Descartes' First Proof for the Existence of God

by Dr. Jan Garrett

revised slightly: March 9, 2007

I am providing this to help students review for the Midterm exam in PHIL 303. I am assuming that I have received all the "first major papers" regarding Descartes' proofs for the existence of God that I am going to receive. Reliance on this web page for the purpose of constructing the first major paper is not acceptable.

I am aware that this reconstruction of Descartes' first proof for the existence of God is not completely polished. But it contains many of the essentials that a completely polished reconstruction would have.

"MP" refers to the anthology, Modern Philosophy, edited by Ariew and Watkins and published by Hackett in 1998.

IS stands for intermediate step (or a conclusion based on previous reasoning within the passage and subsequently used to support further steps); A stands for unstated assumption (that functions as a premise); FC stands for "final conclusion." Other steps are premises more or less stated but not defended in the passage.

(1) The order of Objective reality from highest to lowest is, as follows:

ideas of supreme deity,
ideas of angels,
ideas of human minds,
ideas of bodies,
ideas of modes of bodies.
(2) What is revealed by the light of nature is clear and distinct, and what is clear and distinct must be true.

(3) It is revealed by the light of nature that R

R: There must be at least as much reality in the efficient and total cause as there is in the effect of that same cause. (MP 36.2)
(4, IS) R. (2,3)

(5, A) The order of Formal reality parallels that of Objective reality insofar as the beings involved exist.

(6) R holds not merely for effects whose reality is actual or formal but also for effects that are ideas considered in terms of their objective reality (reality of ideas as ideas). (MP 36.2)

(7) No infinite regress in the causation of ideas by other ideas is permitted. (MP 37.1)

(8, A) For every idea there is a cause.

(9, IS) If I have an idea, it must directly or indirectly be the effect of a formal reality (some real being) that contains at least as much formal reality as the idea contains objective reality. (MP 37.1)(7-8)

(10, IS) There must be at least as much formal reality in the cause of an idea as there is objective reality in the idea. (MP 36.2) (6, 9; at least 9 is argued for.)

(11, IS) Ideas of beings below God could have been fashioned from ideas of beings superior to them. (MP 37.1) (10)

(12, IS) The existence of such ideas is compatible with these beings' not-existing. (MP 37.1) (11)

(13, IS) My ideas of corporeal things could have been fabricated by me. (MP 37.2) (11)

(14) I have an idea of God as an infinite, independent, supremely intelligent and powerful substance that created me along with everything else that exists. (MP 38.1)

(15, IS) There is no being whose Formal Reality would be greater than God's. (14)

(16, IS) God would be superior to me in the order of Formal Reality. (15)

(17, IS) The idea of God could not have been fabricated by me (even unconsciously). (MP 38.1) (10, 16)

(18, IS) The idea of God could not have been fabricated by or from a being superior to me but inferior to God. (10)

(19, IS) There is no idea whose Objective Reality is greater than that of the idea of God. (5, 15)

(20, IS) The idea of God must come from a being on the same (i.e., maximum) level of perfection as that idea. (10, 19)

(21, FC). The idea of God must come from God himself. (MP 38.1) (20)