René Descartes

Introduction

René Descartes is the philosopher conventionally identified as the father of modern philosophy. His Meditations on First Philosophy (1641) and Discourse on Method (1637) reframed the central questions of Western philosophy by relocating its starting point: not in the inherited metaphysics of nature or in revealed theology, but in the certainty of the thinking subject reflecting on the contents of its own mind. The methodological move — I think, therefore I am, the cogito — became the foundation of modern epistemology and the source of the modern problem of the relation between mind and world.

Descartes was also one of the major mathematicians of the seventeenth century. The Cartesian coordinate system (which bears his name) and the foundational work that became analytic geometry are independent legacies of comparable historical importance. The unity of his philosophical and mathematical projects — both rest on the conviction that reason can establish substantive truths about reality through clearly perceived premises and valid deduction — is the distinguishing feature of his work.

Life

Descartes was born in 1596 in La Haye en Touraine, France (the town was renamed Descartes in his honor in 1967), to a family of the provincial nobility. He was educated by the Jesuits at La Flèche (1607–1614) and took a law degree at Poitiers in 1616, though he never practiced law.

From 1618 he served as a soldier of fortune in the armies of the Netherlands and Bavaria, traveling widely across Europe. The famous three dreams of November 10, 1619 (in winter quarters at Ulm), in which he reports being struck by the foundations of a wonderful science, are sometimes cited as the moment his philosophical program took shape; the exact content of the dreams and their relation to the later work has been continuously debated.

From 1628 he settled in the Netherlands, then unusually tolerant of unorthodox philosophical and scientific work. He spent twenty years there, in various locations, working on the philosophical, mathematical, and scientific texts of his maturity. In 1649 he accepted an invitation from Queen Christina of Sweden to come to Stockholm as her tutor; he was required to give lessons at five in the morning in the unheated palace, contracted pneumonia, and died in February 1650.

His remains were eventually returned to France, where they were buried at the church of Saint-Germain-des-Prés in Paris; the skull was separated and is now in the Musée de l'Homme.

The problem he worked on

Descartes inherited a philosophical and scientific situation in crisis. The Scholastic Aristotelianism that had structured European thought for centuries was visibly failing under the pressure of the new science (Galileo's mechanics, the new astronomy). The wars of religion had demonstrated the political danger of unresolvable theological disputes. Skepticism, especially in the Pyrrhonian revival through Montaigne and his followers, had made the very possibility of secure knowledge a live question.

Descartes's project was to find a new foundation for knowledge that could survive this collapse. The method: doubt everything that could be doubted, find what remained, and rebuild from there. The result of the methodical doubt was the cogito — the recognition that doubting itself confirms the existence of the doubter as a thinking thing. From this single fixed point, Descartes attempted to derive (with the aid of the existence of a non-deceiving God, also demonstrated by reason) the reality of the external world, the structure of mathematical physics, the existence of the soul, and most of what he wanted to preserve from the old framework.

Contributions

The cogito and the foundationalist project

The cogito ergo sum (Latin in the Principles of Philosophy; the French Je pense, donc je suis in the Discourse) is the most-quoted single sentence in modern philosophy. The argument: I can doubt everything in principle, including the existence of the external world, the reliability of my senses, the existence of my own body. What I cannot coherently doubt is the existence of myself as a thinking thing, because the very act of doubting requires a doubter. I am, I exist is therefore the foundational certainty from which the rest of knowledge can be rebuilt.

The foundationalist project the cogito launches — the search for indubitable foundations from which all knowledge can be derived — organized modern epistemology for centuries. Whether the project succeeds (whether Descartes can actually get from the cogito to the external world) is contested; the Cartesian Circle objection, raised by Descartes's contemporaries and elaborated since, holds that the route requires the existence of God, which itself depends on the reliability of clear and distinct perception, which depends on the existence of God. Whether the circle can be broken has been one of the longest-running questions in modern philosophy.

Mind-body dualism

Descartes's most famous and most contested metaphysical doctrine. There are two finite kinds of substance: thinking substance (res cogitans), whose essence is thought, and extended substance (res extensa), whose essence is extension in space. Human beings are unique in being unions of both: the mind is a thinking substance, the body is an extended substance, and they are causally united (in the pineal gland, on Descartes's specific account).

The doctrine generated the mind-body problem that has shaped philosophy of mind ever since. If thinking and extended substances have no shared attributes, how can they causally interact? How does the mind move the body? How does the body affect the mind? Descartes's own answers were widely judged inadequate by his contemporaries (Princess Elisabeth of Bohemia's correspondence with Descartes contains a famous statement of the difficulty). The problem has remained central to modern philosophy of mind, with positions ranging from epiphenomenalism through various forms of monism to contemporary functionalism and physicalism.

Method and the criterion of clear and distinct perception

Descartes's epistemological criterion: when something is clearly and distinctly perceived by the intellect, it is true. The criterion is supposed to provide a way of distinguishing genuine knowledge from mere opinion. Its applicability has been continuously contested; what makes a perception clear and distinct, and why should we trust the criterion itself? Descartes's answer (that God is no deceiver and therefore guarantees the reliability of clear and distinct perception) is what produces the Cartesian Circle.

Analytic geometry and the mathematization of physics

Descartes's mathematical work (La Géométrie, 1637, published as one of the three essays appended to the Discourse on Method) introduced the Cartesian coordinate system and the algebraic treatment of geometric problems. The work effectively created analytic geometry and provided the mathematical framework on which Newton and Leibniz would develop the calculus. The Cartesian conviction that nature is fundamentally mathematical — that physical reality consists of extended substance behaving according to mathematical law — was a foundational commitment of the Scientific Revolution.

The wax argument

A single famous illustration in Meditations II. A piece of wax has certain sensible properties (color, texture, scent, the sound it makes when struck). Heated, all these change; the wax becomes liquid, transparent, scentless. Yet we judge it to be the same wax. What we know in this judgment is not given by any of the sense impressions (which have all changed); it is given by the intellect's grasp of the wax as an extended thing capable of taking various sensible forms. The argument is meant to show that even our knowledge of ordinary physical objects ultimately rests on intellectual rather than sensory cognition.

Key works

• Rules for the Direction of the Mind (composed c. 1628, published posthumously 1684). Early methodological treatise.
• The World (Le Monde, composed by 1633, suppressed after Galileo's condemnation, published posthumously). Cosmological treatise; Descartes suppressed it on hearing of Galileo's troubles.
• Discourse on Method (1637). The accessible French-language statement of the method, published with three scientific essays (La Dioptrique, Les Météores, La Géométrie).
• Meditations on First Philosophy (1641). The major work; six meditations developing the systematic doubt, the cogito, and the reconstruction of knowledge. Published with the Objections and Replies of six prominent contemporaries (Mersenne, Hobbes, Gassendi, Arnauld, and others).
• Principles of Philosophy (1644). Textbook-format summary of the philosophy.
• The Passions of the Soul (1649). Late treatise on emotion and the union of mind and body.
• Extensive correspondence (the Adam-Tannery edition of the Oeuvres runs to thirteen volumes, much of it correspondence).

Influences and influenced

Influenced by: the Jesuit Scholastic tradition of his education (especially at La Flèche); Aristotle and the Scholastic tradition (against which much of his work is directed); Augustine (whose Si fallor, sum in De Civitate Dei XI.26 prefigures the cogito); Montaigne and the Pyrrhonian skeptical tradition; Galileo and the new science; the mathematical tradition through Viète.

Influenced: virtually all subsequent modern philosophy. Direct heirs include the rationalist tradition through Malebranche, Spinoza, and Leibniz. Critics include Hobbes and the empiricist tradition (Locke, Berkeley, Hume), each of whom rejected the rationalist program but in ways that took the Cartesian framework as starting point. Kant's Critical philosophy is in part a response to the failure of the Cartesian program. Husserl explicitly identified his phenomenology as a recovery of the Cartesian project. Wittgenstein and the analytic tradition have remained substantially anti-Cartesian, but the framework against which they argue is recognizably Cartesian. Contemporary philosophy of mind has not escaped the mind-body problem Descartes bequeathed.

Reception

Descartes's reception was immediate and substantial. The Meditations (1641) was published with the Objections and Replies of six major contemporaries, giving the work an unusual public-philosophical character from the start. The Cartesian movement in France through Malebranche, Arnauld, and the Port-Royal circle was dominant in mid- and late-seventeenth-century French philosophy.

The Dutch reception was bifurcated. Spinoza absorbed and radically transformed the Cartesian framework. The orthodox Calvinist establishment was generally hostile; Descartes's works were banned at various Dutch universities at various points.

The early modern empiricist reception (Locke, Berkeley, Hume) developed substantially in dialogue with Descartes, generally rejecting the rationalist program but accepting the framework that organized the rejection. Kant's Critique of Pure Reason engages Descartes throughout, especially in the famous Refutation of Idealism (B274–79).

The modern reception has been continuously active. Husserl's Cartesian Meditations (1931) presented phenomenology as a recovery of the Cartesian project. The analytic tradition through Ryle's The Concept of Mind (1949) attacked Cartesian dualism (Ryle's ghost in the machine) as the foundational error of modern philosophy of mind, while continuing to define itself against it. The recent Cartesian recovery in contemporary analytic philosophy (especially the work of John Carriero, Anthony Kenny, Margaret Wilson, and Bernard Williams) has substantially revised the standard picture of Descartes and restored him to active engagement.

Continuing engagement

Major recent scholarly work includes Bernard Williams's Descartes: The Project of Pure Enquiry (1978), Margaret Wilson's Descartes (1978), John Cottingham's Descartes (1986), Stephen Gaukroger's Descartes: An Intellectual Biography (1995), and John Carriero's Between Two Worlds: A Reading of Descartes's Meditations (2009). The Cambridge Cottingham-Stoothoff-Murdoch translation (1985–1991) is the standard English edition. Active scholarly debates concern the structure of the Cartesian Circle, the cogito's logical form, the adequacy of Descartes's responses to Princess Elisabeth's interaction objection, and the relation between Descartes's philosophical and scientific work.

Further reading

• Rationalism — the tradition he founded
• Spinoza — the most consequential immediate successor
• Leibniz — the great late-seventeenth-century rationalist
• Substance — the metaphysical category his dualism transforms
• Episteme — the cognitive achievement he sought to ground
• Augustine — the predecessor whose Si fallor, sum prefigures the cogito

The father of modern philosophy. The founder of analytic geometry and of the modern problem of mind and body.