What is Discourse on the Method about?

The Discourse on the Method is Descartes' intellectual autobiography and the founding document of modern Western philosophy. Written in French rather than Latin so that it could reach educated readers beyond the universities, it was published in 1637 as a preface to three scientific essays on optics, meteorology, and geometry. The brief philosophical text in the middle is what endured: Descartes' account of how he arrived at the method of systematic doubt and what he found at its foundation.

Descartes describes his dissatisfaction with the education he received, which offered a mass of contradictory opinions without any secure foundation. His project was to rebuild knowledge from scratch using a single reliable method: accept nothing as true that you have not clearly and distinctly perceived to be true; divide problems into the smallest parts; proceed from simple to complex; and review thoroughly to avoid omissions. This four-part method reflects his mathematical training and his conviction that certainty, once found, could be extended systematically.

The philosophical core arrives when Descartes applies radical doubt. He imagines that a malicious demon might be deceiving him about everything — the external world, mathematics, even the contents of his own mind. What survives? The very act of doubting proves one thing: there must be something doing the doubting. "Cogito ergo sum" — I think, therefore I am — is the one indubitable truth, the foundation on which the whole edifice of knowledge will be rebuilt. From this Descartes reconstructs his belief in God and the external world, though these arguments have satisfied very few subsequent readers.

The Discourse is short, personal, and unusually readable for a canonical philosophical text. It models a kind of intellectual courage — the willingness to tear down everything you think you know and start over — that influenced both the scientific revolution and the Enlightenment project of subjecting all inherited beliefs to rational scrutiny. The Meditations on First Philosophy, published five years later, develops the same project in more rigorous form.