THE QUICKENING OF PHILOSOPHY
RICHARD J.KOSCIEJEW
BOOK II
We may consider Descartes as the first finding founder of the modern school of mathematics. René Descartes was born near Tours on March 31, 1596, and died at Stockholm on February 11, 1650; thus he was a contemporary of Galileo and Desargues. His father, who, as the name implies, was of good family, was accustomed to spend half the year at Rennes when the local parliament, in which he held a commission as councillor, was in session, and the rest of the time on his family estate of Les Cartes at La Haye. René, the second of a family of two sons and one daughter, was sent at the age of eight years to the Jesuit School at La Flêche, and of the admirable discipline and education there given he speaks most highly. On account of his delicate health he was permitted to lie in bed till late in the mornings; this was a custom which he always followed, and when he visited Pascal in 1647 he told him that the only way to do good work in mathematics and to preserve his health was never to allow anyone to make him get up in the morning before he felt inclined to do so; an opinion which I chronicle for the benefit of any schoolboy into whose hands this work may fall
On leaving school in 1612 Descartes went to Paris to be introduced to the world of fashion. Here, through the medium of the Jesuits, he made the acquaintance of Mydorge, and renewed his schoolboy friendship with Mersenne, and together with them he devoted the two years of 1615 and 1616 to the study of mathematics. At that time a man of position usually entered either the army or the church; Descartes chose the former profession, and in 1617 joined the army of Prince Maurice of Orange, then at Breda. Walking through the streets there he saw a placard in Dutch which excited his curiosity, and stopping the first passer, asked him to translate it into either French or Latin. The stranger, who happened to be Isaac Beeckman, the head of the Dutch College at Dort, offered to do so if Descartes would answer it; the placard being, in fact, a challenge to all the world to solve a certain geometrical problem. Descartes worked it out within a few hours, and a warm friendship between him and Beeckman was the result. This unexpected test of his mathematical attainments made the uncongenial life of the army distasteful to him, but under family influence and tradition he remained a soldier, and was persuaded at the commencement of the Thirty Years' War to volunteer under Count de Bucquoy in the army of Bavaria. He continued all this time to occupy his leisure with mathematical studies, and was accustomed to date the first ideas of his new philosophy and of his analytical geometry from three dreams which he experienced on the night of November 10, 1619, at Neuberg, when campaigning on the Danube. He regarded this as the critical day of his life, and one which determined his whole future.
He resigned his commission in the spring of 1621, and spent the next five years in travel, during most of which time he continued to study pure mathematics. In 1626 we find him settled at Paris, ``a little well-built figure, modestly clad in green taffety, and only wearing sword and feather in token of his quality as a gentleman.'' During the first two years there he interested himself in general society, and spent his leisure in the construction of optical instruments; but these pursuits were merely the relaxations of one who failed to find in philosophy that theory of the universe which he was convinced finally awaited him.
In 1628 Cardinal de Berulle, the founder of the Oratorians, met Descartes, and was so much impressed by his conversation that he urged on him the duty of devoting his life to the examination of truth. Descartes agreed, and the better to secure himself from interruption moved to Holland, then at the height of his power. There for twenty years he lived, giving up all his time to philosophy and mathematics. Science, he says, may be compared to a tree; metaphysics is the root, physics is the trunk, and the three chief branches are mechanics, medicine, and morals, these forming the three applications of our knowledge, namely, to the external world, to the human body, and to the conduct of life.
He spend the first four years, 1629 to 1633, of his stay in Holland in writing Le Monde, which embodies an attempt to give a physical theory of the universe; but finding that its publication was likely to bring on him the hostility of the church, and having no desire to pose as a martyr, he abandoned it: the incomplete manuscript was published in 1664. He then devoted himself to composing a treatise on universal science; this was published at Leyden in 1637 under the title Discours de la méthode pour bien conduire sa raison et chercher la vérité dans les sciences, and was accompanied with three appendices (which possibly were not issued till 1638) entitled La Dioptrique, Les Météores, and La Géométrie; it is from the last of these that the invention of analytical geometry dates. In 1641 he published a work called Meditationes, in which he explained at some length his views on philosophy as sketched out in the Discours. In 1644 he issued the Principia Philosophiae, the greater part of which was devoted to physical science, especially the laws of motion and the theory of vortices. In 1647 he received a pension from the French court in honour of his discoveries. He went to Sweden on the invitation of the Queen in 1649, and died a few months later of inflammation of the lungs.
In appearance, Descartes was a small man with large head, projecting brow, prominent nose, and black hair coming down to his eyebrows. His voice was feeble. In disposition he was cold and selfish. Considering the range of his studies he was by no means widely read, and he despised both learning and art unless something tangible could be extracted therefrom. He never married, and left no descendants, though he had one illegitimate daughter, who died young.
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 effected 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 inter-relations 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's 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. Alytical 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; and 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 the co-ordinates of a number of 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 seen 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. says he, `qu'à dessein ... j'avois prévu que certaines 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 pour 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 shewed 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 trancendental 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 in the limit a tangent 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 letters Descartes illustrated his theory by giving the general rule for drawing tangents and normals to a 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 text-books 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 should note 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; but 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 then current, 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 I would here 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; and 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 regard 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; but, 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 shewed 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 which experiment shows to be true on the 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 consciousnesses, 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
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 explain 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 consciousnesses, 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 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 nonbasic 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.
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 motives or drives do people have? 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) overwhelms the intellectual, rational psyche. 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 dualists 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. Nativist 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 in all other matters 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 Flèche in Anjou, where his masters allowed him to stay late in bed because of his poor health. Descartes later described La Flèche 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 earlier 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, poêle), 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; but for all that I saw nothing that assured me that there was any triangle 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 such a being, 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, resolve "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 nothing so long as I think I am something." Descartes argued that one can doubt all, but not one's own existence as a thinking being, "for example that I am here seated by the fire wearing a dressing gown." Existence, being a 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 certain that 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 was 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. The 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, but 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 sensations consist of motions in the body which travel through the nerves to this gland and there give 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 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.
Meditations 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 metaphysics. 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 philosophy functions 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 metaphysics is possible at all, or even 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 the God he has always believed in 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, gets 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; and 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; but no sensible person, not even Descartes, really doubts that external objects are there. 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. It is something else that people have thought funny or absurd since Descartes. The great difficulty with it was always how souls 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 unextended and so 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 a 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 goo. 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 more real and the other less so. 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 thing is more real than us or anything in us. 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 argue 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 nothing.
With the existence of God, presumably, proven, Descartes wraps 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, s/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.
In the sixth meditation, Descartes states that the body has spacial parts; "…the body, by its very nature, is something divisible, whereas the mind is plainly indivisible." He also maintains that the body has extension (i.e. it occupies physical space) while mind does not have this property.
Descartes epistemological arguments have not been refuted. However there have may criticisms against his arguments for dualism. For example Elliott Sober (1995) claims that Descartes arguments for dualism does not work.
Earnest reviews Descartes arguments for dualism and notes how Leibniz law is at work in both of these arguments. He finds Descartes first argument invalid. He claims that indubitable existence is not a property. Doubting is rather something one does or fails to do to a proposition. Sober finds Descartes second argument valid. However he believes that its premises are not true. He sees no reason for accepting the premises that mind is indivisible and lacks extension unless one already believes that dualism is true.
The recognition of the mind/body distinction entails the second question which was posed in the beginning of this essay. How does the non-physical mind causally interacts with the physical body. Descartes did not deny that there are causal interaction between the mental and the physical. However the nature of causality is so that causes and effects must have a necessary connection and be of a similar type. If the natural world is divided into two different types namely the mental and the physical so that the physical is extended in space and the mental is not, then Cartesian mind/body interaction is untenable. This problem, which has been referred to as Descartes impasse, did not drive Descartes to abandon dualism. He claimed that pineal gland is the interface between the mind and the brain.
An alternative to the classical dualism is provided by identity theory. Identity theory is a position in the philosophy of mind which maintains that mind and brain are one and the same object viewed from two perspectives. Identity theory is therefore a form of monistic materialism, since it claims that mind is essentially material in nature.
It seems that identity theory evades the complex question of how causality can cross over from the mental to the physical and vice versa by simply denying dualism. This has been the view employed by traditional science until recently. Barasch M refers to a shift in the traditional scientific view brought about by a branch of science called psychoneuroimmunology (PNI)
. Psychoneuroimunlogy is defined by Lovejoy & Sisson (1989) as "the study of the interactions among the mind, immune system, and the neurological system that odulate susceptibility to disease or its progression." At a more general level PNI has been referred to as the Art and Science of the Mind-Body Connection. PNI has shown that the mind can have dramatic effects on the body. For example it has been shown that meditation and relaxation have effect on blood platelets, norepinephrine receptors and cortisol levels. Hypnosis has been used for curing a genetic skin disease. Barasch states that researches are even considering the possibility of spontaneous remission of cancer through mind-body effects.
The history of philosophizing about the relation of body and mind since Descartes is the history of attempts to escape the Cartesian impasse. Early maneuvers of this sort, such as those of Malebranche, Spinoza, Leibniz, and the French materialists La Mettrie and Cabanis, were formulated in the context of metaphysics, in direct response to Cartesian dualism. Later views which arose in the 19th century needed to reconcile evidence from studies on the localization of cerebral function and on functional nervous disorders with prevailing theory in biology and psychology. These discussions reflected the newly accepted view that the brain serves as the organ of mind. Although these theories of mind/brain relations - epiphenomenalism, interactionism, dual-aspect monism, and mind-stuff theory - were formulated in the context of science, they too were oriented toward circumventing the Cartesian impasse.
An alternative and much more enduring attempt to respond to the Cartesian impasse was that of Benedictus de Spinoza (1632-1677). Born in Amsterdam, Spinoza spent his life as a lens grinder. A Jew who had been expelled from the synagogue for unorthodoxy, he maintained few ties to either Dutch or Jewish contemporaries and published little during his lifetime. The metaphysical masterpiece, De ethica, appeared in his Opera posthuma, first published in 1677. In order to retain the notion of God as the one true cause without sacrificing the idea of causality as operative in both the mental and the physical spheres, Spinoza abandoned Descartes' two-substance view in favour of what has come to be called double-aspect theory. Double-aspect theories are based on the notion that the mental and the physical are simply different aspects of one and the same substance. For Spinoza, that single substance was God. While agreeing with Descartes that the world of consciousness and that of extension are qualitatively separate, Spinoza rejected the Cartesian view that consciousness and extension are attributes of two finite substances in favour of the notion that they are attributes of only one infinite substance. That substance, God, is the universal essence or nature of everything that exists.
The direct implication of Spinoza's view is that while mental occurrences can determine only other mental occurrences and physical motions can determine only other physical motions, mind and body nonetheless exist in pre-established coordination, since the same divine essence forms the connections within both classes and cannot be self-contradictory. In the later half of the 19th century, as we shall see, dual-aspect theories underwent a revival.
Til another alternative to Cartesian interactionism is that of psychophysical parallelism. This view retains both the dualism of mind and body and the notion of a regular correlation between mental and physical events, but avoids any assumption of causal mind/body connection, direct or indirect. Psychophysical parallelism eschews interactionism on the grounds that events so totally dissimilar as those of mind and body could not possibly affect one another. It also rejects occasionalism and dual-aspect theory on the grounds that no third entity, whatever that might be, could be responsible for such vastly different effects. Parallelists simply accept the fact that every mental event is correlated with a physical event in such a way that when one occurs, so too does the other.
Parallelism in this form is usually traced to Gottfried Wilhelm Leibniz (1646-1716). Historian, mathematician, philosopher, scientist, and diplomat, Leibniz was born and received most of his education in Leipzig. In 1676, after a period at Mainz and four years at Paris, he went to Hanover, where he spent the remainder of his life. An inveterate correspondent, contributor to scholarly journals, and creator of manuscripts, much of Leibniz' most important work was embodied in letters, published in article form, or left unpublished at his death.
In the Système nouveau de la nature (1695) and the Eclaircissement du nouveau sisteme (1696), Leibniz presented the famous articulation of psychophysical parallelism in which he adapted an occasionalist metaphor to support the view that soul and body exist in a pre-established harmony. Comparing soul and body to two clocks that agree perfectly, Leibniz argued that there are only three possible sources for this agreement. It may occur through mutual influence (interactionism), through the efforts of a skilled workman who regulates the clocks and keeps them in accord (occasionalism), or by virtue of the fact that they have been so constructed from the outset that their future harmony is assured (parallelism). Leibniz rejects interactionism because it is impossible to conceive of material particles passing from one substance to the other and occasionalism as invoking the intervention of a Deus ex machina in a natural series of events. All that remains is parallelism - the notion that mind and body exist in a harmony that has been pre- established by God from the moment of creation.
The term metaphysics is believed to have originated in Rome about 70 bc, with the Greek Peripatetic philosopher Andronicus of Rhodes (flourished 1st century bc) in his edition of the works of Aristotle. In the arrangement of Aristotle's works by Andronicus, the treatise originally called First Philosophy, or Theology, followed the treatise Physics. Hence, the First Philosophy came to be known as meta (ta) physica, or “following (the) Physics,” later shortened to Metaphysics. The word took on the connotation, in popular usage, of matters transcending material reality. In the philosophic sense, however, particularly as opposed to the use of the word by occultists, metaphysics applies to all reality and is distinguished from other forms of inquiry by its generality.
The subjects treated in Aristotle's Metaphysics (substance, causality, the nature of being, and the existence of God) fixed the content of metaphysical speculation for centuries. Among the medieval Scholastic philosophers, metaphysics was known as the “transphysical science” on the assumption that, by means of it, the scholar philosophically could make the transition from the physical world to a world beyond sense perception. The 13th-century Scholastic philosopher and theologian St. Thomas Aquinas declared that the cognition of God, through a causal study of finite sensible beings, was the aim of metaphysics. With the rise of scientific study in the 16th century the reconciliation of science and faith in God became an increasingly important problem.
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.”
Before the time of the German philosopher Immanuel Kant metaphysics was characterized by a tendency to construct theories on the basis of a priori knowledge, that is, knowledge derived from reason alone, in contradistinction to a posteriori knowledge, which is gained by reference to the facts of experience. From a priori knowledge were deduced general propositions that were held to be true of all things. The method of inquiry based on a priori principles is known as rationalistic. This method may be subdivided into monism, which holds that the universe is made up of a single fundamental substance; dualism, the belief in two such substances; and pluralism, which proposes the existence of many fundamental substances.
The monists, agreeing that only one basic substance exists, differ in their descriptions of its principal characteristics. Thus, in idealistic monism the substance is believed to be purely mental; in materialistic monism it is held to be purely physical, and in neutral monism it is considered neither exclusively mental nor solely physical. The idealistic position was held by the Irish philosopher George Berkeley, the materialistic by the English philosopher Thomas Hobbes, and the neutral by the Dutch philosopher Baruch Spinoza. The latter expounded a pantheistic view of reality in which the universe is identical with God and everything contains God's substance.
Irish philosopher and clergyman George Berkeley set out to challenge what he saw as the atheism and skepticism inherent in the prevailing philosophy of the early 18th century. His initial publications, which asserted that no objects or matter existed outside the human mind, were met with disdain by the London intelligentsia of the day. Berkeley aimed to explain his “Immaterialist” theory, part of the school of thought known as idealism, to a more general audience in Three Dialogues between Hylas and Philonous (1713). This passage is from the close of the third dialogue.
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 analyzed in terms of actual or possible occurrences, or phenomena, and that anything that cannot be analyzed 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.
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