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Daniel Silliman
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| 15.2.02 |
CARTESIAN LOGIC (philosophy paper)--
“Now, however, I have perceived that God exists, and at the same time I have understood that everything else depends on him, and that he is no deceiver; and I have drawn the conclusion that everything which I clearly and distinctly perceive is of necessity true…. Thus I see plainly that the certainty and truth of all knowledge depends uniquely on my awareness of God, to such an extent that I was incapable of perfect knowledge about anything else until I became aware of him. And now it is possible for me to achieve full and certain knowledge of countless matters, both concerning God himself and other things whose nature is intellectual, and also concerning the whole of that corporeal nature which is the subject-matter of pure mathematics.”
—Descartes, fifth Meditation
1.
When Descartes ends his fifth Meditation, he describes his logic by saying he has perceived God’s existence and, knowing he is not a deceiver, knew that everything else in nature, depending on him, was true. Descartes says that which he clearly and distinctly perceives is true, thus God is true and thus the world is knowable. The logic he describes in the end of the fifth Meditation looks thus:
1. I perceive God (infinitely good).
2. Things I clearly and distinctly perceived are true.
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.: God exists
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.: The world corresponds with my perception of it.
But is this the logic Descartes followed in the forming of his arguments? It is and it isn’t.
Descartes begins his Meditations with the knowable world all around him. Then, desiring not just knowability but certainty, he believes only that which cannot be doubted, holding the rest to be false until proven. Thus in the first Meditation he moves from the knowable world to universal doubt. In the second Meditation he finds that which he cannot doubt: his own existence and his own experiences. He cannot doubt his existence in that the act of doubting authenticates his existence. He cannot doubt his experiences in that he knows he experienced them. He can doubt the cause of the experience but he cannot doubt that he had the experience. Thus in the second Meditation he moves from universal doubt to certainty of the things within his mind. In the third Meditation he finds that, assuming cause and effect, he cannot have caused the idea of God in his own mind. Effects are like the cause that caused them thus an idea of the infinite, an effect, must have an infinite cause. Thus the idea of God, if it had an equal cause, could only have come from God. Thus, in the third Meditation Descartes moves from the proof of the mind to the proof of God. His logic in the first, second, and third Meditations look like this:
1. I exist
2. I think
3. I have an idea of God
4. Effect = cause
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.: God exists
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.: The world corresponds with my perception of it.
This is the logic Descartes uses in the first, second, and third Meditations but it is not the logic he describes in the end of the fifth Meditations.
In the fifth Meditation Descartes backtracks and covers the same ground as the third Meditation. He tries to prove God a second way. This time Descartes discards his work with causes and effects and moves to work with perception. “But whatever method of proof I use I am brought back to the fact that it is only what I clearly and distinctly perceives that completely convinces me,” says Descartes. Thus, when he perceives an infinitely good God who does not deceive, he knows he is true. As he says later: “For what is more self evident than the fact that the supreme being exists, or that God, to whose essence alone existence belongs, exists.”
Thus the logic Descartes uses to prove the existence of God in the fifth Meditation matches the logic he describes in the end of that Meditation but not the logic he uses in the first, second, and third meditation.
2.
Descartes’ logic, as he describes it above, is not valid because it fails to answer the questions and the doubts raised in the early Meditations. His line of reasoning ends in a circle because he answers his doubts as to the certainty of the things he sees by restating that he sees them. His logic does not answer his doubts because he contradicts his premises. His doubt comes because he can doubt the accuracy of his perception and he ends his doubt by asserting the accuracy of his perception without giving us any argument to affirm it.
In the logic of the early Meditations he introduces us to Cartesian doubt in this form:
1. I perceive the world around me.
2. Sometimes my perceptions are in error. (I’m sleeping, delusional, deceived).
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.: I cannot be certain of the correspondence between the perception and the world.
In the fifth Meditation he attempts to escape through the veil of ideas and back into the comfortable world of correspondence by proving God. With the premise of the existence of a good God that does not deceive we can deduce the correspondence of the world to our perception of it. When Descartes tries to get us from our perception to God he does so with a shifting of his premises, introducing us to the Cartesian circle. His evidence for God, as he defines it in the passage above and in the fifth Meditation, takes the following form:
1. I perceive God (infinitely good).
2. Things I clearly and distinctly perceived are true.
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.: God exists
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.: The world corresponds with my perception of it.
Thus with the mere reversal of his original cause to doubt the problem goes away. Quite simply if I am occasionally wrong in an occasional perception then I must doubt my other perceptions, but if I am right when I perceive something clearly than there is no need to doubt. If the Descartes of the first Meditation had meet the Descartes of the fifth Meditation the former would have questioned the latter as to if he had perceived something clearly that was not true and how did he know he was not deceived and how did he know that he was not delusional and how did he know that what he clearly and distinctly perceived was true. The Descartes of the fifth Meditation does not answer these questions, he does not supply the answer to his original doubt, but only changes his premise without warrant.
by Daniel Silliman @
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| 13.2.02 |
GREAT COMPLIMENT-- I was told at lunch today that it was great to eat at a table with me because there was always an interesting conversation when I was around. This was from someone more of an aquantence than a friend and he wasn't saying that I dominated the conversation but that I encouraged it.
This is the third time this semester someone has said something similar to me and I'm feeling really good about this skill.
by Daniel Silliman @
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TALKING CRITO--The great thing about a liberal arts education with a core curriculum is to be able to bring into a given class great literature from outside and discuss it intelligently.
Today in philosophy we were taling about Gyges Ring (having read the appropriate portions of Plato's Republic for class) and the Prof and I argued about Socrates' motivation to accept death at the judgement of the Athenians for about five minutes. We slipped easily from the text read for class, The Republic, to another text, Crito, without loosing the class or straying significantly from the topic.
You gotta love this education.
by Daniel Silliman @
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| 10.2.02 |
PRESUPPOSITIONALISM-- I was talking with a friend (Matt Gaetano) over lunch today and he was relating how he got into an arguement with some Calvinists over limited atonement and they used their theology as evidence for their case. Gaetano doesn't accept their theology so an appeal to it was pointless and a little silly.
I found this interesting in its relation to Presuppositionalism.
In discussions with those in agreement with the basic truths of a woldview or an ideaology those views can be appealed to. In a discussion with those who hold some other basic truths you must either appeal to truths you both agree upon or assume to agree or decide you have no grounds for debate.
by Daniel Silliman @
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