René Descartes

René Descartes was a famous French philosopher and mathematician who lived a long time ago. He is best known for his famous phrase, "I think, therefore I am." This means that Descartes thought that by simply being able to think, you know that you exist. He also said that mathematics was the only real way of knowing something - that if you can prove something with math, then it must be true. Descartes is known as the Father of Modern Philosophy because many of his ideas are still used in philosophy today.