Discourse on Method

Introduction

The Discourse on Method appeared in Leiden in 1637, without its author's name, as the preface to three scientific essays: the Dioptrics, on light and lenses; the Meteors, on winds, clouds and the rainbow; and the Geometry, which founded analytic geometry. Its full title announces its purpose: a discourse on the method of rightly conducting one's reason and seeking truth in the sciences. René Descartes was then forty-one, living in the Dutch Republic, and had withheld his great treatise on the physical world after learning of Galileo's condemnation. The Discourse was his way of presenting to the public, in a short and personal form, both his method and a sample of its fruits.

What makes the book unique is its form. Descartes does not write a treatise but tells the story of his own mind: the schooling that left him with more doubts than certainties, the years of travel spent reading "the great book of the world", the winter day in a stove-heated room in Germany when he resolved to rebuild his knowledge from the foundations. Out of this story come the four rules of the method — accept nothing that is not evident, divide difficulties, proceed in order from the simple to the complex, review everything — and a provisional morality to live by while the work of doubt goes on.

At the heart of the book, in the fourth part, stands the most famous sentence in modern philosophy: "I think, therefore I am." Having resolved to reject everything in which he could imagine the least doubt, Descartes finds that the very act of doubting proves the existence of the one who doubts. From this first certainty he draws the distinction between mind and body, the rule that what we conceive clearly and distinctly is true, and proofs of the existence of God. The fifth part sketches his physics and his account of the circulation of the blood, and argues that neither machines nor animals can use language as human beings do; the sixth explains why he publishes, and looks forward to a practical science that would make us "masters and possessors of nature".

The Discourse was written in French rather than Latin, so that it could be judged by "those who use only their natural reason". It became one of the founding texts of modern thought: the starting point of rationalism, a charter for scientific method, and a model of philosophical prose in the French language. Thinkers from Spinoza and Leibniz to Kant, Hegel and Husserl have measured themselves against its argument.

This edition gives the French text in its original form, as printed in the edition of Descartes's works by Charles Adam and Paul Tannery (Paris, 1902), with the spelling of 1637. The translations follow the same text, paragraph by paragraph; the brief summary with which Descartes opened the book is kept at the beginning of the first part, and short notes identify persons, works and events to which he alludes.