The following argument may be found on marginal pages 41-46 of Meditation Three in Descartes’ Meditations on First Philosophy. Hyphens indicate sub-conclusions.
1. A cause must have at least as much reality as its effect.
2. An idea can only be caused by something that has as much reality formally as the idea has objectively.
3. I have an idea of the infinite, which has infinite objective reality.
4. I am aware that I am finite, so have limited formal reality.
—The objective reality of the infinite is greater than my formal reality.
—I am not the cause of my idea of the infinite.
/:. There must be a being with infinite formal reality that could have caused my idea.
This causal argument is one way Descartes attempts to show the existence of God. He takes the first premise, that a cause must have at least as much reality as its effect, to be evident. He develops the account on the basis of a causal relationship between an infinite being (God) and the idea of the infinite.
The first premise is relevant because Descartes makes a distinction between formal and objective reality. The term ‘formal reality’ is used to refer to a usual notion of reality; that is, an existence external to the mind. Objective reality is the reality of the content of an idea. This distinction becomes essential when bridging the gap between existence as an idea and existence outside of the mind—the difference between the idea of the infinite and an infinite being.
Descartes argues that a person has an idea of the infinite. A key element of this concept is that a person does not simply have an idea that is a negative of the finite, but an actual notion of infinity. In this way, the idea does not hinge on purely negating the finite. An idea of infinity has infinite objective reality.
A person is a finite being, and he is aware of this lack. A thinking thing is The finite nature of a person has limited formal reality. Here, Descartes shows that a person who is a finite being has less formal reality than his idea of the infinite, which has unlimited objective reality; a sub-conclusion to this effect is noted. Descartes demonstrates that there is clear contradiction with premise 2, and therefore draws the second sub-conclusion: that a person, as a finite being, cannot be the cause of his own idea of God, or the infinite. awareness, and part of this awareness is recognizing that a person is finite.
Descartes has thus far only proved the existence of the mind by Meditation Three; by showing that the mind cannot have caused an idea of the infinite, he shifts the source of the idea to an external being. Because of premise two, the cause of the idea must have at least as much formal reality—it must be an infinite being. Descartes then concludes that there must be an infinite being that caused the idea of the infinite. Thus, he claims that God exists.
What do you say to that? Haha, oh dear. It's called the causal argument.. for obvious reasons.
We started Spinoza today. Having only reading through Proposition 12 or so of his Ethics, I'm not quite sure what to make of it. If I understand his definition of substance correctly (which is highly debatable), I think he must be a bundle theorist, as far as his ontology. Hm. I'll be very interested in finding out.
