Descartes on the Existence of God
(Meditation III)
Argument Interpretation #1
1. I exist.
2. I have an idea of an infinite God, intelligent and powerful in the highest
degree, who created me.
3. For everything that exists, there must be a reason for its existence.
4. An idea must derive its objective reality from a cause that has “at least as
much formal reality as the idea has objective reality.”
5. Therefore, God exists.
Note about premise 3:

This is called the Principle of Sufficient Reason.

However, there is an ambiguity here between these claims:
o “there must be a reason”
o “there must be a cause”
o “there must be an explanation”
Argument Interpretation #2
1. I exist.
2. I have an idea of infinity.
3. For everything that exists, there must be a reason for its existence.
4. There are three possible explanations for the source of the idea of infinity.
a. Explanation 1: It came from the world.
b. Explanation 2: It came from me.
c. Explanation 3: It came from an infinite being.
5. Explanation 1 is doubtful.
a. I never experience anything infinite in the world.
b. I have already thrown out beliefs about extended objects
(Meditation I).
6. Explanation 2 is doubtful (impossible?).
a. I am a finite being.
b. A finite being cannot produce an infinite idea.
7. Explanation 3 is the most probable (only possible?) explanation.
a. Only an infinite being can produce the idea of infinity.
8. Therefore, God exists.