More Descartes Lecture Notes

The Clear and Distinct Criterion
I am inclined to agree, even though some people don't, that Descartes successfully proves that "I think" and "I exist are immune from doubt. But then Descartes does something that strikes me as weird. First, he asks himself how he became convinced of the conclusion of the cogito argument and concludes that he accepts it because he clearly and distinctly perceives it to be good.
Justifying the criterion
Hey wait a minute Descartes? Didn't you just produce a self-refutation argument against the claims "I do not exist" and "I do not think." As a result he claims this supports his clear and distinct criterion. Then he considers whether or not God exists, and he does this in order to reassure himself that his clear and distinct perceptions are not Satanic deceptions. But to do this, it seems to me that the premises of his arguments have to be premises he can be sure of, even if Satan is controlling his mind. This argument, the argument based on the cause of his idea of God, fails to achieve this, even if it were a good argument (and I don't think it is a good argument).

The Circularity charge against Descartes
Critics of Descartes accuse him of arguing in a circle. They claim that the reason he can accept the existence of a nondeceptive God in order to believe be sure that ideas that seem clear and distinct are really true. But is his case for God based on the presupposition that whatever he clearly and distinctly perceives to be true really is.

A different complaint?
My complaint is a little different, in that it doesn’t rest on the idea that he is using the clear and distinct criterion to justify the premises of the argument.
I think my objection rests on the assumption that Descartes needs to refute demon-scenario objections to beliefs in order to have any justification at all for believing them. What is seems impossible to have is an argument for the existence of God that is based entirely on Satan-tested premises.

Descartes’ argument for God
At the very least Descartes can’t try to prove God with experience-based premises, which is what Aquinas did. Descartes has to work from the contents of his own mind. So his first argument is a cosmological argument, but what has to be caused are ideas in his mind, not the physical universe.

The Cartesian Cosmological Argument
1. Something cannot be derived from nothing. In other words, all effects, including ideas, are derived from something.
2. There must be at least as much reality in the cause as there is in the effect.
3. I have an idea of God (as an infinite and perfect being).
4. The idea of God in my mind is an effect that was caused by something.
5. I am finite and imperfect, and thus I could not be the cause of the idea of an infinite and perfect God.
6. Only and infinite and perfect God could be the cause of such an idea.
7. Therefore God (an infinite and perfect being) exists.

Criticisms of the Cartesian Argument
1. If Descartes is going to be so skeptical about everything he believes, why does he accept certain principles like that which is found in premise 1 or in premise 2.
Some things, Descartes thinks, can be believed because the “light of nature” guarantees that they are true.
He wants to distinguish between natural impulses and the light of nature, but how can he do this? What criteria do you use for making the distinction?
2. Why doubt this and not that?
Descartes used the demon conjecture to doubt whether basic mathematical truths like 2 + 3 = 5 were true, but did not doubt that the principle “there must be at least as much reality in the total efficient cause as in the effect” was true.
3. Could we have invented the idea of God?
Some theologians of Descartes’ time thought that we could build the idea of God ourselves without God having given it to us.
“I can surely take a given degree of being, which I perceive within myself, and add on a further degree, and thus construct the idea a perfect being from all the degrees which are capable of being added on.”

The second Cartesian cosmological argument
Descartes says that his own sustained existence requires an adequate cause. A being like himself who contains the idea of perfection could not have come from an imperfect cause. There cannot be an infinite regress of causes, so God must exist to cause his existence

Descartes’ Ontological argument
Descartes uses a version of the ontological argument for the existence of God, which was first introduced by St. Anselm but rejected by Aquinas.

The OA
1. I have the idea of a God that possesses all perfections (good qualities). Existence is a kind of perfection.
If the God I am thinking of lacked existence, then he would not be perfect.
Hence, if I have the idea of a perfect God, I must conclude that existence is one of his essential properties.
If existence is one of his essential properties, he must exist.
Therefore, God exists.
The Problem of Error
While he takes his argument to overcome the problem of demon skepticism, he must overcome the opposite problem
If God supports our rationality, why do we make so many mistakes.
“So what then is the source of my mistakes? It must be simply this: the scope of the will is wider than that of the intellect; but instead of restricting it within the same limits, I extend its use to matters which I do not understand. Since the will is indifferent in such cases, it is easily turned aside from what is true and good, and this is the source of my error and sin.”