Book: Discourse on the Method

Overview
René Descartes’ Discourse on the Method (1637) outlines a new way to direct the mind toward certain knowledge and to rebuild the sciences on secure foundations. Written in clear French rather than Latin and presented as an intellectual autobiography, it combines a personal narrative with a concise statement of method, sketches of metaphysics and ethics, and a preface to three scientific essays, Dioptrics, Meteors, and Geometry, that demonstrate the method in practice.

Dissatisfaction and the Turn to Method
Descartes begins by recounting his education and his disillusionment with inherited learning. Schools supply erudition, but not certainty; opinions proliferate where proof is lacking. Seeking firm ground, he decides to rely only on the judgments of his own reason, provided he can regulate it by strict rules. He resolves to leave the labyrinth of scholastic disputes and to search for a method as precise as that used in mathematics.

The Four Rules
He formulates a procedure to guide inquiry. First, accept nothing as true that is not known clearly and distinctly, avoiding precipitancy and prejudice. Second, divide problems into as many parts as necessary for better resolution. Third, conduct thoughts in order, beginning with the simplest and most easily known and ascending step by step to more complex matters. Fourth, make thorough enumerations and general reviews to ensure nothing is omitted. These rules aim to transform scattered insights into a disciplined, cumulative science.

Methodic Doubt and the Cogito
To secure indubitable starting points, Descartes undertakes a radical suspension of assent, doubting the senses, inherited teachings, and even mathematical demonstrations. Amid universal doubt he discovers a truth that resists it: while doubting, he is thinking; therefore he exists, “I think, therefore I am.” This self-evident recognition, grasped by a clear and distinct intuition, provides the benchmark for certainty and the model for further knowledge.

Provisional Morality
While theoretical foundations are being rebuilt, life requires action. Descartes adopts temporary maxims: conform to the laws and religion of one’s country and prefer moderate opinions; be firm and resolute once a decision is made; strive to conquer oneself rather than fortune by changing desires rather than the world; and dedicate life to cultivating reason and advancing knowledge. These maxims protect practical life from paralysis during the period of doubt.

God, Soul, and the Grounds of Certainty
To shore up the reliability of clear and distinct perceptions beyond the immediate cogito, Descartes sketches arguments for the existence of a perfect God who is no deceiver. Among them is a causal argument from the idea of an infinite, perfect being that cannot arise from a finite mind. From God’s veracity he infers that what is perceived clearly and distinctly can be trusted. He also argues for the distinctness and immortality of the soul, a thinking substance different from extended, bodily substance.

Nature and the New Science
The Discourse introduces a mechanistic vision of nature governed by mathematical laws. The appended essays display the method at work: Dioptrics explains vision and refraction, Meteors accounts for atmospheric phenomena such as the rainbow, and Geometry invents analytic geometry by uniting algebra with spatial problems. These applications show how complex phenomena can be resolved into simpler elements and reconstructed stepwise, in line with the method’s rules.

Style, Prudence, and Aim
Descartes writes in a modest, personal tone and explains his caution in publishing, alluding to recent controversies over natural philosophy. He chooses French to reach a broader audience and invites correction rather than authority. The book’s enduring contribution is a disciplined ideal of reason, clarity and distinctness, ordered analysis, and systematic verification, joined to a bold reorientation of metaphysics and science that helped inaugurate modern philosophy.