ABSTRACT
Rene Descartes was a French philosopher, mathematician, and scientist who wrote arguably the most influential work in the history of modern philosophy, the Meditations on First Philosophy. According to Descartes, the Cogito, as it is called by philosophers, is undeniable, because in the act of attempting to deny one is thinking, one thinks and so renders the denial false. Using the Cogito as the premise of his philosophical system, Descartes argues that because he is certain he is thinking but not certain of the existence of anything other than his own mind, he is to be identified with his mind. Descartes' line of reasoning, however, appears open to a serious objection that has come to be known as the "Cartesian Circle". The problem is that Descartes validates the use of clear and distinct ideas by first proving the existence of God and yet that proof itself depends on the use of clear and distinct ideas.
