The official task of the Third Meditation is to prove God’s existence.
There are two arguments for this conclusion. They both claim that only God could produce observed effects. One of these effects is the idea of God that Descartes assumed his meditator would have (AT 42-7). The other concerns the creation and continuous existence of finite things (AT 47-51). We only discussed the first argument in class.
(For those who like vocabulary, these arguments from effects that only God is alleged to be able to produce are called “cosmological” arguments for the existence of God. The “ontological” argument in the Fifth Meditation concerns what is said to be God’s essence rather than effects.)
In addition to the proofs of God’s existence, the Third Meditation includes important claims about our ability to attain certain knowledge. We do this through “clear and distinct” perceptions and seeing things in the “natural light.”
Clear and distinct perception
What is Descartes saying on AT 36 (p. 25)?
Is it that God could deceive me even about my ‘clear and distinct’ perceptions? Or is it that not even God could do that?
I think the answer is supposed to be “both.” Not even God could deceive me about a clear and distinct perception that, say, 2 + 3 = 5. But God could deceive me about this when I am not perceiving it. Say I’m going through a series of calculations.
- 2 + 3 = W
- 4 + 7 = X
- 80 + 5 = Y
- W + X + Y = Z
I can’t be mistaken about X while I’m perceiving step 1. But when I get to step 4 I will no longer perceive step 1 directly. Then, God might deceive me and lead me to think that W, in step 1, is 6 rather than 5. If that happens, I will believe that Z = 102 rather than the correct answer of 101.
I think that Descartes meant something like that.
What the heck are clear and distinct perceptions?
We don’t get much by the way of explanation, much less a criterion for distinguishing genuine cases of clear and distinct perception from false ones.
But, just speaking for myself, I can’t do a much better job of explaining why it’s obvious that 1 = 1 or that 2 + 3 = 5. It’s just obvious.
Causes of ideas
“[T]he chief question at this point concerns the ideas which I take to be derived from things existing outside me: what is my reason for thinking that they resemble those things?” (AT 38, p. 26).
In normal life, we think that our ideas are caused by objects. I see a desk because light reflects off of a real, external object: a desk. But Descartes’s meditator has given up on this normal thought. The meditator cannot be certain that the senses are reliable; the desk that I think I see may be a dream or a phantasm caused by a supernatural deceiver.
Normally, if I have some doubt about whether I’m seeing things accurately, I try to get in a better position: I turn on a light, I move closer, I reach out to see if I can touch what I think is the desk. I might also ask someone else, who is in a better position to see or feel whether there’s really a desk in front of me. But none of this will work for the meditator either. Everything that I see or feel may be a dream or a phantasm caused by a supernatural deceiver. And the answer that I think I hear from another person may be a dream or a phantasm caused by a supernatural deceiver too. None of these normal procedures can give the meditator certainty.
So all the meditator has to work with are a collection of ideas in his or her head. Can the meditator draw any conclusions about what exists outside of his or her head by looking solely at the features of the ideas in his or her head?
Descartes’s answer is “yes.” The idea of God could only be in the meditator’s head if there were a God to cause it to be there.