
Descartes was a french philosopher, he also did other things in his spare time like be a mathematician, physicist, and writer. He is the mac daddy of Modern Philosophy, menny of his writings are still studied today, and thanks to him math gained the Cartesian coordinate system help geometric shapes to be expressed in algebraic equations. He is also remembered for his famous phrase Cogito ergo sum. i Thin there for i am. He came to this conclusion when he was in an existential crisis that would have killed a prepubescent emo child, but Descartes toughed it out and through a series of inductions and deductions that if he thought he existed.
He favored rationalism, because he practically came up with it, believing stuff like that geometry was the answer to everything, that through reason you could understand universal questions, and that truth was born into us not gained through experience. He was excellent having influenced menny future philosophers, a all around mac daddy of Modern Philosophy