Cartesian Philosophy

   The philosophical system of Rene Descartes (1596-1650) was based on doubt, because to doubt is to think. His system became known as Cartesian philosophy, derived from the Latinized form of his name. His most famous conclusion was expressed in three words: Cogito, ergo sum ("I think, therefore I am"). His theory of the importance of doubt is based on the assumption that all existing knowledge rests on an unstable foundation; therefore everything that can be doubted should be doubted. The only fact that he could not doubt was that he was doubting. He reasoned that to doubt is to think, and to think is to exist. Hence the above three-word conclusion.

   Descartes provided many expressions that have been passed down through the ages; for example, "Common sense is the most widely distributed commodity in the world, for everyone is convinced that he is well supplied with it." And another: "The reading of all good books is like a conversation with the finest men of past centuries."

   Descartes was born at La Haye in Touraine, attended the Jesuit College at La Fleche, and was graduated in law from the University of Poitiers. After ten years' service in the army, and then travel throughout Europe, he settled in Holland where he remained the rest of his life and where he did his most important work. In 1649 he accepted an invitation to teach philosophy to Queen Christina of Sweden. He died a few months after arriving at the court at Stockholm.

   Descartes was an eminent mathematician. He is often called the father of modern philosophy. His two chief works are Discourse on Method and Meditations. Descartes' explanation of heavenly bodies has been replaced by Newton's theory of gravitation.