In Meditations on First Philosophy Meditations III and V Rene provides arguments for the existence of God. Arguments for the Existence of god: If he can conceive of some idea with so much objective reality that it must come from some cause with more formal reality than he possesses, the Meditator reasons that he will then know that something outside his mind exists. God is an infinite substance whereas he is only a finite substance. Since the idea of God cannot have originated in himself, he concludes that God must be the cause of this idea and must therefore necessarily exist. God: his existence would immediately be perceived clearly and distinctly if it weren’t for the confusions caused by the senses and preconceived opinions.
Now that God’s existence has been established, it is as certain as any other perception. Why does he offer these arguments? He wishes to prove the existence of the external world in order to achieve his aim of a new system of knowledge built on solid foundations. Do they work for his purpose? Are these arguments sound? he cannot doubt the existence of God, since he has such a clear and distinct perception of God’s existence. The idea has infinite objective reality, and is therefore more likely to be true than any other idea. He concludes that he comes to know these facts through clear and distinct perception, and reasons that it should follow that all his other clear and distinct perceptions are true… Do they accomplish for him what he thinks they do? Why? He cannot doubt that he exists or that this fact follows from the fact that he doubts, because that truth is ‘revealed…
by the natural light.’ Natural assumptions, on the other hand, are far less certain than the natural light, and have misled him in the past. He concludes that his knowledge of the cogito and the sum res cogitans are clear and distinct perceptions. Thus, he concludes, all clear and distinct perceptions (which he sometimes refers to as ‘the natural light’) must be certain. no effect can have a greater amount of reality than its cause. That is, everything that comes into being must be made to be by something that has an equal or greater amount of reality. For instance, a stone can be made by chipping off a larger piece of rock, since.