Descartes and the Metaphysical Doubt

Descartes proves that God exists in his third meditation. He proves that God exists because he wants to be certain about things outside of himself. But, he cannot be certain of these things if he is ignorant about the existence of God. This is because if a supreme God exists, he could cause Descartes to be mistaken in the one avenue to certainty that he has. This avenue is known as clear and distinct perception, and, according to Descartes, it is what is necessary to be certain about a thing. However, a supreme God could easily be deceiving him even when he thinks he is correct as a result of this clear and distinct perception. This is known as the metaphysical doubt. Therefore, to remove this basis for doubt, it is important to Descartes to establish whether this supreme God is capable of deceiving him. But first, he must establish whether this God exists.

The basis of Descartes proof that God exists is in the nature of ideas. What is the nature of ideas? To explain what they are, Descartes splits ideas into two categories. The first group of ideas is like the images of things, for example, a man, or an angel. These ideas are basic, and are not truth apt. What that means is that they are neither true nor false. For example, if I am having an idea of an angel, it doesn’t seem sensible to ask, “is that idea you are having of an angel true or false?”, because it can never be less true that I am in fact imagining the angel. The main point is that these ideas do not have a truth value. However, other ideas are capable of being true or false. For these ideas, they are connected to the outside World in a way that involves a claim. For example, if I claimed, “this ball is red”, this claim could be true or false because the ball could in fact be red, or I could be mistaken! This second group of ideas is known as judgments, and judgments are truth apt. Descartes says that to remove this possibility for falsity in judgments, ideas should be taken simply as modes of