Although existentialist thought encompasses the uncompromising atheism of Nietzsche and Sartre and the agnosticism of Heidegger, its origin in the intensely religious philosophies of Pascal and Kierkegaard foreshadowed its profound influence on 20th-century theology. The 20th-century German philosopher Karl Jaspers, although he rejected explicit religious doctrines, influenced contemporary theology through his preoccupation with transcendence and the limits of human experience. The German Protestant theologian’s Paul Tillich and Rudolf Bultmann, the French Roman Catholic theologian Gabriel Marcel, the Russian Orthodox philosopher Nikolay Berdyayev, and the German Jewish philosopher Martin Buber inherited many of Kierkegaard's concerns, especially that a personal sense of authenticity and commitment is essential to religious faith.

Renowned as one of the most important writers in world history, 19th-century Russian author Fyodor Dostoyevsky wrote psychologically intense novels which probed the motivations and moral justifications for his characters’ actions. Dostoyevsky commonly addressed themes such as the struggle between good and evil within the human soul and the idea of salvation through suffering. The Brothers Karamazov (1879-1880), generally considered Dostoyevsky’s best work, interlaces religious exploration with the story of a family’s violent quarrels over a woman and a disputed inheritance.

A number of existentialist philosophers used literary forms to convey their thought, and existentialism has been as vital and as extensive a movement in literature as in philosophy. The 19th-century Russian novelist Fyodor Dostoyevsky is probably the greatest existentialist literary figure. In Notes from the Underground (1864), the alienated antihero rages against the optimistic assumptions of rationalist humanism. The view of human nature that emerges in this and other novels of Dostoyevsky is that it is unpredictable and perversely self-destructive; only Christian love can save humanity from itself, but such love cannot be understood philosophically. As the character Alyosha says in The Brothers Karamazov (1879-80), “We must love life more than the meaning of it.”

The opening lines of Russian novelist Fyodor Dostoyevsky’s Notes from Underground (1864)—“I am a sick man.… I am a spiteful man”—are among the most famous in 19th-century literature. Published five years after his release from prison and involuntary military service in Siberia, Notes from Underground is a sign of Dostoyevsky’s rejection of the radical social thinking he had embraced in his youth. The unnamed narrator is antagonistic in tone, questioning the reader’s sense of morality as well as the foundations of rational thinking. In this excerpt from the beginning of the novel, the narrator describes himself, derisively referring to himself as an “overly conscious” intellectual.

In the 20th century, the novels of the Austrian Jewish writer Franz Kafka, such as The Trial (1925; trans. 1937) and The Castle (1926; trans. 1930), present isolated men confronting vast, elusive, menacing bureaucracies; Kafka's themes of anxiety, guilt, and solitude reflect the influence of Kierkegaard, Dostoyevsky, and Nietzsche. The influence of Nietzsche is also discernible in the novels of the French writer’s André Malraux and in the plays of Sartre. The work of the French writer Albert Camus is usually associated with existentialism because of the prominence in it of such themes as the apparent absurdity and futility of life, the indifference of the universe, and the necessity of engagement in a just cause. Existentialist themes are also reflected in the theatre of the absurd, notably in the plays of Samuel Beckett and Eugène Ionesco. In the United States, the influence of existentialism on literature has been more indirect and diffuse, but traces of Kierkegaard's thought can be found in the novels of Walker Percy and John Updike, and various existentialist themes are apparent in the work of such diverse writers as Norman Mailer, John Barth, and Arthur

The problem of defining knowledge in terms of true belief plus some favoured relation between the believer and the facts began with Plato’s view in the Theaetetus, that knowledge is true belief plus a logos, an epistemology is to begin of holding the foundations of knowledge, a special branch of philosophy that addresses the philosophical problems surrounding the theory of knowledge. Epistemology is concerned with the definition of knowledge and related concepts, the sources and criteria of knowledge, the kinds of knowledge possible and the degree to which each is certain, and the exact relation among the one who knows and the object known.

Thirteenth-century Italian philosopher and theologian Saint Thomas Aquinas attempted to synthesize Christian belief with a broad range of human knowledge, embracing diverse sources such as Greek philosopher Aristotle and Islamic and Jewish scholars. His thought exerted lasting influence on the development of Christian theology and Western philosophy. Author Anthony Kenny examines the complexities of Aquinas’s concepts of substance and accident.

In the 5th century Bc, the Greek Sophists questioned the possibility of reliable and objective knowledge. Thus, a leading Sophist, Gorgias, argued that nothing really exists, that if anything did exist it could not be known, and that if knowledge were possible, it could not be communicated. Another prominent Sophist, Protagoras, maintained that no person's opinions can be said to be more correct than another's, because each is the sole judge of his or her own experience. Plato, following his illustrious teacher Socrates, tried to answer the Sophists by postulating the existence of a world of unchanging and invisible forms, or ideas, about which it is possible to have exact and certain knowledge. The thing’s one sees and touches, they maintained, are imperfect copies of the pure forms studied in mathematics and philosophy. Accordingly, only the abstract reasoning of these disciplines yields genuine knowledge, whereas reliance on sense perception produces vague and inconsistent opinions. They concluded that philosophical contemplation of the unseen world of forms is the highest goal of human life.

Aristotle followed Plato in regarding abstract knowledge as superior to any other, but disagreed with him as to the proper method of achieving it. Aristotle maintained that almost all knowledge is derived from experience. Knowledge is gained either directly, by abstracting the defining traits of a species, or indirectly, by deducing new facts from those already known, in accordance with the rules of logic. Careful observation and strict adherence to the rules of logic, which were first set down in systematic form by Aristotle, would help guard against the pitfalls the Sophists had exposed. The Stoic and Epicurean schools agreed with Aristotle that knowledge originates in sense perception, but against both Aristotle and Plato they maintained that philosophy is to be valued as a practical guide to life, rather than as an end in itself.

After many centuries of declining interest in rational and scientific knowledge, the Scholastic philosopher Saint Thomas Aquinas and other philosophers of the Middle Ages helped to restore confidence in reason and experience, blending rational methods with faith into a unified system of beliefs. Aquinas followed Aristotle in regarding perception as the starting point and logic as the intellectual procedure for arriving at reliable knowledge of nature, but he considered faith in scriptural authority as the main source of religious belief.

From the 17th to the late 19th century, the main issue in epistemology was reasoning versus sense perception in acquiring knowledge. For the rationalists, of whom the French philosopher René Descartes, the Dutch philosopher Baruch Spinoza, and the German philosopher Gottfried Wilhelm Leibniz were the leaders, the main source and final test of knowledge was deductive reasoning based on self-evident principles, or axioms. For the empiricists, beginning with the English philosophers Francis Bacon and John Locke, the main source and final test of knowledge was sense perception.

Bacon inaugurated the new era of modern science by criticizing the medieval reliance on tradition and authority and also by setting down new rules of scientific method, including the first set of rules of inductive logic ever formulated. Locke attacked the rationalist belief that the principles of knowledge are intuitively self-evident, arguing that all knowledge is derived from experience, either from experience of the external world, which stamps sensations on the mind, or from internal experience, in which the mind reflects on its own activities. Human knowledge of external physical objects, he claimed, is always subject to the errors of the senses, and he concluded that one cannot have absolutely certain knowledge of the physical world.

Irish-born philosopher and clergyman George Berkeley (1685-1753) argued that everything that human beings conceive of exists as an idea in a mind, a philosophical focus which is known as idealism. Berkeley reasoned that because one cannot control one’s thoughts, they must come directly from a larger mind: that of God. In this excerpt from his Treatise Concerning the Principles of Human Knowledge, written in 1710, Berkeley explained why he believed that it is “impossible … that there should be any such thing as an outward object.”

The Irish philosopher George Berkeley agreed with Locke that knowledge comes through ideas, but he denied Locke's belief that a distinction can be made between ideas and objects. The British philosopher David Hume continued the empiricist tradition, but he did not accept Berkeley's conclusion that knowledge was of ideas only. He divided all knowledge into two kinds: knowledge of relations of ideas-that is, the knowledge found in mathematics and logic, which is exact and certain but no information about the world; and knowledge of matters of fact-that is, the knowledge derived from sense perception. Hume argued that most knowledge of matters of fact depends upon cause and effect, and since no logical connection exists between any given cause and its effect, one cannot hope to know any future matter of fact with certainty. Thus, the most reliable laws of science might not remain true—a conclusion that had a revolutionary impact on philosophy.

The German philosopher Immanuel Kant tried to solve the crisis precipitated by Locke and brought to a climax by Hume; his proposed solution combined elements of rationalism with elements of empiricism. He agreed with the rationalists that one can have exact and certain knowledge, but he followed the empiricists in holding that such knowledge is more informative about the structure of thought than about the world outside of thought. He distinguished three kinds of knowledge: analytical a priori, which is exact and certain but uninformative, because it makes clear only what is contained in definitions; synthetic a posteriori, which conveys information about the world learned from experience, but is subject to the errors of the senses; and synthetic a priori, which is discovered by pure intuition and is both exact and certain, for it expresses the necessary conditions that the mind imposes on all objects of experience. Mathematics and philosophy, according to Kant, provide this last. Since the time of Kant, one of the most frequently argued questions in philosophy has been whether or not such a thing as synthetic a priori knowledge really exists.

During the 19th century, the German philosopher Georg Wilhelm Friedrich Hegel revived the rationalist claim that absolutely certain knowledge of reality can be obtained by equating the processes of thought, of nature, and of history. Hegel inspired an interest in history and a historical approach to knowledge that was further emphasized by Herbert Spencer in Britain and by the German school of historicism. Spencer and the French philosopher Auguste Comte brought attention to the importance of sociology as a branch of knowledge, and both extended the principles of empiricism to the study of society.

The American school of pragmatism, founded by the philosophers Charles Sanders Peirce, William James, and John Dewey at the turn of this century, carried empiricism further by maintaining that knowledge is an instrument of action and that all beliefs should be judged by their usefulness as rules for predicting experiences.

In the early 20th century, epistemological problems were discussed thoroughly, and subtle shades of difference grew into rival schools of thought. Special attention was given to the relation between the act of perceiving something, the object directly perceived, and the thing that can be said to be known as a result of the perception. The phenomenalists contended that the objects of knowledge are the same as the objects perceived. The neorealists argued that one has direct perceptions of physical objects or parts of physical objects, rather than of one's own mental states. The critical realists took a middle position, holding that although one perceives only sensory data such as colours and sounds, these stand for physical objects and provide knowledge thereof.

A method for dealing with the problem of clarifying the relation between the act of knowing and the object known was developed by the German philosopher Edmund Husserl. He outlined an elaborate procedure that he called phenomenology, by which one is said to be able to distinguish the way things appear to be from the way one thinks they really are, thus gaining a more precise understanding of the conceptual foundations of knowledge.

During the second quarter of the 20th century, two schools of thought emerged, each indebted to the Austrian philosopher Ludwig Wittgenstein. The first of these schools, logical empiricism, or logical positivism, had its origins in Vienna, Austria, but it soon spread to England and the United States. The logical empiricists insisted that there is only one kind of knowledge: scientific knowledge; that any valid knowledge claim must be verifiable in experience; and hence that much that had passed for philosophy was neither true nor false but literally meaningless. Finally, following Hume and Kant, a clear distinction must be maintained between analytic and synthetic statements. The so-called verifiability criterion of meaning has undergone changes as a result of discussions among the logical empiricists themselves, as well as their critics, but has not been discarded. More recently, the sharp distinction between the analytic and the synthetic has been attacked by a number of philosophers, chiefly by American philosopher W.V.O. Quine, whose overall approach is in the pragmatic tradition.

The latter of these recent schools of thought, generally referred to as linguistic analysis, or ordinary language philosophy, seems to break with traditional epistemology. The linguistic analysts undertake to examine the actual way key epistemological terms are used—terms such as knowledge, perception, and probability—and to formulate definitive rules for their use in order to avoid verbal confusion. British philosopher John Langshaw Austin argued, for example, that to say a statement was true added nothing to the statement except a promise by the speaker or writer. Austin does not consider truth a quality or property attaching to statements or utterances. However, the ruling thought is that it is only through a correct appreciation of the role and point of this language that we can come to a better conception of what the language is about, and avoid the oversimplifications and distortion we are apt to bring to its subject matter.

Linguistics is the scientific study of language. It encompasses the description of languages, the study of their origin, and the analysis of how children acquire language and how people learn languages other than their own. Linguistics is also concerned with relationships between languages and with the ways languages change over time. Linguists may study language as a thought process and seek a theory that accounts for the universal human capacity to produce and understand language. Some linguists examine language within a cultural context. By observing talk, they try to determine what a person needs to know in order to speak appropriately in different settings, such as the workplace, among friends, or among family. Other linguists focus on what happens when speakers from different language and cultural backgrounds interact. Linguists may also concentrate on how to help people learn another language, using what they know about the learner’s first language and about the language being acquired.

Although there are many ways of studying language, most approaches belong to one of the two main branches of linguistics: descriptive linguistics and comparative linguistics.

Descriptive linguistics is the study and analysis of spoken language. The techniques of descriptive linguistics were devised by German American anthropologist Franz Boas and American linguist and anthropologist Edward Sapir in the early 1900s to record and analyze Native American languages. Descriptive linguistics begins with what a linguist hears native speakers say. By listening to native speakers, the linguist gathered a body of data and analysed it in order to identify distinctive sounds, called phonemes. Individual phonemes, such as /p/ and /b/, are established on the grounds that substitution of one for the other changes the meaning of a word. After identifying the entire inventory of sounds in a language, the linguist looks at how these sounds combine to create morphemes, or units of sound that carry meaning, such as the words push and bush. Morphemes may be individual words such as push; root words, such as berry in blueberry; or prefixes (pre- in preview) and suffixes (-ness in openness).

The linguist’s next step is to see how morphemes combine into sentences, obeying both the dictionary meaning of the morpheme and the grammatical rules of the sentence. In the sentence “She pushed the bush,” the morpheme she, a pronoun, is the subject; push, a transitive verb, is the verb; the, a definite article, is the determiner; and bush, a noun, is the object. Knowing the function of the morphemes in the sentence enables the linguist to describe the grammar of the language. The scientific procedures of phonemics (finding phonemes), morphology (discovering morphemes), and syntax (describing the order of morphemes and their function) provide descriptive linguists with a way to write down grammars of languages never before written down or analysed. In this way they can begin to study and understand these languages.

Comparative linguistics is the study and analysis, by means of written records, of the origins and relatedness of different languages. In 1786 Sir William Jones, a British scholar, asserted that Sanskrit, Greek, and Latin were related to one another and had descended from a common source. He based this assertion on observations of similarities in sounds and meanings among the three languages. For example, the Sanskrit word bhratar for “brother” resembles the Latin word phrater, the Greek word phrater, (and the English word brother).

Other scholars went on to compare Icelandic with Scandinavian languages, and Germanic languages with Sanskrit, Greek, and Latin. The correspondences among languages, known as genetic relationships, came to be represented on what comparative linguists refer to as family trees. Family trees established by comparative linguists include the Indo-European, relating Sanskrit, Greek, Latin, German, English, and other Asian and European languages; the Algonquian, relating Fox, Cree, Menomini, Ojibwa, and other Native North American languages; and the Bantu, relating Swahili, Xhosa, Zulu, Kikuyu, and other African languages.

Comparative linguists also look for similarities in the way words are formed in different languages. Latin and English, for example, change the form of a word to express different meanings, as when the English verb go changes to go and gone to express a past action. Chinese, on the other hand, has no such inflected forms; the verb remains the same while other words indicate the time (as in “go store tomorrow”). In Swahili, prefixes, suffixes, and infixes (additions in the body of the word) combine with a root word to change its meaning. For example, a single word might express when something was done, by whom, to whom, and in what manner.

Some comparative linguists reconstruct hypothetical ancestral languages known as proto-languages, which they use to demonstrate relatedness among contemporary languages. A proto-language is not intended to depict a real language, however, and does not represent the speech of ancestors of people speaking modern languages. Unfortunately, some groups have mistakenly used such reconstructions in efforts to demonstrate the ancestral homeland of a people.

Comparative linguists have suggested that certain basic words in a language do not change over time, because people are reluctant to introduce new words for such constants as arm, eye, or mother. These words are termed culture free. By comparing lists of culture-free words in languages within a family, linguists can derive the percentage of related words and use a formula to figure out when the languages separated from one another.

By the 1960s comparativists were no longer satisfied with focussing on origins, migrations, and the family tree method. They challenged as unrealistic the notion that an earlier language could remain sufficiently isolated for other languages to be derived exclusively from it over a period of time. Today comparativists seek to understand the more complicated reality of language history, taking language contact into account. They are concerned with universal characteristics of language and with comparisons of grammars and structures.

The field of linguistics both borrows from and lends its own theories and methods to other disciplines. The many subfields of linguistics have expanded our understanding of languages. Linguistic theories and methods are also used in other fields of study. These overlapping interests have led to the creation of several cross-disciplinary fields.

Sociolinguistics is the study of patterns and variations in language within a society or community. It focuses on the way people use language to express social class, group status, gender, or ethnicity, and it looks at how they make choices about the form of language they use. It also examines the way people use language to negotiate their role in society and to achieve positions of power. For example, sociolinguistic studies have found that the way a New Yorker pronounces the phoneme /r/ in an expression such as “fourth floor” can indicate the person’s social class. According to one study, people aspiring to move from the lower middle class to the upper middle class attach prestige to pronouncing the /r/. Sometimes they even overcorrect their speech, pronouncing a /r/ where those whom they wish to copy may not.

Some sociolinguists believe that analysing such variables as the use of a particular phoneme can predict the direction of language change. Change, they say, moves toward the variable associated with power, prestige, or other quality having high social value. Other sociolinguists focus on what happens when speakers of different languages interact. This approach to language change emphasizes the way languages mix rather than the direction of change within a community. The goal of Sociolinguistics is to understand communicative competence—what people need to know to use the appropriate language for a given social setting.

Psycholinguistics merges the fields of psychology and linguistics to study how people process language and how language use is related to underlying mental processes. Studies of children’s language acquisition and of second-language acquisition are psycholinguistic in nature. Psycholinguists work to develop models for how language is processed and understood, using evidence from studies of what happens when these processes go awry. They also study language disorders such as aphasia (impairment of the ability to use or comprehend words) and dyslexia (impairment of the ability to make out written language).

Computational linguistics involves the use of computers to compile linguistic data, analyze languages, translate from one language to another, and develop and test models of language processing. Linguists use computers and large samples of actual language to analyze the relatedness and the structure of languages and to look for patterns and similarities. Computers also aid in stylistic studies, information retrieval, various forms of textual analysis, and the construction of dictionaries and concordances. Applying computers to language studies has resulted in machine translation systems and machines that recognize and produce speech and text. Such machines facilitate communication with humans, including those who are perceptually or linguistically impaired.

Applied linguistics employs linguistic theory and methods in teaching and in research on learning a second language. Linguists look at the errors people make as they learn another language and at their strategies for communicating in the new language at different degrees of competence. In seeking to understand what happens in the mind of the learner, applied linguists recognize that motivation, attitude, learning style, and personality affect how well a person learns another language.

Anthropological linguistics, also known as linguistic anthropology, uses linguistic approaches to analyze culture. Anthropological linguists examine the relationship between a culture and its language. The way cultures and languages have changed over time, and how different cultures and languages are related to one another. For example, the present English use of family and given names arose in the late 13th and early 14th centuries when the laws concerning registration, tenure, and inheritance of property were changed.

Philosophical linguistics examines the philosophy of language. Philosophers of language search for the grammatical principles and tendencies that all human languages share. Among the concerns of linguistic philosophers is the range of possible word order combinations throughout the world. One finding is that 95 percent of the world’s languages use a subject-verb-object (SVO) order as English does (“She pushed the bush.”). Only 5 percent use a subject-object-verb (SOV) order or verb-subject-object (VSO) order.

Neurolinguistics is the study of how language is processed and represented in the brain. Neurolinguists seek to identify the parts of the brain involved with the production and understanding of language and to determine where the components of language (phonemes, morphemes, and structure or syntax) are stored. In doing so, they make use of techniques for analysing the structure of the brain and the effects of brain damage on language.

Speculation about language goes back thousands of years. Ancient Greek philosophers speculated on the origins of language and the relationship between objects and their names. They also discussed the rules that govern language, or grammar, and by the 3rd century Bc they had begun grouping words into parts of speech and devising names for different forms of verbs and nouns.

In India religion provided the motivation for the study of language nearly 2500 years ago. Hindu priests noted that the language they spoke had changed since the compilation of their ancient sacred texts, the Vedas, starting about 1000 Bc. They believed that for certain religious ceremonies based upon the Vedas to succeed, they needed to reproduce the language of the Vedas precisely. Panini, an Indian grammarian who lived about 400 Bc, produced the earliest work describing the rules of Sanskrit, the ancient language of India.

The Romans used Greek grammars as models for their own, adding commentary on Latin style and usage. Statesman and orator Marcus Tullius Cicero wrote on rhetoric and style in the 1st century Bc. Later grammarian’s Aelius Donatus (4th century ad) and Priscian (6th century ad) produced detailed Latin grammars. Roman works served as textbooks and standards for the study of language for more than 1000 years.

It was not until the end of the 18th century that language was researched and studied in a scientific way. During the 17th and 18th centuries, modern languages, such as French and English, replaced Latin as the means of universal communication in the West. This occurrence, along with developments in printing, meant that many more texts became available. At about this time, the study of phonetics, or the sounds of a language, began. Such investigations led to comparisons of sounds in different languages; in the late 18th century the observation of correspondences among Sanskrit, Latin, and Greek gave birth to the field of Indo-European linguistics.

During the 19th century, European linguists focussed on philology, or the historical analysis and comparison of languages. They studied written texts and looked for changes over time or for relationships between one language and another.

American linguist, writer, teacher, and political activist Noam Chomsky is considered the founder of transformational-generative linguistic analysis, which revolutionized the field of linguistics. This system of linguistics treats grammar as a theory of language—that is, Chomsky believes that in addition to the rules of grammar specific to individual languages, there are universal rules common to all languages that indicate that the ability to form and understand language is innate to all human beings. Chomsky also is well known for his political activism—he opposed United States involvement in Vietnam in the 1960s and 1970s and has written various books and articles and delivered many lectures in an attempt to educate and empower people on various political and social issues.

In the early 20th century, linguistics expanded to include the study of unwritten languages. In the United States linguists and anthropologists began to study the rapidly disappearing spoken languages of Native North Americans. Because many of these languages were unwritten, researchers could not use historical analysis in their studies. In their pioneering research on these languages, anthropologists’ Franz Boas and Edward Sapir developed the techniques of descriptive linguistics and theorized on the ways in which language shapes our perceptions of the world.

An important outgrowth of descriptive linguistics is a theory known as structuralism, which assumes that language is a system with a highly organized structure. Structuralism began with publication of the work of Swiss linguist Ferdinand de Saussure in Cours de linguistique générale (1916; Course in General Linguistics, 1959). This work, compiled by Saussure’s students after his death, is considered the foundation of the modern field of linguistics. Saussure made a distinction between actual speech, and spoken language, and the knowledge underlying speech that speakers share about what is grammatical. Speech, he said, represents instances of grammar, and the linguist’s task is to find the underlying rules of a particular language from examples found in speech. To the structuralist, grammar is a set of relationships that account for speech, rather than a set of instances of speech, as it is to the descriptivist.

Once linguists began to study language as a set of abstract rules that somehow account for speech, other scholars began to take an interest in the field. They drew analogies between language and other forms of human behaviour, based on the belief that a shared structure underlies many aspects of a culture. Anthropologists, for example, became interested in a structuralist approach to the interpretation of kinship systems and analysis of myth and religion. American linguist Leonard Bloomfield promoted structuralism in the United States.

Saussure’s ideas also influenced European linguistics, most notably in France and Czechoslovakia (now the Czech Republic). In 1926 Czech linguist Vilem Mathesius founded the Linguistic Circle of Prague, a group that expanded the focus of the field to include the context of language use. The Prague circle developed the field of phonology, or the study of sounds, and demonstrated that universal features of sounds in the languages of the world interrelate in a systematic way. Linguistic analysis, they said, should focus on the distinctiveness of sounds rather than on the ways they combine. Where descriptivists tried to locate and describe individual phonemes, such as /b/ and /p/, the Prague linguists stressed the features of these phonemes and their interrelationships in different languages. In English, for example, the voice distinguishes between the similar sounds of /b/ and /p/, but these are not distinct phonemes in a number of other languages. An Arabic speaker might pronounce the cities Pompei and Bombay the same way.

As linguistics developed in the 20th century, the notion became prevalent that language is more than speech—specifically, that it is an abstract system of interrelationships shared by members of a speech community. Structural linguistics led linguists to look at the rules and the patterns of behaviour shared by such communities. Whereas structural linguists saw the basis of language in the social structure, other linguists looked at language as a mental process.

The 1957 publication of Syntactic Structures by American linguist Noam Chomsky initiated what many view as a scientific revolution in linguistics. Chomsky sought a theory that would account for both linguistic structure and the creativity of language—the fact that we can create entirely original sentences and understand sentences never before uttered. He proposed that all people have an innate ability to acquire language. The task of the linguist, he claimed, is to describe this universal human ability, known as language competence, with a grammar from which the grammars of all languages could be derived. The linguist would develop this grammar by looking at the rules children use in hearing and speaking their first language. He termed the resulting model, or grammar, a transformational-generative grammar, referring to the transformations (or rules) that generate (or account for) language. Certain rules, Chomsky asserted, are shared by all languages and form part of a universal grammar, while others are language specific and associated with particular speech communities. Since the 1960s much of the development in the field of linguistics has been a reaction to or against Chomsky’s theories.

At the end of the 20th century, linguists used the term grammar primarily to refer to a subconscious linguistic system that enables people to produce and comprehend an unlimited number of utterances. Grammar thus accounts for our linguistic competence. Observations about the actual language we use, or language performance, are used to theorize about this invisible mechanism known as grammar.

The orientation toward the scientific study of language led by Chomsky has had an impact on nongenerative linguists as well. Comparative and historically oriented linguists are looking for the various ways linguistic universals show up in individual languages. Psycholinguists, interested in language acquisition, are investigating the notion that an ideal speaker-hearer is the origin of the acquisition process. Sociolinguists are examining the rules that underlie the choice of language variants, or codes, and allow for switching from one code to another. Some linguists are studying language performance—the way people use language—to see how it reveals a cognitive ability shared by all human beings. Others seek to understand animal communication within such a framework. What mental processes enable chimpanzees to make signs and communicate with one another and how do these processes differ from those of humans?

A written bibliographic note in gratification to Ludwig Wittgenstein (1889-1951), an Austrian-British philosopher, who was one of the most influential thinkers of the 20th century, particularly noted for his contribution to the movement known as analytic and linguistic philosophy.

Born in Vienna on April 26, 1889, Wittgenstein was raised in a wealthy and cultured family. After attending schools in Linz and Berlin, he went to England to study engineering at the University of Manchester. His interest in pure mathematics led him to Trinity College, University of Cambridge, to study with Bertrand Russell. There he turned his attention to philosophy. By 1918 Wittgenstein had completed his Tractatus Logico-philosophicus (1921; trans. 1922), a work he then believed provided the “final solution” to philosophical problems. Subsequently, he turned from philosophy and for several years taught elementary school in an Austrian village. In 1929 he returned to Cambridge to resume his work in philosophy and was appointed to the faculty of Trinity College. Soon he began to reject certain conclusions of the Tractatus and to develop the position reflected in his Philosophical Investigations (pub. posthumously 1953; trans. 1953). Wittgenstein retired in 1947; he died in Cambridge on April 29, 1951. A sensitive, intense man who often sought solitude and was frequently depressed, Wittgenstein abhorred pretense and was noted for his simple style of life and dress. The philosopher was forceful and confident in personality, however, and he exerted considerable influence on those with whom he came in contact.

Wittgenstein’s philosophical life may be divided into two distinct phases: an early period, represented by the Tractatus, and a later period, represented by the Philosophical Investigations. Throughout most of his life, however, Wittgenstein consistently viewed philosophy as linguistic or conceptual analysis. In the Tractatus he argued that “philosophy aims at the logical clarification of thoughts.” In the Philosophical Investigations, however, he maintained that “philosophy is a battle against the bewitchment of our intelligence by means of language.”

Language, Wittgenstein argued in the Tractatus, is composed of complex propositions that can be analysed into less complex propositions until one arrives at simple or elementary propositions. Correspondingly, the world is composed of complex facts that can be analysed into less complex facts until one arrives at simple, or atomic, facts. The world is the totality of these facts. According to Wittgenstein’s picture theory of meaning, it is the nature of elementary propositions logically to picture atomic facts, or “states of affairs.” He claimed that the nature of language required elementary propositions, and his theory of meaning required that there be atomic facts pictured by the elementary propositions. On this analysis, only propositions that picture facts—the propositions of science—are considered cognitively meaningfully. Metaphysical and ethical statements are not meaningful assertions. The logical positivists associated with the Vienna Circle were greatly influenced by this conclusion (see Positivism).

Wittgenstein came to believe, however, that the narrow view of language reflected in the Tractatus was mistaken. In the Philosophical Investigations he argued that if one actually looks to see how language is used, the variety of linguistic usage becomes clear. Words are like tools, and just as tools serve different functions, so linguistic expressions serve many functions. Although some propositions are used to picture facts, others are used to command, question, pray, thank, curse, and so on. This recognition of linguistic flexibility and variety led to Wittgenstein’s concept of a language game and to the conclusion that people play different language games. The scientist, for example, is involved in a different language game than the theologian. Moreover, the meaning of a proposition must be understood in terms of its context, that is, in terms of the rules of the game of which that proposition is a part. The key to the resolution of philosophical puzzles is the therapeutic process of examining and describing language in use.

Analytic and Linguistic Philosophy, is a product out of the 20th-century philosophical movement, and dominant in Britain and the United States since World War II, that aims to clarify language and analyze the concepts expressed in it. The movement has been given a variety of designations, including linguistic analysis, logical empiricism, logical positivism, Cambridge analysis, and ‘Oxford philosophy’. The last two labels are derived from the universities in England where this philosophical method has been particularly influential. Although no specific doctrines or tenets are accepted by the movement as a whole, analytic and linguistic philosophers agree that the proper activity of philosophy is clarifying language, or, as some prefer, clarifying concepts. The aim of this activity is to settle philosophical disputes and resolve philosophical problems, which, it is argued, originate in linguistic confusion.

A considerable diversity of views exists among analytic and linguistic philosophers regarding the nature of conceptual or linguistic analysis. Some have been primarily concerned with clarifying the meaning of specific words or phrases as an essential step in making philosophical assertions clear and unambiguous. Others have been more concerned with determining the general conditions that must be met for any linguistic utterance to be meaningful; their intent is to establish a criterion that will distinguish between meaningful and nonsensical sentences. Still other analysts have been interested in creating formal, symbolic languages that are mathematical in nature. Their claim is that philosophical problems can be more effectively dealt with once they are formulated in a rigorous logical language.

By contrast, many philosophers associated with the movement have focussed on the analysis of ordinary, or natural, language. Difficulties arise when concepts such as time and freedom, for example, are considered apart from the linguistic context in which they normally appear. Attention to language as it is ordinarily put-upon for the considered liking, it is argued, to resolving many philosophical puzzles.

Linguistic analysis as a method of philosophy is as old as the Greeks. Several of the dialogues of Plato, for example, are specifically concerned with clarifying terms and concepts. Nevertheless, this style of philosophizing has received dramatically renewed emphasis in the 20th century. Influenced by the earlier British empirical tradition of John Locke, George Berkeley, David Hume, and John Stuart Mill and by the writings of the German mathematician and philosopher Gottlob Frigg, the 20th-century English philosopher’s G. E. Moore and Bertrand Russell became the founders of this contemporary analytic and linguistic trend. As students together at the University of Cambridge, Moore and Russell rejected Hegelian idealism, particularly as it was reflected in the work of the English metaphysician F. H. Bradley, who held that nothing is completely real except the Absolute. In their opposition to idealism and in their commitment to the view that careful attention to language is crucial in philosophical inquiry. They set the mood and style of philosophizing for much of the 20th century English-speaking world.

For Moore, philosophy was first and foremost analysis. The philosophical task involves clarifying puzzling propositions or concepts by indicating less puzzling propositions or concepts to which the originals are held to be logically equivalent. Once this task has been completed, the truth or falsity of problematic philosophical assertions can be determined more adequately. Moore was noted for his careful analyses of such puzzling philosophical claims as “time is unreal,” analyses that then aided in determining the truth of such assertions.

Russell, strongly influenced by the precision of mathematics, was concerned with developing an ideal logical language that would accurately reflect the nature of the world. Complex propositions, Russell maintained, can be resolved into their simplest components, which he called atomic propositions. These propositions refer to atomic facts, the ultimate constituents of the universe. The metaphysical view based on this logical analysis of language and the insistence that meaningful propositions must correspond to facts constitute what Russell called logical atomism. His interest in the structure of language also led him to distinguish between the grammatical form of a proposition and its logical form. The statements ‘John is good’ and ‘John is tall’ have the same grammatical form but different logical forms. Failure to recognize this would lead one to treat the property ‘goodness’ as if it were a characteristic of John in the same way that the property ‘tallness’ is a characteristic of John. Such failure results in philosophical confusion.

Russell’s work in mathematics attracted to Cambridge the Austrian philosopher Ludwig Wittgenstein, who became a central figure in the analytic and linguistic movement. In his first major work, Tractatus Logico-Philosophicus (1921; trans. 1922), in which he first presented his theory of language, Wittgenstein argued that ‘all philosophy is a ‘critique of language’ and that ‘philosophy aims at the logical clarification of thoughts’. The results of Wittgenstein’s analysis resembled Russell’s logical atomism. The world, he argued, is ultimately composed of simple facts, which it is the purpose of language to picture. To be meaningful, statements about the world must be reducible to linguistic utterances that have a structure similar to the simple facts pictured. In this early Wittgensteinian analysis, only propositions that picture facts-the propositions of science-are considered factually meaningful. Metaphysical, theological, and ethical sentences were judged to be factually meaningless.

Influenced by Russell, Wittgenstein, Ernst Mach, and others, a group of philosophers and mathematicians in Vienna in the 1920s initiated the movement known as logical positivism. Led by Moritz Schlick and Rudolf Carnap, the Vienna Circle initiated one of the most important chapters in the history of analytic and linguistic philosophy. According to the positivists, the task of philosophy is the clarification of meaning, not the discovery of new facts (the job of the scientists) or the construction of comprehensive accounts of reality (the misguided pursuit of traditional metaphysics).

The positivists divided all meaningful assertions into two classes: analytic propositions and empirically verifiable ones. Analytic propositions, which include the propositions of logic and mathematics, are statements the truth or falsity of which depend altogether on the meanings of the terms constituting the statement. An example would be the proposition “two plus two equals four.” The second class of meaningful propositions includes all statements about the world that can be verified, at least in principle, by sense experience. Indeed, the meaning of such propositions is identified with the empirical method of their verification. This verifiability theory of meaning, the positivists concluded, would demonstrate that scientific statements are legitimate factual claims and that metaphysical, religious, and ethical sentences are factually empty. The ideas of logical positivism were made popular in England by the publication of

A.J. Ayer’s Language, Truth and Logic in 1936.

The positivists’ verifiability theory of meaning came under intense criticism by philosophers such as the Austrian-born British philosopher Karl Popper. Eventually this narrow theory of meaning yielded to a broader understanding of the nature of language. Again, an influential figure was Wittgenstein. Repudiating many of his earlier conclusions in the Tractatus, he initiated a new line of thought culminating in his posthumously published Philosophical Investigations (1953; trans. 1953). In this work, Wittgenstein argued that once attention is directed to the way language is actually used in ordinary discourse, the variety and flexibility of language become clear. Propositions do much more than simply picture facts.

This recognition led to Wittgenstein’s influential concept of language games. The scientist, the poet, and the theologian, for example, are involved in different language games. Moreover, the meaning of a proposition must be understood in its context, that is, in terms of the rules of the language game of which that proposition is a part. Philosophy, concluded Wittgenstein, is an attempt to resolve problems that arise as the result of linguistic confusion, and the key to the resolution of such problems is ordinary language analysis and the proper use of language.

Additional contributions within the analytic and linguistic movement include the work of the British philosopher’s Gilbert Ryle, John Austin, and P. F. Strawson and the American philosopher W. V. Quine. According to Ryle, the task of philosophy is to restate ‘systematically misleading expressions’ in forms that are logically more accurate. He was particularly concerned with statements the grammatical form of which suggests the existence of nonexistent objects. For example, Ryle is best known for his analysis of mentalistic language, language that misleadingly suggests that the mind is an entity in the same way as the body.

Austin maintained that one of the most fruitful starting points for philosophical inquiry is attention to the extremely fine distinctions drawn in ordinary language. His analysis of language eventually led to a general theory of speech acts, that is, to a description of the variety of activities that an individual may be performing when something is uttered.

Strawson is known for his analysis of the relationship between formal logic and ordinary language. The complexity of the latter, he argued, is inadequately represented by formal logic. A variety of analytic tools, therefore, is needed in addition to logic in analysing ordinary language.

Quine discussed the relationship between language and ontology. He argued that language systems tend to commit their users to the existence of certain things. For Quine, the justification for speaking one way rather than another is a thoroughly pragmatic one.

The commitment to language analysis as a way of pursuing philosophy has continued as a significant contemporary dimension in philosophy. A division also continues to exist between those who prefer to work with the precision and rigour of symbolic logical systems and those who prefer to analyze ordinary language. Although few contemporary philosophers maintain that all philosophical problems are linguistic, the view continues to be widely held that attention to the logical structure of language and to how language is used in everyday discourse can often aid in resolving philosophical problems

Is term of logical calculus is also called a formal language, and a logical system? A system in which explicit rules are provided to determining (1) which are the expressions of the system (2) which sequence of expressions count as well formed (well-forced formulae) (3) which sequence would count ss proofs. A system may include axioms for which leaves terminate a proof, however, it shows of the prepositional calculus and the predicated calculus.

Its most immediate of issues surrounding certainty are especially connected with those concerning ‘scepticism’. Although Greek scepticism entered on the value of enquiry and questioning, scepticism is now the denial that knowledge or even rational belief is possible, either about some specific subject-matter, e.g., ethics, or in any area whatsoever. Classical scepticism, springs from the observation that the best methods in some area seems to fall short of giving us contact with the truth, e.g., there is a gulf between appearances and reality, it frequently cites the conflicting judgements that our methods deliver, with the result that questions of truth become undefinable. In classic thought the various examples of this conflict were systemized in the tropes of Aenesidemus. So that, the scepticism of Pyrrho and the new Academy was a system of argument and inasmuch as opposing dogmatism, and, particularly the philosophical system building of the Stoics.

As it has come down to us, particularly in the writings of Sextus Empiricus, its method was typically to cite reasons for finding our issue undesirable (sceptics devoted particular energy to undermining the Stoics conception of some truths as delivered by direct apprehension or some katalepsis). As a result the sceptics concludes eposhé, or the suspension of belief, and then go on to celebrate a way of life whose object was ataraxia, or the tranquillity resulting from suspension of belief.

Fixed by its will for and of itself, the mere mitigated scepticism which accepts everyday or commonsense belief, is that, not the delivery of reason, but as due more to custom and habit. Nonetheless, it is self-satisfied at the proper time, however, the power of reason to give us much more. Mitigated scepticism is thus closer to the attitude fostered by the accentuations from Pyrrho through to Sextus Expiricus. Despite the fact that the phrase ‘Cartesian scepticism’ is sometimes used. Descartes himself was not a sceptic, however, in the ‘method of doubt’ uses a sceptical scenario in order to begin the process of finding a general distinction to mark its point of knowledge. Descartes trusts in categories of ‘clear and distinct’ ideas, not far removed from the phantasiá kataleptikê of the Stoics.

For many sceptics had traditionally held that knowledge requires certainty, artistry. And, of course, they claim that certain knowledge is not possible. In part, nonetheless, of the principle that every effect it’s a consequence of an antecedent cause or causes. For causality to be true it is not necessary for an effect to be predictable as the antecedent causes may be numerous, too complicated, or too interrelated for analysis. Nevertheless, in order to avoid scepticism, this participating sceptic has generally held that knowledge does not require certainty. Except for alleged cases of things that are evident for one just by being true. It has often been thought, that any thing known must satisfy certain criteria as well for being true. It is often taught that anything is known must satisfy certain standards. In so saying, that by ‘deduction’ or ‘induction’, there will be criteria specifying when it is. As these alleged cases of self-evident truths, the general principle specifying the sort of consideration that will make such standards in the apparent or justly conclude in accepting it warranted to some degree.

Besides, there is another view-the absolute globular view that we do not have any knowledge whatsoever. In whatever manner,

It is doubtful that any philosopher seriously entertains of an absolute scepticism. Even the Pyrrhonist sceptics, who held that we should refrain from accenting to any non-evident standards that no such hesitancy about asserting to ‘the evident’, the non-evident is any belief that requires evidences because it is warranted.

René Descartes (1596-1650), in his sceptical guise, never doubted the content of his own ideas. Its challenging logic, inasmuch as of whether they ‘corresponded’ to anything beyond ideas.

All the same, Pyrrhonism and Cartesian form of a virtual globular scepticism, in having been held and defended, that of assuming that knowledge is some form of true, sufficiently warranted belief, it is the warranted condition that provides the truth or belief conditions, in that of providing the grist for the sceptic’s mill about. The Pyrrhonist will suggest that no non-evident, empirically deferring the sufficiency of giving in but warranted. Whereas, a Cartesian sceptic will agree that no empirical standard about anything other than one’s own mind and its contents is sufficiently warranted, because there are always legitimate grounds for doubting it. In which, the essential difference between the two views concerns the stringency of the requirements for a belief being sufficiently warranted to take account of as knowledge.

A Cartesian requires certainty. A Pyrrhonist merely requires that the standards in case are more warranted then its negation.

Cartesian scepticism was by an unduly influence with which Descartes agues for scepticism, than his reply holds, in that we do not have any knowledge of any empirical standards, in that of anything beyond the contents of our own minds. The reason is roughly in the position that there is a legitimate doubt about all such standards, only because there is no way to justifiably deny that our senses are being stimulated by some sense, for which it is radically different from the objects which we normally think, in whatever manner they affect our senses. Therefrom, if the Pyrrhonist are the agnostics, the Cartesian sceptic is the atheist.

Because the Pyrrhonist require much less of a belief in order for it to be confirmed as knowledge than do the Cartesian, the argument for Pyrrhonism are much more difficult to construct. A Pyrrhonist must show that there is no better set of reasons for believing to any standards, of which are in case that any knowledge learnt of the mind is understood by some of its forms, that has to require certainty.

The underlying latencies that are given among the many derivative contributions as awaiting their presence to the future that of specifying to the theory of knowledge, is, but, nonetheless, the possibility to identify a set of shared doctrines, however, identity to discern two broad styles of instances to discern, in like manner, these two styles of pragmatism, clarify the innovation that a Cartesian approval is fundamentally flawed, nonetheless, of responding very differently but not fordone.

Repudiating the requirements of absolute certainty or knowledge, insisting on the connection of knowledge with activity, as, too, of pragmatism of a reformist distributing knowledge upon the legitimacy of traditional questions about the truth-unconductiveness of our cognitive practices, and sustain a conception of truth objectives, enough to give those questions that undergo of a gathering in their own purposive latencies, yet we are given to the spoken word for which a dialectic awareness sparks the flame from the ambers of fire.

Pragmatism of a determinant revolution, by contrast, relinquishing the objectivity of youth, acknowledges no legitimate epistemological questions over and above those that are naturally kindred of our current cognitive conviction.

It seems clear that certainty is a property that can be assembled to either a person or a belief. We can say that a person, ‘S’ is certain, or we can say that its descendable alinement are aligned as of ‘p’, is certain. The two uses can be connected by saying that ‘S’ has the right to be certain just in case the value of ‘p’ is sufficiently verified.

In defining certainty, it is crucial to note that the term has both an absolute and relative sense. More or less, we take a proposition to be certain when we have no doubt about its truth. We may do this in error or unreasonably, but objectively a proposition is certain when such absence of doubt is justifiable. The sceptical tradition in philosophy denies that objective certainty is often possible, or ever possible, either for any proposition at all, or for any proposition from some suspect family (ethics, theory, memory, empirical judgement etc.) a major sceptical weapon is the possibility of upsetting events that Can cast doubt back onto what were hitherto taken to be certainties. Others include reminders of the divergence of human opinion, and the fallible source of our confidence. Fundamentalist approaches to knowledge look for a basis of certainty, upon which the structure of our system is built. Others reject the metaphor, looking for mutual support and coherence, without foundation.

However, in moral theory, the view that there are inviolable moral standards or absolute variable human desires or policies or prescriptions.

In spite of the notorious difficulty of reading Kantian ethics, a hypothetical imperative embeds a command which is in place only given some antecedent desire or project: ‘If you want to look wise, stay quiet’. The injunction to stay quiet only applies to those with the antecedent desire or inclination. If one has no desire to look wise the injunction cannot be so avoided: It is a requirement that binds anybody, regardless of their inclination. It could be represented as, for example, ‘tell the truth (regardless of whether you want to or not)’. The distinction is not always signalled by presence or absence of the conditional or hypothetical form: ‘If you crave drink, don’t become a bartender’ may be regarded as an absolute injunction applying to anyone, although only activated in case of those with the stated desire.

In Grundlegung zur Metaphsik der Sitten (1785), Kant discussed five forms of the categorical imperative: (1) the formula of universal law: ‘act only on that maxim through which you can at the same times will that it should become universal law: (2) the formula of the law of nature: ‘act as if the maxim of your action were to become through your will a universal law of nature’: (3) the formula of the end-in-itself: ‘act in such a way that you always treat humanity, whether in your own person or in the person of any other, never simply as a means, but always at the same time as an end’: (4) the formula of autonomy, or considering ‘the will of every rational being as a will which makes universal law’: (5) the formula of the Kingdom of Ends, which provides a model for the systematic union of different rational beings under common laws.

Even so, a proposition that is not a conditional ‘p’. Moreover, the affirmative and negative, modern opinion is wary of this distinction, since what appears categorical may vary notation. Apparently, categorical propositions may also turn out to be disguised conditionals: ‘X’ is intelligent (categorical?) = if ‘X’ is given a range of tasks she performs them better than many people (conditional?) The problem. Nonetheless, is not merely one of classification, since deep metaphysical questions arise when facts that seem to be categorical and therefore solid, come to seem by contrast conditional, or purely hypothetical or potential.

A limited area of knowledge or endeavour to which pursuits, activities and interests are a central representation held to a concept of physical theory. In this way, a field is defined by the distribution of a physical quantity, such as temperature, mass density, or potential energy y, at different points in space. In the particularly important example of force fields, such ad gravitational, electrical, and magnetic fields, the field value at a point is the force which a test particle would experience if it were located at that point. The philosophical problem is whether a force field is to be thought of as purely potential, so the presence of a field merely describes the propensity of masses to move relative to each other, or whether it should be thought of in terms of the physically real modifications of a medium, whose properties result in such powers that is, are force fields purely potential, fully characterized by dispositional statements or conditionals, or are they categorical or actual? The former option seems to require within ungrounded dispositions, or regions of space hat differ only in what happens if an object is placed there. The law-like shape of these dispositions, apparent for example in the curved lines of force of the magnetic field, may then seem quite inexplicable. To atomists, such as Newton it would represent a return to Aristotelian entelechies, or quasi-psychological affinities between things, which are responsible for their motions. The latter option requires understanding of how forces of attraction and repulsion can be ‘grounded’ in the properties of the medium.

The basic idea of a field is arguably present in Leibniz, who was certainly hostile to Newtonian atomism. Despite the fact that his equally hostility to ‘action at a distance’ muddies the water. It is usually credited to the Jesuit mathematician and scientist Joseph Boscovich (1711-87) and Immanuel Kant (1724-1804), both of whom influenced the scientist Faraday, with whose work the physical notion became established. In his paper ‘On the Physical Character of the Lines of Magnetic Force’ (1852). Faraday was to suggest several criteria for assessing the physical reality of lines of force, such as whether they are affected by an intervening material medium, whether the motion depends on the nature of what is placed at the receiving end. As far as electromagnetic fields go, Faraday himself inclined to the view that the mathematical similarity between heat flow, currents, and electromagnetic lines of force was evidence for the physical reality of the intervening medium.

Once, again, our mentioning recognition for which its case value, whereby its view is especially associated the American psychologist and philosopher William James (1842-1910), that the truth of a statement can be defined in terms of a ‘utility’ of accepting it. Communicated, so much as a dispiriting position for which its place of valuation may be viewed as an objection. Since there are things that are false, as it may be useful to accept, and conversely there are things that are true and that it may be damaging to accept. Nevertheless, there are deep connections between the idea that a representation system is accorded, and the likely success of the projects in progressive formality, by its possession. The evolution of a system of representation either perceptual or linguistic, seems bounded to connect successes with everything adapting or with utility in the modest sense. The Wittgenstein doctrine stipulates the meaning of use that upon the nature of belief and its relations with human attitude, emotion and the idea that belief in the truth on one hand, the action of the other. One way of binding with cement, wherefore the connection is found in the idea that natural selection becomes much as much in adapting us to the cognitive creatures, because beliefs have effects, they work. Pragmatism can be found in Kant’s doctrine, and continued to play an influencing role in the theory of meaning and truth.

James, (1842-1910), although with characteristic generosity exaggerated in his debt to Charles S. Peirce (1839-1914), he charted that the method of doubt encouraged people to pretend to doubt what they did not doubt in their hearts, and criticize its individualist’s insistence, that the ultimate test of certainty is to be found in the individuals personalized consciousness.

From his earliest writings, James understood cognitive processes in teleological terms. Thought, he held, assists us in the satisfactory interests. His will to Believe doctrine, the view that we are sometimes justified in believing beyond the evidential relics upon the notion that a belief’s benefits are relevant to its justification. His pragmatic method of analysing philosophical problems, for which requires that we find the meaning of terms by examining their application to objects in experimental situations, similarly reflects the teleological approach in its attention to consequences.

Such an approach, however, set’s James’ theory of meaning apart from verification, dismissive of metaphysics. Unlike the verificationalist, who takes cognitive meaning to be a matter only of consequences in sensory experience. James’ took pragmatic meaning to include emotional and matter responses. Moreover, his ,metaphysical standard of value, not a way of dismissing them as meaningless. It should also be noted that in a greater extent, circumspective moment’s James did not hold that even his broad set of consequences were exhaustive of a terms meaning. ‘Theism’, for example, he took to have antecedent, definitional meaning, in addition to its varying degree of importance and chance upon an important pragmatic meaning.

James’ theory of truth reflects upon his teleological conception of cognition, by considering a true belief to be one which is compatible with our existing system of beliefs, and leads us to satisfactory interaction with the world.

However, Peirce’s famous pragmatist principle is a rule of logic employed in clarifying our concepts and ideas. Consider the claim the liquid in a flask is an acid, if, we believe this, we except that it would turn red: We except an action of ours to have certain experimental results. The pragmatic principle holds that listing the conditional expectations of this kind, in that we associate such immediacy with applications of a conceptual representation that provides a complete and orderly sets clarification of the concept. This is relevant ti the logic of abduction: Clarificationists using the pragmatic principle provides all the information about the content of a hypothesis that is relevantly to decide whether it is worth testing.

To a greater extent, and most important, is the famed apprehension of the pragmatic principle, in so that, Pierces’s account of reality: When we take something to be rea that by this single case, we think it is ‘fated to be agreed upon by all who investigate’ the matter to which it stand, in other words, if I believe that it is really the case that ‘P’, then I except that if anyone were to inquire depthfully into the finding its measure into whether ‘p’, they would arrive at the belief that ‘p’. It is not part of the theory that the experimental consequences of our actions should be specified by a warranted empiricist vocabulary-Peirce insisted that perceptual theories are abounding in latency. Even so, nor is it his view that the collected conditionals do or not clarify a concept as all analytic. In addition, in later writings, he argues that the pragmatic principle could only be made plausible to someone who accepted its metaphysical realism: It requires that ‘would-bees’ are objective and, of course, real.

If realism itself can be given a fairly quick clarification, it is more difficult to chart the various forms of supposition, for they seem legendary. Other opponents deny that the entitles posited by the relevant discourse that exist or at least exists: The standard example is ‘idealism’ that reality is somehow mind-curative or mind-co-ordinated-that real object comprising the ‘external world’ are not independently of eloping minds, but only exist as in some way correlative to the mental operations. The doctrine assembled of ‘idealism’ enters on the conceptual note that reality as we understand this as meaningful and reflects the working of mindful purposes. And it construes this as meaning that the inquiring mind itself makes of a formative constellations and not of any mere understanding of the nature of the ‘real’ bit even the resulting charger we attribute to it.

Wherefore, the term ids most straightforwardly used when qualifying another linguistic form of grammatik: a real ‘x’ may be contrasted with a fake, a failed ‘x’, a near ‘x’, and so on. To trat something as real, without qualification, is to suppose it to be part of the actualized world. To reify something is to suppose that we have committed by some indoctrinated treatise, as that of a theory. The central error in thinking of reality and the totality of existence is to think of the ‘unreal’ as a separate domain of things, perhaps, unfairly to that of the benefits of existence.

Such that non-existence of all things, as the product of logical confusion of treating the term ‘nothing’ as itself a referring expression instead of a ‘quantifier’. (Stating informally as a quantifier is an expression that reports of a quantity of times that a predicate is satisfied in some class of things, i.e., in a domain.) This confusion leads the unsuspecting to think that a sentence such as ‘Nothing is all around us’ talks of a special kind of thing that is all around us, when in fact it merely denies that the predicate ‘is all around us’ has appreciations. The feelings that lad some philosophers and theologians, notably Heidegger, to talk of the experience of Nothing, is not properly the experience of nothing, but rather the failure of a hope or expectations that there would be something of some kind at some point. This may arise in quite everyday cases, as when one finds that the article of functions one expected to see as usual, in the corner has disappeared. The difference between ‘existentialist’’ and ‘analytic philosophy’, on the point of what, whereas the former is afraid of nothing, and the latter thinks that there is nothing to be afraid of.

A rather different set of concerns arise when actions are specified in terms of doing nothing, saying nothing may be an admission of guilt, and doing nothing in some circumstances may be tantamount to murder. Still, other substitutional problems arise over conceptualizing empty space and time.

Whereas, the standard opposition between those who affirm and those who deny, the real existence of some kind of thing or some kind of fact or state of affairs. Almost any area of discourse may be the focus of its dispute: The external world, the past and future, other minds, mathematical objects, possibilities, universals, moral or aesthetic properties are examples. There be to one influential suggestion, as associated with the British philosopher of logic and language, and the most determinative of philosophers centred round Anthony Dummett (1925), to which is borrowed from the ‘intuitionistic’ critique of classical mathematics, and suggested that the unrestricted use of the ‘principle of bivalence’ is the trademark of ‘realism’. However, this ha to overcome counter-examples both ways: Although Aquinas wads a moral ‘realist’, he held that moral really was not sufficiently structured to make true or false every moral claim. Unlike Kant who believed that he could use the law of bivalence happily in mathematics, precisely because it wad only our own construction. Realism can itself be subdivided: Kant, for example, combines empirical realism (within the phenomenal world the realist says the right things-surrounding objects really exist and independent of us and our mental stares) with transcendental idealism (the phenomenal world as a whole reflects the structures imposed on it by the activity of our minds as they render it intelligible to us). In modern philosophy the orthodox oppositions to realism has been from philosopher such as Goodman, who, impressed by the extent to which we perceive the world through conceptual and linguistic lenses of our own making.

Assigned to the modern treatment of existence in the theory of ‘quantification’ is sometimes put by saying that existence is not a predicate. The idea is that the existential quantifies itself as an operator on a predicate, indicating that the property it expresses has instances. Existence is therefore treated as a second-order property, or a property of properties. It is fitting to say, that in this it is like number, for when we say that these things of a kind, we do not describe the thing (ad we would if we said there are red things of the kind), but instead attribute a property to the kind itself. The parallelled numbers are exploited by the German mathematician and philosopher of mathematics Gottlob Frége in the dictum that affirmation of existence is merely denied of the number nought. A problem, nevertheless, proves accountable for its crated by sentences like ‘This exists’, where some particular thing is undirected, such that a sentence seems to express a contingent truth (for this insight has not existed), yet no other predicate is involved. ‘This exists’ is. Therefore, unlike ‘Tamed tigers exist’, where a property is said to have an instance, for the word ‘this’ and does not locate a property, but only an individual.

Possible worlds seem able to differ from each other purely in the presence or absence of individuals, and not merely in th distribution of exemplification of properties.

The philosophical ponderance over which to set upon the unreal, as belonging to the domain of Being. Nonetheless, there is little for us that can be said with the philosopher’s study. So it is not apparent that there can be such a subject for being by itself. Nevertheless, the concept had a central place in philosophy from Parmenides to Heidegger. The essential question of ‘why is there something and not of nothing’? Prompting over logical reflection on what it is for a universal to have an instance, nd as long history of attempts to explain contingent existence, by which id to reference and a necessary ground.

In the transition, ever since Plato, this ground becomes a self-sufficient, perfect, unchanging, and external something, identified with the Good or God, but whose relation with the everyday world remains obscure. The celebrated argument for the existence of God first propounded by Anselm in his Proslogin. The argument by defining God as ‘something than which nothing greater can be conceived’. God then exists in the understanding since we understand this concept. However, if He only existed in the understanding something greater could be conceived, for a being that exists in reality is greater than one that exists in the understanding. Bu then, we can conceive of something greater than that than which nothing greater can be conceived, which is contradictory. Therefore, God cannot exist on the understanding, but exists in reality.

An influential argument (or family of arguments) for the existence of God, finding its premisses are that all natural things are dependent for their existence on something else. The totality of dependent brings must then itself depend upon a non-dependent, or necessarily existent bring of which is God. Like the argument to design, the cosmological argument was attacked by the Scottish philosopher and historian David Hume (1711-76) and Immanuel Kant.

Its main problem, nonetheless, is that it requires us to make sense of the notion of necessary existence. For if the answer to the question of why anything exists is that some other tings of a similar kind exists, the question merely arises gain. So the ‘God’ that ends the question must exist necessarily: It must not be an entity of which the same kinds of questions can be raised. The other problem with the argument is attributing concern and care to the deity, not for connecting the necessarily existent being it derives with human values and aspirations.

The ontological argument has been treated by modern theologians such as Barth, following Hegel, not so much as a proof with which to confront the unconverted, but as an explanation of the deep meaning of religious belief. Collingwood, regards the argument s proving not that because our idea of God is that of id quo maius cogitare viequit, therefore God exists, but proving that because this is our idea of God, we stand committed to belief in its existence. Its existence is a metaphysical point or absolute pre-supposition of certain forms of thought.

In the 20th century, modal versions of the ontological argument have been propounded by the American philosophers Charles Hertshorne, Norman Malcolm, and Alvin Plantinge. One version is to define something as unsurpassably great, if it exists and is perfect in every ‘possible world’. Then, to allow that it is at least possible that an unsurpassable great being existing. This means that there is a possible world in which such a being exists. However, if it exists in one world, it exists in all (for the fact that such a being exists in a world that entails, in at least, it exists and is perfect in every world), so, it exists necessarily. The correct response to this argument is to disallow the apparently reasonable concession that it is possible that such a being exists. This concession is much more dangerous than it looks, since in the modal logic, involved from possibly necessarily ‘p’, we can device necessarily ‘p’. A symmetrical proof starting from the assumption that it is possible that such a being not exist would derive that it is impossible that it exists.

The doctrine that it makes an ethical difference of whether an agent actively intervenes to bring about a result, or omits to act in circumstances in which it is foreseen, that as a result of the omission the same result occurs. Thus, suppose that I wish you dead. If I act to bring about your death, I am a murderer, however, if I happily discover you in danger of death, and fail to act to save you, I am not acting, and therefore, according to the doctrine of acts and omissions not a murderer. Critics implore that omissions can be as deliberate and immoral as I am responsible for your food and fact to feed you. Only omission is surely a killing, ‘Doing nothing’ can be a way of doing something, or in other worlds, absence of bodily movement can also constitute acting negligently, or deliberately, and defending on the context ,may be a way of deceiving, betraying, or killing. Nonetheless, criminal law offers to find its conveniences, from which to distinguish discontinuous intervention, for which is permissible, from bringing about result, which may not be, if, for instance, the result is death of a patient. The question is whether the difference, if there is one, is, between acting and omitting to act be discernibly or defined in a way that bars a general moral might.

The double effect of a principle attempting to define when an action that had both good and bad results is morally permissible. I one formation such an action is permissible if (1) The action is not wrong in itself, (2) the bad consequences is not that which is intended (3) the good is not itself a result of the bad consequences, and (4) the two consequential affects are.

It is, therefore, in some sense available to reactivate a new body, therefore, not I who survives body death, but I may be resurrected in the same personalized bod y that becomes reanimated by the same form, that which Aquinas’s account, as a person has no privileged self-understanding, we understand ourselves as we do everything else, by way of sense experience and abstraction, and knowing the principle of our own lives is an achievement, not as a given. Difficultly at this point led the logical positivist to abandon the notion of an epistemological foundation altogether, and to flirt with the coherence theory of truth, it is widely accepted that trying to make the connection between thought and experience through basic sentence s depends on an untenable ‘myth of the given

The special way that we each have of knowing our own thoughts, intentions, and sensationalist have brought in the many philosophical ‘behaviorist and functionalist tendencies, that have found it important to deny that there is such a special way , arguing the way that I know of my own mind inasmuch as the way that I know of yours, e.g., by seeing what I say when asked. Others, however, point out that the behaviour of reporting the result of introspection in a particular and legitimate kind of behavioural access that deserves notice in any account of historically human psychology. The historical philosophy of reflection upon the astute of history, or of historical, thinking, finds the term was used in the 18th century, e.g., by Volante was to mean critical historical thinking as opposed to the mere collection and repetition of stories about the past. In Hegelian, particularly by conflicting elements within his own system, however, it came to man universal or world history. The Enlightenment confidence was being replaced by science, reason, and understanding that gave history a progressive moral thread, and under the influence of the German philosopher, whom is in spreading Romanticism, came Gottfried Herder (1744-1803),and, Immanuel Kant, this idea took it further to hold, so that philosophy of history cannot be the detecting of a grand system, the unfolding of the evolution of human nature as witnessed in successive sages (the progress of rationality or of Spirit). This essential speculative philosophy of history is given a extra Kantian twist in the German idealist Johann Fichte, in whom the extra association of temporal succession with logical implication introduces the idea that concepts themselves are the dynamic engine of historical change. The idea is readily intelligible in that there world of nature and of thought become identified. The work of Herder, Kant, Flichte and Schelling is synthesized by Hegel: History has a plot, as too, this to the moral development of man, equates with freedom within the state, this in turn is the development of thought, or a logical development in which various necessary moment in the life of the concept are successively achieved and improved upon. Hegel’s method is at its most successful, when the object is the history of ideas, and the evolution of thinking may march in steps with logical oppositions and their resolution encounters red by various systems of thought.

Within the revolutionary communism, Karl Marx (1818-83) and the German social philosopher Friedrich Engels (1820-95), there emerges a rather different kind of story, based upon Hefl’s progressive structure not laying the achievement of the goal of history to a future in which the political condition for freedom comes to exist, so that economic and political fears than ‘reason’ is in the engine room. Although, itself is such that speculations upon the history may that it be continued to be written, notably: late examples, by the late 19th century large-scale speculation of tis kind with the nature of historical understanding, and in particular with a comparison between the ,methos of natural science and with the historians. For writers such as the German neo-Kantian Wilhelm Windelband and the German philosopher and literary critic and historian Wilhelm Dilthey, it is important to show that the human sciences such. as history are objective and legitimate, nonetheless they are in some way deferent from the enquiry of the scientist. Since the subjective-matter is the past thought and actions of human brings, what is needed and actions of human beings, past thought and actions of human beings, what is needed is an ability to re-live that past thought, knowing the deliberations of past agents, as if they were the historian’s own. The most influential British writer on this theme was the philosopher and historian George Collingwood (1889-1943) whose, The Idea of History (1946), contains an extensive defence of the verstehe approach, but it is nonetheless, the explanation from there actions, however, by re-living the situation as our understanding that understanding others is not gained by the tactic use of a ‘theory’, enabling us to infer what thoughts or intentionality experienced, again, the matter to which the subjective-matters of past thoughts and actions , as I have a human ability of knowing the deliberations of past agents as if they were the historian’s own. The immediate question of the form of historical explanation, and the fact that general laws have other than no place or any apprentices in the order of a minor place in the human sciences, it is also prominent in thoughts about distinctiveness as to regain their actions, but by re-living the situation

in or thereby an understanding of what they experience and thought.

The view that everyday attributions of intention, belief and meaning to other persons proceeded via tacit use of a theory that enables ne to construct these interpretations as explanations of their doings. The view is commonly hld along with functionalism, according to which psychological states theoretical entities, identified by the network of their causes and effects. The theory-theory had different implications, depending on which feature of theories is being stressed. Theories may be though of as capable of formalization, as yielding predications and explanations, as achieved by a process of theorizing, as achieved by predictions and explanations, as achieved by a process of theorizing, as answering to empirical evince that is in principle describable without them, as liable to be overturned by newer and better theories, and o on. The main problem with seeing our understanding of others as the outcome of a piece of theorizing is the non-existence of a medium in which this theory can be couched, as the child learns simultaneously he minds of others and the meaning of terms in its native language.

Our understanding of others is not gained by the tacit use of a ‘theory’. Enabling us to infer what thoughts or intentions explain their actions, however, by re-living the situation ‘in their moccasins’, or from their point of view, and thereby understanding what hey experienced and thought, and therefore expressed. Understanding others is achieved when we can ourselves deliberate as they did, and hear their words as if they are our own. The suggestion is a modern development of the ‘Verstehen’ tradition associated with Dilthey, Weber and Collngwood.

Much as much, it is therefore, in some sense available to reactivate a new body, however, not that I, who survives bodily death, but I may be resurrected in the same body that becomes reanimated by the same form, in that of Aquinas’s account, a person has no privileged self-understanding. We understand ourselves, just as we do everything else, that through the sense experience, in that of an abstraction, may justly be of knowing the principle of our own lives, is to obtainably achieve, and not as a given. In the theory of knowledge that knowing Aquinas holds the Aristotelian doctrine that knowing entails some similarities between the Knower and what there is to be known: A human’s corporal nature, therefore, requires that knowledge start with sense perception. As yet, the same limitations that do not apply of bringing further he levelling stabilities that are contained within the hierarchical mosaic, such as the celestial heavens that open in bringing forth to angles.

In the domain of theology Aquinas deploys the distraction emphasized by Eringena, between the existence of God in understanding the significance; of five arguments: The are (1) Motion is only explicable if there exists an unmoved, a first mover (2) the chain of efficient causes demands a first cause (3) the contingent character of existing things in the wold demands a different order of existence, or in other words as something that has a necessary existence (4) the gradation of value in things in the world require the existence of something that is most valuable, or perfect, and (5) the orderly character of events points to a final cause, or end t which all things are directed, and the existence of this end demands a being that ordained it. All the arguments are physico-theological arguments, in that between reason and faith, Aquinas lays out proofs of the existence of God.

He readily recognizes that there are doctrines such that are the Incarnation and the nature of the Trinity, know only through revelations, and whose acceptance is more a matter of moral will. God’s essence is identified with his existence, as pure activity. God is simple, containing no potential. No matter how, we cannot obtain knowledge of what God is (his quiddity), perhaps, doing the same work as the principle of charity, but suggesting that we regulate our procedures of interpretation by maximizing the extent to which we see the subject s humanly reasonable, than the extent to which we see the subject as right about things. Whereby remaining content with descriptions that apply to him partly by way of analog y , God reveals of himself is not himself.

The immediate problem availed of ethics is posed b y the English philosopher Phillippa Foot, in her ‘The Problem of Abortion and the Doctrine of the Double Effect’ (1967). A runaway train or trolley comes to a section in the track that is under construction and impassable. One person is working on one part and five on the other, and the trolley will put an end to anyone working on the branch it enters. Clearly, to most minds, the driver should steer for the fewest populated branch. But now suppose that, left to itself, it will enter the branch with its five employs that are there, and you as a bystander can intervene, altering the points so that it veers through the other. Is it right or obligors, or even permissible for you to do this, thereby, apparently involving yourself in ways that responsibility ends in a death of one person? After all, whom have you wronged if you leave it to go its own way? The situation is similarly standardized of others in which utilitarian reasoning seems to lead to one course of action, but a person’s integrity or principles may oppose it.

Describing events that haphazardly happen does not of itself permit us to talk of rationality and intention, which are the categories we may apply if we conceive of them as action. We think of ourselves not only passively, as creatures that make things happen. Understanding this distinction gives forth of its many major problems concerning the nature of an agency for the causation of bodily events by mental events, and of understanding the ‘will’ and ‘free will’. Other problems in the theory of action include drawing the distinction between an action and its consequence, and describing the structure involved when we do one thing ‘by;’ dong another thing. Even the planning and dating where someone shoots someone on one day and in one place, whereby the victim then dies on another day and in another place. Where and when did the murderous act take place?

Causation, least of mention, is not clear that only events are created by and for itself. Kant cites the example o a cannonball at rest and stationed upon a cushion, but causing the cushion to be the shape that it is, and thus to suggest that the causal states of affairs or objects or facts may also be casually related. All of which, the central problem is to understand the elements of necessitation or determinacy of the future. Events, Hume thought, are in themselves ‘loose and separate’: How then are we to conceive of others? The relationship seems not to perceptible, for all that perception gives us (Hume argues) is knowledge of the patterns that events do, actually falling into than any acquaintance with the connections determining the pattern. It is, however, clear that our conception of everyday objects ids largely determined by their casual powers, and all our action is based on the belief that these causal powers are stable and reliable. Although scientific investigation can give us wider and deeper dependable patterns, it seems incapable of bringing us any nearer to the ‘must’ of causal necessitation. Particular examples’ o f puzzles with causalities are quite apart from general problems of forming any conception of what it is: How are we to understand the casual interaction between mind and body? How can the present, which exists, or its existence to a past that no longer exists? How is the stability of the casual order to be understood? Is backward causality possible? Is causation a concept needed in science, or dispensable?

The news concerning free-will, is nonetheless, a problem for which is to reconcile our everyday consciousness of ourselves as agent, with the best view of what science tells us that we are. Determinism is one part of the problem. It may be defined as the doctrine that every event has a cause. More precisely, for any event ‘C’, there will be one antecedent states of nature ‘N’, and a law of nature ‘L’, such that given L, N will be followed by ‘C’. But if this is true of every event, it is true of events such as my doing something or choosing to do something. So my choosing or doing something is fixed by some antecedent state ‘N’ an d the laws. Since determinism is universal these in turn are fixed, and so backwards to events for which I am clearly not responsible (events before my birth, for example). So, no events can be voluntary or free, where that means that they come about purely because of my willing them I could have done otherwise. If determinism is true, then there will be antecedent states and laws already determining such events: How then can I truly be said to be their author, or be responsible for them?

Reactions to this problem are commonly classified as: (1) Hard determinism. This accepts the conflict and denies that you have real freedom or responsibility (2) Soft determinism or compatibility, whereby reactions in this family assert that everything you should be from a notion of freedom is quite compatible with determinism. In particular, if your actions are caused, it can often be true of you that you could have done otherwise if you had chosen, and this may be enough to render you liable to be held unacceptable (the fact that previous events will have caused you to choose as you did, and is deemed irrelevant on this option). (3) Libertarianism, as this is the view that while compatibilism is only an evasion, there is a more substantiative, real notion of freedom that can yet be preserved in the face of determinism (or, of indeterminism). In Kant, while the empirical or phenomenal self is determined and not free, whereas the noumenal or rational self is capable of being rational, free action. However, the noumeal self exists outside the categorical priorities of space and time, as this freedom seems to be of a doubtful value as other libertarian avenues do include of suggesting that the problem is badly framed, for instance, because the definition of determinism breaks down, or postulates by its suggesting that there are two independent but consistent ways of looking at an agent, the scientific and the humanistic, wherefore it is only through confusing them that the problem seems urgent. Nevertheless, these avenues have gained general popularity, as an error to confuse determinism and fatalism.

The dilemma for which determinism is for itself often supposes of an action that seems as the end of a causal chain, or, perhaps, by some hieratical set of suppositional actions that would stretch back in time to events for which an agent has no conceivable responsibility, then the agent is not responsible for the action.

Once, again, the dilemma adds that if an action is not the end of such a chain, then either two or one of its causes occurs at random, in that no antecedent events brought it about, and in that case nobody is responsible for its ever to occur. So, whether or not determinism is true, responsibility is shown to be illusory.

Still, there is to say, to have a will is to be able to desire an outcome and to purpose to bring it about. Strength of will, or firmness of purpose, is supposed to be good and weakness of will or akrasia bad.

A mental act of willing or trying whose presence is sometimes supposed to make the difference between intentional or voluntary action, as well of mere behaviour. The theory that there are such acts is problematic, and the idea that they make the required difference is a case of explaining a phenomenon by citing another that raises exactly the same problem, since the intentional or voluntary nature of the set of volition now needs explanation. For determinism to act in accordance with the law of autonomy or freedom, is that in ascendance with universal moral law and regardless of selfish advantage.

A categorical notion in the work as contrasted in Kantian ethics show of a hypothetical imperative that embeds of a commentary which is in place only given some antecedent desire or project. ‘If you want to look wise, stay quiet’. The injunction to stay quiet only applies to those with the antecedent desire or inclination: If one has no desire to look wise the injunction or advice lapses. A categorical imperative cannot be so avoided, it is a requirement that binds anybody, regardless of their inclination,. It could be repressed as, for example, ‘Tell the truth (regardless of whether you want to or not)’. The distinction is not always mistakably presumed or absence of the conditional or hypothetical form: ‘If you crave drink, don’t become a bartender’ may be regarded as an absolute injunction applying to anyone, although only activated in the case of those with the stated desire.

In Grundlegung zur Metaphsik der Sitten (1785), Kant discussed some of the given forms of categorical imperatives, such that of (1) The formula of universal law: ‘act only on that maxim through which you can at the same time will that it should become universal law’, (2) the formula of the law of nature: ‘Act as if the maxim of your action were to become through your will a universal law of nature’, (3) the formula of the end-in-itself, ‘Act in such a way that you always trat humanity of whether in your own person or in the person of any other, never simply as an end, but always at the same time as an end’, (4) the formula of autonomy, or consideration; ’the will’ of every rational being a will which makes universal law’, and (5) the formula of the Kingdom of Ends, which provides a model for systematic union of different rational beings under common laws.

A central object in the study of Kant’s ethics is to understand the expressions of the inescapable, binding requirements of their categorical importance, and to understand whether they are equivalent at some deep level. Kant’s own application of the notions are always convincing: One cause of confusion is relating Kant’s ethical values to theories such as ;expressionism’ in that it is easy but imperatively must that it cannot be the expression of a sentiment, yet, it must derive from something ‘unconditional’ or necessary’ such as the voice of reason. The standard mood of sentences used to issue request and commands are their imperative needs to issue as basic the need to communicate information, and as such to animals signalling systems may as often be interpreted either way, and understanding the relationship between commands and other action-guiding uses of language, such as ethical discourse. The ethical theory of ‘prescriptivism’ in fact equates the two functions. A further question is whether there is an imperative logic. ‘Hump that bale’ seems to follow from ‘Tote that barge and hump that bale’, follows from ‘Its windy and its raining’:.But it is harder to say how to include other forms, does ‘Shut the door or shut the window’ follow from ‘Shut the window’, for example? The usual way to develop an imperative logic is to work in terms of the possibility of satisfying the other one command without satisfying the other, thereby turning it into a variation of ordinary deductive logic.

Despite the fact that the morality of people and their ethics amount to the same thing, there is a usage that I restart morality to systems such as that of Kant, based on notions given as duty, obligation, and principles of conduct, reserving ethics for the more Aristotelian approach to practical reasoning as based on the valuing notions that are characterized by their particular virtue, and generally avoiding the separation of ‘moral’ considerations from other practical considerations. The scholarly issues are complicated and complex, with some writers seeing Kant as more Aristotelian,. And Aristotle as more involved with a separate sphere of responsibility and duty, than the simple contrast suggests.

A major topic of philosophical inquiry, especially in Aristotle, and subsequently since the 17th and 18th centuries, when the ‘science of man’ began to probe into human motivation and emotion. For such as these, the French moralist, or Hutcheson, Hume, Smith and Kant, a prime task as to delineate the variety of human reactions and motivations. Such an inquiry would locate our propensity for moral thinking among other faculties, such as perception and reason, and other tendencies as empathy, sympathy or self-interest. The task continues especially in the light of a post-Darwinian understanding of ourselves.

In some moral systems, notably that of Immanuel Kant, real moral worth comes only with interactivity, justly because it is right. However, if you do what is purposely becoming, equitable, but from some other equitable motive, such as the fear or prudence, no moral merit accrues to you. Yet, that in turn seems to discount other admirable motivations, as acting from main-sheet benevolence, or ‘sympathy’. The question is how to balance these opposing ideas and how to understand acting from a sense of obligation without duty or rightness , through which their beginning to seem a kind of fetish. It thus stands opposed to ethics and relying on highly general and abstractive principles, particularly. Those associated with the Kantian categorical imperatives. The view may go as far back as to say that taken in its own, no consideration point, for that which of any particular way of life, that, least of mention, the contributing steps so taken as forwarded by reason or be to an understanding estimate that can only proceed by identifying salient features of a situation that weigh on one’s side or another.

As random moral dilemmas set out with intense concern, inasmuch as philosophical matters that exert a profound but influential defence of common sense. Situations in which each possible course of action breeches some otherwise binding moral principle, are, nonetheless, serious dilemmas making the stuff of many tragedies. The conflict can be described in different was. One suggestion is that whichever action the subject undertakes, that he or she does something wrong. Another is that his is not so, for the dilemma means that in the circumstances for what she or he did was right as any alternate. It is important to the phenomenology of these cases that action leaves a residue of guilt and remorse, even though it had proved it was not the subject’s fault that she or he were considering the dilemma, that the rationality of emotions can be contested. Any normality with more than one fundamental principle seems capable of generating dilemmas, however, dilemmas exist, such as where a mother must decide which of two children to sacrifice, least of mention, no principles are pitted against each other, only if we accept that dilemmas from principles are real and important, this fact can then be used to approach in themselves, such as of ‘utilitarianism’, to espouse various kinds may, perhaps, be centred upon the possibility of relating to independent feelings, liken to recognize only one sovereign principle. Alternatively, of regretting the existence of dilemmas and the unordered jumble of furthering principles, in that of creating several of them, a theorist may use their occurrences to encounter upon that which it is to argue for the desirability of locating and promoting a single sovereign principle.

Nevertheless, some theories into ethics see the subject in terms of a number of laws (as in the Ten Commandments). Th status of these laws may be that they are the edicts of a divine lawmaker, or that they are truths of reason, given to its situational ethics, virtue ethics, regarding them as at best rules-of-thumb, and, frequently disguising the great complexity of practical representations that for reason has placed the Kantian notions of their moral law.

In continence, the natural law possibility points of the view of the states that law and morality are especially associated with St Thomas Aquinas (1225-74), such that his synthesis of Aristotelian philosophy and Christian doctrine was eventually to provide the main philosophical underpinning of th Catholic church. Nevertheless, to a greater extent of any attempt to cement the moral and legal order and together within the nature of the cosmos or the nature of human beings, in which sense it found in some Protestant writings, under which had arguably derived functions. From a Platonic view of ethics and its agedly implicit advance of Stoicism. Its law stands above and apart from the activities of human lawmakers: It constitutes an objective set of principles that can be seen as in and for themselves by means of ‘natural usages’ or by reason itself, additionally, (in religious verses of them), that express of God’s will for creation. Non-religious versions of the theory substitute objective conditions for humans flourishing as the source of constraints, upon permissible actions and social arrangements within the natural law tradition. Different views have been held about the relationship between the rule of the law and God’s will. Grothius, for instance, sides with the view that the content of natural law is independent of any will, including that of God.

While the German natural theorist and historian Samuel von Pufendorf (1632-94) takes the opposite view. His great work was the De Jure Naturae et Gentium, 1672, and its English translation is ‘Of the Law of Nature and Nations, 1710. Pufendorf was influenced by Descartes, Hobbes and the scientific revolution of the 17th century, his ambition was to introduce a newly scientific ‘mathematical’ treatment on ethics and law, free from the tainted Aristotelian underpinning of ‘scholasticism’. Like that of his contemporary-Locke. His conception of natural laws include rational and religious principles, making it only a partial forerunner of more resolutely empiricist and political treatment in the Enlightenment.

Pufendorf launched his explorations in Plato’s dialogue ‘Euthyphro’, with whom the pious things are pious because the gods love them, or do the gods love them because they are pious? The dilemma poses the question of whether value can be conceived as the upshot o the choice of any mind, even a divine one. On the fist option the choice of the gods crates goodness and value. Even if this is intelligible it seems to make it impossible to praise the gods, for it is then vacuously true that they choose the good. On the second option we have to understand a source of value lying behind or beyond the will even of the gods, and by which they can be evaluated. The elegant solution of Aquinas is and is therefore distinct from is willing, but not distinct from him.

The dilemma arises whatever the source of authority is supposed to be. Do we care about the good because it is good, or do we just call good those things that we care about? It also generalizes to affect our understanding of the authority of other things: Mathematics, or necessary truth, for example, are truths necessary because we deem them to be so, or do we deem them to be so because they are necessary?

The natural aw tradition may either assume a stranger form, in which it is claimed that various fact’s entails of primary and secondary qualities, any of which is claimed that various facts entail values, reason by itself is capable of discerning moral requirements. As in the ethics of Knt, these requirements are supposed binding on all human beings, regardless of their desires.

The supposed natural or innate abilities of the mind to know the first principle of ethics and moral reasoning, wherein, those expressions are assigned and related to those that distinctions are which make in terms contribution to the function of the whole, as completed definitions of them, their phraseological impression is termed ‘synderesis’ (or, syntetesis) although traced to Aristotle, the phrase came to the modern era through St Jerome, whose scintilla conscientiae (gleam of conscience) wads a popular concept in early scholasticism. Nonetheless, it is mainly associated in Aquinas as an infallible natural, simple and immediate grasp of first moral principles. Conscience, by contrast, is ,more concerned with particular instances of right and wrong, and can be in error, under which the assertion that is taken as fundamental, at least for the purposes of the branch of enquiry in hand.

It is, nevertheless, the view interpreted within he particular states of law and morality especially associated with Aquinas and the subsequent scholastic tradition, showing for itself the enthusiasm for reform for its own sake. Or for ‘rational’ schemes thought up by managers and theorists, is therefore entirely misplaced. Major o exponent s of this theme include the British absolute idealist Herbert Francis Bradley (1846-1924) and Austrian economist and philosopher Friedrich Hayek. The notably the idealism of Bradley, there ids the same doctrine that change is contradictory and consequently unreal: The Absolute is changeless. A way of sympathizing a little with his idea is to reflect that any scientific explanation of change will proceed by finding an unchanging law operating, or an unchanging quantity conserved in the change, so that explanation of change always proceeds by finding that which is unchanged. The metaphysical problem of change is to shake off the idea that each moment is created afresh, and to obtain a conception of events or processes as having a genuinely historical reality, Really extended and unfolding in time, as opposed to being composites of discrete temporal atoms. A step towards this end may be to see time itself not as an infinite container within which discrete events are located, bu as a kind of logical construction from the flux of events. This relational view of time was advocated by Leibniz and a subject of the debate between him and Newton’s Absolutist pupil, Clarke.

Generally, nature is an indefinitely mutable term, changing as our scientific conception of the world changes, and often best seen as signifying a contrast with something considered not part of nature. The term applies both to individual species (it is the nature of gold to be dense or of dogs to be friendly), and also to the natural world as a whole. The sense in which it applies to species quickly links up with ethical and aesthetic ideals: A thing ought to realize its nature, what is natural is what it is good for a thing to become, it is natural for humans to be healthy or two-legged, and departure from this is a misfortune or deformity,. The associations of what is natural with what it is good to become is visible in Plato, and is the central idea of Aristotle’s philosophy of nature. Unfortunately, the pinnacle of nature in this sense is the mature adult male citizen, with he rest of hat we would call the natural world, including women, slaves, children and other species, not quite making it.

Nature in general can, however, function as a foil to any idea inasmuch as a source of ideals: In this sense fallen nature is contrasted with a supposed celestial realization of the ‘forms’. The theory of ‘forms’ is probably the most characteristic, and most contested of the doctrines of Plato. In the background, i.e., the Pythagorean conception of form as the initial orientation to physical nature, bu also the sceptical doctrine associated with the Greek philosopher Cratylus, and is sometimes thought to have been a teacher of Plato before Socrates. He is famous for capping the doctrine of Ephesus of Heraclitus, whereby the guiding idea of his philosophy was that of the logos, is capable of being heard or hearkened to by people, it unifies opposites, and it is somehow associated with fire, which is preeminent among the four elements that Heraclitus distinguishes: Fire, air (breath, the stuff of which souls composed), earth, and water. Although he is principally remembered for the doctrine of the ‘flux’ of all things, and the famous statement that you cannot step into the same river twice, for new waters are ever flowing in upon you. The more extreme implication of the doctrine of flux, e.g., the impossibility of categorizing things truly, do not seem consistent with his general epistemology and views of meaning, and were to his follower Cratylus, although the proper conclusion of his views was that the flux cannot be captured in words. According to Aristotle, he eventually held that since ‘regarding that which everywhere in every respect is changing nothing ids just to stay silent and wag one’s finger. Plato ‘s theory of forms can be seen in part as an action against the impasse to which Cratylus was driven.

The Galilean world view might have been expected to drain nature of its ethical content, however, the term seldom loses its normative force, and the belief in universal natural laws provided its own set of ideals. In the 18th century for example, a painter or writer could be praised as natural, where the qualities expected would include normal (universal) topics treated with simplicity, economy , regularity and harmony. Later on, nature becomes an equally potent emblem of irregularity, wildness, and fertile diversity, but also associated with progress of human history, its incurring definition that has been taken to fit many things as well as transformation, including ordinary human self-consciousness. Nature, being in contrast with in integrated phenomenon may include (1) that which is deformed or grotesque or fails to achieve its proper form or function or just the statistically uncommon or unfamiliar, (2) the supernatural, or the world of gods and invisible agencies, (3) the world of rationality and unintelligence, conceived of as distinct from the biological and physical order, or the product of human intervention, and (5) related to that, the world of convention and artifice.

Different conceptions of nature continue to have ethical overtones, foe example, the conception of ‘nature red in tooth and claw’ often provides a justification for aggressive personal and political relations, or the idea that it is women’s nature to be one thing or another is taken to be a justification for differential social expectations. The term functions as a fig-leaf for a particular set of stereotypes, and is a proper target of much feminist writings. Feminist epistemology has asked whether different ways of knowing for instance with different criteria of justification, and different emphases on logic and imagination, characterize male and female attempts to understand the world. Such concerns include awareness of the ‘masculine’ self-image, itself a socially variable and potentially distorting picture of what thought and action should be. Again, there is a spectrum of concerns from the highly theoretical principles to the relatively practical. In this latter area particular attention is given to the institutional biases that stand in the way of equal opportunities in science and other academic pursuits, or the ideologies that stand in the way of women seeing themselves as leading contributors to various disciplines. However, to more radical feminists such concerns merely exhibit women wanting for themselves the same power and rights over others that men have claimed, and failing to confront the real problem, which is how to live without such symmetrical powers and rights.

In biological determinism, not only influences but constraints and makes inevitable our development as persons with a variety of traits. At its silliest the view postulates such entities as a gene predisposing people to poverty, and it is the particular enemy of thinkers stressing the parental, social, and political determinants of the way we are.

The philosophy of social science is more heavily intertwined with actual social science than in the case of other subjects such as physics or mathematics, since its question is centrally whether there can be such a thing as sociology. The idea of a ‘science of man’, devoted to uncovering scientific laws determining the basic dynamic s of human interactions was a cherished ideal of the Enlightenment and reached its heyday with the positivism of writers such as the French philosopher and social theorist Auguste Comte (1798-1957), and the historical materialism of Marx and his followers. Sceptics point out that what happens in society is determined by peoples’ own ideas of what should happen, and like fashions those ideas change in unpredictable ways as self-consciousness is susceptible to change by any number of external event s: Unlike the solar system of celestial mechanics a society is not at all a closed system evolving in accordance with a purely internal dynamic, but constantly responsive to shocks from outside.

Among the features that are proposed for this kind of explanation are such things as male dominance, male promiscuity versus female fidelity, propensities to sympathy and other emotions, and the limited altruism characteristic of human beings. The strategy has proved unnecessarily controversial, with proponents accused of ignoring the influence of environmental and social factors in moulding people’s characteristics, e.g., at the limit of silliness, by postulating a ‘gene for poverty’, however, there is no need for the approach to commit such errors, since the feature explained sociobiological may be indexed to environment: For instance, it ma y be a propensity to develop some feature in some other environments (for even a propensity to develop propensities . . .) The main problem is to separate genuine explanation from speculative, just so stories which may or may not identify as really selective mechanisms.

Subsequently, in the 19th century attempts were made to base ethical reasoning on the presumed facts about evolution. The movement is particularly associated with the English philosopher of evolution Herbert Spencer (1820-1903),. His first major work was the book Social Statics (1851), which advocated an extreme political libertarianism. The Principles of Psychology was published in 1855, and his very influential Education advocating natural development of intelligence, the creation of pleasurable interest, and the importance of science in the curriculum, appeared in 1861. His First Principles (1862) was followed over the succeeding years by volumes on the Principles of biology and psychology, sociology and ethics. Although he attracted a large public following and attained the stature of a sage, his speculative work has not lasted well, and in his own time there was dissident voices. T.H. Huxley said that Spencer’s definition of a tragedy was a deduction killed by a fact. Writer and social prophet Thomas Carlyle (1795-1881) called him a perfect vacuum, and the American psychologist and philosopher William James (1842-1910) wondered why half of England wanted to bury him in Westminister Abbey, and talked of the ‘hurdy-gurdy’ monotony of him, his whole system wooden, as if knocked together out of cracked hemlock.





The premise is that later elements in an evolutionary path are better than earlier ones, the application of this principle then requires seeing western society, laissez-faire capitalism, or some other object of approval, as more evolved than more ‘primitive’ social forms. Neither the principle nor the applications command much respect. The version of evolutionary ethics called ‘social Darwinism’ emphasizes the struggle for natural selection, and drawn the conclusion that we should glorify such struggle, usually by enhancing competitive and aggressive relations between people in society or between societies themselves. More recently the relation between evolution and ethics has been re-thought in the light of biological discoveries concerning altruism and kin-selection.

In that, the study of the say in which a variety of higher mental function may be adaptions applicable of a psychology of evolution, a formed in response to selection pressures on human populations through evolutionary time. Candidates for such theorizing include material and paternal motivations, capabilities for love and friendship, the development of language as a signalling system, cooperative and aggressive tendencies, our emotional repertoires, our moral reaction, including the disposition to direct and punish those who cheat on an agreement or who turn towards free-riders-those of which who take away the things of others, our cognitive structure and many others. Evolutionary psychology goes hand-in-hand with neurophysiological evidence about the underlying circuitry in the brain which subserves the psychological mechanisms it claims to identify.

For all that, an essential part of the British absolute idealist Herbert Bradley (1846-1924) was largely on the ground s that the self-sufficiency individualized through community and one’s self is to contribute to social and other ideals. However, truth as formulated in language is always partial, and dependent upon categories that themselves are inadequate to the harmonious whole. Nevertheless, these self-contradictory elements somehow contribute to the harmonious whole, or Absolute, lying beyond categorization. Although absolute idealism maintains few adherents today, Bradley’s general dissent from empiricism, his holism, and the brilliance and style of his writing continue to make him the most interesting of the late 19th century writers influenced by the German philosopher Friedrich Hegel (1770-1831).

Understandably, something less than the fragmented division that belonging of Bradley’s case has a preference, voiced much earlier by the German philosopher, mathematician and polymath was Gottfried Leibniz (1646-1716), for categorical monadic properties over relations. He was particularly troubled by the relation between that which ids known and the more that knows it. In philosophy, the Romantics took from the German philosopher and founder of critical philosophy Immanuel Kant (1724-1804) both the emphasis on free-will and the doctrine that reality is ultimately spiritual, with nature itself a mirror of the human soul. To fix upon one among alternatives as the one to be taken, Friedrich Schelling (1775-1854) foregathers nature of becoming a creative spirit whose aspiration is ever further and more to completed self-realization. Although a movement of more general to naturalized imperative. Romanticism drew on the same intellectual and emotional resources as German idealism was increasingly culminating in the philosophy of Hegel (1770-1831) and of absolute idealism.

Being such in comparison with nature may include (1) that which is deformed or grotesque, or fails to achieve its proper form or function, or just the statistically uncommon or unfamiliar, (2) the supernatural, or th world of gods and invisible agencies, (3) the world of rationality and intelligence, conceived of as distinct from the biological and physical order, (4) that which is manufactured and artefactual, or the product of human invention, and (5) related to it, the world of convention and artifice.

Different conceptions of nature continue to have ethical overtones, for example, the conception of ‘nature red in tooth and claw’ often provide a justification for aggressive personal and political relations, or the idea that it is a women’s nature to be one thing or another, as taken to be a justification for differential social expectations. The term functions as a fig-leaf for a particular set of stereotype, and is a proper target of much ‘feminist’ writing.

This brings to question, that most of all ethics are contributively distributed as an understanding for which a dynamic function in and among the problems that are affiliated with human desire and needs the achievements of happiness, or the distribution of goods. The central problem specific to thinking about the environment is the independent value to place on ‘such-things’ as preservation of species, or protection of the wilderness. Such protection can be supported as a mans to ordinary human ends, for instance, when animals are regarded as future sources of medicines or other benefits. Nonetheless, many would want to claim a non-utilitarian, absolute value for the existence of wild things and wild places. It is in their value that thing consist. They put u in our proper place, and failure to appreciate this value is not only an aesthetic failure but one of due humility and reverence, a moral disability. The problem is one of expressing this value, and mobilizing it against utilitarian agents for developing natural areas and exterminating species, more or less at will.

Many concerns and disputed cluster around the idea associated with the term ‘substance’. The substance of a thin may be considered in: (1) Its essence, or that which makes it what it is. This will ensure that the substance of a thing is that which remains through change in properties. Again, in Aristotle, this essence becomes more than just the matter, but a unity of matter and form. (2) That which can exist by itself, or does not need a subject for existence, in the way that properties need objects, hence (3) that which bears properties, as a substance is then the subject of predication, that about which things are said as opposed to the things said about it. Substance in the last two senses stands opposed to modifications such as quantity, quality, relations, etc. it is hard to keep this set of ideas distinct from the doubtful notion of a substratum, something distinct from any of its properties, and hence, as an incapable characterization. The notion of substances tend to disappear in empiricist thought in fewer of the sensible questions of things with the notion of that in which they infer of giving way to an empirical notion of their regular occurrence. However, this is in turn is problematic, since it only makes sense to talk of the occurrence of instance of qualities, not of quantities themselves. So the problem of what it is for a value quality to be the instance that remains.

Metaphysics inspired by modern science tends to reject the concept of substance in favour of concepts such as that of a field or a process, each of which may seem to provide a better example of a fundamental physical category.

It must be spoken of a concept that is deeply embedded in 18th century aesthetics, but deriving from the 1st century rhetorical treatise On the Sublime, by Longinus. The sublime is great, fearful, noble, calculated to arouse sentiments of pride and majesty, as well as awe and sometimes terror. According to Alexander Gerard’s writing in 1759, ‘When a large object is presented, the mind expands itself to the extent of that objects, and is filled with one grand sensation, which totally possessing it, composes it into a solemn sedateness and strikes it with deep silent wonder, and administration’: It finds such a difficulty in spreading itself to the dimensions of its object, as enliven and invigorates which this occasions, it sometimes images itself present in every part of the sense which it contemplates, and from the sense of this immensity, feels a noble pride, and entertains a lofty conception of its own capacity.

In Kant’s aesthetic theory the sublime ‘raises the soul above the height of vulgar complacency’. We experience the vast spectacles of nature as ‘absolutely great’ and of irresistible might and power. This perception is fearful, but by conquering this fear, and by regarding as small ‘those things of which we are wont to be solicitous’ we quicken our sense of moral freedom. So we turn the experience of frailty and impotence into one of our true, inward moral freedom as the mind triumphs over nature, and it is this triumph of reason that is truly sublime. Kant thus paradoxically places our sense of the sublime in an awareness of ourselves as transcending nature, than in an awareness of ourselves as a frail and insignificant part of it.

Nevertheless, the doctrine that all relations are internal was a cardinal thesis of absolute idealism, and a central point of attack by the British philosophers George Edward Moore (1873-1958) and Bertrand Russell (1872-1970). It is a kind of ‘essentialism’, stating that if two things stand in some relationship, then they could not be what they are, did they not do so, if, for instance, I am wearing a hat mow, then when we imagine a possible situation that we would be got to describe as my not wearing the hat now, we would strictly not be imaging as one and the hat, but only some different individual.

The countering partitions a doctrine that bears some resemblance to the metaphysically based view of the German philosopher and mathematician Gottfried Leibniz (1646-1716), that if a person had any other attributes that the ones he has, he would not have been the AME person. Leibniz thought that when asked hat would have happened if Peter had not denied Christ. That being that if I am asking what would have happened if Peter had not been Peter, denying Christ is contained in the complete notion of Peter. But he allowed that by the name ‘Peter’ might be understood as ‘what is involved in those attributes [of Peter] from which the denial does not follow’. In order that we are held accountable to allow of external relations, in that these being relations which individuals could have or not depending upon contingent circumstances. The relations of ideas is used by the Scottish philosopher David Hume (1711-76) in the First Enquiry of Theoretical Knowledge. All the objects of human reason or enquiring naturally, be divided into two kinds: To unit all the , ‘relations of ideas’ and ‘matter of fact ‘ (Enquiry Concerning Human Understanding) the terms reflect the belief that any thing that can be known dependently must be internal to the mind, and hence transparent to us.

In Hume, objects of knowledge are divided into matter of fact (roughly empirical things known by means of impressions) and the relation of ideas. The contrast, also called “Hume’s Fork’, is a version of the speculative deductivity distinction, but reflects the 17th and early 18th centauries behind that the deductivity is established by chains of infinite certainty as comparable to ideas. It is extremely important that in the period between Descartes and J.S. Mill that a demonstration is not, but only a chain of ‘intuitive’ comparable ideas, whereby a principle or maxim can be established by reason alone. It ids in this sense that the English philosopher John Locke (1632-1704) who believed that theological and moral principles are capable of demonstration, and Hume denies that they are, and also denies that scientific enquiries proceed in demonstrating its results.



A mathematical proof is formally inferred as to an argument that is used to show the truth of a mathematical assertion. In modern mathematics, a proof begins with one or more statements called premises and demonstrates, using the rules of logic, that if the premises are true then a particular conclusion must also be true.

The accepted methods and strategies used to construct a convincing mathematical argument have evolved since ancient times and continue to change. Consider the Pythagorean theorem, named after the 5th century Bc Greek mathematician and philosopher Pythagoras, which states that in a right-angled triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides. Many early civilizations considered this theorem true because it agreed with their observations in practical situations. But the early Greeks, among others, realized that observation and commonly held opinion do not guarantee mathematical truth. For example, before the 5th century Bc it was widely believed that all lengths could be expressed as the ratio of two whole numbers. But an unknown Greek mathematician proved that this was not true by showing that the length of the diagonal of a square with an area of 1 is the irrational number Ã.

The Greek mathematician Euclid laid down some of the conventions central to modern mathematical proofs. His book The Elements, written about 300 Bc, contains many proofs in the fields of geometry and algebra. This book illustrates the Greek practice of writing mathematical proofs by first clearly identifying the initial assumptions and then reasoning from them in a logical way in order to obtain a desired conclusion. As part of such an argument, Euclid used results that had already been shown to be true, called theorems, or statements that were explicitly acknowledged to be self-evident, called axioms; this practice continues today.

In the 20th century, proofs have been written that are so complex that no one person understands every argument used in them. In 1976, a computer was used to complete the proof of the four-colour theorem. This theorem states that four colours are sufficient to colour any map in such a way that regions with a common boundary line have different colours. The use of a computer in this proof inspired considerable debate in the mathematical community. At issue was whether a theorem can be considered proven if human beings have not actually checked every detail of the proof.

What is more, the use of a model to test for consistencies in an ‘axiomatized system’ which is older than modern logic. Descartes’ algebraic interpretation of Euclidean geometry provides a way of showing that if the theory of real numbers is consistent, so is the geometry. Similar representation had been used by mathematicians in the 19th century, for example to show that if Euclidean geometry is consistent, so are various non-Euclidean geometries. Model theory is the general study of this kind of procedure: The ‘proof theory’ studies relations of deductibility between formulae of a system, but once the notion of an interpretation is in place we can ask whether a formal system meets certain conditions. In particular, can it lead us from sentences that are true under some interpretation? And if a sentence is true under all interpretations, is it also a theorem of the system? We can define a notion of validity (a formula is valid if it is true in all interpret rations) and semantic consequence (a formula ‘B’ is a semantic consequence of a set of formulae, written {A1 . . . An} ⊨B, if it is true in all interpretations in which they are true) Then the central questions for a calculus will be whether all and only its theorems are valid, and whether {A1 . . . An} ⊨ B if and only if {A1 . . . An} ⊢B. There are the questions of the soundness and completeness of a formal system. For the propositional calculus this turns into the question of whether the proof theory delivers as theorems all and only ‘tautologies’. There are many axiomatizations of the propositional calculus that are consistent and complete. The mathematical logician Kurt Gödel (1906-78) proved in 1929 that the first-order predicate under every interpretation is a theorem of the calculus. In that mathematical method for solving those physical problems that can be stated in the form that a certain value definite integral shall have a stationary value for small changes of the functions in the integrands and of the limit of integration.

The Euclidean geometry is the greatest example of the pure ‘axiomatic method’, and as such had incalculable philosophical influence as a paradigm of rational certainty. It had no competition until the 19th century when it was realized that the fifth axiom of his system (parallel lines never meet) could be denied without inconsistency, leading to Riemannian spherical geometry. The significance of Riemannian geometry lies in its use and extension of both Euclidean geometry and the geometry of surfaces, leading to a number of generalized differential geometries. Its most important effect was that it made a geometrical application possible for some major abstractions of tensor analysis, leading to the pattern and concepts for general relativity later used by Albert Einstein in developing his theory of relativity. Riemannian geometry is also necessary for treating electricity and magnetism in the framework of general relativity. The fifth chapter of Euclid’s Elements, is attributed to the mathematician Eudoxus, and contains a precise development of the real number, work which remained unappreciated until rediscovered in the 19th century.

The Axiom, in logic and mathematics, is a basic principle that is assumed to be true without proof. The use of axioms in mathematics stems from the ancient Greeks, most probably during the 5th century Bc, and represents the beginnings of pure mathematics as it is known today. Examples of axioms are the following: 'No sentence can be true and false at the same time' (the principle of contradiction); 'If equals are added to equals, the sums are equal'. 'The whole is greater than any of its parts'. Logic and pure mathematics begin with such unproved assumptions from which other propositions (theorems) are derived. This procedure is necessary to avoid circularity, or an infinite regression in reasoning. The axioms of any system must be consistent with one another, that is, they should not lead to contradictions. They should be independent in the sense that they cannot be derived from one another. They should also be few in number. Axioms have sometimes been interpreted as self-evident truths. The present tendency is to avoid this claim and simply to assert that an axiom is assumed to be true without proof in the system of which it is a part.

The terms 'axiom' and 'postulate' are often used synonymously. Sometimes the word axiom is used to refer to basic principles that are assumed by every deductive system, and the term postulate is used to refer to first principles peculiar to a particular system, such as Euclidean geometry. Infrequently, the word axiom is used to refer to first principles in logic, and the term postulate is used to refer to first principles in mathematics.

The applications of game theory are wide-ranging and account for steadily growing interest in the subject. Von Neumann and Morgenstern indicated the immediate utility of their work on mathematical game theory by linking it with economic behaviour. Models can be developed, in fact, for markets of various commodities with differing numbers of buyers and sellers, fluctuating values of supply and demand, and seasonal and cyclical variations, as well as significant structural differences in the economies concerned. Here game theory is especially relevant to the analysis of conflicts of interest in maximizing profits and promoting the widest distribution of goods and services. Equitable division of property and of inheritance is another area of legal and economic concern that can be studied with the techniques of game theory.

In the social sciences, n-person game theory has interesting uses in studying, for example, the distribution of power in legislative procedures. This problem can be interpreted as a three-person game at the congressional level involving vetoes of the president and votes of representatives and senators, analysed in terms of successful or failed coalitions to pass a given bill. Problems of majority rule and individual decision making are also amenable to such study.

Sociologists have developed an entire branch of game theory devoted to the study of issues involving group decision making. Epidemiologists also make use of game theory, especially with respect to immunization procedures and methods of testing a vaccine or other medication. Military strategists turn to game theory to study conflicts of interest resolved through 'battles' where the outcome or payoff of a given war game is either victory or defeat. Usually, such games are not examples of zero-sum games, for what one player loses in terms of lives and injuries is not won by the victor. Some uses of game theory in analyses of political and military events have been criticized as a dehumanizing and potentially dangerous oversimplification of necessarily complicating factors. Analysis of economic situations is also usually more complicated than zero-sum games because of the production of goods and services within the play of a given 'game'.

All is the same in the classical theory of the syllogism, a term in a categorical proposition is distributed if the proposition entails any proposition obtained from it by substituting a term denoted by the original. For example, in ‘all dogs bark’ the term ‘dogs’ is distributed, since it entails ‘all terriers bark’, which is obtained from it by a substitution. In ‘Not all dogs bark’, the same term is not distributed, since it may be true while ‘not all terriers bark’ is false.

When a representation of one system by another is usually more familiar, in and for itself, that those extended in representation that their workings are supposed analogous to that of the first. This one might model the behaviour of a sound wave upon that of waves in water, or the behaviour of a gas upon that to a volume containing moving billiard balls. While nobody doubts that models have a useful ‘heuristic’ role in science, there has been intense debate over whether a good model, or whether an organized structure of laws from which it can be deduced and suffices for scientific explanation. As such, the debate of topic was inaugurated by the French physicist Pierre Marie Maurice Duhem (1861-1916), in ‘The Aim and Structure of Physical Theory’ (1954) by which Duhem’s conception of science is that it is simply a device for calculating as science provides deductive system that is systematic, economical, and predictive, but not that represents the deep underlying nature of reality. Steadfast and holding of its contributive thesis that in isolation, and since other auxiliary hypotheses will always be needed to draw empirical consequences from it. The Duhem thesis implies that refutation is a more complex matter than might appear. It is sometimes framed as the view that a single hypothesis may be retained in the face of any adverse empirical evidence, if we prepared to make modifications elsewhere in our system, although strictly speaking this is a stronger thesis, since it may be psychologically impossible to make consistent revisions in a belief system to accommodate, say, the hypothesis that there is a hippopotamus in the room when visibly there is not.

Primary and secondary qualities are the division associated with the 17th-century rise of modern science, wit h its recognition that the fundamental explanatory properties of things that are not the qualities that perception most immediately concerns. There latter are the secondary qualities, or immediate sensory qualities, including colour, taste, smell, felt warmth or texture, and sound. The primary properties are less tied to there deliverance of one particular sense, and include the size, shape, and motion of objects. In Robert Boyle (1627-92) and John Locke (1632-1704) the primary qualities are scientifically tractable, objective qualities essential to anything material, are of a minimal listing of size, shape, and mobility, i.e., the state of being at rest or moving. Locke sometimes adds number, solidity, texture (where this is thought of as the structure of a substance, or way in which it is made out of atoms). The secondary qualities are the powers to excite particular sensory modifications in observers. Once, again, that Locke himself thought in terms of identifying these powers with the texture of objects that, according to corpuscularian science of the time, were the basis of an object’s causal capacities. The ideas of secondary qualities are sharply different from these powers, and afford us no accurate impression of them. For Renè Descartes (1596-1650), this is the basis for rejecting any attempt to think of knowledge of external objects as provided by the senses. But in Locke our ideas of primary qualities do afford us an accurate notion of what shape, size,. And mobility are. In English-speaking philosophy the first major discontent with the division was voiced by the Irish idealist George Berkeley (1685-1753), who probably took for a basis of his attack from Pierre Bayle (1647-1706), who in turn cites the French critic Simon Foucher (1644-96). Modern thought continues to wrestle with the difficulties of thinking of colour, taste, smell, warmth, and sound as real or objective properties to things independent of us.

Continuing as such, is the doctrine advocated by the American philosopher David Lewis (1941-2002), in that different possible worlds are to be thought of as existing exactly as this one does. Thinking in terms of possibilities is thinking of real worlds where things are different. The view has been charged with making it impossible to see why it is good to save the child from drowning, since there is still a possible world in which she (or her counterpart) drowned, and from the standpoint of the universe it should make no difference which world is actual. Critics also charge either that the notion fails to fit with a coherent theory lf how we know about possible worlds, or with a coherent theory of why we are interested in them, but Lewis denied that any other way of interpreting modal statements is tenable.

The proposal set forth that characterizes the ‘modality’ of a proposition as the notion for which it is true or false. The most important division is between propositions true of necessity, and those true as things are: Necessary as opposed to contingent propositions. Other qualifiers sometimes called ‘modal’ include the tense indicators, ‘it will be the case that ‘p’, or ‘it was the case that ‘p’, and there are affinities between the ‘deontic’ indicators, ‘it ought to be the case that ‘p’, or ‘it is permissible that ‘p’, and the of necessity and possibility.

The aim of a logic is to make explicit the rules by which inferences may be drawn, than to study the actual reasoning processes that people use, which may or may not conform to those rules. In the case of deductive logic, if we ask why we need to obey the rules, the most general form of answer is that if we do not we contradict ourselves(or, strictly speaking, we stand ready to contradict ourselves. Someone failing to draw a conclusion that follows from a set of premises need not be contradicting him or herself, but only failing to notice something. However, he or she is not defended against adding the contradictory conclusion to his or fer set of beliefs.) There is no equally simple answer in the case of inductive logic, which is in general a less robust subject, but the aim will be to find reasoning such hat anyone failing to conform to it will have improbable beliefs. Traditional logic dominated the subject until the 19th century., and has become increasingly recognized in the 20th century, in that finer work that were done within that tradition, but syllogistic reasoning is now generally regarded as a limited special case of the form of reasoning that can be reprehend within the promotion and predated values, these form the heart of modern logic, as their central notions or qualifiers, variables, and functions were the creation of the German mathematician Gottlob Frége, who is recognized as the father of modern logic, although his treatment of a logical system as an abreact mathematical structure, or algebraic, has been heralded by the English mathematician and logician George Boole (1815-64), his pamphlet The Mathematical Analysis of Logic (1847) pioneered the algebra of classes. The work was made of in An Investigation of the Laws of Thought (1854). Boole also published many works in our mathematics, and on the theory of probability. His name is remembered in the title of Boolean algebra, and the algebraic operations he investigated are denoted by Boolean operations.

The syllogistic, or categorical syllogism is the inference of one proposition from two premises. For example is, ‘all horses have tails, and things with tails are four legged, so all horses are four legged. Each premise has one term in common with the other premises. The term that ds not occur in the conclusion is called the middle term. The major premise of the syllogism is the premise containing the predicate of the contraction (the major term). And the minor premise contains its subject (the minor term). So the first premise of the example in the minor premise the second the major term. So the first premise of the example is the minor premise, the second the major premise and ‘having a tail’ is the middle term. This enable syllogisms that there of a classification, that according to the form of the premises and the conclusions. The other classification is by figure, or way in which the middle term is placed or way in within the middle term is placed in the premise.

Although the theory of the syllogism dominated logic until the 19th century, it remained a piecemeal affair, able to deal with only relations valid forms of valid forms of argument. There have subsequently been reargued actions attempting, but in general it has been eclipsed by the modern theory of quantification, the predicate calculus is the heart of modern logic, having proved capable of formalizing the calculus rationing processes of modern mathematics and science. In a first-order predicate calculus the variables range over objects: In a higher-order calculus the may range over predicate and functions themselves. The fist-order predicated calculus with identity includes ‘=’ as primitive (undefined) expression: In a higher-order calculus I t may be defined by law that χ- y iff (∀F)(Fχ↔Fy), which gives grater expressive power for less complexity.

Modal logic was of great importance historically, particularly in the light of the deity, but was not a central topic of modern logic in its gold period as the beginning of the 20th century. It was, however, revived by the American logician and philosopher Irving Lewis (1883-1964), although he wrote extensively on most central philosophical topis, he is remembered principally as a critic of the intentional nature of modern logic, and as the founding father of modal logic. His two independent proofs showing that from a contradiction anything follows a relevance logic, using a notion of entailment stronger than that of strict implication.

The imparting information has been conduced or carried out of the prescribed procedures, as impeding of something that tajes place in the chancing encounter out to be to enter ons’s mind may from time to time occasion of various doctrines concerning th necessary properties, ;east of mention, by adding to a prepositional or predicated calculus two operator, □and ◊(sometimes written ‘N’ and ‘M’),meaning necessarily and possible, respectfully. These like ‘p ➞◊p and □p ➞p will be wanted. Controversial these include □p ➞□□p (if a proposition is necessary,. It its necessarily, characteristic of a system known as S4) and ◊p ➞□◊p (if as preposition is possible, it its necessarily possible, characteristic of the system known as S5). The classical modal theory for modal logic, due to the American logician and philosopher (1940-) and the Swedish logician Sig Kanger, involves valuing prepositions not true or false simpiciter, but as true or false at possible worlds with necessity then corresponding to truth in all worlds, and possibility to truth in some world. Various different systems of modal logic result from adjusting the accessibility relation between worlds.

In Saul Kripke, gives the classical modern treatment of the topic of reference, both clarifying the distinction between names and definite description, and opening te door to many subsequent attempts to understand the notion of reference in terms of a causal link between the use of a term and an original episode of attaching a name to the subject.

One of the three branches into which ‘semiotic’ is usually divided, the study of semantical meaning of words, and the relation of signs to the degree to which the designs are applicable. In that, in formal studies, a semantics is provided for a formal language when an interpretation of ‘model’ is specified. However, a natural language comes ready interpreted, and the semantic problem is not that of specification but of understanding the relationship between terms of various categories (names, descriptions, predicate, adverbs . . . ) and their meaning. An influential proposal by attempting to provide a truth definition for the language, which will involve giving a full structure of different kinds have on the truth conditions of sentences containing them.

Holding that the basic casse of reference is the relation between a name and the persons or object which it names. The philosophical problems include trying to elucidate that relation, to understand whether other semantic relations, such s that between a predicate and the property it expresses, or that between a description an what it describes, or that between myself or the word ‘I’, are examples of the same relation or of very different ones. A great deal of modern work on this was stimulated by the American logician Saul Kripke’s, Naming and Necessity (1970). It would also be desirable to know whether we can refer to such things as objects and how to conduct the debate about each and issue. A popular approach, following Gottlob Frége, is to argue that the fundamental unit of analysis should be the whole sentence. The reference of a term becomes a derivative notion it is whatever it is that defines the term’s contribution to the trued condition of the whole sentence. There need be nothing further to say about it, given that we have a way of understanding the attribution of meaning or truth-condition to sentences. Other approach, searching for a more substantive possibly that causality or psychological or social constituents are pronounced between words and things.

However, following Ramsey and the Italian mathematician G. Peano (1858-1932), it has been customary to distinguish logical paradoxes that depend upon a notion of reference or truth (semantic notions) such as those of the ‘Liar family, Berry, Richard, etc. form the purely logical paradoxes in which no such notions are involved, such as Russell’s paradox, or those of Canto and Burali-Forti. Paradoxes of the fist type sem to depend upon an element of self-reference, in which a sentence is about itself, or in which a phrase refers to something about itself, or in which a phrase refers to something defined by a set of phrases of which it is itself one. It is to feel that this element is responsible for the contradictions, although self-reference itself is often benign (for instance, the sentence ‘All English sentences should have a verb’, includes itself happily in the domain of sentences it is talking about), so the difficulty lies in forming a condition that existence only pathological self-reference. Paradoxes of the second kind then need a different treatment. Whilst the distinction is convenient. In allowing set theory to proceed by circumventing the latter paradoxes by technical mans, even when there is no solution to the semantic paradoxes, it may be a way of ignoring the similarities between the two families. There is still th possibility that while there is no agreed solution to the semantic paradoxes, our understand of Russell’s paradox may be imperfect as well.

Truth and falsity are two classical truth-values that a statement, proposition or sentence can take, as it is supposed in classical (two-valued) logic, that each statement has one of these values, and non has both. A statement is then false if and only if it is not true. The basis of this scheme is that to each statement there corresponds a determinate truth condition, or way the world must be for it to be true: If this condition obtains the statement is true, and otherwise false. Statements may indeed be felicitous or infelicitous in other dimensions (polite, misleading, apposite, witty, etc.) but truth is the central normative notion governing assertion. Considerations o vagueness may introduce greys into this black-and-white scheme. For the issue to be true, any suppressed premise or background framework of thought necessary make an agreement valid, or a position tenable, a proposition whose truth is necessary for either the truth or the falsity of another statement. Thus if ‘p’ presupposes ‘q’, ‘q’ must be true for ‘p’ to be either true or false. In the theory of knowledge, the English philologer and historian George Collingwood (1889-1943), announces hat any proposition capable of truth or falsity stand on bed of ‘absolute presuppositions’ which are not properly capable of truth or falsity, since a system of thought will contain no way of approaching such a question (a similar idea later voiced by Wittgenstein in his work On Certainty). The introduction of presupposition therefore mans that either another of a truth value is fond, ‘intermediate’ between truth and falsity, or the classical logic is preserved, but it is impossible to tell whether a particular sentence empresses a preposition that is a candidate for truth and falsity, without knowing more than the formation rules of the language. Each suggestion carries coss, and there is some consensus that at least who where definite descriptions are involved, examples equally given by regarding the overall sentence as false as the existence claim fails, and explaining the data that the English philosopher Frederick Strawson (1919-) relied upon as the effects of ‘implicature’.

Views about the meaning of terms will often depend on classifying the implicature of sayings involving the terms as implicatures or as genuine logical implications of what is said. Implicatures may be divided into two kinds: Conversational implicatures of the two kinds and the more subtle category of conventional implicatures. A term may as a matter of convention carry an implicature, thus one of the relations between ‘he is poor and honest’ and ‘he is poor but honest’ is that they have the same content (are true in just the same conditional) but the second has implicatures (that the combination is surprising or significant) that the first lacks.

It is, nonetheless, that we find in classical logic a proposition that may be true or false,. In that, if the former, it is said to take the truth-value true, and if the latter the truth-value false. The idea behind the terminological phrases is the analogues between assigning a propositional variable one or other of these values, as is done in providing an interpretation for a formula of the propositional calculus, and assigning an object as the value of any other variable. Logics with intermediate value are called ‘many-valued logics’.

Nevertheless, an existing definition of the predicate’ . . . is true’ for a language that satisfies convention ‘T’, the material adequately condition laid down by Alfred Tarski, born Alfred Teitelbaum (1901-83), whereby his methods of ‘recursive’ definition, enabling us to say for each sentence what it is that its truth consists in, but giving no verbal definition of truth itself. The recursive definition or the truth predicate of a language is always provided in a ‘metalanguage’, Tarski is thus committed to a hierarchy of languages, each with its associated, but different truth-predicate. Whist this enables the approach to avoid the contradictions of paradoxical contemplations, it conflicts with the idea that a language should be able to say everything that there is to be said, and other approaches have become increasingly important.

So, that the truth condition of a statement is the condition for which the world must meet if the statement is to be true. To know this condition is equivalent to knowing the meaning of the statement. Although this sounds as if it gives a solid anchorage for meaning, some of the securities disappear when it turns out that the truth condition can only be defined by repeating the very same statement: The truth condition of ‘now is white’ is that ‘snow is white’, the truth condition of ‘Britain would have capitulated had Hitler invaded’, is that ‘Britain would have capitulated had Hitler invaded’. It is disputed whether this element of running-on-the-spot disqualifies truth conditions from playing the central role in a substantives theory of meaning. Truth-conditional theories of meaning are sometimes opposed by the view that to know the meaning of a statement is to be able to use it in a network of inferences.

Taken to be the view, inferential semantics take on the role of sentence in inference give a more important key to their meaning than this ‘external’ relations to things in the world. The meaning of a sentence becomes its place in a network of inferences that it legitimates. Also known as functional role semantics, procedural semantics, or conception to the coherence theory of truth, and suffers from the same suspicion that it divorces meaning from any clar association with things in the world.

Moreover, a theory of semantic truth be that of the view if language is provided with a truth definition, there is a sufficient characterization of its concept of truth, as there is no further philosophical chapter to write about truth: There is no further philosophical chapter to write about truth itself or truth as shared across different languages. The view is similar to the disquotational theory.

The redundancy theory, or also known as the ‘deflationary view of truth’ fathered by Gottlob Frége and the Cambridge mathematician and philosopher Frank Ramsey (1903-30), who showed how the distinction between the semantic paradoses, such as that of the Liar, and Russell’s paradox, made unnecessary the ramified type theory of Principia Mathematica, and the resulting axiom of reducibility. By taking all the sentences affirmed in a scientific theory that use some terms e.g., quark, and to a considerable degree of replacing the term by a variable instead of saying that quarks have such-and-such properties, the Ramsey sentence says that there is something that has those properties. If the process is repeated for all of a group of the theoretical terms, the sentence gives ‘topic-neutral’ structure of the theory, but removes any implication that we know what the terms so treated denote. It leaves open the possibility of identifying the theoretical item with whatever it is that best fits the description provided. However, it was pointed out by the Cambridge mathematician Newman, that if the process is carried out for all except the logical bones of a theory, then by the Löwenheim-Skolem theorem, the result will be interpretable, and the content of the theory may reasonably be felt to have been lost.

All the while, both Frége and Ramsey are agreed that the essential claim is that the predicate’ . . . is true’ does not have a sense, i.e., expresses no substantive or profound or explanatory concept that ought to be the topic of philosophical enquiry. The approach admits of different versions, but centres on the points (1) that ‘it is true that ‘p’ says no more nor less than ‘p’ (hence, redundancy): (2) that in less direct contexts, such as ‘everything he said was true’, or ‘all logical consequences of true propositions are true’, the predicate functions as a device enabling us to generalize than as an adjective or predicate describing the things he said, or the kinds of propositions that follow from true preposition. For example, the second ma y translate as ‘(∀p, q)(p & p ➞q ➞q)’ where there is no use of a notion of truth.

There are technical problems in interpreting all uses of the notion of truth in such ways, nevertheless, they are not generally felt to be insurmountable. The approach needs to explain away apparently substantive uses of the notion, such as ‘science aims at the truth’, or ‘truth is a norm governing discourse’. Postmodern writing frequently advocates that we must abandon such norms. Along with a discredited ‘objective’ conception of truth. Perhaps, we can have the norms even when objectivity is problematic, since they can be framed without mention of truth: Science wants it to be so that whatever science holds that ‘p’, then ‘p’. Discourse is to be regulated by the principle that it is wrong to assert ‘p’, when ‘not-p’.

Something that tends of something in addition of content, or coming by way to justify such a position can very well be more that in addition to several reasons, as to bring in or join of something might that there be more so as to a larger combination for us to consider the simplest formulation , is that the claim that expression of the form ‘S is true’ mean the same as expression of the form ‘S’. Some philosophers dislike the ideas of sameness of meaning, and if this I disallowed, then the claim is that the two forms are equivalent in any sense of equivalence that matters. This is, it makes no difference whether people say ‘Dogs bark’ id Tue, or whether they say, ‘dogs bark’. In the former representation of what they say of the sentence ‘Dogs bark’ is mentioned, but in the later it appears to be used, of the claim that the two are equivalent and needs careful formulation and defence. On the face of it someone might know that ‘Dogs bark’ is true without knowing what it means (for instance, if he kids in a list of acknowledged truths, although he does not understand English), and tis is different from knowing that dogs bark. Disquotational theories are usually presented as versions of the ‘redundancy theory of truth’.

The relationship between a set of premises and a conclusion when the conclusion follows from the premise,. Many philosophers identify this with it being logically impossible that the premises should all be true, yet the conclusion false. Others are sufficiently impressed by the paradoxes of strict implication to look for a stranger relation, which would distinguish between valid and invalid arguments within the sphere of necessary propositions. The seraph for a strange notion is the field of relevance logic.

From a systematic theoretical point of view, we may imagine the process of evolution of an empirical science to be a continuous process of induction. Theories are evolved and are expressed in short compass as statements of as large number of individual observations in the form of empirical laws, from which the general laws can be ascertained by comparison. Regarded in this way, the development of a science bears some resemblance to the compilation of a classified catalogue. It is , a it were, a purely empirical enterprise.

But this point of view by no means embraces the whole of the actual process, for it slurs over the important part played by intuition and deductive thought in the development of an exact science. As soon as a science has emerged from its initial stages, theoretical advances are no longer achieved merely by a process of arrangement. Guided by empirical data, the investigators rather develops a system of thought which, in general, it is built up logically from a small number of fundamental assumptions, the so-called axioms. We call such a system of thought a ‘theory’. The theory finds the justification for its existence in the fact that it correlates a large number of single observations, and is just here that the ‘truth’ of the theory lies.

Corresponding to the same complex of empirical data, there may be several theories, which differ from one another to a considerable extent. But as regards the deductions from the theories which are capable of being tested, the agreement between the theories may be so complete, that it becomes difficult to find any deductions in which the theories differ from each other. As an example, a case of general interest is available in the province of biology, in the Darwinian theory of the development of species by selection in the struggle for existence, and in the theory of development which is based on the hypophysis of the hereditary transmission of acquired characters. THE Origin of Species was principally successful in marshalling the evidence for evolution, than providing a convincing mechanisms for genetic change. And Darwin himself remained open to the search for additional mechanisms, while also remaining convinced that natural selection was at the hart of it. It was only with the later discovery of the gene as the unit of inheritance that the synthesis known as ‘neo-Darwinism’ became the orthodox theory of evolution in the life sciences.

In the 19th century the attempt to base ethical reasoning o the presumed facts about evolution, the movement is particularly associated with the English philosopher of evolution Herbert Spencer (1820-1903). The premise is that later elements in an evolutionary path are better than earlier ones: The application of this principle then requires seeing western society, laissez-faire capitalism, or some other object of approval, as more evolved than more ‘primitive’ social forms. Neither the principle nor the applications command much respect. The version of evolutionary ethics called ‘social Darwinism’ emphasises the struggle for natural selection, and draws the conclusion that we should glorify and assist such struggle, usually by enhancing competition and aggressive relations between people in society or between evolution and ethics has been re-thought in the light of biological discoveries concerning altruism and kin-selection.

Once again, the psychology proving attempts are founded to evolutionary principles, in which a variety of higher mental functions may be adaptations, forced in response to selection pressures on the human populations through evolutionary time. Candidates for such theorizing include material and paternal motivations, capacities for love and friendship, the development of language as a signalling system cooperative and aggressive , our emotional repertoire, our moral and reactions, including the disposition to detect and punish those who cheat on agreements or who ‘free-ride’ on =the work of others, our cognitive structures, nd many others. Evolutionary psychology goes hand-in-hand with neurophysiological evidence about the underlying circuitry in the brain which subserves the psychological mechanisms it claims to identify. The approach was foreshadowed by Darwin himself, and William James, as well as the sociology of E.O. Wilson. The term of use are applied, more or less aggressively, especially to explanations offered in Sociobiology and evolutionary psychology.

Another assumption that is frequently used to legitimate the real existence of forces associated with the invisible hand in neoclassical economics derives from Darwin’s view of natural selection as a war-like competing between atomized organisms in the struggle for survival. In natural selection as we now understand it, cooperation appears to exist in complementary relation to competition. It is complementary relationships between such results that are emergent self-regulating properties that are greater than the sum of parts and that serve to perpetuate the existence of the whole.

According to E.O Wilson, the ‘human mind evolved to believe in the gods’ and people ‘need a sacred narrative’ to have a sense of higher purpose. Yet it id also clear that the ‘gods’ in his view are merely human constructs and, therefore, there is no basis for dialogue between the world-view of science and religion. ‘Science for its part’, said Wilson, ‘will test relentlessly every assumption about the human condition and in time uncover the bedrock of the moral an religious sentiments. The eventual result of the competition between each of the other, will be the secularization of the human epic and of religion itself.

Man has come to the threshold of a state of consciousness, regarding his nature and his relationship to te Cosmos, in terms that reflect ‘reality’. By using the processes of nature as metaphor, to describe the forces by which it operates upon and within Man, we come as close to describing ‘reality’ as we can within the limits of our comprehension. Men will be very uneven in their capacity for such understanding, which, naturally, differs for different ages and cultures, and develops and changes over the course of time. For these reasons it will always be necessary to use metaphor and myth to provide ‘comprehensible’ guides to living. In thus way. Man’s imagination and intellect play vital roles on his survival and evolution.

Since so much of life both inside and outside the study is concerned with finding explanations of things, it would be desirable to have a concept of what counts as a good explanation from bad. Under the influence of ‘logical positivist’ approaches to the structure of science, it was felt that the criterion ought to be found in a definite logical relationship between the ‘exlanans’ (that which does the explaining) and the explanandum (that which is to be explained). The approach culminated in the covering law model of explanation, or the view that an event is explained when it is subsumed under a law of nature, that is, its occurrence is deducible from the law plus a set of initial conditions. A law would itself be explained by being deduced from a higher-order or covering law, in the way that Johannes Kepler(or Keppler, 1571-1630), was by way of planetary motion that the laws were deducible from Newton’s laws of motion. The covering law model may be adapted to include explanation by showing that something is probable, given a statistical law. Questions for the covering law model include querying for the covering law are necessary to explanation (we explain whether everyday events without overtly citing laws): Querying whether they are sufficient (it ma y not explain an event just to say that it is an example of the kind of thing that always happens). And querying whether a purely logical relationship is adapted to capturing the requirements we make of explanations. These may include, for instance, that we have a ‘feel’ for what is happening, or that the explanation proceeds in terms of things that are familiar to us or unsurprising, or that we can give a model of what is going on, and none of these notions is captured in a purely logical approach. Recent work, therefore, has tended to stress the contextual and pragmatic elements in requirements for explanation, so that what counts as good explanation given one set of concerns may not do so given another.

The argument to the best explanation is the view that once we can select the best of any in something in explanations of an event, then we are justified in accepting it, or even believing it. The principle needs qualification, since something it is unwise to ignore the antecedent improbability of a hypothesis which would explain the data better than others, e.g., the best explanation of a coin falling heads 530 times in 1,000 tosses might be that it is biassed to give a probability of heads of 0.53 but it might be more sensible to suppose that it is fair, or to suspend judgement.

In a philosophy of language is considered as the general attempt to understand the components of a working language, the relationship th understanding speaker has to its elements, and the relationship they bear to the world. The subject therefore embraces the traditional division of semiotic into syntax, semantics, an d pragmatics. The philosophy of language thus mingles with the philosophy of mind, since it needs an account of what it is in our understanding that enables us to use language. It so mingles with the metaphysics of truth and the relationship between sign and object. Much as much is that the philosophy in the 20th century, has been informed by the belief that philosophy of language is the fundamental basis of all philosophical problems, in that language is the distinctive exercise of mind, and the distinctive way in which we give shape to metaphysical beliefs. Particular topics will include the problems of logical form,. And the basis of the division between syntax and semantics, as well as problems of understanding the number and nature of specifically semantic relationships such as meaning, reference, predication, and quantification. Pragmatics include that of speech acts, while problems of rule following and the indeterminacy of translation infect philosophies of both pragmatics and semantics.

On this conception, to understand a sentence is to know its truth-conditions, and, yet, in a distinctive way the conception has remained central that those who offer opposing theories characteristically define their position by reference to it. The Concepcion of meaning s truth-conditions need not and should not be advanced as being in itself as complete account of meaning. For instance, one who understands a language must have some idea of the range of speech acts contextually performed by the various types of sentence in the language, and must have some idea of the insufficiencies of various kinds of speech act. The claim of the theorist of truth-conditions should rather be targeted on the notion of content: If indicative sentence differ in what they strictly and literally say, then this difference is fully accounted for by the difference in the truth-conditions.

The meaning of a complex expression is a function of the meaning of its constituent. This is just as a sentence of what it is for an expression to be semantically complex. It is one of th initial attractions of the conception of meaning truth-conditions tat it permits a smooth and satisfying account of th way in which the meaning of s complex expression is a function of the meaning of its constituents. On the truth-conditional conception, to give the meaning of an expression is to state the contribution it makes to the truth-conditions of sentences in which it occurs. For singular terms-proper names, indexical, and certain pronouns-this is done by stating the reference of the terms in question. For predicates, it is done either by stating the conditions under which the predicate is true of arbitrary objects, or by stating th conditions under which arbitrary atomic sentences containing it are true. The meaning of a sentence-forming operator is given by stating its contribution to the truth-conditions of as complex sentence, as a function of he semantic values of the sentences on which it operates.

The theorist of truth conditions should insist that not every true statement about the reference of an expression is fit to be an axiom in a meaning-giving theory of truth for a language, such is the axiom: ‘London’ refers to the city in which there was a huge fire in 1666, is a true statement about the reference of ‘London’. It is a consequent of a theory which substitutes this axiom for no different a term than of our simple truth theory that ‘London is beautiful’ is true if and only if the city in which there was a huge fire in 1666 is beautiful. Since a subject can understand the name ‘London’ without knowing that last-mentioned truth condition, this replacement axiom is not fit to be an axiom in a meaning-specifying truth theory. It is, of course, incumbent on a theorised meaning of truth conditions, to state in a way which does not presuppose any previous, non-truth conditional conception of meaning

Among the many challenges facing the theorist of truth conditions, two are particularly salient and fundamental. First, the theorist has to answer the charge of triviality or vacuity, second, the theorist must offer an account of what it is for a person’s language to be truly describable by as semantic theory containing a given semantic axiom.

Since the content of a claim that the sentence ‘Paris is beautiful’ is true amounts to no more than the claim that Paris is beautiful, we can trivially describers understanding a sentence, if we wish, as knowing its truth-conditions, but this gives us no substantive account of understanding whatsoever. Something other than grasp of truth conditions must provide the substantive account. The charge rests upon what has been called the redundancy theory of truth, the theory which, somewhat more discriminatingly. Horwich calls the minimal theory of truth. Its conceptual representation that the concept of truth is exhausted by the fact that it conforms to the equivalence principle, the principle that for any proposition ‘p’, it is true that ‘p’ if and only if ‘p’. Many different philosophical theories of truth will, with suitable qualifications, accept that equivalence principle. The distinguishing feature of the minimal theory is its claim that the equivalence principle exhausts the notion of truth. It is now widely accepted, both by opponents and supporters of truth conditional theories of meaning, that it is inconsistent to accept both minimal theory of ruth and a truth conditional account of meaning. If the claim that the sentence ‘Paris is beautiful’ is true is exhausted by its equivalence to the claim that Paris is beautiful, it is circular to try of its truth conditions. The minimal theory of truth has been endorsed by the Cambridge mathematician and philosopher Plumpton Ramsey (1903-30), and the English philosopher Jules Ayer, the later Wittgenstein, Quine, Strawson. Horwich and-confusing and inconsistently if this article is correct-Frége himself. but is the minimal theory correct?

The minimal theory treats instances of the equivalence principle as definitional of truth for a given sentence, but in fact, it seems that each instance of the equivalence principle can itself be explained. The truths from which such an instance as: ‘London is beautiful’ is true if and only if London is beautiful. This would be a pseudo-explanation if the fact that ‘London’ refers to London consists in part in the fact that ‘London is beautiful’ has the truth-condition it does. But it is very implausible, it is, after all, possible to understand the name ‘London’ without understanding the predicate ‘is beautiful’.

Sometimes, however, the counterfactual conditional is known as subjunctive conditionals, insofar as a counterfactual conditional is a conditional of the form ‘if p were to happen q would’, or ‘if p were to have happened q would have happened’, where the supposition of ‘p’ is contrary to the known fact that ‘not-p’. Such assertions are nevertheless, use=ful ‘if you broken the bone, the X-ray would have looked different’, or ‘if the reactor were to fail, this mechanism wold click in’ are important truths, even when we know that the bone is not broken or are certain that the reactor will not fail. It is arguably distinctive of laws of nature that yield counterfactuals (‘if the metal were to be heated, it would expand’), whereas accidentally true generalizations may not. It is clear that counterfactuals cannot be represented by the material implication of the propositional calculus, since that conditionals comes out true whenever ‘p’ is false, so there would be no division between true and false counterfactuals.

Although the subjunctive form indicates a counterfactual, in many contexts it does not seem to matter whether we use a subjunctive form, or a simple conditional form: ‘If you run out of water, you will be in trouble’ seems equivalent to ‘if you were to run out of water, you would be in trouble’, in other contexts there is a big difference: ‘If Oswald did not kill Kennedy, someone else did’ is clearly true, whereas ‘if Oswald had not killed Kennedy, someone would have’ is most probably false.

The best-known modern treatment of counterfactuals is that of David Lewis, which evaluates them as true or false according to whether ‘q’ is true in the ‘most similar’ possible worlds to ours in which ‘p’ is true. The similarity-ranking this approach needs has proved controversial, particularly since it may need to presuppose some notion of the same laws of nature, whereas art of the interest in counterfactuals is that they promise to illuminate that notion. There is a growing awareness tat the classification of conditionals is an extremely tricky business, and categorizing them as counterfactuals or not be of limited use.

The pronouncing of any conditional; preposition of the form ‘if p then q’. The condition hypothesizes, ‘p’. Its called the antecedent of the conditional, and ‘q’ the consequent. Various kinds of conditional have been distinguished. The weaken in that of material implication, merely telling us that with not-p. or q. stronger conditionals include elements of modality, corresponding to the thought that ‘if p is true then q must be true’. Ordinary language is very flexible in its use of the conditional form, and there is controversy whether, yielding different kinds of conditionals with different meanings, or pragmatically, in which case there should be one basic meaning which case there should be one basic meaning, with surface differences arising from other implicatures.

We now turn to a philosophy of meaning and truth, for which it is especially associated with the American philosopher of science and of language (1839-1914), and the American psychologist philosopher William James (1842-1910), wherefore the study in Pragmatism is given to various formulations by both writers, but the core is the belief that the meaning of a doctrine is the same as the practical effects of adapting it. Peirce interpreted of theocratical sentence ids only that of a corresponding practical maxim (telling us what to do in some circumstance). In James the position issues in a theory of truth, notoriously allowing that belief, including for example, belief in God, are the widest sense of the works satisfactorily in the widest sense of the word. On James’s view almost any belief might be respectable, and even rue, provided it works (but working is no simple matter for James). The apparently subjectivist consequences of tis were wildly assailed by Russell (1872-1970), Moore (1873-1958), and others in the early years of the 20 century. This led to a division within pragmatism between those such as the American educator John Dewey (1859-1952), whose humanistic conception of practice remains inspired by science, and the more idealistic route that especially by the English writer F.C.S. Schiller (1864-1937), embracing the doctrine that our cognitive efforts and human needs actually transform the reality that we seek to describe. James often writes as if he sympathizes with this development. For instance, in The Meaning of Truth (1909), he considers the hypothesis that other people have no minds (dramatized in the sexist idea of an ‘automatic sweetheart’ or female zombie) and remarks hat the hypothesis would not work because it would not satisfy our egoistic craving for the recognition and admiration of others. The implication that this is what makes it true that the other persons have minds in the disturbing part.

Modern pragmatists such as the American philosopher and critic Richard Rorty (1931-) and some writings of the philosopher Hilary Putnam (1925-) who have usually tried to dispense with an account of truth and concentrate, as perhaps James should have done, upon the nature of belief and its relations with human attitude, emotion, and need. The driving motivation of pragmatism is the idea that belief in the truth on te one hand must have a close connection with success in action on the other. One way of cementing the connection is found in the idea that natural selection must have adapted us to be cognitive creatures because belief have effects, as they work. Pragmatism can be found in Kant’s doctrine of the primary of practical over pure reason, and continues to play an influential role in the theory of meaning and of truth.

In case of fact, the philosophy of mind is the modern successor to behaviourism, as do the functionalism that its early advocates were Putnam (1926-) and Sellars (1912-89), and its guiding principle is that we can define mental states by a triplet of relations they have on other mental stares, what effects they have on behaviour. The definition need not take the form of a simple analysis, but if w could write down the totality of axioms, or postdates, or platitudes that govern our theories about what things of other mental states, and our theories about what things are apt to cause (for example), a belief state, what effects it would have on a variety of other mental states, and what effects it is likely to have on behaviour, then we would have done all tat is needed to make the state a proper theoretical notion. It could be implicitly defied by these theses. Functionalism is often compared with descriptions of a computer, since according to mental descriptions correspond to a description of a machine in terms of software, that remains silent about the underlaying hardware or ‘realization’ of the program the machine is running. The principle advantage of functionalism include its fit with the way we know of mental states both of ourselves and others, which is via their effects on behaviour and other mental states. As with behaviourism, critics charge that structurally complex items tat do not bear mental states might nevertheless, imitate the functions that are cited. According to this criticism functionalism is too generous and would count too many things as having minds. It is also queried whether functionalism is too paradoxical, able to see mental similarities only when there is causal similarity, when our actual practices of interpretations enable us to ascribe thoughts and desires to different from our own, it may then seem as though beliefs and desires can be ‘variably realized’ causal architecture, just as much as they can be in different neurophysiological states.

The philosophical movement of Pragmatism had a major impact on American culture from the late 19th century to the present. Pragmatism calls for ideas and theories to be tested in practice, by assessing whether acting upon the idea or theory produces desirable or undesirable results. According to pragmatists, all claims about truth, knowledge, morality, and politics must be tested in this way. Pragmatism has been critical of traditional Western philosophy, especially the notion that there are absolute truths and absolute values. Although pragmatism was popular for a time in France, England, and Italy, most observers believe that it encapsulates an American faith in know-how and practicality and an equally American distrust of abstract theories and ideologies.

In mentioning the American psychologist and philosopher we find William James, who helped to popularize the philosophy of pragmatism with his book Pragmatism: A New Name for Old Ways of Thinking (1907). Influenced by a theory of meaning and verification developed for scientific hypotheses by American philosopher C. S. Peirce, James held that truth is what works, or has good experimental results. In a related theory, James argued the existence of God is partly verifiable because many people derive benefits from believing.

The Association for International Conciliation first published William James’s pacifist statement, 'The Moral Equivalent of War', in 1910. James, a highly respected philosopher and psychologist, was one of the founders of pragmatism-a philosophical movement holding that ideas and theories must be tested in practice to assess their worth. James hoped to find a way to convince men with a long-standing history of pride and glory in war to evolve beyond the need for bloodshed and to develop other avenues for conflict resolution. Spelling and grammar represent standards of the time.

Pragmatists regard all theories and institutions as tentative hypotheses and solutions. For this reason they believed that efforts to improve society, through such means as education or politics, must be geared toward problem solving and must be ongoing. Through their emphasis on connecting theory to practice, pragmatist thinkers attempted to transform all areas of philosophy, from metaphysics to ethics and political philosophy.

Pragmatism sought a middle ground between traditional ideas about the nature of reality and radical theories of nihilism and irrationalism, which had become popular in Europe in the late 19th century. Traditional metaphysics assumed that the world has a fixed, intelligible structure and that human beings can know absolute or objective truths about the world and about what constitutes moral behaviour. Nihilism and irrationalism, on the other hand, denied those very assumptions and their certitude. Pragmatists today still try to steer a middle course between contemporary offshoots of these two extremes.

The ideas of the pragmatists were considered revolutionary when they first appeared. To some critics, pragmatism’s refusal to affirm any absolutes carried negative implications for society. For example, pragmatists do not believe that a single absolute idea of goodness or justice exists, but rather that these concepts are changeable and depend on the context in which they are being discussed. The absence of these absolutes, critics feared, could result in a decline in moral standards. The pragmatists’ denial of absolutes, moreover, challenged the foundations of religion, government, and schools of thought. As a result, pragmatism influenced developments in psychology, sociology, education, semiotics (the study of signs and symbols), and scientific method, as well as philosophy, cultural criticism, and social reform movements. Various political groups have also drawn on the assumptions of pragmatism, from the progressive movements of the early 20th century to later experiments in social reform.

Pragmatism is best understood in its historical and cultural context. It arose during the late 19th century, a period of rapid scientific advancement typified by the theories of British biologist Charles Darwin, whose theories suggested to many thinkers that humanity and society are in a perpetual state of progress. During this same period a decline in traditional religious beliefs and values accompanied the industrialization and material progress of the time. In consequence it became necessary to rethink fundamental ideas about values, religion, science, community, and individuality.

The three most important pragmatists are American philosophers Charles Sanders Peirce, William James, and John Dewey. Peirce was primarily interested in scientific method and mathematics; his objective was to infuse scientific thinking into philosophy and society, and he believed that human comprehension of reality was becoming ever greater and that human communities were becoming increasingly progressive. Peirce developed pragmatism as a theory of meaning-in particular, the meaning of concepts used in science. The meaning of the concept 'brittle', for example, is given by the observed consequences or properties that objects called 'brittle' exhibit. For Peirce, the only rational way to increase knowledge was to form mental habits that would test ideas through observation, experimentation, or what he called inquiry. Many philosophers known as logical positivists, a group of philosophers who have been influenced by Peirce, believed that our evolving species was fated to get ever closer to Truth. Logical positivists emphasize the importance of scientific verification, rejecting the assertion of positivism that personal experience is the basis of true knowledge.

James moved pragmatism in directions that Peirce strongly disliked. He generalized Peirce’s doctrines to encompass all concepts, beliefs, and actions; he also applied pragmatist ideas to truth as well as to meaning. James was primarily interested in showing how systems of morality, religion, and faith could be defended in a scientific civilization. He argued that sentiment, as well as logic, is crucial to rationality and that the great issues of life-morality and religious belief, for example-are leaps of faith. As such, they depend upon what he called 'the will to believe' and not merely on scientific evidence, which can never tell us what to do or what is worthwhile. Critics charged James with relativism (the belief that values depend on specific situations) and with crass expediency for proposing that if an idea or action works the way one intends, it must be right. But James can more accurately be described as a pluralist-someone who believes the world to be far too complex for any one philosophy to explain everything.

Dewey’s philosophy can be described as a version of philosophical naturalism, which regards human experience, intelligence, and communities as ever-evolving mechanisms. Using their experience and intelligence, Dewey believed, human beings can solve problems, including social problems, through inquiry. For Dewey, naturalism led to the idea of a democratic society that allows all members to acquire social intelligence and progress both as individuals and as communities. Dewey held that traditional ideas about knowledge, truth, and values, in which absolutes are assumed, are incompatible with a broadly Darwinian world-view in which individuals and society are progressing. In consequence, he felt that these traditional ideas must be discarded or revised. Indeed, for pragmatists, everything people know and do depends on a historical context and is thus tentative rather than absolute.

Many followers and critics of Dewey believe he advocated elitism and social engineering in his philosophical stance. Others think of him as a kind of romantic humanist. Both tendencies are evident in Dewey’s writings, although he aspired to synthesize the two realms.

The pragmatist tradition was revitalized in the 1980s by American philosopher Richard Rorty, who has faced similar charges of elitism for his belief in the relativism of values and his emphasis on the role of the individual in attaining knowledge. Interest has renewed in the classic pragmatists-Pierce, James, and Dewey-have an alternative to Rorty’s interpretation of the tradition.

The Philosophy of Mind, is the branch of philosophy that considers mental phenomena such as sensation, perception, thought, belief, desire, intention, memory, emotion, imagination, and purposeful action. These phenomena, which can be broadly grouped as thoughts and experiences, are features of human beings; many of them are also found in other animals. Philosophers are interested in the nature of each of these phenomena as well as their relationships to one another and to physical phenomena, such as motion.

The most famous exponent of dualism was the French philosopher René Descartes, who maintained that body and mind are radically different entities and that they are the only fundamental substances in the universe. Dualism, however, does not show how these basic entities are connected.

In the work of the German philosopher Gottfried Wilhelm Leibniz, the universe is held to consist of an infinite number of distinct substances, or monads. This view is pluralistic in the sense that it proposes the existence of many separate entities, and it is monistic in its assertion that each monad reflects within itself the entire universe.

Other philosophers have held that knowledge of reality is not derived from a priori principles, but is obtained only from experience. This type of metaphysics is called empiricism. Still another school of philosophy has maintained that, although an ultimate reality does exist, it is altogether inaccessible to human knowledge, which is necessarily subjective because it is confined to states of mind. Knowledge is therefore not a representation of external reality, but merely a reflection of human perceptions. This view is known as skepticism or agnosticism in respect to the soul and the reality of God.

The 18th-century German philosopher Immanuel Kant published his influential work The Critique of Pure Reason in 1781. Three years later, he expanded on his study of the modes of thinking with an essay entitled 'What is Enlightenment'? In this 1784 essay, Kant challenged readers to 'dare to know', arguing that it was not only a civic but also a moral duty to exercise the fundamental freedoms of thought and expression.

Several major viewpoints were combined in the work of Kant, who developed a distinctive critical philosophy called transcendentalism. His philosophy is agnostic in that it denies the possibility of a strict knowledge of ultimate reality; it is empirical in that it affirms that all knowledge arises from experience and is true of objects of actual and possible experience; and it is rationalistic in that it maintains the a priori character of the structural principles of this empirical knowledge.

These principles are held to be necessary and universal in their application to experience, for in Kant's view the mind furnishes the archetypal forms and categories (space, time, causality, substance, and relation) to its sensations, and these categories are logically anterior to experience, although manifested only in experience. Their logical anteriority to experience makes these categories or structural principles transcendental; they transcend all experience, both actual and possible. Although these principles determine all experience, they do not in any way affect the nature of things in themselves. The knowledge of which these principles are the necessary conditions must not be considered, therefore, as constituting a revelation of things as they are in themselves. This knowledge concerns things only insofar as they appear to human perception or as they can be apprehended by the senses. The argument by which Kant sought to fix the limits of human knowledge within the framework of experience and to demonstrate the inability of the human mind to penetrate beyond experience strictly by knowledge to the realm of ultimate reality constitutes the critical feature of his philosophy, giving the key word to the titles of his three leading treatises, Critique of Pure Reason, Critique of Practical Reason, and Critique of Judgment. In the system propounded in these works, Kant sought also to reconcile science and religion in a world of two levels, comprising noumena, objects conceived by reason although not perceived by the senses, and phenomena, things as they appear to the senses and are accessible to material study. He maintained that, because God, freedom, and human immortality are noumenal realities, these concepts are understood through moral faith rather than through scientific knowledge. With the continuous development of science, the expansion of metaphysics to include scientific knowledge and methods became one of the major objectives of metaphysicians.

Some of Kant's most distinguished followers, notably Johann Gottlieb Fichte, Friedrich Schelling, Georg Wilhelm Friedrich Hegel, and Friedrich Schleiermacher, negated Kant's criticism in their elaborations of his transcendental metaphysics by denying the Kantian conception of the thing-in-itself. They thus developed an absolute idealism in opposition to Kant's critical transcendentalism.

Since the formation of the hypothesis of absolute idealism, the development of metaphysics has resulted in as many types of metaphysical theory as existed in pre-Kantian philosophy, despite Kant's contention that he had fixed definitely the limits of philosophical speculation. Notable among these later metaphysical theories are radical empiricism, or pragmatism, a native American form of metaphysics expounded by Charles Sanders Peirce, developed by William James, and adapted as instrumentalism by John Dewey; voluntarism, the foremost exponents of which are the German philosopher Arthur Schopenhauer and the American philosopher Josiah Royce; phenomenalism, as it is exemplified in the writings of the French philosopher Auguste Comte and the British philosopher Herbert Spencer; emergent evolution, or creative evolution, originated by the French philosopher Henri Bergson; and the philosophy of the organism, elaborated by the British mathematician and philosopher Alfred North Whitehead. The salient doctrines of pragmatism are that the chief function of thought is to guide action, that the meaning of concepts is to be sought in their practical applications, and that truth should be tested by the practical effects of belief; according to instrumentalism, ideas are instruments of action, and their truth is determined by their role in human experience. In the theory of voluntarism the will is postulated as the supreme manifestation of reality. The exponents of phenomenalism, who are sometimes called positivists, contend that everything can be analysed in terms of actual or possible occurrences, or phenomena, and that anything that cannot be analysed in this manner cannot be understood. In emergent or creative evolution, the evolutionary process is characterized as spontaneous and unpredictable rather than mechanistically determined. The philosophy of the organism combines an evolutionary stress on constant process with a metaphysical theory of God, the eternal objects, and creativity.

In the 20th century the validity of metaphysical thinking has been disputed by the logical positivists (see Analytic and Linguistic Philosophy; Positivism) and by the so-called dialectical materialism of the Marxists. The basic principle maintained by the logical positivists is the verifiability theory of meaning. According to this theory a sentence has factual meaning only if it meets the test of observation. Logical positivists argue that metaphysical expressions such as 'Nothing exists except material particles' and 'Everything is part of one all-encompassing spirit' cannot be tested empirically. Therefore, according to the verifiability theory of meaning, these expressions have no factual cognitive meaning, although they can have an emotive meaning relevant to human hopes and feelings.

The dialectical materialists assert that the mind is conditioned by and reflects material reality. Therefore, speculations that conceive of constructs of the mind as having any other than material reality are themselves unreal and can result only in delusion. To these assertions metaphysicians reply by denying the adequacy of the verifiability theory of meaning and of material perception as the standard of reality. Both logical positivism and dialectical materialism, they argue, conceal metaphysical assumptions, for example, that everything is observable or at least connected with something observable and that the mind has no distinctive life of its own. In the philosophical movement known as existentialism, thinkers have contended that the questions of the nature of being and of the individual's relationship to it are extremely important and meaningful in terms of human life. The investigation of these questions is therefore considered valid whether or not its results can be verified objectively.

Since the 1950s the problems of systematic analytical metaphysics have been studied in Britain by Stuart Newton Hampshire and Peter Frederick Strawson, the former concerned, in the manner of Spinoza, with the relationship between thought and action, and the latter, in the manner of Kant, with describing the major categories of experience as they are embedded in language. In the U.S. metaphysics has been pursued much in the spirit of positivism by Wilfred Stalker Sellars and Willard Van Orman Quine. Sellars has sought to express metaphysical questions in linguistic terms, and Quine has attempted to determine whether the structure of language commits the philosopher to asserting the existence of any entities whatever and, if so, what kind. In these new formulations the issues of metaphysics and ontology remain vital.

n the 17th century, French philosopher René Descartes proposed that only two substances ultimately exist; mind and body. Yet, if the two are entirely distinct, as Descartes believed, how can one substance interact with the other? How, for example, is the intention of a human mind able to cause movement in the person’s limbs? The issue of the interaction between mind and body is known in philosophy as the mind-body problem.

Many fields other than philosophy share an interest in the nature of mind. In religion, the nature of mind is connected with various conceptions of the soul and the possibility of life after death. In many abstract theories of mind there is considerable overlap between philosophy and the science of psychology. Once part of philosophy, psychology split off and formed a separate branch of knowledge in the 19th century. While psychology uses scientific experiments to study mental states and events, philosophy uses reasoned arguments and thought experiments in seeking to understand the concepts that underlie mental phenomena. Also influenced by philosophy of mind is the field of artificial intelligence (AI), which endeavours to develop computers that can mimic what the human mind can do. Cognitive science attempts to integrate the understanding of mind provided by philosophy, psychology, AI, and other disciplines. Finally, all of these fields benefit from the detailed understanding of the brain that has emerged through neuroscience in the late 20th century.

Philosophers use the characteristics of inward accessibility, subjectivity, intentionality, goal-directedness, creativity and freedom, and consciousness to distinguish mental phenomena from physical phenomena.

Perhaps the most important characteristic of mental phenomena is that they are inwardly accessible, or available to us through introspection. We each know our own minds-our sensations, thoughts, memories, desires, and fantasies-in a direct sense, by internal reflection. We also know our mental states and mental events in a way that no one else can. In other words, we have privileged access to our own mental states.

Certain mental phenomena, those we generally call experiences, have a subjective nature-that is, they have certain characteristics we become aware of when we reflect. For instance, there is ‘something it is like’ to feel pain, or have an itch, or see something red. These characteristics are subjective in that they are accessible to the subject of the experience, the person who has the experience, but not to others.

Other mental phenomena, which we broadly refer to as thoughts, have a characteristic philosophers call intentionality. Intentional thoughts are about other thoughts or objects, which are represented as having certain properties or as being related to one another in a certain way. The belief that California is west of Nevada, for example, is about California and Nevada and represents the former as being west of the latter. Although we have privileged access to our intentional states, many of them do not seem to have a subjective nature, at least not in the way that experiences do.

A number of mental phenomena appear to be connected to one another as elements in an intelligent, goal-directed system. The system works as follows: First, our sense organs are stimulated by events in our environment; next, by virtue of these stimulations, we perceive things about the external world; finally, we use this information, as well as information we have remembered or inferred, to guide our actions in ways that further our goals. Goal-directedness seems to accompany only mental phenomena.

Another important characteristic of mind, especially of human minds, is the capacity for choice and imagination. Rather than automatically converting past influences into future actions, individual minds are capable of exhibiting creativity and freedom. For instance, we can imagine things we have not experienced and can act in ways that no one expects or could predict.

Mental phenomena are conscious, and consciousness may be the closest term we have for describing what is special about mental phenomena. Minds are sometimes referred to as consciousness, yet it is difficult to describe exactly what consciousness is. Although consciousness is closely related to inward accessibility and subjectivity, these very characteristics seem to hinder us in reaching an objective scientific understanding of it.

Although philosophers have written about mental phenomena since ancient times, the philosophy of mind did not garner much attention until the work of French philosopher René Descartes in the 17th century. Descartes’s work represented a turning point in thinking about mind by making a strong distinction between bodies and minds, or the physical and the mental. This duality between mind and body, known as Cartesian dualism, has posed significant problems for philosophy ever since.

Descartes believed there are two basic kinds of things in the world, a belief known as substance dualism. For Descartes, the principles of existence for these two groups of things-bodies and minds-are completely different from one another: Bodies exist by being extended in space, while minds exist by being conscious. According to Descartes, nothing can be done to give a body thought and consciousness. No matter how we shape a body or combine it with other bodies, we cannot turn the body into a mind, a thing that is conscious, because being conscious is not a way of being extended.

For Descartes, a person consists of a human body and a human mind causally interacting with one another. For example, the intentions of a human being may cause that person’s limbs to move. In this way, the mind can affect the body. In addition, the sense organs of a human being may be affected by light, pressure, or sound, external sources which in turn affect the brain, affecting mental states. Thus the body may affect the mind. Exactly how mind can affect body, and vice versa, is a central issue in the philosophy of mind, and is known as the mind-body problem. According to Descartes, this interaction of mind and body is peculiarly intimate. Unlike the interaction between a pilot and his ship, the connection between mind and body more closely resembles two substances that have been thoroughly mixed together.

In response to the mind-body problem arising from Descartes’s theory of substance dualism, a number of philosophers have advocated various forms of substance monism, the doctrine that there is ultimately just one kind of thing in reality. In the 18th century, Irish philosopher George Berkeley claimed there were no material objects in the world, only minds and their ideas. Berkeley thought that talk about physical objects was simply a way of organizing the flow of experience. Near the turn of the 20th century, American psychologist and philosopher William James proposed another form of substance monism. James claimed that experience is the basic stuff from which both bodies and minds are constructed.

Most philosophers of mind today are substance monists of a third type: They are materialists who believe that everything in the world is basically material, or a physical object. Among materialists, there is still considerable disagreement about the status of mental properties, which are conceived as properties of bodies or brains. Materialists who are property dualists believe that mental properties are an additional kind of property or attribute, not reducible to physical properties. Property dualists have the problem of explaining how such properties can fit into the world envisaged by modern physical science, according to which there are physical explanations for all things.

Materialists who are property monists believe that there is ultimately only one type of property, although they disagree on whether or not mental properties exist in material form. Some property monists, known as reductive materialists, hold that mental properties exist simply as a subset of relatively complex and non-basic physical properties of the brain. Reductive materialists have the problem of explaining how the physical states of the brain can be inwardly accessible and have a subjective character, as mental states do. Other property monists, known as eliminative materialists, consider the whole category of mental properties to be a mistake. According to them, mental properties should be treated as discredited postulates of an outmoded theory. Eliminative materialism is difficult for most people to accept, since we seem to have direct knowledge of our own mental phenomena by introspection and because we use the general principles we understand about mental phenomena to predict and explain the behaviour of others.

Philosophy of mind concerns itself with a number of specialized problems. In addition to the mind-body problem, important issues include those of personal identity, immortality, and artificial intelligence.

During much of Western history, the mind has been identified with the soul as presented in Christian theology. According to Christianity, the soul is the source of a person’s identity and is usually regarded as immaterial; thus it is capable of enduring after the death of the body. Descartes’s conception of the mind as a separate, nonmaterial substance fits well with this understanding of the soul. In Descartes’s view, we are aware of our bodies only as the cause of sensations and other mental phenomena. Consequently our personal essence is composed more fundamentally of mind and the preservation of the mind after death would constitute our continued existence.

The mind conceived by materialist forms of substance monism does not fit as neatly with this traditional concept of the soul. With materialism, once a physical body is destroyed, nothing enduring remains. Some philosophers think that a concept of personal identity can be constructed that permits the possibility of life after death without appealing to separate immaterial substances. Following in the tradition of 17th-century British philosopher John Locke, these philosophers propose that a person consists of a stream of mental events linked by memory. It is these links of memory, rather than a single underlying substance, that provides the unity of a single consciousness through time. Immortality is conceivable if we think of these memory links as connecting a later consciousness in heaven with an earlier one on earth.

The field of artificial intelligence also raises interesting questions for the philosophy of mind. People have designed machines that mimic or model many aspects of human intelligence, and there are robots currently in use whose behaviour is described in terms of goals, beliefs, and perceptions. Such machines are capable of behaviour that, were it exhibited by a human being, would surely be taken to be free and creative. As an example, in 1996 an IBM computer named Deep Blue won a chess game against Russian world champion Garry Kasparov under international match regulations. Moreover, it is possible to design robots that have some sort of privileged access to their internal states. Philosophers disagree over whether such robots truly think or simply appear to think and whether such robots should be considered to be conscious

Dualism, in philosophy, the theory that the universe is explicable only as a whole composed of two distinct and mutually irreducible elements. In Platonic philosophy the ultimate dualism is between 'being' and 'nonbeing'-that is, between ideas and matter. In the 17th century, dualism took the form of belief in two fundamental substances: mind and matter. French philosopher René Descartes, whose interpretation of the universe exemplifies this belief, was the first to emphasize the irreconcilable difference between thinking substance (mind) and extended substance (matter). The difficulty created by this view was to explain how mind and matter interact, as they apparently do in human experience. This perplexity caused some Cartesians to deny entirely any interaction between the two. They asserted that mind and matter are inherently incapable of affecting each other, and that any reciprocal action between the two is caused by God, who, on the occasion of a change in one, produces a corresponding change in the other. Other followers of Descartes abandoned dualism in favor of monism.

In the 20th century, reaction against the monistic aspects of the philosophy of idealism has to some degree revived dualism. One of the most interesting defences of dualism is that of Anglo-American psychologist William McDougall, who divided the universe into spirit and matter and maintained that good evidence, both psychological and biological, indicates the spiritual basis of physiological processes. French philosopher Henri Bergson in his great philosophic work Matter and Memory likewise took a dualistic position, defining matter as what we perceive with our senses and possessing in itself the qualities that we perceive in it, such as colour and resistance. Mind, on the other hand, reveals itself as memory, the faculty of storing up the past and utilizing it for modifying our present actions, which otherwise would be merely mechanical. In his later writings, however, Bergson abandoned dualism and came to regard matter as an arrested manifestation of the same vital impulse that composes life and mind.

Dualism, in philosophy, the theory that the universe is explicable only as a whole composed of two distinct and mutually irreducible elements. In Platonic philosophy the ultimate dualism is between 'being' and 'nonbeing-that is, between ideas and matter. In the 17th century, dualism took the form of belief in two fundamental substances: mind and matter. French philosopher René Descartes, whose interpretation of the universe exemplifies this belief, was the first to emphasize the irreconcilable difference between thinking substance (mind) and extended substance (matter). The difficulty created by this view was to explain how mind and matter interact, as they apparently do in human experience. This perplexity caused some Cartesians to deny entirely any interaction between the two. They asserted that mind and matter are inherently incapable of affecting each other, and that any reciprocal action between the two is caused by God, who, on the occasion of a change in one, produces a corresponding change in the other. Other followers of Descartes abandoned dualism in favor of monism.

In the 20th century, reaction against the monistic aspects of the philosophy of idealism has to some degree revived dualism. One of the most interesting defences of dualism is that of Anglo-American psychologist William McDougall, who divided the universe into spirit and matter and maintained that good evidence, both psychological and biological, indicates the spiritual basis of physiological processes. French philosopher Henri Bergson in his great philosophic work Matter and Memory likewise took a dualistic position, defining matter as what we perceive with our senses and possessing in itself the qualities that we perceive in it, such as colour and resistance. Mind, on the other hand, reveals itself as memory, the faculty of storing up the past and utilizing it for modifying our present actions, which otherwise would be merely mechanical. In his later writings, however, Bergson abandoned dualism and came to regard matter as an arrested manifestation of the same vital impulse that composes life and mind.

For many people understanding the place of mind in nature is the greatest philosophical problem. Mind is often though to be the last domain that stubbornly resists scientific understanding and philosophers defer over whether they find that cause for celebration or scandal. The mind-body problem in the modern era was given its definitive shape by Descartes, although the dualism that he espoused is in some form whatever there is a religious or philosophical tradition there is a religious or philosophical tradition whereby the soul may have an existence apart from the body. While most modern philosophers of mind would reject the imaginings that lead us to think that this makes sense, there is no consensus over the best way to integrate our understanding of people as bearers of physical properties lives on the other.

Occasionalism find from its term as employed to designate the philosophical system devised by the followers of the 17th-century French philosopher René Descartes, who, in attempting to explain the interrelationship between mind and body, concluded that God is the only cause. The occasionalists began with the assumption that certain actions or modifications of the body are preceded, accompanied, or followed by changes in the mind. This assumed relationship presents no difficulty to the popular conception of mind and body, according to which each entity is supposed to act directly on the other; these philosophers, however, asserting that cause and effect must be similar, could not conceive the possibility of any direct mutual interaction between substances as dissimilar as mind and body.

According to the occasionalists, the action of the mind is not, and cannot be, the cause of the corresponding action of the body. Whenever any action of the mind takes place, God directly produces in connection with that action, and by reason of it, a corresponding action of the body; the converse process is likewise true. This theory did not solve the problem, for if the mind cannot act on the body (matter), then God, conceived as mind, cannot act on matter. Conversely, if God is conceived as other than mind, then he cannot act on mind. A proposed solution to this problem was furnished by exponents of radical empiricism such as the American philosopher and psychologist William James. This theory disposed of the dualism of the occasionalists by denying the fundamental difference between mind and matter.

Generally, along with consciousness, that experience of an external world or similar scream or other possessions, takes upon itself the visual experience or deprive of some normal visual experience, that this, however, does not perceive the world accurately. In its frontal experiment. As researchers reared kittens in total darkness, except that for five hours a day the kittens were placed in an environment with only vertical lines. When the animals were later exposed to horizontal lines and forms, they had trouble perceiving these forms.

Philosophers have long debated the role of experience in human perception. In the late 17th century, Irish philosopher William Molyneux wrote to his friend, English philosopher John Locke, and asked him to consider the following scenario: Suppose that you could restore sight to a person who was blind. Using only vision, would that person be able to tell the difference between a cube and a sphere, which she or he had previously experienced only through touch? Locke, who emphasized the role of experience in perception, thought the answer was no. Modern science actually allows us to address this philosophical question, because a very small number of people who were blind have had their vision restored with the aid of medical technology.

Two researchers, British psychologist Richard Gregory and British-born neurologist Oliver Sacks, have written about their experiences with men who were blind for a long time due to cataracts and then had their vision restored late in life. When their vision was restored, they were often confused by visual input and were unable to see the world accurately. For instance, they could detect motion and perceive colours, but they had great difficulty with complex stimuli, such as faces. Much of their poor perceptual ability was probably due to the fact that the synapses in the visual areas of their brains had received little or no stimulation throughout their lives. Thus, without visual experience, the visual system does not develop properly.

Visual experience is useful because it creates memories of past stimuli that can later serve as a context for perceiving new stimuli. Thus, you can think of experience as a form of context that you carry around with you. A visual illusion occurs when your perceptual experience of a stimulus is substantially different from the actual stimulus you are viewing. In the previous example, you saw the green circles as different sizes, even though they were actually the same size. To experience another illusion, look at the illustration entitled 'Zöllner Illusion'. What shape do you see? You may see a trapezoid that is wider at the top, but the actual shape is a square. Such illusions are natural artifacts of the way our visual systems work. As a result, illusions provide important insights into the functioning of the visual system. In addition, visual illusions are fun to experience.

Consider the pair of illusions in the accompanying illustration, “Illusions of Length.” These illusions are called geometrical illusions, because they use simple geometrical relationships to produce the illusory effects. The first illusion, the Müller-Lyer illusion, is one of the most famous illusions in psychology. Which of the two horizontal lines is longer? Although your visual system tells you that the lines are not equal, a ruler would tell you that they are equal. The second illusion is called the Ponzo illusion. Once again, the two lines do not appear to be equal in length, but they are. For further information about illusions

Prevailing states of consciousness, are not as simple, or agreed-upon by any steadfast and held definition of itself, in so, that, consciousness exists. Attempted definitions tend to be tautological (for example, consciousness defined s awareness) or merely descriptive (for example, consciousness described as sensations, thoughts, or feelings). Despite this problem of definition, the subject of consciousness has had a remarkable history. At one time the primary subject matter of psychology, consciousness as an area of study suffered an almost total demise, later reemerging to become a topic of current interest.

René Descartes applied rigorous scientific methods of deduction to his exploration of philosophical questions. Descartes is probably best known for his pioneering work in philosophical skepticism. Author Tom Sorell examines the concepts behind Descartes’s work Meditationes de Prima Philosophia (1641; Meditations on First Philosophy), focussing on its unconventional use of logic and the reactions it aroused. Most of the philosophical discussions of consciousness arose from the mind-body issues posed by the French philosopher and mathematician René Descartes in the 17th century. Descartes asked: Is the mind, or consciousness, independent of matter? Is consciousness extended (physical) or unextended (nonphysical)? Is consciousness determinative, or is it determined? English philosophers such as John Locke equated consciousness with physical sensations and the information they provide, whereas European philosophers such as Gottfried Wilhelm Leibniz and Immanuel Kant gave a more central and active role to consciousness.

The philosopher who most directly influenced subsequent exploration of the subject of consciousness was the 19th-century German educator Johann Friedrich Herbart, who wrote that ideas had quality and intensity and that they may inhibit or facilitate one another. Thus, ideas may pass from “states of reality” (consciousness) to “states of tendency” (unconsciousness), with the dividing line between the two states being described as the threshold of consciousness. This formulation of Herbart clearly presages the development, by the German psychologist and physiologist Gustav Theodor Fechner, of the psychophysical measurement of sensation thresholds, and the later development by Sigmund Freud of the concept of the unconscious.

The experimental analysis of consciousness dates from 1879, when the German psychologist Wilhelm Max Wundt started his research laboratory. For Wundt, the task of psychology was the study of the structure of consciousness, which extended well beyond sensations and included feelings, images, memory, attention, duration, and movement. Because early interest focussed on the content and dynamics of consciousness, it is not surprising that the central methodology of such studies was introspection; that is, subjects reported on the mental contents of their own consciousness. This introspective approach was developed most fully by the American psychologist Edward Bradford Titchener at Cornell University. Setting his task as that of describing the structure of the mind, Titchener attempted to detail, from introspective self-reports, the dimensions of the elements of consciousness. For example, taste was “dimensionalized” into four basic categories: sweet, sour, salt, and bitter. This approach was known as structuralism.

By the 1920s, however, a remarkable revolution had occurred in psychology that was to essentially remove considerations of consciousness from psychological research for some 50 years: Behaviourism captured the field of psychology. The main initiator of this movement was the American psychologist John Broadus Watson. In a 1913 article, Watson stated, “I believe that we can write a psychology and never use the terms consciousness, mental states, mind . . . imagery and the like.” Psychologists then turned almost exclusively to behaviour, as described in terms of stimulus and response, and consciousness was totally bypassed as a subject. A survey of eight leading introductory psychology texts published between 1930 and the 1950s found no mention of the topic of consciousness in five texts, and in two it was treated as a historical curiosity.

Beginning in the late 1950s, however, interest in the subject of consciousness returned, specifically in those subjects and techniques relating to altered states of consciousness: sleep and dreams, meditation, biofeedback, hypnosis, and drug-induced states. Much of the surge in sleep and dream research was directly fuelled by a discovery relevant to the nature of consciousness. A physiological indicator of the dream state was found: At roughly 90-minute intervals, the eyes of sleepers were observed to move rapidly, and at the same time the sleepers' brain waves would show a pattern resembling the waking state. When people were awakened during these periods of rapid eye movement, they almost always reported dreams, whereas if awakened at other times they did not. This and other research clearly indicated that sleep, once considered a passive state, was instead an active state of consciousness (see Dreaming; Sleep).

During the 1960s, an increased search for “higher levels” of consciousness through meditation resulted in a growing interest in the practices of Zen Buddhism and Yoga from Eastern cultures. A full flowering of this movement in the United States was seen in the development of training programs, such as Transcendental Meditation, that were self-directed procedures of physical relaxation and focussed attention. Biofeedback techniques also were developed to bring body systems involving factors such as blood pressure or temperature under voluntary control by providing feedback from the body, so that subjects could learn to control their responses. For example, researchers found that persons could control their brain-wave patterns to some extent, particularly the so-called alpha rhythms generally associated with a relaxed, meditative state. This finding was especially relevant to those interested in consciousness and meditation, and a number of “alpha training” programs emerged.

Another subject that led to increased interest in altered states of consciousness was hypnosis, which involves a transfer of conscious control from the subject to another person. Hypnotism has had a long and intricate history in medicine and folklore and has been intensively studied by psychologists. Much has become known about the hypnotic state, relative to individual suggestibility and personality traits; the subject has now largely been demythologized, and the limitations of the hypnotic state are fairly well known. Despite the increasing use of hypnosis, however, much remains to be learned about this unusual state of focussed attention.

Finally, many people in the 1960s experimented with the psychoactive drugs known as hallucinogens, which produce disorders of consciousness. The most prominent of these drugs are lysergic acid diethylamide, or LSD; mescaline, and psilocybin; the latter two have long been associated with religious ceremonies in various cultures. LSD, because of its radical thought-modifying properties, was initially explored for its so-called mind-expanding potential and for its psychotomimetic effects (imitating psychoses). Little positive use, however, has been found for these drugs, and their use is highly restricted.

Scientists have long considered the nature of consciousness without producing a fully satisfactory definition. In the early 20th century American philosopher and psychologist William James suggested that consciousness is a mental process involving both attention to external stimuli and short-term memory. Later scientific explorations of consciousness mostly expanded upon James’s work. In this article from a 1997 special issue of Scientific American, Nobel laureate Francis Crick, who helped determine the structure of DNA, and fellow biophysicist Christof Koch explain how experiments on vision might deepen our understanding of consciousness.

As the concept of a direct, simple linkage between environment and behaviour became unsatisfactory in recent decades, the interest in altered states of consciousness may be taken as a visible sign of renewed interest in the topic of consciousness. That persons are active and intervening participants in their behaviour has become increasingly clear. Environments, rewards, and punishments are not simply defined by their physical character. Memories are organized, not simply stored. An entirely new area called cognitive psychology has emerged that canters on these concerns. In the study of children, increased attention is being paid to how they understand, or perceive, the world at different ages. In the field of animal behaviour, researchers increasingly emphasize the inherent characteristics resulting from the way a species has been shaped to respond adaptively to the environment. Humanistic psychologists, with a concern for self-actualization and growth, have emerged after a long period of silence. Throughout the development of clinical and industrial psychology, the conscious states of persons in terms of their current feelings and thoughts were of obvious importance. The role of consciousness, however, was often de-emphasized in favor of unconscious needs and motivations. Trends can be seen, however, toward a new emphasis on the nature of states of consciousness.

Perception (psychology), spreads of a process by which organisms interpret and organize sensation to produce a meaningful experience of the world. Sensation usually refers to the immediate, relatively unprocessed result of stimulation of sensory receptors in the eyes, ears, nose, tongue, or skin. Perception, on the other hand, better describes one’s ultimate experience of the world and typically involves further processing of sensory input. In practice, sensation and perception are virtually impossible to separate, because they are part of one continuous process.

Our sense organs translate physical energy from the environment into electrical impulses processed by the brain. For example, light, in the form of electromagnetic radiation, causes receptor cells in our eyes to activate and send signals to the brain. But we do not understand these signals as pure energy. The process of perception allows us to interpret them as objects, events, people, and situations.

Without the ability to organize and interpret sensations, life would seem like a meaningless jumble of colours, shapes, and sounds. A person without any perceptual ability would not be able to recognize faces, understand language, or avoid threats. Such a person would not survive for long. In fact, many species of animals have evolved exquisite sensory and perceptual systems that aid their survival.

Organizing raw sensory stimuli into meaningful experiences involves cognition, a set of mental activities that includes thinking, knowing, and remembering. Knowledge and experience are extremely important for perception, because they help us make sense of the input to our sensory systems. To understand these ideas, try to read the following passage:

You could probably read the text, but not as easily as when you read letters in their usual orientation. Knowledge and experience allowed you to understand the text. You could read the words because of your knowledge of letter shapes, and maybe you even have some prior experience in reading text upside down. Without knowledge of letter shapes, you would perceive the text as meaningless shapes, just as people who do not know Chinese or Japanese see the characters of those languages as meaningless shapes. Reading, then, is a form of visual perception.

Note that as above, whereby you did not stop to read every single letter carefully. Instead, you probably perceived whole words and phrases. You may have also used context to help you figure out what some of the words must be. For example, recognizing upside may have helped you predict down, because the two words often occur together. For these reasons, you probably overlooked problems with the individual letters-some of them, such as the n in down, are mirror images of normal letters. You would have noticed these errors immediately if the letters were right side up, because you have much more experience seeing letters in that orientation.

How people perceive a well-organized pattern or whole, instead of many separate parts, is a topic of interest in Gestalt psychology. According to Gestalt psychologists, the whole is different than the sum of its parts. Gestalt is a German word meaning configuration or pattern.

The three founders of Gestalt psychology were German researchers Max Wertheimer, Kurt Koffka, and Wolfgang Köhler. These men identified a number of principles by which people organize isolated parts of a visual stimulus into groups or whole objects. There are five main laws of grouping: proximity, similarity, continuity, closure, and common fate. A sixth law, that of simplicity, encompasses all of these laws.

Although most often applied to visual perception, the Gestalt laws also apply to perception in other senses. When we listen to music, for example, we do not hear a series of disconnected or random tones. We interpret the music as a whole, relating the sounds to each other based on how similar they are in pitch, how close together they are in time, and other factors. We can perceive melodies, patterns, and form in music. When a song is transposed to another key, we still recognize it, even though all of the notes have changed.

The law of proximity states that the closer objects are to one another, the more likely we are to mentally group them together. In the illustration below, we perceive as groups the boxes that are closest to one another. Note that we do not see the second and third boxes from the left as a pair, because they are spaced farther apart.

The law of similarity leads us to link together parts of the visual field that are similar in colour, lightness, texture, shape, or any other quality. That is why, in the following illustration, we perceive rows of objects instead of columns or other arrangements.

The law of continuity leads us to see a line as continuing in a particular direction, rather than making an abrupt turn. In the drawing on the left below, we see a straight line with a curved line running through it. Notice that we do not see the drawing as consisting of the two pieces in the drawing on the right.

According to the law of closure, we prefer complete forms to incomplete forms. Thus, in the drawing below, we mentally close the gaps and perceive a picture of a duck. This tendency allows us to perceive whole objects from incomplete and imperfect forms.

The law of common fate leads us to group together objects that move in the same direction. In the following illustration, imagine that three of the balls are moving in one direction, and two of the balls are moving in the opposite direction. If you saw these in actual motion, you would mentally group the balls that moved in the same direction. Because of this principle, we often see flocks of birds or schools of fish as one unit.

Central to the approach of Gestalt psychologists is the law of prägnanz, or simplicity. This general notion, which encompasses all other Gestalt laws, states that people intuitively prefer the simplest, most stable of possible organizations. For example, look at the illustration below. You could perceive this in a variety of ways: as three overlapping disks; as one whole disk and two partial disks with slices cut out of their right sides; or even as a top view of three-dimensional, cylindrical objects. The law of simplicity states that you will see the illustration as three overlapping disks, because that is the simplest interpretation.

Not only does perception involve organization and grouping, it also involves distinguishing an object from its surroundings. Notice that once you perceive an object, the area around that object becomes the background. For example, when you look at your computer monitor, the wall behind it becomes the background. The object, or figure, is closer to you, and the background, or ground, is farther away.

Gestalt psychologists have devised ambiguous figure-ground relationships-that is, drawings in which the figure and ground can be reversed-to illustrate their point that the whole is different from the sum of its parts. Consider the accompanying illustration entitled “Figure and Ground.” You may see a white vase as the figure, in which case you will see it displayed on a dark ground. However, you may also see two dark faces that point toward one another. Notice that when you do so, the white area of the figure becomes the ground. Even though your perception may alternate between these two possible interpretations, the parts of the illustration are constant. Thus, the illustration supports the Gestalt position that the whole is not determined solely by its parts. The Dutch artist M. C. Escher was intrigued by ambiguous figure-ground relationships.

Although such illustrations may fool our visual systems, people are rarely confused about what they see. In the real world, vases do not change into faces as we look at them. Instead, our perceptions are remarkably stable. Considering that we all experience rapidly changing visual input, the stability of our perceptions is more amazing than the occasional tricks that fool our perceptual systems. How we perceive a stable world is due, in part, to a number of factors that maintain perceptual constancy.

As we view an object, the image it projects on the retinas of our eyes changes with our viewing distance and angle, the level of ambient light, the orientation of the object, and other factors. Perceptual constancy allows us to perceive an object as roughly the same in spite of changes in the retinal image. Psychologists have identified a number of perceptual consistencies, including lightness constancy, colour constancy, shape constancy, and size constancy.

Lightness constancy means that our perception of an object’s lightness or darkness remains constant despite changes in illumination. To understand lightness constancy, try the following demonstration. First, take a plain white sheet of paper into a brightly lit room and note that the paper appears to be white. Then, turn out a few of the lights in the room. Note that the paper continues to appear white. Next, if it will not make the room pitch black, turn out some more lights. Note that the paper appears to be white regardless of the actual amount of light energy that enters the eye.

Lightness constancy illustrates an important perceptual principle: Perception is relative. Lightness constancy may occur because the white piece of paper reflects more light than any of the other objects in the room—regardless of the different lighting conditions. That is, you may have determined the lightness or darkness of the paper relative to the other objects in the room. Another explanation, proposed by 19th-century German physiologist Hermann von Helmholtz, is that we unconsciously take the lighting of the room into consideration when judging the lightness of objects.

Colour constancy is closely related to lightness constancy. Colour constancy means that we perceive the colour of an object as the same despite changes in lighting conditions. You have experienced colour constancy if you have ever worn a pair of sunglasses with coloured lenses. In spite of the fact that the coloured lenses change the colour of light reaching your retina, you still perceive white objects as white and red objects as red. The explanations for colour constancy parallel those for lightness constancy. One proposed explanation is that because the lenses tint everything with the same colour, we unconsciously “subtract” that colour from the scene, leaving the original colours.

Another perceptual constancy is shape constancy, which means that you perceive objects as retaining the same shape despite changes in their orientation. To understand shape constancy, hold a book in front of your face so that you are looking directly at the cover. The rectangular nature of the book should be very clear. Now, rotate the book away from you so that the bottom edge of the cover is much closer to you than the top edge. The image of the book on your retina will now be quite different. In fact, the image will now be trapezoidal, with the bottom edge of the book larger on your retina than the top edge. (Try to see the trapezoid by closing one eye and imagining the cover as a two-dimensional shape.) In spite of this trapezoidal retinal image, you will continue to see the book as rectangular. In large measure, shape constancy occurs because your visual system takes depth into consideration.

Depth perception also plays a major role in size constancy, the tendency to perceive objects as staying the same size despite changes in our distance from them. When an object is near to us, its image on the retina is large. When that same object is far away, its image on the retina is small. In spite of the changes in the size of the retinal image, we perceive the object as the same size. For example, when you see a person at a great distance from you, you do not perceive that person as very small. Instead, you think that the person is of normal size and far away. Similarly, when we view a skyscraper from far away, its image on our retina is very small-yet we perceive the building as very large.

Psychologists have proposed several explanations for the phenomenon of size constancy. First, people learn the general size of objects through experience and use this knowledge to help judge size. For example, we know that insects are smaller than people and that people are smaller than elephants. In addition, people take distance into consideration when judging the size of an object. Thus, if two objects have the same retinal image size, the object that seems farther away will be judged as larger. Even infants seem to possess size constancy.

Another explanation for size constancy involves the relative sizes of objects. According to this explanation, we see objects as the same size at different distances because they stay the same size relative to surrounding objects. For example, as we drive toward a stop sign, the retinal image sizes of the stop sign relative to a nearby tree remain constant-both images grow larger at the same rate.

Depth perception is the ability to see the world in three dimensions and to perceive distance. Although this ability may seem simple, depth perception is remarkable when you consider that the images projected on each retina are two-dimensional. From these flat images, we construct a vivid three-dimensional world. To perceive depth, we depend on two main sources of information: binocular disparity, a depth cue that requires both eyes; and monocular cues, which allow us to perceive depth with just one eye.

An autostereogram is a remarkable kind of two-dimensional image that appears three-dimensional (3-D) when viewed in the right way. To see the 3-D image, first make sure you are viewing the expanded version of this picture. Then try to focus your eyes on a point in space behind the picture, keeping your gaze steady. An image of a person playing a piano will appear.

Beaus our eyes are spaced about 7 cm (about 3 in) apart, the left and right retinas receive slightly different images. This difference in the left and right images is called binocular disparity. The brain integrates these two images into a single three-dimensional image, allowing us to perceive depth and distance.

For a demonstration of binocular disparity, fully extend your right arm in front of you and hold up your index finger. Now, alternate closing your right eye and then your left eye while focussing on your index finger. Notice that your finger appears to jump or shift slightly-a consequence of the two slightly different images received by each of your retinas. Next, keeping your focus on your right index finger, hold your left index finger up much closer to your eyes. You should notice that the nearer finger creates a double image, which is an indication to your perceptual system that it is at a different depth than the farther finger. When you alternately close your left and right eyes, notice that the nearer finger appears to jump much more than the more distant finger, reflecting a greater amount of binocular disparity.

You have probably experienced a number of demonstrations that use binocular disparity to provide a sense of depth. A stereoscope is a viewing device that presents each eye with a slightly different photograph of the same scene, which generates the illusion of depth. The photographs are taken from slightly different perspectives, one approximating the view from the left eye and the other representing the view from the right eye. The View-Master, a children’s toy, is a modern type of stereoscope.

Filmmakers have made use of binocular disparity to create 3-D (three-dimensional) movies. In 3-D movies, two slightly different images are projected onto the same screen. Viewers wear special glasses that use coloured filters (as for most 3-D movies) or polarizing filters (as for 3-D IMAX movies). The filters separate the image so that each eye receives the image intended for it. The brain combines the two images into a single three-dimensional image. Viewers who watch the film without the glasses see a double image.

Another phenomenon that makes use of binocular disparity is the autostereogram. The autostereogram is a two-dimensional image that can appear three-dimensional without the use of special glasses or a stereoscope. Several different types of autostereograms exist. The most popular, based on the single-image random dot stereogram, seemingly becomes three-dimensional when the viewer relaxes or refocuses the eyes, as if focussing on a point in space behind the image. The two-dimensional image usually consists of random dots or lines, which, when viewed properly, coalesce into a previously unseen three-dimensional image. This type of autostereogram was first popularized in the Magic Eye series of books in the early 1990s, although its invention traces back to 1979. Most autostereograms are produced using computer software. The mechanism by which autostereograms work is complex, but they employ the same principle as the stereoscope and 3-D movies. That is, each eye receives a slightly different image, which the brain fuses into a single three-dimensional image.

Although binocular disparity is a very useful depth cue, it is only effective over a fairly short range-less than 3 m (10 ft). As our distance from objects increases, the binocular disparity decreases-that is, the images received by each retina become more and more similar. Therefore, for distant objects, your perceptual system cannot rely on binocular disparity as a depth cue. However, you can still determine that some objects are nearer and some farther away because of monocular cues about depth.

To portray a realistic three-dimensional world on a two-dimensional canvas, artists must make use of a variety of depth cues. It was not until the 1400s, during the Italian Renaissance, that artists began to understand linear perspective fully and to portray depth convincingly. Shown here are several paintings that produce a sense of depth.

Close one eye and look around you. Notice the richness of depth that you experience. How does this sharp sense of three-dimensionality emerge from input to a single two-dimensional retina? The answer lies in monocular cues, or cues to depth that are effective when viewed with only one eye.

The problem of encoding depth on the two-dimensional retina is quite similar to the problem faced by an artist who wishes to realistically portray depth on a two-dimensional canvas. Some artists are amazingly adept at doing so, using a variety of monocular cues to give their works a sense of depth.

Although there are many kinds of monocular cues, the most important are interposition, atmospheric perspective, texture gradient, linear perspective, size cues, height cues, and motion parallax.

People commonly rely on interposition, or the overlap between objects, to judge distances. When one object partially obscures our view of another object, we judge the covered object as farther away from us.

Probably the most important monocular cue is interposition, or overlap. When one object overlaps or partly blocks our view of another object, we judge the covered object as being farther away from us. This depth cue is all around us-look around you and notice how many objects are partly obscured by other objects. To understand how much we rely on interposition, try this demonstration. Hold two pens, one in each hand, a short distance in front of your eyes. Hold the pens several centimetres apart so they do not overlap, but move one pen just slightly farther away from you than the other. Now close one eye. Without binocular vision, notice how difficult it is to judge which pen is more distant. Now, keeping one eye closed, move your hands closer and closer together until one pen moves in front of the other. Notice how interposition makes depth perception much easier.

When we look out over vast distances, faraway points look hazy or blurry. This effect is known as atmospheric perspective, and it helps us to judge distances. In this picture, the ridges that are farther away appear hazier and less detailed than the closer ridges.

The air contains microscopic particles of dust and moisture that make distant objects look hazy or blurry. This effect is called atmospheric perspective or aerial perspective, and we use it to judge distance. In the anthem, ’Oh Canada’ it draws reference to the effect of atmospheric perspectives, which makes distant mountains appear bluish or purple. When you are standing on a mountain, you see brown earth, gray rocks, and green trees and grass-but little that is purple. When you are looking at a mountain from a distance, however, atmospheric particles bend the light so that the rays that reach your eyes lie in the blue or purple part of the colour spectrum. This same effect makes the sky appear blue.

An influential American psychologist, James J. Gibson, was among the first people to recognize the importance of texture gradient in perceiving depth. A texture gradient arises whenever we view a surface from a slant, rather than directly from above. Most surfaces-such as the ground, a road, or a field of flowers-have a texture. The texture becomes denser and less detailed as the surface recedes into the background, and this information helps us to judge depth. For example, look at the floor or ground around you. Notice that the apparent texture of the floor changes over distance. The texture of the floor near you appears more detailed than the texture of the floor farther away. When objects are placed at different locations along a texture gradient, judging their distance from you becomes fairly easy.

Linear perspective means that parallel lines, such as the white lines of this road, appear to converge with greater distance and reach a vanishing point at the horizon. We use our knowledge of linear perspective to help us judge distances.

Artists have learned to make great use of linear perspective in representing a three-dimensional world on a two-dimensional canvas. Linear perspective refers to the fact that parallel lines, such as railroad tracks, appear to converge with distance, eventually reaching a vanishing point at the horizon. The more the lines converge, the farther away they appear.

When estimating an object’s distance from us, we take into account the size of its image relative to other objects. This depth cue is known as relative size. In this photograph, because we assume that the aeroplanes are the same size, we judge the aeroplanes that take up less of the image as being farther away from the camera.

Another visual cue to apparent depth is closely related to size constancy. According to size constancy, even though the size of the retinal image may change as an object moves closer to us or farther from us, we perceive that object as staying about the same size. We are able to do so because we take distance into consideration. Thus, if we assume that two objects are the same size, we perceive the object that casts a smaller retinal image as farther away than the object that casts a larger retinal image. This depth cue is known as relative size, because we consider the size of an object’s retinal image relative to other objects when estimating its distance.

Another depth cue involves the familiar size of objects. Through experience, we become familiar with the standard size of certain objects, such as houses, cars, aeroplanes, people, animals, books, and chairs. Knowing the size of these objects helps us judge our distance from them and from objects around them.

When judging an object’s distance, we consider its height in our visual field relative to other objects. The closer an object is to the horizon in our visual field, the farther away we perceive it to be. For example, the wildebeest that are higher in this photograph appear farther away than those that are lower.

We perceive points nearer to the horizon as more distant than points that are farther away from the horizon. This means that below the horizon, objects higher in the visual field appear farther away than those that are lower. Above the horizon, objects lower in the visual field appear farther away than those that are higher. For example, in the accompanying picture entitled 'Relative Height', the animals higher in the photo appear farther away than the animals lower in the photo. But above the horizon, the clouds lower in the photo appear farther away than the clouds higher in the photo. This depth cue is called relative elevation or relative height, because when judging an object’s distance, we consider its height in our visual field relative to other objects.

The monocular cues discussed so far-interposition, atmospheric perspective, texture gradient, linear perspective, size cues, and height cues-are sometimes called pictorial cues, because artists can use them to convey three-dimensional information. Another monocular cue cannot be represented on a canvas. Motion parallax occurs when objects at different distances from you appear to move at different rates when you are in motion. The next time you are driving along in a car, pay attention to the rate of movement of nearby and distant objects. The fence near the road appears to whiz past you, while the more distant hills or mountains appear to stay in virtually the same position as you move. The rate of an object’s movement provides a cue to its distance.

Although motion plays an important role in depth perception, the perception of motion is an important phenomenon in its own right. It allows a baseball outfielder to calculate the speed and trajectory of a ball with extraordinary accuracy. Automobile drivers rely on motion perception to judge the speeds of other cars and avoid collisions. A cheetah must be able to detect and respond to the motion of antelopes, its chief prey, in order to survive.

Initially, you might think that you perceive motion when an object’s image moves from one part of your retina to another part of your retina. In fact, that is what occurs if you are staring straight ahead and a person walks in front of you. Motion perception, however, is not that simple-if it were, the world would appear to move every time we moved our eyes. Keep in mind that you are almost always in motion. As you walk along a path, or simply move your head or your eyes, images from many stationary objects move around on your retina. How does your brain know which movement on the retina is due to your own motion and which is due to motion in the world? Understanding that distinction is the problem that faces psychologists who want to explain motion perception.

One explanation of motion perception involves a form of unconscious inference. That is, when we walk around or move our head in a particular way, we unconsciously expect that images of stationary objects will move on our retina. We discount such movement on the retina as due to our own bodily motion and perceive the objects as stationary.

In contrast, when we are moving and the image of an object does not move on our retina, we perceive that object as moving. Consider what happens as a person moves in front of you and you track that person’s motion with your eyes. You move your head and your eyes to follow the person’s movement, with the result that the image of the person does not move on your retina. The fact that the person’s image stays in roughly the same part of the retina leads you to perceive the person as moving.

Psychologist James J. Gibson thought that this explanation of motion perception was too complicated. He reasoned that perception does not depend on internal thought processes. He thought, instead, that the objects in our environment contain all the information necessary for perception. Think of the aerial acrobatics of a fly. Clearly, the fly is a master of motion and depth perception, yet few people would say the fly makes unconscious inferences. Gibson identified a number of cues for motion detection, including the covering and uncovering of background. Research has shown that motion detection is, in fact, much easier against a background. Thus, as a person moves in front of you, that person first covers and then uncovers portions of the background.

People may perceive motion when none actually exists. For example, motion pictures are really a series of slightly different still pictures flashed on a screen at a rate of 24 pictures, or frames, per second. From this rapid succession of still images, our brain perceives fluid motion-a phenomenon known as stroboscopic movement. For more information about illusions of motion, see Illusion: Illusory Motion .

Experience in interacting with the world is vital to perception. For instance, kittens raised without visual experience or deprived of normal visual experience do not perceive the world accurately. In one experiment, researchers reared kittens in total darkness, except that for five hours a day the kittens were placed in an environment with only vertical lines. When the animals were later exposed to horizontal lines and forms, they had trouble perceiving these forms.

Philosophers have long debated the role of experience in human perception. In the late 17th century, Irish philosopher William Molyneux wrote to his friend, English philosopher John Locke, and asked him to consider the following scenario: Suppose that you could restore sight to a person who was blind. Using only vision, would that person be able to tell the difference between a cube and a sphere, which she or he had previously experienced only through touch? Locke, who emphasized the role of experience in perception, thought the answer was no. Modern science actually allows us to address this philosophical question, because a very small number of people who were blind have had their vision restored with the aid of medical technology.

Two researchers, British psychologist Richard Gregory and British-born neurologist Oliver Sacks, have written about their experiences with men who were blind for a long time due to cataracts and then had their vision restored late in life. When their vision was restored, they were often confused by visual input and were unable to see the world accurately. For instance, they could detect motion and perceive colours, but they had great difficulty with complex stimuli, such as faces. Much of their poor perceptual ability was probably due to the fact that the synapses in the visual areas of their brains had received little or no stimulation throughout their lives. Thus, without visual experience, the visual system does not develop properly.

Visual experience is useful because it creates memories of past stimuli that can later serve as a context for perceiving new stimuli. Thus, you can think of experience as a form of context that you carry around with you.

Ordinarily, when you read, you use the context of your prior experience with words to process the words you are reading. Context may also occur outside of you, as in the surrounding elements in a visual scene. When you are reading and you encounter an unusual word, you may be able to determine the meaning of the word by its context. Your perception depends on the context.

Although context is useful most of the time, on some rare occasions context can lead you to misperceive a stimulus. Look at Example B in the 'Context Effects' illustration. Which of the green circles is larger? You may have guessed that the green circle on the right is larger. In fact, the two circles are the same size. Your perceptual system was fooled by the context of the surrounding red circles.

Against a background of slanted lines, a perfect square appears trapezoidal-that is, wider at the top than at the bottom. This illusion may occur because the lines create a sense of depth, making the top of the square seem farther away and larger.

A visual illusion occurs when your perceptual experience of a stimulus is substantially different from the actual stimulus you are viewing. In the previous example, you saw the green circles as different sizes, even though they were actually the same size. To experience another illusion, look at the illustration entitled 'Zöllner Illusion'. What shape do you see? You may see a trapezoid that is wider at the top, but the actual shape is a square. Such illusions are natural artifacts of the way our visual systems work. As a result, illusions provide important insights into the functioning of the visual system. In addition, visual illusions are fun to experience.

An ascribing notion to awaiting the idea that something debated finds to its intent of meaning the explicit significance of the same psychology that is immeasurably the scientific study of behaviour and the mind. This definition contains three elements. The first is that psychology is a scientific enterprise that obtains knowledge through systematic and objective methods of observation and experimentation. Second is that psychologists study behaviour, which refers to any action or reaction that can be measured or observed-such as the blink of an eye, an increase in heart rate, or the unruly violence that often erupts in a mob. Third is that psychologists study the mind, which refers to both conscious and unconscious mental states. These states cannot actually be seen, only inferred from observable behaviour.

Many people think of psychologists as individuals who dispense advice, analyze personality, and help those who are troubled or mentally ill. But psychology is far more than the treatment of personal problems. Psychologists strive to understand the mysteries of human nature-why people think, feel, and act as they do. Some psychologists also study animal behaviour, using their findings to determine laws of behaviour that apply to all organisms and to formulate theories about how humans behave and think.

With its broad scope, psychology investigates an enormous range of phenomena: learning and memory, sensation and perception, motivation and emotion, thinking and language, personality and social behaviour, intelligence, infancy and child development, mental illness, and much more. Furthermore, psychologists examine these topics from a variety of complementary perspectives. Some conduct detailed biological studies of the brain, others explore how we process information; others analyze the role of evolution, and still others study the influence of culture and society.

Psychologists seek to answer a wide range of important questions about human nature: Are individuals genetically predisposed at birth to develop certain traits or abilities? How accurate are people at remembering faces, places, or conversations from the past? What motivates us to seek out friends and sexual partners? Why do so many people become depressed and behave in ways that seem self-destructive? Do intelligence test scores predict success in school, or later in a career? What causes prejudice, and why is it so widespread? Can the mind be used to heal the body? Discoveries from psychology can help people understand themselves, relate better to others, and solve the problems that confront them.

The term psychology comes from two Greek words: psyche, which means “soul,” and logos, "the study of." These root words were first combined in the 16th century, at a time when the human soul, spirit, or mind was seen as distinct from the body.

Psychology overlaps with other sciences that investigate behaviour and mental processes. Certain parts of the field share much with the biological sciences, especially physiology, the biological study of the functions of living organisms and their parts. Like physiologists, many psychologists study the inner workings of the body from a biological perspective. However, psychologists usually focus on the activity of the brain and nervous system.

The social sciences of sociology and anthropology, which study human societies and cultures, also intersect with psychology. For example, both psychology and sociology explore how people behave when they are in groups. However, psychologists try to understand behaviour from the vantage point of the individual, whereas sociologists focus on how behaviour is shaped by social forces and social institutions. Anthropologists investigate behaviour as well, paying particular attention to the similarities and differences between human cultures around the world.

Psychology is closely connected with psychiatry, which is the branch of medicine specializing in mental illnesses. The study of mental illness is one of the largest areas of research in psychology. Psychiatrists and psychologists differ in their training. A person seeking to become a psychiatrist first obtains a medical degree and then engages in further formal medical education in psychiatry. Most psychologists have a doctoral graduate degree in psychology.

The study of psychology draws on two kinds of research: basic and applied. Basic researchers seek to test general theories and build a foundation of knowledge, while applied psychologists study people in real-world settings and use the results to solve practical human problems. There are five major areas of research: biopsychology, clinical psychology, cognitive psychology, developmental psychology, and social psychology. Both basic and applied research is conducted in each of these fields of psychology.

This section describes basic research and other activities of psychologists in the five major fields of psychology. Applied research is discussed in the Practical Applications of Psychology section of this article.

Magnetic resonance imaging (MRI) reveals structural differences between a normal adult brain, left, and the brain of a person with schizophrenia, right. The schizophrenic brain has enlarged ventricles (fluid-filled cavities), shown in light gray. However, not all people with schizophrenia show this abnormality.

How do body and mind interact? Are body and mind fundamentally different parts of a human being, or are they one and the same, interconnected in important ways? Inspired by this classic philosophical debate, many psychologists specialize in biopsychology, the scientific study of the biological underpinnings of behaviour and mental processes.

At the heart of this perspective is the notion that human beings, like other animals, have an evolutionary history that predisposes them to behave in ways that are uniquely adaptive for survival and reproduction. Biopsychologists work in a variety of subfields. Researchers in the field of ethology observe fish, reptiles, birds, insects, primates, and other animal species in their natural habitats. Comparative psychologists study animal behaviour and make comparisons among different species, including humans. Researchers in evolutionary psychology theorize about the origins of human aggression, altruism, mate selection, and other behaviours. Those in behavioural genetics seek to estimate the extent to which human characteristics such as personality, intelligence, and mental illness are inherited.

Particularly important to biopsychology is a growing body of research in behavioural neuroscience, the study of the links between behaviour and the brain and nervous system. Facilitated by computer-assisted imaging techniques that enable researchers to observe the living human brain in action, this area is generating great excitement. In the related area of cognitive neuroscience, researchers record physical activity in different regions of the brain as the subject reads, speaks, solves math problems, or engages in other mental tasks. Their goal is to pinpoint activities in the brain that correspond to different operations of the mind. In addition, many biopsychologists are involved in psychopharmacology, the study of how drugs affect mental and behavioural functions.

This chart illustrates the percentage of people in the United States who experience a particular mental illness at some point during their lives. The figures are derived from the National Comorbidity Survey, in which researchers interviewed more than 8000 people aged 15 to 54 years. Homeless people and those living in prisons, nursing homes, or other institutions were not included in the survey.

Clinical psychology is dedicated to the study, diagnosis, and treatment of mental illnesses and other emotional or behavioural disorders. More psychologists work in this field than in any other branch of psychology. In hospitals, community clinics, schools, and in private practice, they use interviews and tests to diagnose depression, anxiety disorders, schizophrenia, and other mental illnesses. People with these psychological disorders often suffer terribly. They experience disturbing symptoms that make it difficult for them to work, relate to others, and cope with the demands of everyday life.

Over the years, scientists and mental health professionals have made great strides in the treatment of psychological disorders. For example, advances in psychopharmacology have led to the development of drugs that relieve severe symptoms of mental illness. Clinical psychologists usually cannot prescribe drugs, but they often work in collaboration with a patient’s physician. Drug treatment is often combined with psychotherapy, a form of intervention that relies primarily on verbal communication to treat emotional or behavioural problems. Over the years, psychologists have developed many different forms of psychotherapy. Some forms, such as psychoanalysis, focus on resolving internal, unconscious conflicts stemming from childhood and past experiences. Other forms, such as cognitive and behavioural therapies, focus more on the person’s current level of functioning and try to help the individual change distressing thoughts, feelings, or behaviours.

In addition to studying and treating mental disorders, many clinical psychologists study the normal human personality and the ways in which individuals differ from one another. Still others administer a variety of psychological tests, including intelligence tests and personality tests. These tests are commonly given to individuals in the workplace or in school to assess their interests, skills, and level of functioning. Clinical psychologists also use tests to help them diagnose people with different types of psychological disorders.

The field of counselling psychology is closely related to clinical psychology. Counselling psychologists may treat mental disorders, but they more commonly treat people with less-severe adjustment problems related to marriage, family, school, or career. Many other types of professionals care for and treat people with psychological disorders, including psychiatrists, psychiatric social workers, and psychiatric nurses.

To take the Stroop test, name aloud each colour in the two columns at left as quickly as you can. Next, look at the right side of the illustration and quickly name the colours in which the words are printed. Which task took longer to complete? The test, devised in 1935 by American psychologist John Stroop, shows that people cannot help but process word meanings, and that this processing interferes with the colour-naming task.

How do people learn from experience? How and where in the brain are visual images, facts, and personal memories stored? What causes forgetting? How do people solve problems or make difficult life decisions? Does language limit the way people think? And to what extent are people influenced by information outside of conscious awareness?

These are the kinds of questions posed within cognitive psychology, the scientific study of how people acquire, process, and utilize information. Cognition refers to the process of knowing and encompasses nearly the entire range of conscious and unconscious mental processes: sensation and perception, conditioning and learning, attention and consciousness, sleep and dreaming, memory and forgetting, reasoning and decision making, imagining, problem solving, and language.

Decades ago, the invention of digital computers gave cognitive psychologists a powerful new way of thinking about the human mind. They began to see human beings as information processors who receive input, process and store information, and produce output. This approach became known as the information-processing model of cognition. As computers have become more sophisticated, cognitive psychologists have extended the metaphor. For example, most researchers now reject the idea that information is processed in linear, sequential steps. Instead they find that the human mind is capable of parallel processing, in which multiple operations are carried out simultaneously.

In this information-processing model of memory, information that enters the brain is briefly recorded in sensory memory. If we focus our attention on it, the information may become part of working memory (also called short-term memory), where it can be manipulated and used. Through encoding techniques such as repetition and rehearsal, information may be transferred to long-term memory. Retrieving long-term memories makes them active again in working memory.

Are people programmed by inborn biological dispositions? Or is an individual's fate moulded by culture, family, peers, and other socializing influences within the environment? These questions about the roles of nature and nurture are central to the study of human development.

An incredibly complex array of influences, including families, acquaintances, mass media, and society as a whole, help determine the moral development of children. Although a rash of violent incidents in American schools in the late 1990s focussed attention on deviant youth behaviour, the vast majority of children seem to function harmoniously with others. In this August 1999 article from Scientific American, William Damon, director of the Centre on Adolescence at Stanford University in California, explores recent findings on how young people develop morality.

Developmental psychology focuses on the changes that come with age. By comparing people of different ages, and by tracking individuals over time, researchers in this area study the ways in which people mature and change over the life span. Within this area, those who specialize in child development or child psychology study physical, intellectual, and social development in fetuses, infants, children, and adolescents. Recognizing that human development is a lifelong process, other developmental psychologists study the changes that occur throughout adulthood. Still others specialize in the study of old age, even the process of dying.

A 'shock generator', top, was used by American psychologist Stanley Milgram in experiments designed to test the obedience of people to authority. An experimenter instructed subjects to administer what they believed were painful electric shocks to Mr. Wallace, bottom, an accomplice of the experimenter who was strapped into a chair and connected to the generator by electrodes on his skin. No actual shocks occurred. The experimenter ordered the subjects to continue as the shocks increased to a level the subjects believed were dangerous or even lethal. In Milgram’s initial study, 65 percent of people obeyed the experimenter and delivered the maximum shock of 450 volts. Milgram discusses his conclusions in this sound clip.

Social psychology is the scientific study of how people think, feel, and behave in social situations. Researchers in this field ask questions such as, How do we form impressions of others? How are people persuaded to change their attitudes or beliefs? What causes people to conform in group situations? What leads someone to help or ignore a person in need? Under what circumstances do people obey or resist orders?

By observing people in real-world social settings, and by carefully devising experiments to test people’s social behaviour, social psychologists learn about the ways people influence, perceive, and interact with one another. The study of social influence includes topics such as conformity, obedience to authority, the formation of attitudes, and the principles of persuasion. Researchers interested in social perception study how people come to know and evaluate one another, how people form group stereotypes, and the origins of prejudice. Other topics of particular interest to social psychologists include physical attraction, love and intimacy, aggression, altruism, and group processes. Many social psychologists are also interested in cultural influences on interpersonal behaviour.

Whereas basic researchers test theories about mind and behaviour, applied psychologists are motivated by a desire to solve practical human problems. Four particularly active areas of application are health, education, business, and law.

Today, many psychologists work in the emerging area of health psychology, the application of psychology to the promotion of physical health and the prevention and treatment of illness. Researchers in this area have shown that human health and well-being depends on both biological and psychological factors.

Many psychologists in this area study psychophysiological disorders (also called psychosomatic disorders), conditions that are brought on or influenced by psychological states, most often stress. These disorders include high blood pressure, headaches, asthma, and ulcers. Researchers have discovered that chronic stress is associated with an increased risk of coronary heart disease. In addition, stress can compromise the body's immune system and increase susceptibility to illness.

Health psychologists also study how people cope with stress. They have found that people who have family, friends, and other forms of social support are healthier and live longer than those who are more isolated. Other researchers in this field examine the psychological factors that underlie smoking, drinking, drug abuse, risky sexual practices, and other behaviours harmful to health.

Psychologists in all branches of the discipline contribute to our understanding of teaching, learning, and education. Some help develop standardized tests used to measure academic aptitude and achievement. Others study the ages at which children become capable of attaining various cognitive skills, the effects of rewards on their motivation to learn, computerized instruction, bilingual education, learning disabilities, and other relevant topics. Perhaps the best-known application of psychology to the field of education occurred in 1954 when, in the case of Brown v. Board of Education, the Supreme Court of the United States outlawed the segregation of public schools by race. In its ruling, the Court cited psychological studies suggesting that segregation had a damaging effect on black students and tended to encourage prejudice.

In addition to the contributions of psychology as a whole, two fields within psychology focus exclusively on education: educational psychology and school psychology. Educational psychologists seek to understand and improve the teaching and learning process within the classroom and other educational settings. Educational psychologists study topics such as intelligence and ability testing, student motivation, discipline and classroom management, curriculum plans, and grading. They also test general theories about how students learn most effectively. School psychologists work in elementary and secondary school systems administering tests, making placement recommendations, and counselling children with academic or emotional problems.

The business world, psychology is applied in the workplace and in the marketplace. Industrial-organizational (I-O) psychology focuses on human behaviour in the workplace and other organizations. I-O psychologists conduct research, teach in business schools or universities, and work in private industry. Many I-O psychologists study the factors that influence worker motivation, satisfaction, and productivity. Others study the personal traits and situations that foster great leadership. Still others focus on the processes of personnel selection, training, and evaluation. Studies have shown, for example, that face-to-face interviews sometimes result in poor hiring decisions and may be biassed by the applicant’s gender, race, and physical attractiveness. Studies have also shown that certain standardized tests can help to predict on-the-job performance. See Industrial-Organizational Psychology.

Consumer psychology is the study of human decision making and behaviour in the marketplace. In this area, researchers analyze the effects of advertising on consumers’ attitudes and buying habits. Consumer psychologists also study various aspects of marketing, such as the effects of packaging, price, and other factors that lead people to purchase one product rather than another.

Many psychologists today work in the legal system. They consult with attorneys, testify in court as expert witnesses, counsel prisoners, teach in law schools, and research various justice-related issues. Sometimes referred to as forensic psychologists, those who apply psychology to the law study a range of issues, including jury selection, eyewitness testimony, confessions to police, lie-detector tests, the death penalty, criminal profiling, and the insanity defence.

Studies in forensic psychology have helped to illuminate weaknesses in the legal system. For example, based on trial-simulation experiments, researchers have found that jurors are often biassed by various facts not in evidence-that is, facts the judge tells them to disregard. In studying eyewitness testimony, researchers have staged mock crimes and asked witnesses to identify the assailant or recall other details. These studies have revealed that under certain conditions eyewitnesses are highly prone to error.

Psychologists in this area often testify in court as expert witnesses. In cases involving the insanity defence, forensic clinical psychologists are often called to court to give their opinion about whether individual defendants are sane or insane. Used as a legal defence, insanity means that defendants, because of a mental disorder, cannot appreciate the wrongfulness of their conduct or control it. Defendants who are legally insane at the time of the offense may be absolved of criminal responsibility for their conduct and judged not guilty. Psychologists are often called to testify in court on other controversial matters as well, including the accuracy of eyewitness testimony, the mental competence (fitness) of defendants to stand trial, and the reliability of early childhood memories.

Psychology has applications in many other domains of human life. Environmental psychologists focus on the relationship between people and their physical surroundings. They study how street noise, heat, architectural design, population density, and crowding affect people’s behaviour and mental health. In a related field, human factors psychologists work on the design of appliances, furniture, tools, and other manufactured items in order to maximize their comfort, safety, and convenience. Sports psychologists advise athletes and study the physiological, perceptual-motor, motivational, developmental, and social aspects of athletic performance. Other psychologists specialize in the study of political behaviour, religion, sexuality, or behaviour in the military.

Psychologists from all areas of specialization use the scientific method to test their theories about behaviour and mental processes. A theory is an organized set of principles that is designed to explain and predict some phenomenon. Good theories also provide specific testable predictions, or hypotheses, about the relation between two or more variables. Formulating a hypothesis to be tested is the first important step in conducting research.

Over the years, psychologists have devised numerous ways to test their hypotheses and theories. Many studies are conducted in a laboratory, usually located at a university. The laboratory setting allows researchers to control what happens to their subjects and make careful and precise observations of behaviour. For example, a psychologist who studies memory can bring volunteers into the lab, ask them to memorize a list of words or pictures, and then test their recall of that material seconds, minutes, or days later.

As indicated by the term field research, studies may also be conducted in real-world locations. For example, a psychologist investigating the reliability of eyewitness testimony might stage phony crimes in the street and then ask unsuspecting bystanders to identify the culprit from a set of photographs. Psychologists observe people in a wide variety of other locations outside the laboratory, including classrooms, offices, hospitals, college dormitories, bars, restaurants, and prisons.

In both laboratory and field settings, psychologists conduct their research using a variety of methods. Among the most common methods are archival studies, case studies, surveys, naturalistic observations, correlational studies, experiments, literature reviews, and measures of brain activity.

One way to learn about people is through archival studies, an examination of existing records of human activities. Psychological researchers often examine old newspaper stories, medical records, birth certificates, crime reports, popular books, and artwork. They may also examine statistical trends of the past, such as crime rates, birth rates, marriage and divorce rates, and employment rates. The strength of such measures is that by observing people only secondhand, researchers cannot unwittingly influence the subjects by their presence. However, available records of human activity are not always complete or detailed enough to be useful.

Archival studies are particularly valuable for examining cultural or historical trends. For example, in one study of physical attractiveness, researchers wanted to know if American standards of female beauty have changed over several generations. These researchers looked through two popular women’s magazines between 1901 and 1981 and examined the measurements of the female models. They found that “curvaceousness” (as measured by the bust-to-waist ratio) varied over time, with a boyish, slender look considered desirable in some time periods but not in others.

Sometimes psychologists interview, test, observe, and investigate the backgrounds of specific individuals in detail. Such case studies are conducted when researchers believe that an in-depth look at one individual will reveal something important about people in general.

Case studies often take a great deal of time to complete, and the results may be limited by the fact that the subject is atypical. Yet case studies have played a prominent role in the development of psychology. Austrian physician Sigmund Freud based his theory of psychoanalysis on his experiences with troubled patients. Swiss psychologist Jean Piaget first began to formulate a theory of intellectual development by questioning his own children. Neuroscientists learn about how the human brain works by testing patients who have suffered brain damage. Cognitive psychologists learn about human intelligence by studying child prodigies and other gifted individuals. Social psychologists learn about group decision making by analysing the policy decisions of government and business groups. When an individual is exceptional in some way, or when a hypothesis can be tested only through intensive, long-term observation, the case study is a valuable method.

An electroencephalogram, or EEG, is a recording of the action potential, or electrical, activity of the cerebral cortex of the brain. An EEG is made by attaching electrodes to the scalp, then collecting, amplifying, and recording the electrical impulses of the brain.

Biopsychologists interested in the links between brain and behaviour use a variety of specialized techniques in their research. One approach is to observe and test patients who have suffered damage to a specific region of the brain to determine what mental functions and behaviours were affected by that damage. British-born neurologist Oliver Sacks has written several books in which he describes case studies of brain-damaged patients who exhibited specific deficits in their speech, memory, sleep, and even in their personalities.

This positron emission tomography (PET) scan of the brain shows the activity of brain cells in the resting state and during three types of auditory stimulation. PET uses radioactive substances introduced into the brain to measure such brain functions as cerebral metabolism, blood flow and volume, oxygen use, and the formation of neurotransmitters. This imaging method collects data from many different angles, feeding the information into a computer that produces a series of cross-sectional images.

A second approach is to physically alter the brain and measure the effects of that change on behaviour. The alteration can be achieved in different ways. For example, animal researchers often damage or destroy a specific region of a laboratory animal’s brain through surgery. Other researchers might spark or inhibit activity in the brain through the use of drugs or electrical stimulation.

This magnetic resonance imaging (MRI) scan of a normal adult head shows the brain, airways, and soft tissues of the face. The large cerebral cortex, appearing in yellow and green, forms the bulk of the brain tissue; the circular cerebellum, Centre left, in red, and the elongated brainstem, Centre, in red, are also prominently shown.

Another way to study the relationship between the brain and behaviour is to record the activity of the brain with machines while a subject engages in certain behaviours or activities. One such instrument is the electroencephalograph, a device that can detect, amplify, and record the level of electrical activity in the brain by means of metal electrodes taped to the scalp.

Advances in technology in the early 1970s allowed psychologists to see inside the living human brain for the first time without physically cutting into it. Today, psychologists use a variety of sophisticated brain-imaging techniques. The computerized axial tomography (CT or CAT) scan provides a computer-enhanced X-ray image of the brain. The more advanced positron emission tomography (PET) scan tracks the level of activity in specific parts of the brain by measuring the amount of glucose being used there. These measurements are then fed to a computer, which produces a colour-coded image of brain activity. Another technique is magnetic resonance imaging (MRI), which produces high-resolution cross-sectional images of the brain. A high-speed version of MRI known as functional MRI produces moving images of the brain as its activity changes in real time. These relatively new brain imaging techniques have generated great excitement, because they allow researchers to identify parts of the brain that are active while people read, speak, listen to music, solve math problems, and engage in other mental activities.

In contrast with the in-depth study of one person, surveys describe a specific population or group of people. Surveys involve asking people a series of questions about their behaviours, thoughts, or opinions. Surveys can be conducted in person, over the phone, or through the mail. Most surveys study a specific group-for example, college students, working mothers, men, or homeowners. Rather than questioning every person in the group, survey researchers choose a representative sample of people and generalize the findings to the larger population.

Surveys may pertain to almost any topic. Often surveys ask people to report their feelings about various social and political issues, the TV shows they watch, or the consumer products they purchase. Surveys are also used to learn about people’s sexual practices; to estimate the use of cigarettes, alcohol, and other drugs; and to approximate the proportion of people who experience feelings of life satisfaction, loneliness, and other psychological states that cannot be directly observed.

Surveys must be carefully designed and conducted to ensure their accuracy. The results can be influenced, and biassed, by two factors: who the respondents are and how the questions are asked. For a survey to be accurate, the sample being questioned must be representative of the population on key characteristics such as sex, race, age, region, and cultural background. To ensure similarity to the larger population, survey researchers usually try to make sure that they have a random sample, a method of selection in which everyone in the population has an equal chance of being chosen.

When the sample is not random, the results can be misleading. For example, prior to the 1936 United States presidential election, pollsters for the magazine Literary Digest mailed postcards to more than 10 million people who were listed in telephone directories or as registered owners of automobiles. The cards asked for whom they intended to vote. Based on the more than 2 million ballots that were returned, the Literary Digest predicted that Republican candidate Alfred M. Landon would win in a landslide over Democrat Franklin D. Roosevelt. At the time, however, more Republicans than Democrats owned telephones and automobiles, skewing the poll results. In the election, Landon won only two states.

The results of survey research can also be influenced by the way that questions are asked. For example, when asked about 'welfare', a majority of Americans in one survey said that the government spends too much money. But when asked about 'assistance to the poor', significantly fewer people gave this response.

In naturalistic observation, the researcher observes people as they behave in the real world. The researcher simply records what occurs and does not intervene in the situation. Psychologists use naturalistic observation to study the interactions between parents and children, doctors and patients, police and citizens, and managers and workers.

Naturalistic observation is common in anthropology, in which field workers seek to understand the everyday life of a culture. Ethologists, who study the behaviour of animals in their natural habitat, also use this method. For example, British ethologist Jane Goodall spent many years in African jungles observing chimpanzees-their social structure, courting rituals, struggles for dominance, eating habits, and other behaviours. Naturalistic observation is also common among developmental psychologists who study social play, parent-child attachments, and other aspects of child development. These researchers observe children at home, in school, on the playground, and in other settings.

Case studies, surveys, and naturalistic observations are used to describe behaviour. Correlational studies are further designed to find statistical connections, or correlations, between variables so that some factors can be used to predict others.

A correlation is a statistical measure of the extent to which two variables are associated. A positive correlation exists when two variables increase or decrease together. For example, frustration and aggression are positively correlated, meaning that as frustration rises, so do acts of aggression. More of one means more of the other. A negative correlation exists when increases in one variable are accompanied by decreases in the other, and vice versa. For example, friendships and stress-induced illness are negatively correlated, meaning that the more close friends a person has, the fewer stress-related illnesses the person suffers. More of one means less of the other.

Based on correlational evidence, researchers can use one variable to make predictions about another variable. But researchers must use caution when drawing conclusions from correlations. It is nature-but incorrect-to assume that because one variable predicts another, the first must have caused the second. For example, one might assume that frustration triggers aggression, or that friendships foster health. Regardless of how intuitive or accurate these conclusions may be, correlation does not prove causation. Thus, although it is possible that frustration causes aggression, there are other ways to interpret the correlation. For example, it is possible that aggressive people are more likely to suffer social rejection and become frustrated as a result.

Correlations enable researchers to predict one variable from another. But to determine if one variable actually causes another, psychologists must conduct experiments. In an experiment, the psychologist manipulates one factor in a situation-keeping other aspects of the situation constant-and then observes the effect of the manipulation on behaviour. The people whose behaviour is being observed are the subjects of the experiment. The factor that an experimenter varies (the proposed cause) is known as the independent variable, and the behaviour being measured (the proposed effect) is called the dependent variable. In a test of the hypothesis that frustration triggers aggression, frustration would be the independent variable, and aggression the dependent variable.

There are three requirements for conducting a valid scientific experiment: (1) control over the independent variable, (2) the use of a comparison group, and (3) the random assignment of subjects to conditions. In its most basic form, then, a typical experiment compares a large number of subjects who are randomly assigned to experience one condition with a group of similar subjects who are not. Those who experience the condition compose the experimental group, and those who do not make up the control group. If the two groups differ significantly in their behaviour during the experiment, that difference can be attributed to the presence of the condition, or independent variable. For example, to test the hypothesis that frustration triggers aggression, one group of researchers brought subjects into a laboratory, impeded their efforts to complete an important task (other subjects in the experiment were not impeded), and measured their aggressiveness toward another person. These researchers found that subjects who had been frustrated were more aggressive than those who had not been frustrated.

Psychologists use many different methods in their research. Yet no single experiment can fully prove a hypothesis, so the science of psychology builds slowly over time. First, a new discovery must be replicated. Replication refers to the process of conducting a second, nearly identical study to see if the initial findings can be repeated. If so, then researchers try to determine if these findings can be applied, transferred, or generalized to other settings. Generalizability refers to the extent to which a finding obtained under one set of conditions can also be obtained at another time, in another place, and in other populations.

Because the science of psychology proceeds in small increments, many studies must be conducted before clear patterns emerge. To summarize and interpret an entire body of research, psychologists rely on two methods. One method is a narrative review of the literature, in which a reviewer subjectively evaluates the strengths and weaknesses of the various studies on a topic and argues for certain conclusions. Another method is meta-analysis, a statistical procedure used to combine the results from many different studies. By meta-analysing a body of research, psychologists can often draw precise conclusions concerning the strength and breadth of support for a hypothesis.

Psychological research involving human subjects raises ethical concerns about the subject's right to privacy, the possible harm or discomfort caused by experimental procedures, and the use of deception. Over the years, psychologists have established various ethical guidelines. The American Psychological Association recommends that researchers (1) tell prospective subjects what they will experience so they can give informed consent to participate; (2) instruct subjects that they may withdraw from the study at any time; (3) minimize all harm and discomfort; (4) keep the subjects’ responses and behaviours confidential; and (5) debrief subjects who were deceived in some way by fully explaining the research after they have participated. Some psychologists argue that such rules should never be broken. Others say that some degree of flexibility is needed in order to study certain important issues, such as the effects of stress on test performance.

Laboratory experiments that use rats, mice, rabbits, pigeons, monkeys, and other animals are an important part of psychology, just as in medicine. Animal research serves three purposes in psychology: to learn more about certain types of animals, to discover general principles of behaviour that pertain to all species, and to study variables that cannot ethically be tested with human beings. But is it ethical to experiment on animals?

Some animal rights activists believe that it is wrong to use animals in experiments, particularly in those that involve surgery, drugs, social isolation, food deprivation, electric shock, and other potentially harmful procedures. These activists see animal experimentation as unnecessary and question whether results from such research can be applied to humans. Many activists also argue that like humans, animals have the capacity to suffer and feel pain. In response to these criticisms, many researchers point out that animal experimentation has helped to improve the quality of human life. They note that animal studies have contributed to the treatment of anxiety, depression, and other mental disorders. Animal studies have also contributed to our understanding of conditions such as Alzheimer’s disease, obesity, alcoholism, and the effects of stress on the immune system. Most researchers follow strict ethical guidelines that require them to minimize pain and discomfort to animals and to use the least invasive procedures possible. In addition, federal animal-protection laws in the United States require researchers to provide humane care and housing of animals and to tend to the psychological well-being of primates used in research.

No comments:

Post a Comment