Meditation 5- The ontological argument

". . .when I concentrate more carefully, it is quite evident that existence can no more be separated from the essence of God than the fact that its three angles equal two right angles can be separated from the essence of a triangle, or than the idea of a mountain can be separated from the idea of a valley."
Descartes reasons that he cannot think of God as not existing, so he must exist. Now this seems pretty foolish. Here is his reason: it is the essence of God to exist, just as it is impossible to imagine a triangle without it having three angles equaling 180 degrees, and impossible to think of a mountain which doesn't have a corresponding valley. Here essence can be separated from existence: just because we cannot separate the idea of a mountain from a valley doesn't mean that either one necessarily exists- it just means that IF a mountain exists then it must have a corresponding valley. For Descartes though, it is part of the essence of God to exist, so that God is the only being in which existence is included in or implied by his essence. Descartes says that this is because God is perfect, and existence is a perfection, just as omniscience and omnipotence are. So this sounds a little bit better than it did in the beginning.

So here is Descartes' version of he ontological argument:

1. God is perfect
2. It is part of the essence of something perfect to exist
C: God exists

I'm sure that this argument seems wrong in some way, whether or not you can put your finger on what seems wrong about it. Here is what is wrong: existence is not a predicate (or a property attributable to something). Of course anything which has a property exists, but existence itself is not a property, it is a quantifier ( as Immanuel Kant will later point out).