Descartes's Method of Doubt and the Cogito

René Descartes (1596–1650) laid out his method most fully in the Meditations on First Philosophy, published in Latin in 1641 with a dedication to the Doctors of the Sorbonne and accompanied by six sets of Objections and Replies from contemporaries including Thomas Hobbes, Antoine Arnauld, and Pierre Gassendi. Descartes had already sketched the same method in Part IV of the Discourse on the Method (1637), written in French and published anonymously at Leiden, but the Meditations gives the argument its canonical, first-person form. His stated aim, announced in the First Meditation, is to demolish everything he has ever believed and to start construction again from the foundation, since he had noticed, from his youth, how many false opinions he had accepted as true, and how doubtful was everything he had subsequently built on so insecure a base. Rather than examining each belief individually, Descartes adopts an economical strategy: if he can find reason to doubt the general classes of belief on which particular beliefs rest — sense experience, and the assumption that he is not dreaming — then all beliefs resting on those classes fall together.