Descartes

The next stage in the system, as outlined in the Meditations, seeks to establish that God exists. In his writings, Descartes made use of three principal arguments. The first (at least in the order of presentation in the Meditations) is a causal argument. While its fullest statement is in Meditation III, it is also found in the Discourse (Part IV) and in the Principles (Part I Ð'§Ð'§ 17Ð'-18). The argument begins by examining the thoughts contained in the mind, distinguishing between the formal reality of an idea and its objective reality. The formal reality of any thing is just its actual existence and the degree of its perfection; the formal reality of an idea is thus its actual existence and degree of perfection as a mode of mind. The objective reality of an idea is the degree of perfection it has, considered now with respect to its content. (This conception extends naturally to the formal and objective reality of a painting, a description or any other representation.) In this connection, Descartes recognized three fundamental degrees of perfection connected with the capacity a thing has for independent existence, a hierarchy implicit in the argument of Meditation III and made explicit in the Third Replies (in response to Hobbes). The highest degree is that of an infinite substance (God), which depends on nothing; the next degree is that of a finite substance (an individual body or mind), which depends on God alone; the lowest is that of a mode (a property of a substance), which depends on the substance for its existence. Descartes claims that Ð''it is manifest by the natural light that there must be at least as much reality in the efficient and total cause as in the effect of that cause' . From that he infers that there must be as much formal reality in the cause of an idea as there is objective reality in the idea itself. This is a bridge principle that allows Descartes to infer the existence of causes from the nature of the particular ideas that are in the mind, and thus are effects of some causes or another. In Meditation III, Descartes discusses various classes of ideas, one by one, and concludes that, as a finite substance, he can conceivably be the cause of all the ideas he has in his mind except for one: the idea of God. Since the idea of God is an idea of something that has infinite perfection, the only thing that can cause that idea in my mind is a thing that formally (actually) has the perfection that my idea has objectively Ð'- that is, God himself.

Descartes used two other arguments for the existence of God in his writings. In Meditation III, following the causal argument, he offers a version of the cosmological argument for those who, still blinded by the senses, may be reluctant to accept the bridge principle that his causal argument requires. (Versions of this argument are also found in Discourse Part IV, and in Principles Part I Ð'§Ð'§20Ð'-1.) This argument begins with the author's own existence, as established in Meditation II. But, the author might ask, what could have created me? It will not do, Descartes argues, to suggest that I have been in existence always, and thus I do not need a creator, since it takes as much power to sustain me from moment to moment as it does to create me anew. I could not have created myself because then I would have been able to give myself all the perfections that I so evidently lack. Furthermore, if I could create myself, then I could also sustain myself, which I do not have the power to do; being a thinking thing, if I had such a power, I would be aware of having it. My parents cannot be my creators, properly speaking, since they have neither the ability to create a thinking thing (which is all I know myself to be at this stage of the Meditations), nor to sustain it once created. Finally, I could not have been created by another creature of lesser perfection than God, since I have an idea of God, an idea I could not acquire from a lesser being. (Here one suspects that this cosmological argument really collapses into the first causal argument.) From this Descartes concludes Ð''that the mere fact that I exist and have within me an idea of a most perfect beingÐ'... provides a very clear proof that God indeed exists' .

These first two arguments for the existence of God play a central role