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Descartes 3

Commentary on
Meditations V and VI

The Ascent From the Foundation

Imagining Mathematical Bodies

We have already seen Descartes begin the ascent from the foundation. By proving that God exists, he gets the truths of mathematics back again. Here is a good time to do some more predicting. Think about the descent into the pit of skepticism in Meditation I and the text map of the Meditations.
I. Descent into the pit of skepticism  III. Ascent back out of the pit of skepticism

Meditations I -- beginning of II
 Meditations V-VI
II. Discovery of self-evident and certain truths and beginning of the ascent out of the pit Meditation II-IV

That descent proceeded in stages which called into question, truths known by the senses, the imagination and finally the understanding. It was with certain truths of the understanding that the descent stopped, and Descartes declared that he had attained certain and indubitable knowledge. Now if the ascent is going to be back through the same territory, we should predict that first Descartes will rescue the truths of mathematics and other truths known by reason. Then we will get truths known by the imagination, and finally, truths known by the senses. We have already seen that Descartes has rescued the truths known by reason or understanding. So, as we begin Meditation V, we should expect that he will deal with truths known by the imagination.

At the beginning of Meditation V, Descartes says he now wants to rid himself of the doubts of the last few days, especially about physical objects. To do this, he is going to take what he has learned from Med. III -IV about seeking the truth and avoiding error and consider which of his ideas are clear and distinct. So he goes over them. Continuous quantity, is something he distinctly imagines, (this suggests that we have moved from the realm of the intellect to that of imagination) and along with it length, breadth and depth, and various parts of the thing, and these parts have shapes, sizes, positions and local motions, and the motions have various durations. Being in the realm of the imagination, we can say that these are the things of which dreams are made of.

Descartes takes up the objects of mathematics. He remarks that there are the ideas of countless things, which even if they don't exist outside of me, still cannot be called nothing. They are not my inventions, because they have their own true and immutable nature. One can prove propositions about the nature of triangles, even if none exist outside my thought. Descartes goes on to say that it won't do to say that I discovered triangular shapes through the senses, for there are countless other figures which I have not discovered through the senses about which I can prove that their nature has particular properties. And I recall that when I was completely preoccupied with sensible objects, it was those features of shape or numbers, and other properties related to arithmetic and geometry which I regarded as the most certain truths. So, it is pretty clear that we are in the realm of imagination.

Next, somewhat surprisingly, Descartes gives us what is generally taken as a second proof for the existence of God. This Meditation V proof is a version of the Ontological Argument for the existence of God. It depends on the definition of God, rather than starting as the Cosmological or Teleological arguments do from facts about the world. In this case the definition of God which Descartes employs is that God is a being with all perfections. The argument then is quite simple. God is a being which possesses all perfections. Existence is a perfection. Therefore God possesses existence. Descartes then goes on to defend the argument against objections. Why does Descartes need another proof for the existence of God? After all, he has already given an extensive proof back in Meditation III. He does say, right at the beginning of Meditation V: "Many questions remain about God's attributes and about the nature of my self or mind I may return to these questions later." Rubin Pg. 34 So, maybe we shouldn't be so surprised. Perhaps the point Descartes is making is not so much that God exists, but rather that God's essence is different from that of all other objects -- we can imagine all of those other objects -- like the objects of mathematics, without their having to exist. It is for precisely this reason that they can belong to the imagination. But God's essence is different. Existence is a necessary property of God's essence, inseparable from it in the way a valley is inseparable from a mountain. So, God's existence is necessary and so He must exist; while the existence of all other objects is contingent -- they can either exist or not. (Rubin Pg. 36) As Meditation V ends, Descartes is certain that God exists, that he is no deceiver, and he has recovered the truths of mathematics and other related truths, both on the level of the understanding and the imagination.


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