Descartes's approach to philosophy was to doubt everything until he could prove it to his own satisfaction. The first premise of his philosophy was

A) that God exists.
B) that he could not doubt his own existence.
C) that the world exists.
D) that other people exist.

Descartes's first premise in his philosophy was "Cogito, ergo sum" or "I think, therefore I am." This means that he could not doubt his own existence because he was the one doing the doubting. While Descartes did believe in God and the existence of the external world, these were not his first premises. The existence of other people was also not his first premise, as he believed that their existence could be doubted through the possibility of deception by an evil demon.