DESCARTES = CAUSAL ARGUMENT
1. I have an idea of God.
2. My idea of God is an idea of an infinitely perfect being.
3. Therefore, I have an idea of an infinitely perfect being.
4. Therefore, I have an idea of a-being-which-has-an-infinite-amount-of-FR.
5. Therefore, I have an idea which contains an infinite amount of OR.
7. Therefore, if I have an idea which contains an infinite amount of OR, then the cause of my idea must have an infinite amount of FR. [from 6]
8. I myself am an imperfect being who doubts, lacks knowledge, and so on.
B even if I might someday come to know everything there is to know, and perfect knowledge is within me potentially, the fact remains that I do not now know everything there is to know. And the same is true of all other perfections, e.g. power and beneficence. I am therefore less than a perfect being.
9. Therefore, I do not have an infinite amount of FR.
10. Therefore I could not possibly have been the cause of my idea of God.
11. Something other than me must exist to have caused my idea of God (I am not alone in the world)
12. Only God can be thought of as having an infinite amount of FR.
13. Therefore, only God could have caused by idea of God.
14. Therefore, God exists.
As he says later on, P. 472,
A Indeed, I have no choice but to conclude that the mere fact of my existing and of there being in me an idea of a most perfect being, that is, God, demonstrates most evidently that God too exists.
@ [P. 472]