Presented by: RICHARD J.KOSCIEJEW
If what exists in the mind as a representation (as of something comprehended) or as a formulation (as of a plan) absorbs in the apprehensions toward belief. That is, ‘ideas’, as eternal, mind-independent forms or archetypes of the things in the material world. Neoplatonism created their thoughts in the mind of God who created the world. The much criticized ‘new-way of ideas’, so much a part of seventeenth-and eighteenth-century philosophy, began with Descartes’ conscious extension of ‘idea’ to cover whatever is in human minds too, an extension, of which, Locke made much use. Nevertheless, are they like mental images, of things outside the mind, or non-representational, like sensations? If representation as standing between the mind and what they represent, or are they acts and modifications of a mind perceiving the world directly? Finally, are they neither objects nor acts, but dispositions? Malebranche and Arnauld and Leibniz, disagreed about how ‘ideas’ should be understood. This deducibility where each individual's property, that its completed concept is due too there being an ontological correlate for its completion, or in other words a modification of the substances individual correspondence to each truth about it. Recent scholars disagree about how Arnauld, Descartes, Locke and Malebranche in fact understood them.
Contemporary philosophy of mind, following cognitive science, uses the term ‘representation’ to mean just about anything that can be semantically evaluated. Thus, representations may be said to be true, to refer, to be accurate, and so forth. Representation thus conceived comes in many varieties. The most familiar are pictures, three-dimensional models, e.g., statues, scale model, linguistic text (including mathematical formulas) and various hybrids of these such as diagrams, maps, graphs and tables. It is an open question in cognitive science whether mental representation, which is our real topic, but when it falls within any of these or any-other familiar provinces.
The representational theory of cognition and thought is uncontroversial in contemporary cognitive science that cognitive processes are processes that manipulate representations. This idea seems nearly inevitable. What makes the difference between processes that are cognitive-solving a problem, say and those that are not-a patellar reflexes, for example-is just that cognitive processes are epistemically assessable? A solution procedure can be justified or correct, as a reflex cannot. Since only things with content can be epistemically assessed, processes appear to count as cognitive only in as far as they implicate representations.
It is tempting to think that thoughts are the mind’s representations: Are not thoughts just those mental states that have semantic content? This is, no doubt, harmless enough provided us keep in mind that cognitive science may be characterized by to some thoughts to properties of contents that are foreign too commonsense. First, of these harmless thought properties exist of seems a foreign country, and, after all, they do things differently there. Most of the representations hypothesized by cognitive science do not correspond to anything commonsensical, as would it make out as or perceive to be something previously known. Of what integrative imperatives is directly the line to interconnectivity. The merging - in the mind - or, the external perceptions of something new to knowledge, is, usually already possessed as thought. The explanatory capabilities converging to simplifying the applicability, for which considerations would account for the discrepancies focussed 'interiorly'. As, too, are the interpretative and individualized interpretations, showing that these possibilities that impart information are given hold, in, or, at least, initially, through the existing in or belonging to an individual inherently. Standard psycholinguistic theory, for instance, hypothesizes the construction of representations of the syntactic structures of the utterances one hears and understands. Yet we are not aware of, and nonspecialists do not even understand, the structures represented. Thus, cognitive science may attribute thoughts where common sense would not. Second, cognitive science may find it useful to individuate thoughts in ways foreign to common sense.
However, concepts of action presuppose the propositional attitudes, of course, in a sense, the claim that the concept originates from observing the patterns of those discerning acquirements that the concept has in reserve to propositional-attitude concepts. If so, the existence of the patterns can hardly cause our proposition-attitude concepts. So, the behavioural account of the attitudes would be no more successful than the pattern's attributions to and for of these opposed propositional-attitude concepts, are these patterns revealed to us at all. It is, nonetheless, that the concepts occupy mental states having content: A belief may have the content that I will catch the train, or a hope may have the content that the prime minister will resign. A concept is something that can be a constituent of such contents. More specifically, a concept is a way of thinking of something-a particular object, or property, or relation, or another entity.
Several different concepts may each be ways of thinking of the same object. A person may think of himself in the first-person way, or think of himself as the spouse of Mary Smith, or as the person in a certain room now. More generally, a concept ‘c’ is such-and-such, without believing ‘d’ is such-and-such. As words can be combined to form structured sentences, concepts have also been conceived as combinable into structured complex contents. When these complex contents are expressed in English by ‘that . . . ‘ clauses, as in our opening examples, they could be true or false, depending on the way the world is.
Concepts are to be distinguished from stereotypes and from conceptions. The stereotypical spy may be a middle-level official down on his luck and in need of money. Nonetheless, we can come to learn that Anthony Blunt, art historian and Surveyor of the Queen’s Pictures are secret agents: We can come to believe that something falls under a concept while positively disbelieving that the same thing falls under the stereotype associated with the concept. Similarly, a person’s conception of a just arrangement for resolving disputes may objectivise the view to oppose by arguing against something like contemporary Western legal systems. However, whether or not it would be correct, rejecting this conception by arguing that it does not adequately provide for the elements of fairness is quite intelligible for someone. Also, it does not involve the responsibility that must be taken in the respect with which are required by the concept of justice.
A fundamental question for philosophy may hold: What individuates a given concept-that is, what makes it the one it is, than any other concept? One answer, which has been developed in great detail, is that giving a non-trivial answer to this question is impossible (Schiffer, 1987). An alternative approach, favoured by most, addresses that questionable indication by way of starting from the idea that a concept is individuated by the condition that must be satisfied. If, on the other hand, a thinker is to poses that concept and, in its gross effect, being capable to adhere of having beliefs and other contributing attributes whose contents contain it as a constituent. So, to take a simple case, one could propose that the logical concept ‘and’ is individuated by this condition: It is the unique concept ‘C’ to posses that a thinker has to find these forms of inference compelling, without basing them on any further inference or information: From any two premisses ‘A’ and ‘B’, ‘ABC’ can be inferred, and from any premiss ‘ABC’, and that beyond a normal or acceptable limit as to evaluate in excessive amounts. The exclusion or exception of any condition than that was objectable for being of the ordinary exemption, to be free from requirements or the state of being free or freed from a charge or obligation to which others are subject. As to say from each of all A's and all B’s can be implicitly implied by an unexpressed and wordless understanding. Again, an observational concept such as ‘round’ can be individuated in part by stating that the thinker finds specified contents containing it. The compelling certainty in the assorted kinds in descriptions of perception, and in part by relating those judgements containing the intellection as existing or dealing with what exists only in the mind as an 'ideational' concept is not based on perception. The judgements that are truth-statement which individuates a concept by saying what are required for a thinker to poses it can be described as giving the ‘possession condition’ for the concept.
A possession condition for a particular concept may actually use that concept. The possession condition for ‘and’ does not. We can also expect to use observational concepts in specifying the kind of experiences, least of mention, to which have to be made in defence of the possession conditions for observational concepts. What we must avoid is mention of the concept in question as such within the content of the attributes attributed to the thinker in the possession condition. Otherwise we would be presupposed possession of the concept in an account that was meant to elucidate its possession. In talking of what the thinker finds compelling, the possession conditions can also respect an insight of the later Wittgenstein: That a thinker’s mastery of a concept is inextricably tied to how he finds it natural to go on in new cases in applying the concept.
Sometimes a family of concepts has this property: Mastering any one member of the family without mastering the others is not possible. Two of the families that plausibly have this status are these: The families consisting of some simple concepts as found to, 0, 1, 2, . . . of the natural numbers and the corresponding concepts of numerical quantifiers there are 0-so-and-so’s. Its efficience is contained by 1, so-and-so, . . . traditionally as a group of persons of or regarded as of common ancestry, wherefore consisting of the concepts ‘belief’ and ‘desire’. Such families have become known as ‘local holism’. A local holism does not prevent the individuation of a concept by its possession condition. Comparatively, it demands that all the concepts in the family be individuated simultaneously. So one would say something of this form: Belief and desire form the unique pair of concepts C1 and C2 such that for a thinker to progressive position their possessions of them are to meet such-and-such conditions involving the thinkers, C1 and C2. For these and other possession conditions to individuate properly, it is necessary that there be some ranking of the concept treated. The possession conditions for concepts higher in the ranking must presuppose only possession of concepts at the same or lower levels in the ranking.
A possession condition may in various way's make a thinker’s possession of a particular concept dependent on or upon his relations to his environment. Many possession conditions will mention the links between a concept and the thinker’s perceptual experience. Perceptual experience represents the world for being a certain way. It is arguable that the only satisfactory explanation of what it is for perceptual experience to represent the world in a particular way must refer to the complex relations of the experience to the subject’s environment. If this is so, then mention of such experiences in a possession condition will make possession of that concept dependent in part upon the environmental relations to the thinker. Burge (1979) has also argued from intuitions about particular examples that, though the thinker’s non-environmental properties and relations remain constant, the conceptual content of his mental state can vary if the thinker’s social environment is varied. A possession condition that properly individuates such a concept must take into account his linguistic relations.
Concepts have a normative dimension, a fact strongly emphasized by Kripke. For any judgement whose content involves a given concept, there is a ‘correctness condition’ for that judgement, a condition that is dependent in part on or upon the identity of the concept. The normative character of concepts also extends into the territory of a thinker’s reasons for making judgements. A thinker’s visual perception can give him good reason for judging ‘That man is bald’; even if the man he sees is Rostropovich. All these normative connections must be explained by a theory of concepts. One approach to these matters is to look to the possession condition for a concept, and consider how the referent of the concept is fixed from it, with the world. One proposal is that the referent of the concept is that object, or property, or function . . . which makes the practices of judgement and inference in the possession condition always lead to true judgements and truth-preserving inferences. This proposal would explain why certain reasons are necessarily good reasons for judging given contents. Provided the possession condition permits us to say what it is about a thinker’s previous judgements that make it the case that he is employing one concept than another, this proposal would also have another virtue. It would also allow us to say how the correctness condition is determined for a judgement in which the concept is applied to newly encountered objects. The judgement is correct if the new object had the property that in fact makes the judgement practices in the possession condition yield true judgements, or truth-preserving inferences.
What is more, that innate ideas have been variously defined by philosophers either ideas consciously made in the prevailing presence of to the mind or the inclining inclinations to be aware, mindful of the ever-changing social scene. Nonetheless, these elements or complex of elements in an individual that feels, perceives, thinks, wills, and especially reasons, all of which, are anterior to sense experience. However, the dispositional sense, or as ideas that we have an innate disposition to form, though we need not be actually aware of them at any particular time, e.g., as babies - the dispositional sense.
Understood in either way they were invoked to account for our recognition, in that certain truths without recourse to experiential truths are without recourse verification. Such as those of mathematics, or justify certain moral and religious claims held to be capably known 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 held to be innate and at other times as one about a source of propositional knowledge. In as far as concepts are taken to be innate, the doctrine relates primarily ti claim 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 propositionally, that it is supposed that innateness is taken as evidence for their truth. However, this clearly rests the assumption that innate prepositions 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 capabilities.
The attraction of the theory has been felt strongly by those philosophers who have been unable to give an alternative account of our capacity to recognize that some proposition cannot be justified solely based on an appeal to sense experience. Thus Plato argued that, for example, recognition of mathematical truths could only be explained on the assumption of some form of recollection. Since there were no plausible post-natal sources for which the recollection must refer to the prenatal acquisition of knowledge. Thus understood, the doctrine of innate ideas supposed the views that there were important truths innate in human beings and the senses hindered their proper apprehension.
The ascetic implications of the doctrine were important in Christian philosophy throughout the Middle Ages and the doctrine featured powerfully in scholastic teaching until its displacement by Locke’s philosophy in the eighteenth century. It had meanwhile 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 ideas of God, for example, and our coming to recognize that God must necessarily exist, are, Descartes held, logically independent of sense experience. In England the Cambridge Plantonists such as Henry More 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 y almost totally. Leibniz, in his critique of Locke, attempted to defend it with a sophisticated dispositional version of the theory, but it attracted few followers.
The empiricist alternative to innate ideas as an explanation of the certainty of propositions was in the direction of construing all necessary truths as analytic. Kant’s refinement of the classification of propositions with the fourfold distinction, analytic/synthetic and a priori/a posteriori did nothing to encourage a return to the innate idea's doctrine, which slipped from view. The doctrine may fruitfully be understood as the production of confusion between explaining the genesis of ideas or concepts and the basis for regarding some propositions as necessarily true.
Nevertheless, according to Kant, our knowledge arises from two fundamentally different faculties of the mind, sensibility and understanding, Kant criticized his predecessors for running these faculties together, as in Leibniz for treating comprehensibility as a confused mode of understanding and Locke for treating understanding as an abstracted mode of sense perception. Kant held that each faculty operates with its own distinctive type of mental representation. Concepts, the instruments of the understanding, are mental representations that apply potentially to many things in virtue of their possession of a common feature. Intuitions, the instrument of sensibility, are representation s that refer to just one thing and to that thing is played in Russell’s philosophy by ‘acquaintance’ though intuition's objects are given to us, Kant said; through concepts they are thought.
Nonetheless, it is celebrated, that a Kantian Thesis of knowledge is yielding of neither intuitions nor by concepts alone, but only by the two in conjunction, ‘Thoughts without content are empty’, he says in an often quoted remark, and ‘intuitions without concepts are blind’. Exactly what Kant means by the remark is a debated question, however, answered in different ways by scholars who bring different elements of Kant’s text to bear on it. A minimal reading is that it is only propositionally structured knowledge that requires the collaboration of intuition and concept: This view allows that intuitions without concepts constitute some kind of nonjudgmental awareness. A stronger reading is that it is reference or intentionality that depends on intuition and concept together, so that the blindness of intuition without concept is its referring to an object. A greater diverseness in fundamental extremes that one who favours rapidly and sweeping changes takes the position of 'insurrectionist': The subversive radical view of what is revealed to the vision or can be seen is yet intuitivistic but without concepts seem indeterminate, or just a mere blur, perhaps nothing at all. This last interpretation, though admittedly suggested by some things Kant says, is at odds with his official view about the separation of the faculties.
Least that ‘content’ has become a technical term in philosophy for whatever it is a representation had that makes it semantically evaluable. Wherefore, a statement is sometimes said to have a proposition or truth condition as its content, whereby its term is sometimes said to have a concept as it s content. Much less is known about how to characterize the contents of nonlinguistic representations than is known about characterizing linguistic representations. ‘Content’ is a term precisely because it allows one to abstract away from questions about what semantic properties representations have: A representation’s content is just whatever it is underwrite s its semantic evaluation.
According to most epistemologists, knowledge entails belief, so that I cannot know that such and such is the case unless I believe that such and such am the case. Others think this entailment thesis can be rendered more accurately if we substitute for belief some closely related attitude. For instance, several philosophers would prefer to say that knowledge entail psychological certainty (Prichard, 1950; Ayer, 1956) or the self-assuring, self-confident composites shown by feeling or showing of adequacy and reliance on oneself and one’s powers, is that of one’s capability in the enabling ability which implicates a resulting dependence on or upon the serenity of convictions (Lehrer, 1974) or (with) approving favours of fancy to take or sustain without protest or agreeing (to or with) losing, one must accept the declination as such is to be the acceptable satisfactions for which is of our own acceptance (Lehrer, 1989). Nonetheless, there are arguments against all versions of the thesis that knowledge requires having a belief-like attitude toward the known. These arguments are given by philosophers who think that knowledge and belief, or a facsimile, are mutually incompatible (the incompatibility thesis), or by ones who say that knowledge does not entail belief, or vice versa. In so, that it is made known openly to exist without the other, but, the two may also coexist of the separability thesis.
The incompatibility thesis is sometimes traced to Plato in view of his claim that knowledge is infallible while belief or opinion is fallible (Republic). Nonetheless this claim would not support the thesis. Belief might be a component of an infallible form of knowledge in spite of the fallibility of belief. Perhaps knowledge involves some factor that compensates for the fallibility of belief.
A.Duncan-Jones 1938 and Vendler, 1978, cite linguistic evidence to back up the incompatibility thesis. He notes that people often say ‘I' do not believe she is guilty. I know she is, however, this ‘just’ makes it especially clear that the speaker is signalling that she has something more salient than mere belief, not that she has something inconsistent with belief, namely knowledge. Compare: ‘You did not hurt him, you killed him’.
H.A.Prichard (1966) offers a defence of the incompatibility thesis that hinges on the equation of knowledge with certainty, as both infallibility and psychological certitude give the assumption that when we believe in the truth of a claim we are not certain about its truth. Given that knowledge never does, believing something rules out the possibility of knowing it. Unfortunately, Prichard gives us no-good reason to grant that states of belief are never ones involving confidence. Conscious beliefs clearly involve some level of confidence, only to suggest that we are completely confident is bizarre.
A.D.Woozley (1953) defends a version of the separability thesis. Woozley’s version that deals with psychological certainty rather than belief, whereas knowledge can exist without confidence about the item known, although knowledge might also be accompanied by confidence as well. Woozley remarks that the test of whether I know something is ‘what I can do, where what I can do may include answering questions’. Based on this remark he suggests that even when people are unsure of the truth of a claim, they might know that the claim is true. We unhesitatingly attribute knowledge to people who give correct responses on examinations even if those people show no confidence in their answers. Woozley acknowledges, however, that it would be odd for those who lack confidence to claim knowledge. It would be peculiar to say, ‘I am unsure whether my answer is true, still, I know it s correct’. Nonetheless, this tension Woozley explains using a distinction between conditions under which we are justified in making a claim, such as a claim to know something, and conditions under which the claim we make is true. While ‘I know such and such’ might be true even if I am sure of whether such and such unless I were sure of the truth of my claim.
To a greater extent formal European philosophers, such as Immanuel Kant, sought to reconcile representations of external reality in mind with the motions of matter-based on the dictates of pure reason. This impulse was also apparent in the utilitarian ethics of Jerry Bentham and John Stuart Mill, in the historical materialism of Karl Marx and Friedrich Engels, and in the pragmatism of Charles Smith, William James and John Dewey. These thinkers were painfully aware, however, of the inability of reason to posit a self-consistent basis for bridging the gap between mind and matter, and each remains obliged to conclude that the realm of the mental exists only in the subjective reality of the individual
A distinctive yet peculiar presence that has been in waiting to the future, its foundational frame of a proposal to a new understanding of relationships between mind and world, within the larger context of the history of mathematical physics, the origin and extensions of the classical view of the fundamentals of scientific knowledge, and the various ways that physicists have attempted to prevent previous challenges to the efficacy of classical epistemology.
There is no solid or functional basis in contemporary physics or biology for believing in the stark Cartesian division between mind and world that some have moderately described as ‘the disease of the Western mind’. The dialectic orchestrations will serve as background for understanding a new relationship between parts and wholes in physics, with a similar view of that relationship that has emerged in the co-called ‘new biology’ and in recent studies of the evolution of a scientific understanding to a more conceptualized representation of ideas, and includes its allied ‘content’.
Nonetheless, it seems a strong possibility that Platonic and Whitehead connect upon the issue of the creation of the sensible world may by looking at actual entities as aspects of nature’s contemplation. The contemplation of nature is obviously an immensely intricate affair, involving a myriad of possibilities, therefore one can look at actual entities as, in some sense, the basic elements of a vast and expansive process.
Something such as a thought or conception that potentially or has an actually existence by which of its maintaining element or complex of elements is an individual velleity, which feels, perceives, thinks, wills and especially reasons as a product of mental activity has upon itself the intelligence, intellect, consciousness, mental mentality, faculty, function or power in an ‘idea’. Additionally, and, least of mention, a bethinking inclination of the awareness on knowing its mindful human history is in essence a history of ideas, as thoughts are distinctly intellectual and stresses contemplation and reasoning. Justly as language is the dress of thought. Ideas began with Plato, as eternal, mind-independent forms or archetypes of the things in the material world. Neoplatonism made them thoughts in the mind of God who created the world. The much criticized ‘new way of ideas’, so much a part of seventeenth and eighteenth-century philosophy, began with Descartes’ (1596-1650). As to his philosophical theories, it will be sufficient to say that he discussed the same problems which have been debated for the last two thousand years, and probably will be debated with equal zeal two thousand years hence. It is hardly necessary to say that the problems themselves are of importance and interest, but from the nature of the case no solution ever offered is capable either of rigid proof or of disproof; all that can be affected is to make one explanation more probable than another, and whenever a philosopher like Descartes believes that he has at last finally settled a question it has been possible for his successors to point out the fallacy in his assumptions. I have read somewhere that philosophy has always been chiefly engaged with the interpellations of God, Nature, and Man. The earliest philosophers were Greeks who occupied themselves mainly with the relations between God and Nature, and dealt with Man separately. The Christian Church was so absorbed in the relation of God to Man as entirely to neglect Nature. Finally, modern philosophers concern themselves chiefly with the relations between Man and Nature. Whether this is a correct historical generalization of the views which have been successively prevalent I do not care to discuss here, but the statement as to the scope of modern philosophy marks the limitations of Descartes's writings.
Descartes chief contributions to mathematics were his analytical geometry and his theory of vortices, and it is on his researches in connection with the former of these subjects that his mathematical reputation rests. Analytical geometry does not consist merely (as is sometimes loosely said) in the application of algebra to geometry; that had been done by Archimedes and many others, and had become the usual method of procedure in the works of the mathematicians of the sixteenth century. The great advance made by Descartes was that he saw that a point in a plane could be completely determined if its distances, say x and y, from two fixed lines drawn at right angles in the plane were given, with the convention familiar to us as to the interpretation of positive and negative values. That though an equation f(x, y) = 0 was indeterminate and could be satisfied by an infinite number of values of 'x' and 'y', yet these values of 'x' and 'y' determined coordinate numbers in points which form a curve, of which the equation f(x, y) = 0 expresses some geometrical property, that is, a property true of the curve at every point on it. Descartes asserted that a point in space could be similarly determined by three co-ordinates, but he confined his attention to plane curves.
It was at once certain that in order to investigate the properties of a curve it was sufficient to select, as a definition, any characteristic geometrical property, and to express it by means of an equation between the (current) co-ordinates of any point on the curve, that is, to translate the definition into the language of analytical geometry. The equation so obtained contains implicitly every property of the curve, and any particular property can be deduced from it by ordinary algebra without troubling about the geometry of the figure. This may have been dimly recognized or foreshadowed by earlier writers, but Descartes went further and pointed out the very important facts that two or more curves can be referred to one and the same system of co-ordinates, and that the points in which two curves intersect can be determined by finding the roots common to their two equations. I need not go further into details, for nearly everyone to whom the above is intelligible will have read analytical geometry, and is able to appreciate the value of its invention.
Descartes's Géométrie is divided into three books: the first two of these treat of analytical geometry, and the third includes an analysis of the algebra then current. It is somewhat difficult to follow the reasoning, but the obscurity was intentional. 'Je n'ai rien omis', Stating, qu dessein . . . j'avois prévu que say gens qui se vantent de sçavoir tout n'auroient par manqué de dire que je n'avois rien écrit qu'ils n'eussent sçu auparavant, si je me fusse rendu assez intelligible pours eux.''
The first book commences with an explanation of the principles of analytical geometry, and contains a discussion of a certain problem which had been and of which some particular cases had been considered by Euclid and Apollonius. The general theorem had baffled previous geometricians, and it was in the attempt to solve it that Descartes was led to the invention of analytical geometry. The full enunciation of the problem is rather involved, but the most important case is to find the locus of a point such that the product of the perpendiculars on m given straight lines shall be in a constant ratio to the product of the perpendiculars on n other given straight lines. The ancients had solved this geometrically for the case m = 1, n = 1, and the case m = 1, n = 2. Pappus had further stated that, if m = n = 2, the locus is a conic, but he gave no proof; Descartes also failed to prove this by pure geometry, but he showed that the curve is represented by an equation of the second degree, that is, a conic; subsequently Newton gave an elegant solution of the problem by pure geometry.
In the second book Descartes divides curves into two classes, namely, geometrical and mechanical curves. He defines geometrical curves as those which can be generated by the intersection of two lines each moving parallel to one co-ordinate axis with ``commensurable'' velocities; by which terms he means that dy/dx is an algebraical function, as, for example, is the case in the ellipse and the cissoid. He calls a curve mechanical when the ratio of the velocities of these lines is incommensurable, by which term he means that dy/dx is a transcendental function, as, for example, is the case in the cycloid and the quadratrix. Descartes confined his discussion to geometrical curves, and did not treat of the theory of mechanical curves. The classification into algebraical and transcendental curves now usual is due to Newton.
Descartes also paid particular attention to the theory of the tangents to curves - as perhaps might be inferred from his system of classification just alluded to. The then current definition of a tangent at a point was a straight line through the point such that between it and the curve no other straight line could be drawn, that is, the straight line of closest contact. Descartes proposed to substitute for this a statement equivalent to the assertion that the tangent is the limiting position of the secant; Fermat, and at a later date Maclaurin and Lagrange, adopted this definition. Barrow, followed by Newton and Leibnitz, considered a curve as the limit of an inscribed polygon when the sides become indefinitely small, and stated that the side of the polygon when produced became limited and tangents to the curve. Roberval, on the other hand, defined a tangent at a point as the direction of motion at that instant of a point which was describing the curve. The results are the same whichever definition is selected, but the controversy as to which definition was the correct one was none the less lively. In his letter’s Descartes illustrated his theory by giving the general rule for drawing tangents and normality as roulette.
The method used by Descartes to find the tangent or normal at any point of a given curve was substantially as follows. He determined the centre and radius of a circle which should cut the curve in two consecutive points there. The tangent to the circle at that point will be the required tangent to the curve. In modern textbooks it is usual to express the condition that two of the points in which a straight line (such as y = mx + c) cuts the curve shall coincide with the given point: this enables us to determine m and c, and thus the equation of the tangent there is determined. Descartes, however, did not venture to do this, but selecting a circle as the simplest curve and one to which he knew how to draw a tangent, he so fixed his circle as to make it touch the given curve at the point in question, and thus reduced the problem to drawing a tangent to a circle. I had better to note as in passing, that he only applied this method to curves which are symmetrical about an axis, and he took the centre of the circle on the axis.
The obscure style deliberately adopted by Descartes diminished the circulation and immediate appreciation of these books, however, a Latin translation of them, with explanatory notes, was prepared by F. de Beaune, and an edition of this, with a commentary by F.van Schooten, issued in 1659, was widely read.
The third book of the Géométrie contains an analysis of the algebra, and it has affected the language of the subject by fixing the custom of employing the letters at the beginning of the alphabet to denote known quantities, and those at the end of the alphabet to denote unknown quantities. [On the origin of the custom of using x to represent an unknown example, see a note by G. Eneström in the Bibliotheca Mathematica, 1885, p. 43.] Descartes further introduced the system of indices now in use, very likely it was original on his part, but here and now I remind the reader that the suggestion had been made by previous writers, though it had not been generally adopted. It is doubtful whether or not Descartes recognized that his letters might represent any quantities, positive or negative, and that it was sufficient to prove a proposition for one general case. He was the earliest writer to realise the advantage to be obtained by taking all the terms of an equation to one side of it, though Stifel and Harriot had sometimes employed that form by choice. He realised the meaning of negative quantities and used them freely. In this book he made use of the rule for finding the limit to the number of positive and of negative roots of an algebraical equation, which is still known by his name. Introduced the method of indeterminate coefficients for the solution of equations. He believed that he had given a method by which algebraical equations of any order could be solved, but in this he was mistaken. It may also be mentioned that he enunciated the theorem, commonly attributed to Euler, on the relation between the numbers of faces, edges and angles of a polyhedron: this is in one of the papers published by Careil.
Of the two other appendices to the Discours one was devoted to optics. The chief interest of this consists in the statement given of the law of refraction. This appears to have been taken from Snell's work, though, unfortunately, it is enunciated in a way which might lead a reader to suppose that it is due to the researches of Descartes. Descartes would seem to have repeated Snell's experiments when in Paris in 1626 or 1627, and it is possible that he subsequently forgot how much he owed to the earlier investigations of Snell. A large part of the optics is devoted to determining the best shape for the lenses of a telescope, but the mechanical difficulties in grinding a surface of glass to a required form are so great as to render these investigations of little practical use. Descartes seems to have been doubtful whether to consider the rays of light as proceeding from the eye and so to speak, touching the object, as the Greeks had done, or as proceeding from the object, and so affecting the eye, and, since he considered the velocity of light to be infinite, he did not deem the point particularly important.
The other appendix, on meteors, contains an explanation of numerous atmospheric phenomena, including the rainbow; the explanation of the latter is necessarily incomplete, since Descartes was unacquainted with the fact that the refractive index of a substance is different for lights of different colours.
Descartes's physical theory of the universe, embodying most of the results contained in his earlier and unpublished Le Monde, is given in his Principia, 1644, and rests on a metaphysical basis. He commences with a discussion on motion; and then lays down ten laws of nature, of which the first two are almost identical with the first two laws of motion as given by Newton; the remaining eight laws are inaccurate. He next proceeds to discuss the nature of matter which he regards as uniform in kind though there are three forms of it. He assumes that the matter of the universe must be in motion, and that the motion must result in a number of vortices. He states that the sun is the centre of an immense whirlpool of this matter, in which the planets float and are swept round like straws in a whirlpool of water. Each planet is supposed to be the centre of a secondary whirlpool by which its satellites are carried: these secondary whirlpools are supposed to produce variations of density in the surrounding medium which constitute the primary whirlpool, and so cause the planets to move in ellipses and not in circles. All these assumptions are arbitrary and unsupported by any investigation. It is not difficult to prove that on his hypothesis the sun would be in the centre of these ellipses, and not at a focus (as Kepler had shewn was the case), and that the weight of a body at every place on the surface of the earth except the equator would act in a direction which was not vertical, but it will be sufficient here to say that Newton in the second book of his Principia, 1687, considered the theory in detail, and showed that its consequences are not only inconsistent with each of Kepler's laws and with the fundamental laws of mechanics, but are also at variance with the laws of nature assumed by Descartes. Still, in spite of its crudeness and its inherent defects, the theory of vortices marks a fresh era in astronomy, for it was an attempt to explain the phenomena of the whole universe by the same mechanical laws from which experiments bear witnesses to that which is true on earth.
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 anyone else: 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 some human beings intent to 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 maybe 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
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.
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 explains how experiments on vision might deepen our understanding of consciousness.
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.
According to Descartes, nothing can be done to give a body thought and consciousness. 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 altogether different from anything else: 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. In this way, the mind can affect the body. In addition, the sense organs of a human being maybe 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 the personal indistinguishability, 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 becomes pregnant 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. These links of memory, rather than a single underlying substance, provide 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.
From about 600 to 300 Bc, Greek philosophers inquired about a wide range of psychological topics. They were especially interested in the nature of knowledge and how human beings come to know the world, a field of philosophy known as epistemology. The Greek philosopher Socrates and his followers, Plato and Aristotle, wrote about pleasure and pain, knowledge, beauty, desire, free will, motivation, common sense, rationality, memory, and the subjective nature of perception. They also theorized about whether human traits are innate or the product of experience. In the field of ethics, philosophers of the ancient world probed a variety of psychological questions: Are people inherently good? How can people attain happiness? What descendable motives or instinctual drives are put into effect from an individual's experience? Are human beings naturally social?
Early thinkers also considered the causes of mental illness. Many ancient societies thought that mental illness resulted from supernatural causes, such as the anger of gods or possession by evil spirits. Both Socrates and Plato focussed on psychological forces as the cause of mental disturbance. For example, Plato thought madness results when a person’s irrational, animal-like psyche (mind or soul) overwhelm the intellectual, rational psyche. As the soul is an animating essence or principle held to be inseparably associated with life or living beings, philosophers who teach that life are a manifestation of soul, as mind is sententiously significant and grounded on or upon the element or complex of elements in an individual that feels, perceives, thinks, wills, and especially reasons. Inclined to be aware or mindful of the ever-changing environmental designs or traitful inhabitants (like an idea, conceptualized representation, and contentual representations) for which of the categories, not itemized of their prioritized containment, wherefore some faculty assimilation of those ascertained by the mind as, heedful, observant, operative, observing, regardful, thoughtful, alive, apprehensive, knowing, sensible, and so forth. The Greek physician Hippocrates viewed mental disorders as stemming from natural causes, and he developed the first classification system for mental disorders. Galen, a Greek physician who lived in the 2nd century ad, echoed this belief in a physiological basis for mental disorders. He thought they resulted from an imbalance of the four bodily humours: black bile, yellow bile, blood, and phlegm. For example, Galen thought that melancholia (depression) resulted from a person having too much black bile.
More recently, many other men and women contributed to the birth of modern psychology. In the 1600s French mathematician and philosopher René Descartes theorized that the body and mind are separate entities. He regarded the body as a physical entity and the mind as a spiritual entity, and believed the two interacted only through the pineal gland, a tiny structure at the base of the brain. This position became known as dualism. According to dualism, the behaviour of the body is determined by mechanistic laws and can be measured in a scientific manner. But the mind, which transcends the material world, cannot be similarly studied.
English philosophers’ Thomas Hobbes and John Locke disagreed. They argued that all human experiences - including sensations, images, thoughts, and feelings - are physical processes occurring within the brain and nervous system. Therefore, these experiences are valid subjects of study. In this view, which later became known as monism, the mind and body are one and the same. Today, in light of years of research indicating that the physical and mental aspects of the human experience are intertwined, most psychologists reject a rigid dualist position. See Philosophy of Mind; Dualism; Monism.
Many philosophers of the past also debated the question of whether human knowledge is inborn or the product of experience. Nativists believed that certain elementary truths are innate to the human mind and need not be gained through experience. In contrast, empiricists believed that at birth, a person’s mind is like a tabula rasa, or blank slate, and that all human knowledge ultimately comes from sensory experience. Today, all psychologists agree that both types of factors are important in the acquisition of knowledge.
The French philosopher, "the father of modern philosophy", scientist and mathematician, whose philosophical conclusion, "Cogito; ergo sum" (Je pense, donc je suis; I think, therefore I am), is the best-known quotation in all philosophy and which revolutionized the ways of thinking. In somewhat different form, it is also found in Augustine (354-430), who thought that the mind can have absolute and certain knowledge only about what is directly and immediately presented to it. Being a mathematician, Descartes decided to apply the so certain-seeming methods of mathematical reasoning to philosophy. "Good sense is of all things in the world the most equally distributed, for everybody thinks he is so well supplied with it, that even those most difficult to please never desire more of it than they already possess." (From Le Discours de la Méthode, 1637)
René Descartes was born in La Haye (now called La Haye-Descartes), into a well-to-do family. His mother died soon after his birth. Joachim, his father, was a judge in the High Court of Brittany; he soon remarried and Descartes was brought up by his maternal grandmother. At the age of ten he was sent to the Jesuit College at La Fl che in Anjou, where his masters allowed him to stay late in bed because of his poor health. Descartes later described La Fl che as one of the best schools in Europe. Descartes studied classical literature, history, rhetoric, and natural philosophy. In 1616 he obtained a degree in law from the University of Poitiers. At the age of twenty-two, he enrolled in the Protestant Dutch army of Maurice of Nassau. He spent several years as a soldier and met the Dutchman Isaac Beeckman, who awakened his interest in mathematics. For Beeckman he dedicated one of his earliest works, Compendium Musicae, which was written in 1618. In 1619 he served in the Bavarian army. While on duty at Ulm, he devised a methodology for the unification of the sciences. According to a story, Descartes had spent a cold morning in a "stove-heated room" (or in some sources in a large oven, po le), and when he came out, half of his philosophy had got ready. "I saw quite clearly that, assuming a triangle, its three angles must be equal to two right angles, yet for all that I saw was a containing overflow of emptiness, nothing that assured me that there was of any given trilateral shape or type or form belonging to in the real world. On the other hand, going back to an examination of my idea of a perfect being. I found that this included the existence of a Homo sapiens sapient, in the same way as the idea of a triangle includes the equality of its three angles to two right angles . . . Consequently it is at least as certain that God, the perfect being in question, is or exists, as any proof in geometry can be." (from Le Discours de la Méthode)
From 1619 to 1627 Descartes lived in Paris. He spent the rest of his life travelling outside France, settling eventually in Holland, where he remained from 1629 to 1649, his great creative years. There he devoted himself to philosophy and sciences, resolved "no longer to seek any other science than the knowledge of myself, or of the great book of the world." Although he was Catholic, Descartes opposed scholasticism. To put an end to the current philosophical ideas that went so far as to deny one's own existence, he started to inquire human knowledge on the basis of methodological skepticism, "Cartesian doubt". He introduced the famous of device of a malignant demon, "who has employed all his energies in deceiving me." But however great the demon's deception and how much the senses sometimes deceive, "he can never cause me to be anything so long as I think I am something." Descartes argued that one can doubt all, but not one's own existence of thinking, "for example that I am here seated by the fire wearing a dressing gown." Existence, being recognized of perfection, can no more be separated from the concept of a supremely perfect being. From this he concluded that God must exist and because God cannot be a deceiver, the significance on sensory data must be evaluated by reason. Descartes's friend Antoine Arnaud among others criticized his reasoning. "We can be sure that God exists, only because we clearly and evidently perceive that he does; therefore, prior to being confidently assured that constituting an indeterminate and otherwise unidentified God exists, we need to be certain that whatever we clearly and evidently perceive is true." Although one can doubt that there was any circularity (the "Cartesian circle") in Descartes's original arguments, he had to maintain that there are some basic logical truths, which are present in us from birth, such as something cannot both be and not to be at the same time.
By 1634 Descartes had completed his Le Monde (The World), but withdrew it after hearing what the Inquisition thought of Galileo. Discourses on the First Philosophy were published in 1641, together with a series of Objections by noted thinkers. Descartes also was the founder of analytical geometry. In his thirties he wrote a treatise on Dioptrics which was a substantial contribution to the science of optics and he composed one of the first scientific treatises on meteorology. In 1637 Descartes decided to publish his Dioptrics, his geometry, and his meteorology, and he prefaced these works with a brief Discourse on the Method of rightly conducting one's reason and reaching the truth in the sciences. The three scientific studies are now part of the history of science. According to some estimations, the preface is reprinted every year and has been translated into more than hundred languages.
Discourse on Method was written in French and not in the more conventional Latin, and addressed to the general reader. Constituting autobiographical work is divided into six parts. Descartes portrays himself as a sort of Socrates in search of truth and wisdom. The first two parts depict his early philosophical doubts, and culminate in the discovery of his "method". He finds four rules for reforming his own ways of thinking: first, accept nothing that is not clear and distinct; second, divide difficult subjects into many small parts; third, start with the simplest problems; fourth, be comprehensive. - In the third part Descartes explains his system of morality, metaphysics in part 4, in part 5 he describes his model of cosmos and the mechanics of human body, especially the workings of the circulation system. Part 6 provides an introduction to the essays on meteorology and optics. - Although Discourse was an economical disappointment for Descartes in sales figures, it attracted a wide and immediate reaction.
Descartes's publications brought him fame throughout Europe. He entered into correspondence with most of the learned men of his time. In 1644 he published, in Latin, The Principles of Philosophy, which he hoped to gain similar position as standard texts based on Aristotle. The last of his full-length works, The Passions of the Soul, grew out of his correspondence with Princess Elizabeth of Bohemia, the niece of Charles I of England, nonetheless, it was dedicated to Queen Christina of Sweden. In it he argued, that the mind is not directly affected by any part of the body, except the pineal gland in the brain. All sense experiences dwell of movements in the body which travel through the nerves to this gland and there gives a signal to the mind, which calls up a certain experience. Mind and body are distinct substances, which made immortality possible.
In 1649 Descartes went to Sweden, where he was invited by the Queen Christina (1626-89) to teach her philosophy at five o'clock in the morning and establish an institute for sciences. Descartes became ill with pneumonia and died in Stockholm on February 11, 1650. The illness was contracted through his being forced to break his usual habit of late rising. Four years later Christina abdicated her throne and converted to Catholicism. She died in Rome. "One cannot conceive anything so strange and so implausible that it has not already been said by one philosopher or another." (from Le Discours de la Méthode)
Descartes's conceptions of philosophy and science influenced deeply European culture and thinking. Even his opponents,
Blaise Pascal (1623-1662), and later among others Voltaire (1694-1778), who satirized Descartes's theory of vortices, largely followed him in his emphasis on analysis and in rejection of tradition. Stephen Toulmin has argued in Cosmopolis (1990) that Descartes and his followers suppressed the emergence of true modernity - tolerance, relativism, and indeterminacy - for over 300 years with their attempt to unify all knowledge through the power of reason and create a Cosmopolis, an unchanging, logically based system for the human and natural worlds. "Cartesian dualism" - the separation between the mental and the physical - has been criticized from many points of view. Descartes wrote: "This 'I' - that is, the soul, by which I am what I am, is entirely distinct from the body, and would not fail to be what it is even if the body did not exist." According to Gilbert Ryle, this conception is based on category-mistake. "It is perfectly proper to say, in one logical tone of voice, that there exist minds, and to say, in another logical tone of voice, that there exist bodies. But these expressions do not indicate two different species of existence, for 'existence' is not a generic word like 'coloured' or 'sexed'. They indicate two different senses of 'exist', somewhat as 'rising' has different senses in 'the tide is rising', hopes are rising', and 'the average age of death is rising'." (From the Concept of Mind, 1949).
Descartes is justly regarded as the Father of Modern Philosophy. This is not because of the positive results of his investigations, which were few, but because of the questions that he raised and problems that he created, problems that have still not been answered to everyone's satisfaction: particularly the Problem of Knowledge and the Mind-Body Problem. And in a day when philosophy and science were not distinguished from each other, Descartes was a famous physicist and mathematician as well as a philosopher. Descartes' physics was completely overthrown by that of Newton, so we do not much remember him for that. But Descartes was a great mathematician of enduring importance. He originated analytic geometry, where all of the algebra can be given geometrical expression. Like Galileo combining physics and mathematics, this also combined two things that had previously been apart, arithmetic and geometry. The modern world would not be the same without graphs of equations. Rectangular coordinates for graphing are still called Cartesian coordinates (from Descartes' name: des Cartes). Seeing Descartes as a mathematician explains why he was the kind of philosopher that he was. Now it is hard to reconcile Descartes' status as a scientist and the inspiration he derived from Galileo and others with his clear distrust of experience. Isn't science about experience? We might think so. But the paradox of modern science is its dependence on mathematics. Where does mathematics come from? What makes it true? Many mathematicians will still answer like Plato, but that certainly has little to do with experience. So Descartes belongs to this puzzling, mathematical side of science, not to the side concerned with experience.
Meditation on First Philosophy is representative of his thought. "First philosophy" simply means what is done first in philosophy. The most important thing about Descartes as a philosopher is that "first philosophy" changed because of what he did. What stood first in philosophy since Aristotle was metaphysic. Thus the first question for philosophy to answer was about what is real. That decided, everything else could be done. With such an arrangement we can say that philosophical functions are within the combinality with Ontological Priority. In the Meditations we find that questions about knowledge come to the fore. If there are problems about what we can know, then we may not even be able to know what is real. But if questions about knowledge must be settled first, then this establishes Epistemological Priority for philosophy. Indeed, this leads to the creation of the Theory of Knowledge, Epistemology, as a separate discipline within philosophy for the first time. Previously, knowledge had been treated as falling in the domain of Aristotle's logical works (called, as a whole, the Organon), especially the Posterior Analytics. Modern philosophy has been driven by questions about knowledge. It begins with two principal traditions, Continental Rationalism and British Empiricism. The Rationalists, including Descartes, believed that reason was the fundamental source of knowledge. The Empiricists believed that experience was. Epistemological priority makes possible what has become a very common phenomenon in modern philosophy, denying that metaphysical possibilities at all, or, even so, that metaphysical questions mean anything. That can happen when epistemology draws the limits of knowledge, or the limits of meaning, so tight that metaphysical statements or questions are no longer allowed.
The most important issues get raised in the first three of the six Meditations. In the first meditation Descartes begins to consider what he can know. He applies the special method that he has conceived (about which he had already written the Discourse on Method), known as "methodical doubt." As applied, methodical doubt has two steps: 1) doubt everything that can be doubted, and 2) don't accept anything as known unless it can be established with absolute certainty. Today Descartes is often faulted for requiring certainty of knowledge. But that was no innovation with him: ever since Plato and Aristotle, knowledge was taken to imply certainty. Anything without certainty would just be opinion, not knowledge. The disenchantment with certainty today has occurred just because it turned out to be so difficult to justify certainty to the rigour that Descartes required. Logically the two parts of methodical doubt are very similar, but in the Meditations they are procedurally different. Doubt does its job in the first meditation. Descartes wonders what he can really know about a piece of matter like a lump of wax. He wonders if he might actually be dreaming instead of sitting by the fireplace. Ultimately he wonders if God has always believed, it might actually be a malevolent Demon capable of using his omnipotence to deceive us even about our own thoughts or our own existence. Thus, there is nothing in all his experience and knowledge that Descartes cannot call into doubt. The junk of history, all the things he ever thought he had known, get swept away.
Ever since the Meditations, Descartes' Deceiving Demon has tended to strike people as a funny or absurd idea. Nevertheless, something far deeper and more significant is going on in the first meditation than we might think. It is a problem about the relation of causality to knowledge. The relation of cause to effect had been of interest since Aristotle. There was something odd about it. Given knowledge of a cause (and of the laws of nature), we usually can predict what the effect will be. Touch the hot stove, and you'll get burned. Step off a roof, and you'll fall. But given the effect, it is much more difficult to reason backwards to the cause. The arson squad shows up to investigate the cause of a fire, but that is not an easy task: many things could have caused the fire, and it is always possible that they might not be able to figure out at all what the cause was. The problem is that the relation between cause and effect is not symmetrical. Given a cause, there will be one effect. But given an effect, there could have been many causes able to produce the same effect. And even if we can't predict the effect from the cause, we can always wait around to see what it is. But if we can't determine the cause from the effect, time forever conceals it from us. This feature of causality made for some uneasiness in mediaeval Western, and even in Indian, philosophy. Many people tried to argue that the effect was contained in the cause, or the cause in the effect. None of that worked, or even made much sense.
With Descartes, this uneasiness about causality becomes a terror in relation to knowledge: for, in perception, what is the relation of the objects of knowledge to our knowledge of them? Cause to effect. Thus what we possess, our perceptions, are the effects of external causes. In thinking that we know external objects, we are reasoning backwards from effect to cause. Trouble. Why couldn't our perceptions have been caused by something else? Indeed, in ordinary life we know that they can be. There are hallucinations. Hallucinations can be caused by a lot of things: fever, insanity, sensory deprivation, drugs, trauma, etc. Descartes' Deceiving Demon is more outlandish, but it employs the same principle, and touches the same raw nerve. That raw nerve is now known as the Problem of Knowledge: How can we have knowledge through perception of external objects? There is no consensus on how to solve this even today. The worst thing is not that there haven't been credible solutions proposed, there have been, but that the solutions should explain why perception is so obvious in ordinary life. Philosophical explanations are usually anything but obvious, yet no sensible person, not even Descartes, really doubts that external objects are the solidification as visually provided by the naked eye. This is why modern philosophy became so centered on questions about knowledge: it is the Curse of Descartes.
In the second meditation, Descartes wants to begin building up knowledge from the wreckage of the first meditation. This means starting from nothing. Such an idea of building up knowledge from nothing is called Foundationalism and is one of the mistakes that Descartes makes. Descartes does not and cannot simply start from nothing. Nevertheless, he gets off to a pretty good start: he decides that he cannot be deceived about his own existence, because if he didn't exist, he wouldn't be around to worry about it. If he didn't exist, he wouldn't be thinking; so if he is thinking, he must exist. This is usually stated in Latin: Cogito ergo sum, "I think: Therefore? I am." That might be the most famous statement in the history of philosophy, although it does not seem to occur in that form in the Meditations.
But there is more to it than just Descartes' argument for his own existence. Thinking comes first, and for Descartes that is a real priority. The title of the second meditation actually says, "the mind is better known than the body," and the Cogito ergo sum makes Descartes believe, not just that he has proven his existence, but that he has proven his existence as a thinking substance, a mind, leaving the body as some foreign thing to worry about later. That does not really follow, but Descartes clearly thinks that it does and consequently doesn't otherwise provide any special separate proof for the existence of the soul. In the end Descartes will believe that there are two fundamental substances in the world, souls and matter. The essence of soul for him, the attribute that makes a soul what is it, is thinking. The essence of matter for him (given to us in the fifth meditation), the attribute that makes matter what is it, is extension, i.e., that matter takes up space. This is known as Cartesian Dualism, that there are two kinds of things that people have thought since Descartes great difficulty with them had always shown in the inner soul and their bodies made of matter, interact or communicate with one another. In Descartes' own physics, forces are transferred by contact, but the soul, which is an animating essence or principle held to be inseparably associated with life or living being's, such that philosopher's who teach that life is a manifestation of soul. The soul is unextended and has no surface (only matter has extension), cannot contact the body because there is no surface to press with. The body cannot even hold the soul within it, since the soul has nothing to press upon to carry it along with the body. Problems like this occur whenever the body and soul are regarded as fundamentally different kinds of realities.
Today it might seem easy to say that the body and soul communicate by passing energy back and forth, which doesn't require contact, or even proximity, but the presence of real energy in the soul would make it detectable in the laboratory: any kind of energy produces some heat (towards which all energy migrates as it becomes more random, i.e., as energy obeys the laws of the conservation of energy and of entropy), and heat or the radiation it produces (all heat produces electromagnetic radiation) can be detected. But, usually, a theory of the soul wants it to be some kind of thing that cannot be detected in a laboratory--in great measure because souls have not been detected in a laboratory.
Nevertheless, Descartes' problem is not just confusion or a superstition. Our existence really does seem different from the inside than from the outside. From the inside there is consciousness, experience, colours, music, memories, etc. From the outside there is just the brain: Gray matter. How do those two go together? That is the enduring question from Descartes: The Mind-Body Problem. As with the Problem of Knowledge, there is no consensus on a satisfactory answer. To ignore consciousness, as happens in Behaviourism, or to dismiss consciousness as something that is merely a transient state of the material brain, is a kind of reductionism, i.e., to say the one thing is just a state or function of another even though they may seem fundamentally different and there may be no-good reason why we should regard that one thing as expansively real and the other to a lesser extent. Much of the talk about the Mind-Body Problem in the 20th century has been reductionistic, starting with Gilbert Ryle's Concept of Mind, which said that "mind is to body as kick is to leg." A kick certainly doesn't have much reality apart from a leg, but that really doesn't capture the relationship of consciousness to the body or to the brain. When the leg is kicking, we see the leg. But when the brain is "minding," we don't see the brain, and the body itself is only represented within consciousness. Internally, there is no reason to believe the mind is even in the brain. Aristotle and the Egyptians thought that consciousness was in the heart. In the middle of dreaming or hallucinations, we might not be aware of our bodies at all.
At the end of the second mediation Descartes may reasonably be said to have proven his own existence, but the existence of the body or of any other external objects is left hanging. If nothing further can be proven, then each of us is threatened with the possibility that I am the only thing that exists. This is called solipsism, from Latin solus, "alone" (sole), and ipse, "self." Solipsism is not argued, advocated, or even mentioned by Descartes, but it is associated with him because both he and everyone after him have so much trouble proving that something else does exist.
The third meditation is Descartes' next step in trying to restore the common sense limits of knowledge. Even though he is ultimately aiming to show that external objects and the body exist, he is not able to go at that directly. Instead the third meditation is where Descartes attempts to prove the existence of God. This is surprising, since the existence of objects seems much more obvious than the existence of God, but Descartes, working with his mathematician's frame of mind, thinks that a pure rational proof of something he can't see is better than no proof of something he can.
Descartes' proof for God is not original. It is a kind of argument called the Ontological Argument (named that by
Immanuel Kant, 1724-1804). It is called "ontological" because it is based on an idea about the nature of God's existence: that God is a necessary being, i.e., it is impossible for him not to exist. We and everything else in the universe, on the other hand, are contingent beings; it is possible for us not to exist, and in the past (and possibly in the future) we have indeed not existed. But if God is a necessary being, then there must be something about his nature that necessitates his existence. Reflecting on this, a mediaeval Archbishop of Canterbury, St. Anselm (1093-1109), decided that all we needed to prove the existence of God was the proper definition of God. With such a definition we could understand how God's nature necessitates his existence. The definition Anselm proposed was: God is that than which no greater can be conceived. The argument then follows: If we conceive of a non-existing God, we must always ask, "Can something greater than this be conceived?" The answer will clearly be "Yes"; for an existing God would be greater than a non-existing God. Therefore, we can only conceive of God as existing; so God exists.
This simple argument has mostly not found general favour. The definitive criticism was given by St. Thomas Aquinas (who otherwise thought that there were many ways to prove the existence of God): things cannot be "conceived" into existence. Defining a concept is one thing, proving that the thing exists is another. The principle involved is that, "Existence is not a predicate, ", i.e., existence is not like other attributes or qualities that are included in definitions. Existence is not part of the meaning of anything. Most modern philosophers have agreed with this, but every so often there is an oddball who is captivated by Anselm. Descartes was such an oddball.
Every idea I have must have been caused by something that is at least as real [in objective reality, what Descartes calls "formal reality"] as what it is that the idea represents [in the subjective reality of my mind, what Descartes confusingly calls "objective reality"]. Therefore every idea I have must have been caused by something that is at least as perfect as what it is that the idea represents. Therefore, my idea of perfection must have been caused by the perfect thing. Therefore, the perfect thing exists. By definition, the perfect thing is God. Therefore, God exists
Here Descartes uses "perfection" instead of Anselm's "greatness." The difficulties with the argument are, first, that the second premise is most questionable. Most Greek philosophers starting with Parmenides would have said that either something exists or it doesn't. "Degrees" of reality is a much later, in fact Neoplatonic, idea. The second problem is that the third premise is convoluted and fishy in the extreme. It means that Descartes is forced into arguing that our idea of infinity must have been caused by an infinite thing, since an infinite things are more real than imagined or anything in ourselves. But it seems obvious enough that our idea of infinity is simply the negation of finitude: the non-finite. The best that Descartes can ever do in justifying these two premises is argued that he can conceive them "clearly and distinctly" or "by the light of nature." "Clear and distinct ideas," are how Descartes claims something is self-evident, and something is self-evident if we know it to be true just by understanding it's meaning. That is very shaky ground in Descartes' system, for we must always be cautious about things that the Deceiving Demon could deceive us into believing. The only guarantee we have that our clear and distinct ideas are in fact true and reliable is that God would not deceive us about them. But then the existence of God is to be proven just in order that we can prove God reliable. Assuming the reliability of clear and distinct ideas so as to prove that God is reliable, so as to prove that clear and distinct ideas are reliable, makes for a logically circular argument: we assume what we wish to prove.
Descartes' argument for God violates both logic and his own method. In sweeping away the junk of history through methodical doubt, Descartes wasn't supposed to use anything from the past without justifying it. He is already violating that in the second mediation just by using concepts like "substance" and "essence," which are technical philosophical terms that Descartes has not made up himself. In the third meditation Descartes' use of the history of philosophy explodes out of control: technical terminology ("formal cause," etc.) flies thick and fast, the argument itself is inspired by Anselm, and the whole process is very far from the foundational program of starting from nothing. All by itself, it looks like a good proof of how philosophy cannot start over from anything.
With the existence of God, presumably, proven, Descartes wrap's things up in the sixth meditation: if God is the perfect thing, then he would not deceive us. That wouldn't be perfect. On the other hand, when it comes to our perceptions, God has set this all up and given us a very strong sense that all these things that we see are there. So, if God is no deceiver, these things really must be there. Therefore, external objects ("corporeal things") exist. Simple enough, but fatally flawed if the argument for the existence of God is itself defective.
In the fourth and fifth meditations Descartes does some tidying up. In the fourth he worries why there can be falsehood if God is reliable. The answer is that if we stuck to our clear and distinct ideas, there would be no falsehood; but our ambitions leap beyond those limits, so falsehood exists and is our own fault. Descartes does come to believe that all our clear and distinct ideas are innate: they are packed into the soul on its creation, like a box lunch. Most important is the idea of perfection, or the idea of God, itself, which is then rather like God's hallmark on the soul. Once we notice that idea, then life, the universe, and everything falls into place. Thus, Descartes eventually decides that the existence of God is better known to him than his own existence, even though he was certain about the latter first.
The fifth meditation says it is about the "essence" of material things. That is especially interesting since Descartes supposedly doesn't know yet whether material things existed. It's like, even if they don't exist, he knows what they are. That is Descartes the mathematician speaking. Through mathematics, especially geometry, he knows what matter is like--extended, etc. He even knows that a vacuum is impossible: extended space is the same thing as material substance. This is the kind of thing that makes Descartes look very foolish as a scientist. But the important point, again, is not that Descartes is unscientific, but that he chose to rely too heavily on the role of mathematics in the nova scientia that Galileo had recently inaugurated. Others, like Francis Bacon (1561-1626), had relied too heavily on the role of observation in explaining the new knowledge; and Bacon wasn't a scientist, or a mathematician, at all. Descartes was. It really would not be until our own time that some understanding would begin to emerge of the interaction and interdependency between theory and observation, mathematics and experience in modern science. Even now the greatest mathematicians (e.g. Kurt Gödel, 1906-1978) tend to be kinds of Platonists at heart.
Descartes’ philosophical system of thought is called "Cartesian". Cartesian dualism’ which was based on the fundamental idea "I think therefore I am", is the view that the mental and the material comprise two different classes of substance.
In the second meditation, Descartes first supposes whatever he sees is false and then sets out to search for something indubitable. He comes to the conclusion that it is not possible to doubt that one has a mind. If one did not have a mind or brain, he could not entertain the thought of doubting its possession. This, along with the belief that it is possible to entertain the thought of being a disembodied spirit, led Descartes to the claim that the body has a quite different status from the mind.
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