René Descartes

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• Born: 31 March 1596
• Birthplace: La Haye, France
• Died: 11 February 1650 (lung trouble)
• Best Known As: The philosopher who said "I think, therefore I am"

René Descartes is often called the father of modern science. He established a new, clear way of thinking about philosophy and science by rejecting all ideas based on assumptions or emotional beliefs and accepting only those ideas which could be proved by or systematically deduced from direct observation. He took as his philosophical starting point the statement Cogito ergo sum -- "I think, therefore I am." Descartes made major contributions to modern mathematics, especially in developing the Cartesian coordinate system and advancing the theory of equations.

René Descartes

Library of Congress

[b. La Haye, France, March 31, 1596, d. Stockholm, Sweden, February 11, 1650]

The philosopher Descartes was the first to publish a detailed account of how to use coordinates for locating points in space, called analytic geometry, although Fermat developed the concept slightly earlier. In an appendix to his book Discours de la méthode Descartes gave analytic geometry to the world and used the new technique to solve problems in geometry. Analytic geometry made calculus and many other advances in mathematics possible. Descartes also developed (incorrect) theories of how the planets move and obtained important (correct) results in optics. His emphasis on rational thought was important in creating modern science.

(b La Haye, 31 March 1596; d Stockholm, 11 Feb 1650). French philosopher. His principal contribution to music theory was the Compendium musicae (1618), in which he attempted to define the dual relationship between the physical and psychological phenomena in music. The bulk of the work is devoted to the practical aspects of music as part of the process of sensory perception. He also contributed to music theory on period structure and harmonic inversion.

The French thinker René Descartes (1596-1650) is called the father of modern philosophy. He initiated the movement generally termed rationalism, and his "Discourse on Method and Meditations" defined the basic problems of philosophy for at least a century.

To appreciate the novelty of the thought of René Descartes, one must understand what modern philosophy, or rationalism, means in contrast to medieval, or scholastic, philosophy. The great European thinkers of the 9th to 14th century were not incapable of logical reasoning, but they differed in philosophic interests and aims from the rationalists. Just as the moderns, from Descartes on, usually identified philosophy with the natural and pure sciences, so the medievals made little distinction between philosophical and theological concerns.

The medieval doctors, like St. Thomas Aquinas, wanted to demonstrate that the revelations of faith and the dictates of reason were not incompatible. Their universe was that outlined by Aristotle in his Physics - a universe in which everything was ordered and classified according to the end that it served. During the Renaissance, however, men began exploring scientific alternatives to Aristotle's hierarchical universe. Further, new instruments, especially Galileo's telescope, added precision to scientific generalizations.

By the beginning of the 17th century the medieval tradition had lost its creative impetus. But the schoolmen, so called because they dominated the European universities, continued to adhere dogmatically to the traditional philosophy because of its association with Catholic theology. The rationalists, however, persistently refused professorships in order to preserve their intellectual integrity or to avoid persecution. They rejected the medieval practice of composing commentaries on standard works in favor of writing original, usually anonymous, treatises on topics suggested by their own scientific or speculative interests. Thus the contrast is between a moribund tradition of professorial disputes over trivialities and a new philosophy inspired by original, scientific research.

Descartes participated in this conflict between the scholastic and rationalist approaches. He spent a great part of his intellectual effort - even to the extent of suppressing some of his writings - attempting to convince ecclesiastical authorities of the compatibility of the new science with theology and of its superiority as a foundation for philosophy.

Early Life

Descartes was born on March 31, 1596, in La Haye, in the Touraine region, between the cities of Tours and Poitiers. His father, Joachim, a member of the minor nobility, served in the Parliament of Brittany. Jeanne Brochard Descartes, his mother, died in May 1597. Although his father remarried, Descartes and his older brother and sister were raised by their maternal grandmother and by a nurse for whom he retained a deep affection.

In 1606 Descartes entered La Flèche, a Jesuit college established by the king for the instruction of the young nobility. In the Discourse Descartes tells of the 8-year course of studies at La Flèche, which he considered "one of the most celebrated schools in Europe." According to his account, which is one of the best contemporary descriptions of 17th-century education, his studies left him feeling embarrassed at the extent of his own ignorance.

The young Descartes came to feel that languages, literature, and history relate only fables which incline man to imaginative exaggerations. Poetry and eloquence persuade man, but they do not tell the truth. Mathematics does grasp the truth, but the certainty and evidence of its reasoning seemed to Descartes to have only practical applications. Upon examination, the revelations of religion and morals seem as mysterious to the learned as to the ignorant. Philosophy had been studied by the best minds throughout the centuries, and yet "no single thing is to be found in it which is not subject to dispute." Descartes says that he came to suspect that even science, which depends upon philosophy for its principles, "could have built nothing solid on foundations so far from firm."

Travel and First Writings

The 18-year-old Descartes left college with a reputation for extreme brilliance. In the next years he rounded out the education befitting a young noble. He learned fencing, horsemanship, and dancing and took a law degree from Poitiers.

From 1618 to 1628 Descartes traveled extensively throughout Europe while attached to various military units. Although a devout Catholic, he served in the army of the Protestant prince Maurice of Nassau but later enlisted in the Catholic army of Maximilian I of Bavaria. Living on income from inherited properties, Descartes served without pay and seems to have seen little action; he was present, however, at the Battle of Prague, one of the major engagements of the Thirty Years War. Descartes was reticent about this period of his life, saying only that he left the study of letters in order to travel in "the great book of the world."

This period of travel was not without intellectual effort. Descartes sought out eminent mathematicians, scientists, and philosophers wherever he traveled. The most significant of these friendships was with Isaac Beeckman, the Dutch mathematician, at whose suggestion Descartes began writing scientific treatises on mathematics and music. He perfected a means of describing geometrical figures in algebraic formulas, a process that served as the foundation for his invention of analytic geometry. He became increasingly impressed with the extent to which material reality could be understood mathematically.

During this period Descartes was profoundly influenced by three dreams which he had on Nov. 10, 1619, in Ulm, Germany. He interpreted their symbols as a divine sign that all science is one and that its mastery is universal wisdom. This notion of the unity of all science was a revolutionary concept which contradicted the Aristotelian notion that the sciences were distinguished by their different objects of study. Descartes did not deny the multiplicity of objects, but rather he emphasized that only one mind could know all these diverse things. He felt that if one could generalize man's correct method of knowing, then one would be able to know everything. Descartes devoted the majority of his effort and work to proving that he had, in fact, discovered this correct method of reasoning.

From 1626 to 1629 Descartes resided mainly in Paris. He acquired a wide and notable set of friends but soon felt that the pressures of social life kept him from his work. He then moved to Holland, where he lived, primarily near Amsterdam, for the next 20 years. Descartes cherished the solitude of his life in Holland, and he described himself to a friend as awakening happily after 10 hours of sleep with the memory of charming dreams. He said his life in Holland was peaceful because he was "the only man not engaged in merchandise." There Descartes studied and wrote. He carried on an enormous correspondence throughout Europe, and in Holland he acquired a small, but dedicated, set of friends and disciples. Although he never married, Descartes fathered a natural daughter who was baptized Francine. She died in 1640, when she was 5.

First Works

Descartes's research in mathematics and physics led him to see the need for a new methodology, or way of thinking. His first major work, Rules for the Direction of the Mind, was written by 1629. Although circulated widely in manuscript form, this incomplete treatise was not published until 1701. The work begins with the assumption that man's knowledge has been limited by the erroneous belief that science is determined by the various objects of experience. The first rule therefore states that all true judgment depends on reason alone for its validity. For example, the truths of mathematics are valid independently of observation and experiment. Thus the second rule argues that the standard for any true knowledge should be the certitude demanded of demonstrations in arithmetic and geometry. The third rule begins to specify what this standard of true knowledge entails. The mind should be directed not by tradition, authority, or the history of the problem, but only by what can clearly be observed and deduced.

There are only two mental operations that are permissible in the pure use of reason. The first is intuition, which Descartes defines as "the undoubting conception of an unclouded and attentive mind"; the second is deduction, which consists of "all necessary inference from other facts that are known with certainty. "The basic assumption underlying these definitions is that all first principles are known by way of self-evident intuitions and that the conclusions of this "seeing into" are derived by deduction. The clarity and distinctness of ideas are for Descartes the conceptual counterpart of human vision. (For example, man can know the geometry of a square just as distinctly as he can see a square table in front of him.)

Many philosophers recognized the ideal character of mathematical reasoning, but no one before Descartes had abstracted the conditions of such thinking and applied it generally to all knowledge. If all science is unified by man's reason and if the proper functioning of the mind is identified with mathematical thinking, then the problem of knowledge is reduced to a question of methodology. The end of knowledge is true judgment, but true judgment is equivalent to mathematical demonstrations that are based on intuition and deduction. Thus the method for finding truth in all matters is merely to restrict oneself to these two operations.

According to the fourth rule, "By method I mean certain and simple rules, such that if a man observe them accurately, he shall never assume what is false as true … but will always gradually increase his knowledge and so arrive at a true understanding of all that does not surpass his powers." The remaining sixteen rules are devoted to the elaboration of these principles or to showing their application to mathematical problems. In Descartes's later works he refines these methodological principles, and in the Meditations he attempts a metaphysical justification of this type of reasoning.

By 1634 Descartes had written his speculative physics in a work entitled The World. Unfortunately, only fragments survive because he suppressed the book when he heard that Galileo's Dialogue on the Two Great Systems of the Universe had been condemned by the Catholic Church because of its advocacy of Copernican rather than Ptolemaic astronomy. Descartes also espoused the Copernican theory that the earth is not the center of the universe but revolves about the sun. His fear of censure, however, led him to withdraw his work. In 1634 he also wrote the brief Treatise on Man, which attempted to explain human physiology on mechanistic principles.

Discourse and Meditations

In 1637 Descartes finished Discourse on Method, which was published together with three minor works on geometry, dioptrics, and meteors. This work is significant for several reasons. It is written in French and directed to men of good sense rather than professional philosophers. It is autobiographical and begins with a personal account of his education as an example of the need for a new method of conducting inquiry.

The work contains Descartes's vision of a unity of science based on a common methodology, and it shows that this method can be applied to general philosophic questions. In brief, the method is a sophistication of the earlier Rules for the Direction of the Mind. In the Discourse Descartes presents four general rules for reducing any problem to its fundamentals by analysis and then constructing solutions by general synthesis.

Meditations on First Philosophy appeared in 1641-1642 together with six (later seven) sets of objections by distinguished thinkers including Thomas Hobbes, Antoine Arnauld, and Pierre Gassendi and the author's replies. The Meditations is Descartes's major work and is one of the seminal books in the history of philosophy. While his former works were concerned with elaborating a methodology, this work represents the systematic application of those rules to the principal problems of philosophy: the refutation of skepticism, the existence of the human soul, the nature of God, the metaphysical basis of truth, the extent of man's knowledge of the external world, and the relation between body and soul.

The first meditation is an exercise in methodological skepticism. Descartes states that doubt is a positive means of ascertaining whether there is any certain foundation for knowledge. All knowledge originates either from the senses or from the mind. Examples of color blindness, objects seen in perspective, and so on testify to the distortions inherent in vague sense perception. The recognition of these phenomena as distorted suggests a class of clear perceptions which are more difficult to doubt. But Descartes then points out that such images appear as clear to man in dreams as in an awakened state. Therefore all sensory experience is doubtful because sense data in itself does not indicate whether an object is seen or imagined, true or false.

What about the realm of pure ideas? Descartes simplifies the argument by asking whether it is possible to doubt the fundamental propositions of arithmetic and geometry. Man cannot doubt that two plus two equals four, but he may suspect that this statement has no reality apart from his mind. The standard of truth is the self-evidence of clear and distinct ideas, but the question remains of the correspondence of such ideas to reality. Descartes imagines the existence of an all-powerful "evil genius" who deceives man as to the content of his ideas, so that in reality two plus two equals five.

The second meditation resolves these skeptical issues in a deceptively simple manner by arguing that even if it is doubtful whether sense images or ideas have objects, it is absolutely true that man's mind exists. The famous formula "I think, therefore, I am" is true even if everything else is false. Descartes's solution is known as subjectivism, and it is a radical reversal of previous theories of knowledge. Whereas nature had been assumed to be the cause of man's images and ideas, Descartes states that man is a "thinking thing" whose subjective images and ideas are the sole evidence for the existence of a world.

The third meditation demonstrates that God is "no deceiver," and hence clear and distinct ideas must have objects that exactly and actually correspond to them. Descartes argues that the idea of God is an effect. But an effect gets its reality from its cause, and a cause can only produce what it possesses. Hence either Descartes is a perfect being or God exists as the cause of the idea of God.

The fourth meditation deals with the problem of human error; insofar as man restricts himself to clear and distinct ideas, he will never err. With this connection between ideas and objects Descartes can emerge from his doubts about knowledge. The external world can be known with absolute certainty insofar as it is reducible to clear and distinct ideas. Thus the fifth meditation shows the application of methodology to material reality in its quantifiable dimensions, that is, to the extent to which material reality can be "the object of pure mathematics."

The sixth, and final, meditation attempts to explain the relation between the human soul and the body. Since Descartes believed in mechanism, there could be no absolute connection between a free soul and a bodily machine. After considerable hesitation he expresses the relation between mind and matter as a "felt union." The body is the active faculty that produces the passive images and imaginings man finds in his mind. Actually Descartes's explanation is logically impossible in terms of the "subjective" separation of mind; similarly, the unresolved dualism of the "felt union" violates the principle of assenting only to clear and distinct ideas.

The remainder of Descartes's career was spent in defending his controversial positions. In 1644 he published the Principles of Philosophy, which breaks down the arguments of the Meditations into propositional form and presents extra arguments dealing with their scientific application. In 1649 Descartes accepted an invitation from Queen Christina of Sweden to become her teacher. There he wrote The Passions of the Soul, which is a defense of the mind-body dualism and a mechanistic explanation of the passions. But Descartes's health was undermined by the severity of the northern climate, and after a brief illness he died in Stockholm in 1650.

Further Reading

The most complete edition of Descartes's works in English is The Philosophical Works of Descartes, translated by Elizabeth S. Haldane and G.T.R. Ross (2 vols., 1955), although many editions of individual works in new translations are available in paperback. The standard biography is Haldane's Descartes: His Life and Times (1905; repr. 1966). The best general introductions to Descartes's philosophy are A. Boyce Gibson, The Philosophy of Descartes (1932); Stanley V. Keeling, Descartes (1934; 2d ed. 1968); and Albert G. A. Balz, Descartes and the Modern Mind (1952). Works on specialized topics of an analytic or critical nature include Norman Kemp Smith, Studies in the Cartesian Philosophy (1902) and New Studies in the Philosophy of Descartes: Descartes as Pioneer (1952); Jacques Maritain, Three Reformers: Luther Descartes, Rousseau (trans. 1928) and The Dream of Descartes (trans. 1944); and Leslie J. Beck, The Method of Descartes: A Study of the Regulae (1952).

For more information on René Descartes, visit Britannica.com.

Descartes, René (1596-1650). One of the principal creators of modern philosophy and science, an emblematic figure of the power of independent thinking.

He was born in Touraine and educated at the Jesuit college of La Flèche. From 1618 to 1620 he served in the army; in November 1619, while garrisoned in Germany in a ‘poêle’ (a small house heated by a central stove), he experienced a spell of ‘enthusiasm’ in which he discovered ‘les fondements d'une science admirable’. Between 1620 and 1629 he travelled, but was based in Paris, frequenting scholarly circles. In 1629, having decided to devote himself to philosophy, he settled in Holland, where he lived for the rest of his life. His voluntary exile gave him freedom and solitude, though he entertained many visitors and kept up a voluminous and fascinating correspondence.

In his early years in Holland he was much occupied by scientific research, but metaphysics became his dominant concern in the late 1630s. Having refrained from publishing for many years, he grew increasingly concerned to win over readers to his philosophy, and to oust scholasticism from the schools. In 1649 he accepted an invitation from a royal admirer, Queen Christine of Sweden, but fell ill and died in Stockholm.

Descartes's youthful writings are only preserved in fragmentary form. His first major work, the Regulae ad directionem ingenii (Règles pour la direction de l'esprit), written in Latin before 1629, was published posthumously. It contains 21 ‘rules’ designed to establish a method for achieving, within the field open to human understanding, a scientific certainty as firm as that of mathematics. Using this method, which combines intuition, observation, experiment, and deduction, he then worked on a treatise, Le Monde, ou le Traité de l'homme, in which he offered a mechanistic account of the universe (a heliocentric system) and of human beings, their bodily motions, and sensations. The work was completed by 1633, but Descartes abandoned publication on hearing of Galileo's condemnation.

His first published book, and his most famous, was the Discours de la méthode, published in French in 1637 together with essays on optics, meteorology, and geometry. It is a complex work, whose six parts are given unity as the story of the author's search for truth. In Part 1, starting from the premiss that ‘le bon sens est la chose du monde la mieux partagée’, Descartes offers his intellectual autobiography as a possible model for the proper conduct of the mind. He tells of his book-centred Jesuit education, which failed to satisfy his desire for certain knowledge, and of his decision to make a clean break and think for himself. Part 2 recounts, with superb confidence, the discovery of the true method; as in the Regulae, this consists in taking nothing for granted, accepting only ideas which are entirely self-evident, and proceeding from them by orderly ‘chains’ of reasoning. In Part 3 he sets out the prudently conformist ‘provisional ethics’ which he adopted until he had arrived at a rationally based morality.

Part 4, the centre of the book, sets out Descartes's first metaphysical discoveries. Having submitted all ideas to methodical doubt, he is left with the unshakeable principle: ‘Je pense, donc je suis’ (Cogito, ergo sum, often referred to as ‘the cogito’). He proceeds from this to a radical distinction between the thinking substance (mind, spirit, or soul) and the material world; this is the famous Cartesian ‘dualism’. The final basic principle in Part 4 is the existence of a perfect being, God, which is deduced from the very fact that we possess an idea of perfection. God in turn guarantees the value of sense experience, and thus of experimental science. Part 5 contains a summary of the doctrine of Le Monde, emphasizing the distinction between human beings, with their immaterial souls, and animals, which are seen as ‘machines’—an aspect of Descartes's philosophy that caused much controversy. Part 6 is a fascinating discussion of his publishing strategy and the way he sees his public responsibility as a scientist.

His later works develop the ideas of the Discours. The Méditations (published in Latin in 1641, in French in 1647) is his most important work of pure philosophy. Using the first-person form again, it attempts to establish more firmly the metaphysics of the Discours, in particular the existence of God and the mind-matter distinction. Methodical doubt is given added force here by the fiction of a ‘mauvais génie’ dedicated to deceiving us. The work is followed by a number of lengthy replies to objections from readers such as Gassendi, Hobbes, and Arnauld. The Principes, published in Latin in 1644 and in French in 1647, is Descartes's fullest account of his philosophy. Book 1 is devoted to metaphysics, Books 2-4 to physical science, including cosmology. The work is designed to replace existing school manuals, and is divided into easily assimilated short chapters; declaring that all normal people are capable of philosophy, Descartes in a preface of 1647 urges readers to read it in the first instance ‘like a novel’. An unfinished dialogue, La Recherche de la vérité, shows a similar concern for popularization.

His last major work, Les Passions de l'âme (1650), written at the request of Princess Elizabeth of Bohemia, explains the passions in accordance with his dualistic principles. The pineal gland in the brain is declared to be the place of interaction between body and mind. If the body affects the mind, the converse is also true; writing in Neostoical vein, and expressing values also embodied in the heroes of Pierre Corneille, Descartes exalts the free will of the ‘généreux’.

His ideas, powerful in their own right, are given added force by his rhetorical skill. His tone and style—even his choice between Latin and French—correspond to his projected readers, whose reactions are provoked, anticipated, and answered. The man is very present in the writing. At times he is disarmingly modest, at times fiercely ironic. His plain style is often lifted to a higher plane by the striding rhythm of his sentences and his striking images.

Descartes's philosophy, Cartesianism, exercised a great influence, even when when it was rejected. His cosmology, with its ‘horror of the vacuum’ and its planets whirled around in vortices (tourbillons) of ether, succumbed to Newtonian physics, though not before supplanting Aristotle in the colleges. His doctrine of ‘innate ideas’ was ousted, or at least modified, by Locke's sensationalism. His body-soul dualism, with its need to explain the reciprocal action of the two substances, continued to tease philosophers, notably Malebranche and Leibniz. But his greatest legacy was his method, together with his confidence in the possibility of explaining and conquering nature. For better or worse, he was one of the fathers of the Scientific Revolution; his methodical doubt and his independence of mind continued to inspire Enlightenment thinkers, even if they discarded many of his scientific theories as fantasies.

[Peter France]

Bibliography

• A. J. P. Kenny, Descartes: A Study of his Philosophy (1968)
• G. Rodis-Lewis, L'Œuvre de Descartes (1971)
• B. Williams, Descartes (1978)

Descartes, René (1596-1650) French mathematician and founding father of modern philosophy. Born in La Haye, near Tours, Descartes was educated at the new Jesuit college at La Flèche, before reading law at Poitiers. In 1618 he enlisted at his own expense in the Dutch army of Maurice of Nassau, in order to have the leisure to think. His interest in the methodology of a unified science is supposed to have been stimulated by a dream ‘in a stove-heated room’ when he was serving at Ulm in 1619. In the subsequent ten years he travelled widely, returning to Holland in 1628. Little is known of his private life, but the death of his illegitimate five-year-old daughter Francine in 1640 is known to have been a devastating blow. His first work, the Regulae ad Directionem Ingenii (1628/9), was never completed. In Holland, between 1628 and 1649, Descartes first wrote, and then cautiously suppressed, Le Monde (1634), and in 1637 produced the Discours de la méthode as a preface to the treatise on mathematics and physics in which he introduced the notion of Cartesian coordinates.

His best-known philosophical work, the Meditationes de Prima Philosophia (Meditations on First Philosophy), together with objections by distinguished contemporaries and replies by Descartes (the Objections and Replies), appeared in 1641. The authors of the objections are: first set, the Dutch theologian Johan de Kater; second set, Mersenne; third set, Hobbes; fourth set, Arnauld; fifth set, Gassendi; and sixth set, Mersenne. The second edition (1642) of the Meditations included a seventh set by the Jesuit Pierre Bourdin. Descartes's penultimate work, the Principia Philosophiae (Principles of Philosophy) of 1644 was designed partly for use as a theological textbook. His last work was Les Passions de l’âme (The Passions of the Soul), published in 1649. In that year Descartes visited the court of Kristina of Sweden, where he contracted pneumonia, allegedly through being required to break his normal habit of late rising in order to give lessons at 5:00 a.m. His last words are supposed to have been ‘Ça, mon âme, il faut partir’ (‘So, my soul, it is time to part’).

Descartes's theory of knowledge starts with the quest for certainty, for an indubitable starting-point or foundation on the basis alone of which progress is possible (see method of doubt). This is eventually found in the celebrated ‘Cogito ergo sum’: I think therefore I am. By locating the point of certainty in my own awareness of my own self, Descartes gives a first-person twist to the theory of knowledge that dominated the following centuries in spite of various counter-attacks on behalf of social and public starting-points. The metaphysics associated with this priority is the famous Cartesian dualism, or separation of mind and matter into two different but interacting substances. Descartes rigorously and rightly sees that it takes divine dispensation to certify any relationship between the two realms thus divided, and to prove the reliability of the senses invokes a ‘clear and distinct perception’ of highly dubious proofs of the existence of a benevolent deity. This has not met general acceptance: as Hume drily puts it, ‘to have recourse to the veracity of the supreme Being, in order to prove the veracity of our senses, is surely making a very unexpected circuit’.

In his own time Descartes's conception of the entirely separate substance of the mind was recognized to give rise to insoluble problems of the nature of the causal connection between the two (see occasionalism). It also gives rise to the problem, insoluble in its own terms, of other minds. Descartes's notorious denial that non-human animals are conscious is a stark illustration of the problem. In his conception of matter Descartes also gives preference to rational cogitation over anything derived from the senses. Since we can conceive of the matter of a ball of wax surviving changes to its sensible qualities, matter is not an empirical concept, but eventually an entirely geometrical one, with extension and motion as its only physical nature. Descartes's thought here is reflected in Leibniz's view, held later by Russell, that the qualities of sense experience have no resemblance to qualities of things, so that knowledge of the external world is essentially knowledge of structure rather than of filling. On this basis Descartes erects a remarkable physics. Since matter is in effect the same as extension there can be no empty space or void; since there is no empty space motion is not a question of occupying previously empty space, but is to be thought of in terms of vortices (like the motion of a liquid).

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

Life

Descartes was educated in the Jesuit College at La Flèche and the Univ. of Poitiers, then entered the army of Prince Maurice of Nassau. In 1628 he retired to Holland, where he spent his time in scientific research and philosophic reflection. Even before going to Holland, Descartes had begun his great work, for the essay on algebra and the Compendium musicae probably antedate 1628. But it was with the appearance in 1637 of a group of essays that he first made a name for himself. These writings included the famous Discourse on Method and other essays on optics, meteors, and analytical geometry. In 1649 he was invited by Queen Christina to Sweden, but he was unable to endure the rigors of the northern climate and died not long after arriving in Sweden.

Elements of Cartesian Philosophy

It was with the intention of extending mathematical method to all fields of human knowledge that Descartes developed his methodology, the cardinal aspect of his philosophy. He discards the authoritarian system of the scholastics and begins with universal doubt. But there is one thing that cannot be doubted: doubt itself. This is the kernel expressed in his famous phrase, Cogito, ergo sum [I think, therefore I am].

From the certainty of the existence of a thinking being, Descartes passed to the existence of God, for which he offered one proof based on St. Anselm's ontological proof and another based on the first cause that must have produced the idea of God in the thinker. Having thus arrived at the existence of God, he reaches the reality of the physical world through God, who would not deceive the thinking mind by perceptions that are illusions. Therefore, the external world, which we perceive, must exist. He thus falls back on the acceptance of what we perceive clearly and distinctly as being true, and he studies the material world to perceive connections. He views the physical world as mechanistic and entirely divorced from the mind, the only connection between the two being by intervention of God. This is almost complete dualism.

The development of Descartes' philosophy is in Meditationes de prima philosophia (1641); his Principia philosophiae (1644) is also very important. His influence on philosophy was immense, and was widely felt in law and theology also. Frequently he has been called the father of modern philosophy, but his importance has been challenged in recent years with the demonstration of his great debt to the scholastics. He influenced the rationalists, and Baruch Spinoza also reflects Descartes's doctrines in some degree. The more direct followers of Descartes, the Cartesian philosophers, devoted themselves chiefly to the problem of the relation of body and soul, of matter and mind. From this came the doctrine of occasionalism, developed by Nicolas Malebranche and Arnold Geulincx.

Major Contributions to Science

In science, Descartes discarded tradition and to an extent supported the same method as Francis Bacon, but with emphasis on rationalization and logic rather than upon experiences. In physical theory his doctrines were formulated as a compromise between his devotion to Roman Catholicism and his commitment to the scientific method, which met opposition in the church officials of the day. Mathematics was his greatest interest; building upon the work of others, he originated the Cartesian coordinates and Cartesian curves; he is often said to be the founder of analytical geometry. To algebra he contributed the treatment of negative roots and the convention of exponent notation. He made numerous advances in optics, such as his study of the reflection and refraction of light. He wrote a text on physiology, and he also worked in psychology; he contended that emotion was finally physiological at base and argued that the control of the physical expression of emotion would control the emotions themselves. His chief work on psychology is in his Traité des passions de l'âme (1649).

Bibliography

See biographies by J. R. Vrooman (1970), S. Gaukroger (1995), R. Watson (2002), A. C. Grayling (2005), and D. Clarke (2006); see studies by J. Maritain (tr. 1944, repr. 1969), A. G. Balz (1952, repr. 1967), H. Caton (1973), and S. Gaukroger (1989 and 2002; as ed. 1980, 1998, 2000, and 2006).

Descartes, René (1596–1650), French philosopher, mathematician, and scientist. Descartes was one of the most important intellectual figures of seventeenth-century Europe. His thought, often regarded as ushering in the "modern" period of philosophy, represented a revolutionary attempt to break from the restrictive and tradition-bound medieval Scholastic model that governed the universities and that was dominated by the method and categories of Aristotelian philosophy. By the time of his death, Descartes's influence extended across Europe and into various intellectual domains, including theology, medicine, and even rhetoric.

In 1633 Descartes, who had already written a treatise on method, Regulae ad Directionem Ingenii (Rules for the direction of the mind), was ready to publish a book on cosmology and physics, Le Monde (The world). But Galileo's condemnation that year by the church for propounding scientific ideas very much like what Descartes was about to present, including a heliocentric picture of the universe and a purely mechanistic account of nature's operations, caused him to withhold the work. He first came to public attention with the publication of his Discours de la méthode pour bien conduire sa raison et chercher la verité dans les sciences (1637; Discourse on the method of rightly conducting one's reason and reaching the truth in the sciences) and the ground-breaking essays in geometry, optics, and meteorology that it accompanied. The Meditationes de Prima Philosophiae (1641; Meditations on first philosophy), often regarded as Descartes's philosophical masterpiece, is a short work in epistemology and metaphysics. It was not until his magisterial Principia Philosophiae (1644; Principles of philosophy) that Descartes offered a complete and systematic presentation of his metaphysical and scientific views; he hoped that the work would become a standard textbook in university curricula and supplant the Aristotelian Scholastic works then in use.

Descartes lived most of his adult life in the Netherlands, having left France in search of peace and solitude to pursue his inquiries. His fame led to an invitation to Sweden by Queen Christina in 1649; with misgivings about giving up his quiet, familiar life in the Dutch countryside, he reluctantly joined her court. It was not long, however, before he fell ill from the rigors of the routine imposed upon him in the harsh Swedish winter and died of pneumonia.

Philosophy, for Descartes, encompasses the whole of human knowledge, systematically ordered, and can be compared to a tree. Its roots are metaphysics, or "first philosophy" (including the theory of knowledge); its trunk is physics; and its branches are all of the particular sciences (medicine, ethics, mechanics) that depend on the most general physical principles. Certainty in philosophy or science can be achieved only if one proceeds methodically from well-established first principles to explanations in the particular disciplines by means of a proven method.

In the Meditations, Descartes begins by taking the reader on a journey of intellectual self-discovery. His goal is to determine what exactly can be known for certain, not just about the world around us but especially about ourselves. Even under the most adverse skeptical assumptions about the reliability of our senses and our rational faculties, we can always be absolutely certain of our own existence. As he so famously expresses it in the Discourse on Method, the reasoning represented by the proposition "I think, therefore I am" (Cogito ergo sum) can never be doubted. This single epistemological nugget can serve as the foundation for a host of other certainties. For once I know my own existence and my nature as a thinking being—endowed with certain thoughts or clear and distinct ideas—I can establish not only that God, an absolutely perfect being, exists and cannot be a deceiver, but also that this benevolent God created me with my rational faculties. Thus, to the extent that I use those faculties properly and give my assent only to what I clearly and distinctly perceive, I cannot go wrong and will obtain true beliefs about myself and about the external world.

Among the truths I will thereby discover is the real distinction between mind and matter. One of Descartes's most important and lasting legacies to philosophy is the doctrine that has come to be known as "dualism." Mind and matter (or body), according to Descartes, are two essentially and radically different kinds of substance. Mind is unextended, indivisible, simple thinking; its modes or properties are ideas or thoughts. Matter, on the other hand, is nothing but extension or dimensional space, and is therefore divisible; its modes are shape, size, and mobility. There is nothing materialistic about the mind, and nothing mental or spiritual about the body.

This doctrine is of great importance not only for understanding the nature of the human being, who is a composite—or, to use Descartes's phrase, a "substantial union"—of these two substances, but also for science. According to Descartes, the physical world is nothing but passive matter or extension, divisible ad infinitum into material parts. The active, spiritlike "forms" of the Aristotelian world picture have been banished from nature. All natural phenomena, no matter how complex, and regardless of whether they are terrestrial or celestial, are henceforth to be explained solely in terms of matter and the motion, rest and impact of its parts. Descartes's separation of mind and matter was a crucial step in the scientific revolution of the seventeenth century and laid the metaphysical foundations for the mechanical philosophy that dominated the period until Isaac Newton (1642–1727).

Bibliography

Primary Sources

Descartes, René. Oeuvres de Descartes. Edited by Charles Adam and Paul Tannery. 12 vols. Paris, 1964–1976.

——. The Philosophical Writings of Descartes. Translated by John Cottingham, Robert Stoothoff, and Dugald Murdoch. 2 vols. Cambridge, U.K., 1984–1985.

——. The Philosophical Writings of Descartes. Vol. 3, The Letters. Translated by John Cottingham, Robert Stoothoff, Dugald Murdoch, and Anthony Kenny. Cambridge, U.K., 1991.

Secondary Sources

Cottingham, John, ed. The Cambridge Companion to Descartes. Cambridge, U.K., 1992.

Garber, Daniel. Descartes' Metaphysical Physics. Chicago, 1992.

Gaukroger, Stephen. Descartes: An Intellectual Biography. Oxford and New York, 1995.

Kenny, Anthony. Descartes: A Study of His Philosophy. New York, 1968.

Watson, Richard. Cogito Ergo Sum: The Life of René Descartes. Boston, 2002.

Wilson, Margaret. Descartes. London and Boston, 1978.

—STEVEN NADLER

Quotes:

"If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things."

"Whenever anyone has offended me, I try to raise my soul so high that the offense cannot reach it."

"It is not enough to have a good mind, the main thing is to use it well."

"There is nothing so strange and so unbelievable that it has not been said by one philosopher or another."

"Everything is self-evident."

"Divide each difficulty into as many parts as is feasible and necessary to resolve it."

See more famous quotes by Rene Descartes