Key Texts · Philosophical work · essay
Discours de la méthode · by René Descartes · 1637 · French
In this short, readable work Descartes tears his beliefs down to the foundations and rebuilds them on one unshakeable certainty — "I think, therefore I am." It marks the beginning of modern philosophy and of the modern preoccupation with how knowledge can be securely grounded.
Author: René Descartes (1596–1650)
Published: 1637
Original language: French (notably, not the scholarly Latin of the day)
Form: Autobiographical philosophical essay
Branches: Epistemology, metaphysics, method
Descartes wrote the Discourse as a first-person narrative of how he came to doubt everything and then rebuild knowledge from certainty. It was originally the preface to three scientific essays, but the philosophical part — especially Part IV — became one of the most influential texts in Western thought. He later developed the same ideas more rigorously in his Meditations on First Philosophy (1641).
Meet several core ideas here: cogito, method of doubt, rationalism, and dualism.
Descartes wrote at the dawn of the scientific revolution, when the old Aristotelian picture of the world was giving way to a new mathematical science of nature. He was troubled that so much accepted learning rested on unexamined authority and unreliable senses. Publishing in French rather than Latin, he aimed to reach ordinary educated readers — including, as he pointedly noted, women — and to model a way of thinking anyone could follow.
René Descartes (1596–1650) was a French philosopher, mathematician, and scientist, often called the father of modern philosophy. He invented analytic geometry (the Cartesian coordinate system) and reshaped epistemology and the philosophy of mind. Read more on the Descartes page.
The Discourse has six parts. In brief:
Descartes recounts finding the learning of his day riddled with doubt and disagreement, and resolving to accept nothing as true that he did not clearly know to be so. He adopts four simple rules — roughly: never accept what you can doubt; divide problems into parts; reason from the simple to the complex; and review thoroughly. Applying radical doubt, he finds he can question the evidence of his senses, the truths of mathematics, even whether he has a body or the world exists. But he cannot doubt that he is thinking, and therefore that he exists. From this first certainty he argues that the mind is distinct from the body, extracts a general criterion of truth, and proceeds to argue for God and the reliability of clear reasoning.
Knowledge must be rebuilt on a foundation that cannot be doubted. Systematic doubt clears away everything uncertain; what remains is the thinking self, whose existence is guaranteed by the very act of doubting. On this bedrock — "I think, therefore I am" — and the rule that clear and distinct ideas are true, secure knowledge can be reconstructed. Reason, not sensory experience, is the ultimate ground of certainty; this makes Descartes a founding figure of rationalism.
The passage below, from Part IV, contains the method of doubt, the cogito, and the claim that the mind is distinct from the body — all in Descartes' own words. It is given in John Veitch's translation, which is in the public domain.
Accordingly, seeing that our senses sometimes deceive us, I was willing to suppose that there existed nothing really such as they presented to us; and because some men err in reasoning … I rejected as false all the reasonings I had hitherto taken for demonstrations; and finally, when I considered that the very same thoughts which we experience when awake may also be experienced when we are asleep, while there is at that time not one of them true, I supposed that all the objects that had ever entered into my mind when awake, had in them no more truth than the illusions of my dreams.
But immediately upon this I observed that, whilst I thus wished to think that all was false, it was absolutely necessary that I, who thus thought, should be somewhat; and as I observed that this truth, I think, therefore I am (cogito ergo sum), was so certain and of such evidence that no ground of doubt, however extravagant, could be alleged by the sceptics capable of shaking it, I concluded that I might, without scruple, accept it as the first principle of the philosophy of which I was in search.
In the next place, I attentively examined what I was … I thence concluded that I was a substance whose whole essence or nature consists only in thinking, and which, that it may exist, has need of no place, nor is dependent on any material thing; so that "I," that is to say, the mind by which I am what I am, is wholly distinct from the body …
René Descartes, Discourse on the Method, Part IV, trans. John Veitch (public domain). Read the full text at Project Gutenberg.
Descartes' project has been questioned ever since. Critics charge him with the Cartesian circle: he uses clear and distinct ideas to prove God, then uses God to guarantee that clear and distinct ideas are true — seemingly arguing in a circle. His dualism faces the interaction problem raised sharply by Princess Elisabeth of Bohemia: how can an immaterial mind move a physical body? And later empiricists such as Hume rejected the idea that reason alone, without experience, can establish substantive truths about the world.
The Discourse helped inaugurate modern philosophy. Its method of doubt reframed epistemology around the search for secure foundations; its cogito made the thinking self the starting point of philosophy; and its dualism set the agenda for centuries of debate about the mind–body problem. "I think, therefore I am" remains perhaps the single most famous sentence in philosophy.
Questions to think or write about:
Descartes, René. Discourse on the Method. 1637. Translated by John Veitch, Project Gutenberg, https://www.gutenberg.org/ebooks/59.