René Descartes (1596-1650): French philosopher and mathematician, generally regarded as the father of modern philosophy. Descartes was a rationalist who is well known for his attempt to gain certainty through a process of universal, methodical doubt in which he posed the possibility that his waking experience was indistinguishable from a dream world as well as the possibility that he was being deceived by an all-powerful evil genius. After establishing clear and distinct ideas as his standard for truth, Descartes defended soul-body (or mind-body) dualism and gave a number of proofs for the existence of God.1
1. C.Stephen Evans, Pocket Dictionary of Apologetics & Philosophy of Religion (Downers Grove, IL: InterVarsity Press, 2002), p. 33.