I must have missed the proof as well. If Descartes proved that a specific God existed, then I would love to see the proof.
This one.....
René Descartes's Proof that God Exists
Meditation III
A First Start
1. Ex nihilo nihil fit
(from nothing comes nothing; something does not come from nothing; more reality cannot come from less reality)
2. The cause of an effect must have as much reality as (or more reality than) its effect.
3. The cause of an idea must have as much reality as the idea itself.
4. I have the idea of God, as something perfect and infinite. [the reason for this?]
5. The cause of this idea of God must exist. [by (1)]
6. The cause of this idea of God must have as much reality as the idea of God (its effect).
7. The idea of God has infinite reality.
8. The cause of the idea of God has infinite reality. [by (3) and (7)]
9. Only God has infinite reality. [I don't!]
10. God is the cause of the idea of God (and exists).
Note the contradiction between steps (7) and (9): according to (9), only God has infinite reality, but according to (7) the idea of God also has infinite reality. We can reconcile steps (7) and (9), improve the argument, and remain more faithful to Descartes's reasoning, by acknowledging that in Meditation III Descartes employs two notions of "reality": formal reality and objective reality.
A Second Attempt
Definitions:
--D1: The formal reality of X is the reality X has in virtue of being what it is.
--D2: The objective reality of X is the reality it has in virtue of representing something else.
Examples:
--Some things have only formal reality: a mountain, a hair. A mountain has more formal reality than a hair.
--Some things have both formal and objective reality: these are things that represent other things. Mountains and hairs do not represent anything else, so they have only formal reality. But photographs, painting, and ideas do represent other things. Photographs and ideas have formal reality as photographs, ideas. A big photograph has more formal reality than a tiny photograph. Photographs and ideas have an additional kind of reality (objective) in virtue of the thing that they represent.
Principles:
--P1: The objective reality of a representing thing is a direct function of the formal reality of the thing it represents. Hence a photograph of a large, complex item (a city) has more objective reality than a photograph of a small, simple item (an apple), because the large, complex item has more formal reality than the small, simple item. Corollary: the idea of an infinite thing has infinite objective reality.
--P2: The cause of an idea must have as much reality, formally, as the idea has both formally and objectively. (This is an application of ex nihilo nihil fit.)
Given these definitions and principles, we can refashion Descartes's argument for the existence of God:
1. That I have an idea of a horse (for example) does not entail that a horse really exists. Why not? A horse has only finite formal reality, so the idea of the horse has only finite objective reality. The cause of this idea, then, need have only finite formal reality. I need not postulate that God exists for me to have this idea; I need postulate only that something exists that has finite formal reality. That might as well be me, or my mind, or perhaps something in the external world that has as much formal reality as a horse. Many things fit that bill other than a horse.
2. In the case of God, and only God, matters are different: this is the only idea of X in which the existence of the idea of X necessitates that X itself exists.1 Why? God has infinite formal reality. Hence the idea of God has infinite objective reality (by [P1]). So the cause of this idea must have infinite formal reality (by [P2]). And only God fits the bill.
Note 1: The only case, that is, other than the existence of I, who is not God.
http://www.uno.edu/~asoble/pages/dproof.htm