The third meditation is entitled Meditation Three: Concerning God, That He Exists. The goal of this paper is to display Descartes' argument for the existence of God and also to state why I think Descartes' argument is valid through any possible objections and examples. Meditation three begins with Descartes reviewing with his readers, as he does in other meditations as well, what things he has concluded thus far in the meditations. He knows that he is a thinking thing that has clear and distinct perceptions, perceptions he knows to be true, and also that he doubts, affirms, denies, understands a few things, is ignorant of many things, wills, refrains from willing, imagines, and senses.
Also those things apprehended by the senses he has cast into doubt because he does not perceive the things but only the idea of the things. Descartes is also sure about arithmetic and geometry are clear and distinct perceptions, but he cannot be certain if God is deceiving him. And so to ensure himself of these things he must inquire into the nature of God to see if he would deceive him (Descartes 24). To do this Descartes decides to classify his ideas into separate groups to see which group God would belong to. He reasons that the first source for ideas are innate. An innate idea is one that has been distilled in us from the beginning of our existence.
The second source for ideas, adventitious ideas, come from the outside and transmit their own likeness. Thirdly there are imagined or fabricated ideas. These ideas have been generated by human beings and are composed of separate things we see in the world such as Santa Claus or a unicorn. Now that he has classified all ideas into separate groups, Descartes' goal is to see which idea God would belong to. Firstly he reasons that the ideas are all equal in that all are merely modes of thought and they all seem to proce de from him in the same manner. They also seem to have the same amount of, reality to themselves, but their objective reality, reality of the things they represent, differ greatly (Descartes 27-28).
Now that he has classified ideas into separate groups with more or less formal and objective reality. Descartes then states, "Now it is indeed evident by the light of nature that there must be as much (reality) in the efficient and total cause as there is in the effect of that same cause (Descartes 28)." To elaborate on this concept he uses the idea of a stone. In essence this example is that when you have a large stone you can chip off a piece of that stone because the larger stone has more reality then the piece being chipped off. And now when trying to understand God who is "a supreme deity, eternal, infinite, omniscient, omnipotent, and creator of all things other than himself, clearly has ore objective reality within it than do those ideas through which finite substances are displayed (Descartes 27-28)." Descartes reasons that Go must have more objective reality than he himself has formal reality because God is an infinite substance whereas he is a finite substance. An objection to Descartes' argument for God is in David Hume's book An Enquiry Concerning Human Understanding.
In this book Hume suggests that we could think of such a perfect being as God by simply taking ourselves and augmenting us without limit (Hume 11). But I believe this objection fails in that it fails to provide for the fact that, following Descartes' argument, if God did create each of us with a package that includes, but not limited to, a thinking thing that has clear and distinct perceptions, and also that doubts, affirms, denies, understands a few things, is ignorant of many things, wills, refrains from willing, imagines, and senses. Then perhaps Hume is quite capable of doubting God's existence on the basis that he is in denial and-or ignorant of God's existence because perhaps he has never sensed God or has had any experience with God. Thus, Descartes' argument for the existence of God succeeds. God exists and we have a clear and distinct perception of him. God also has a more infinite and objective reality than we do, and is therefore more likely to be a true-innate idea (Descartes 34-35).
He is also not deceiving us because this would denote some defect or imperfection in God, and a perfect God has no defects.