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Descartes's Proofs of God's Existence

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René Descartes (1596-1650) famously produced some original arguments to prove God's existence. The arguments played a key role in his Meditations on First Philosophy, as they allowed him to conclude that something beyond himself existed. Here goes a reconstruction of the arguments, as found in the third meditation.

Preliminaries I: Will, Passions, Judgments
In preparation of the main claim, Descartes examines his own thoughts to discern them into kinds. He finds that there are three kinds of operations of thought: Will, Passions, Judgments. The first two cannot be said to be true or false, as they do not pretend to represent the way things are. Only among judgments, then, can we find those sorts of thoughts representing something as existing outside of us.

Preliminaries II: Innate, Adventitious, and Fictional Ideas
The next step Descartes takes consists in analyzing his own ideas, to seek out which ones figure as components of a judgment. He finds that he has three types of ideas: innate, adventitious (coming from the outside), fictional (produced by the thinking subject).

Now, adventitious ideas could have been created by Descartes himself. Although they do not depend on his will, he might have a faculty producing them, like the faculty that produces dreams. That is, of those ideas that are adventitious, it might be that we produce them even if we do not do so willingly, as it happens when we are dreaming.

Fictional ideas, too, could have clearly been created by Descartes himself. Of those, we are even aware of having come up with them.

How about innate ideas? Did Descartes create them too? To find an answer to this question he needs to investigate more about the nature of ideas …

Preliminaries II: Innate, Adventitious, and Fictional Ideas
All ideas, for Descartes, have a formal and an objective reality. Also, the following metaphysical principles hold:

  • Nothing from nothing;
  • More cannot come from less;
  • More objective reality cannot come from less formal reality.

Secondly, there is a hierarchy of beings. They can be divided in four categories:

  • Material bodies: which are imperfect;
  • Humans: a mix of material bodies and spirit, which are imperfect;
  • Angels: pure spirit, and imperfect;
  • God: perfect, only spiritual, being.

First Proof
With those preliminary theses at hand, Descartes is now ready to offer us some proofs of God's existence, whose logic is very simple. Here goes the first one.

  • I am an imperfect being [by evidence]
  • I have a clear and distinct idea of a perfect being (i.e. God); that is, the objective reality of perfection exists [by evidence]
  • I am less (formally) than the objective reality of perfection [by g), from last class]
  • Therefore, there have to be a perfect being existing formally from whom my innate idea of a perfect being derives. I could have created the ideas of all substances, but not the one of God.

Second Proof
The second proof is even thinner than the first one.

  • Who keeps me (who have the idea of a perfect being) in existence? If I owe it to myself, I would have given to me all sorts of perfections;
  • Yet, evidently I am not perfect;
  • My parents as well as any other imperfect being could not be the cause of my existence, since they could not have created me (with my idea of perfection);
  • Therefore, a perfect being (God) has to exist and being constantly recreating me.

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