# Descartes René Descartes (1596-1650), French mathematician and philosopher. He is often called the father of modern philosophy. He discarded the authoritarian systems of the scholastic philosophers and began with universal doubt. He believed that only one thing cannot be doubted: doubt itself. Therefore, the doubter must exist. This is the kernel of his famous assertion "I think, therefore 1 am." From this seed of certainty, Descartes expanded knowledge, step by step, to admit the existence of God (as the first cause) and the reality of the physical world which he held to be entirely divorced from the mind.