Rene Descartes (147), in the Third Meditation, draws upon arguments advanced earlier by St. Thomas Aquinas to demonstrate that God exists. Having declared himself to be a "thing that thinks, that is to say, that doubts, affirms, denies, that knows a few things," Descartes (147) makes it clear to his readers that while God "may be a deceiver" (Descartes, 149), he himself nevertheless does not doubt that God exists. Specifically, Descartes (149) asserts, as did Aquinas, that God placed the idea of Himself in man's mind in the same manner that the mark of a craftsman is embedded in that man's work. As Aquinas did before him, Descartes believed in the existence of a supremely perfect being û called God û that is essentially a "First Cause" capable of placing the idea of God in man's minds. This essay will consider this argument.
Aquinas held that there were five specific "ways of knowing" that God exists. First, Aquinas held that motion itself suggests û even necessitates û the presence of something that initiated motion, or a "first mover." Second, Aquinas held that such a cause or mover must be efficient, and therefore incapable of "causing itself." Third, he argued that something necessary must exist û something that is God. Fourth, he stated that there are grades of perfection, with the supreme perfection (to which man at his best cannot aspire) is God. Finally, Aquinas held that there must be some intelligent being by whom all natural things are directed to their, which is called God (Schick and Vaughn, 394 - 395).
Of these arguments, it was the idea of a supremely perfect being that most directly convinced Descartes (156) God did exist û as a first cause and a prime mover to be sure, but most significantly as a perfect entity. As Descartes (156) put it:
"By the name God I understand a substance that is infinite (eternal, immutable), independent, all-knowing, all-powerful, and by which I myself and everything else, ...