If he (Descartes) had this power, he would be conscious of it. Since he is not, there must be a separate Being that cannot be anything less than God, for there must be at least as much reality in the cause as in the effect.
The argument from reality holds that Descartes exists but does not exist necessarily, for only God exists necessarily. Descartes states that he cannot conceive of God except as existing, and therefore it follows that existence is inseparable from God. We cannot think of God without existence, for existence is a perfection. This also means we cannot conceive of God as not existing, for God would then not be a perfect being. Descartes' also compares the idea of God to ideas in mathematics, noting that he cannot think of a triangle that does not have three sides, for one of the triangle's essential elements is must have three sides for it to be a triangle. Descartes says that the fact that he can conceive of God as existing proves the existence of God because to be a perfect being God must necessarily exist.
It could be objected that the fact that Descartes can think of God as existing does not mean that God exists, for Descartes cannot impose necessity on things. Descartes answers this objection in the Fifth Meditation by emphasizing that the fact that he cannot think of God except as existing shows that existence is inseparable from God and that he really exists:
It is not my thought that makes it so, or imposes any necessity on any thing; on the contrary, it is the necessity of the thing itself, namely the existence of God, which determines my thinking in this respect (46).
This argument from reality is called an argument from reality because it delves into the nature of every thing and not merely with the idea of every thing. The idea of every thing contains within it the concept of existence, for we cannot conceive of anything except as existing. There is a distinction to be made, however, bet...
Argument on God's Existence. (1969, December 31). In LotsofEssays.com. Retrieved 19:34, February 28, 2015, from https://www.collegetermpapers.com/viewpaper/1303784349.html