Definition for View source for Descartes, René

Descartes, René (1596 to 1650): Rationalist philosopher and mathematician, born in France. He developed the major features of his philosophy in his most famous work, Meditations on First Philosophy. In this work he argued that God must exist and cannot be a deceiver; therefore, his beliefs based on ordinary sense experience are correct. He also argued that mind and body are distinct substances, believing that this dualism made possible human freedom and immortality. In other work, he virtually founded analytic geometry, and made major contributions to optics.