Meditations on First Philosophy

But if the mere fact that I can produce from my thought the image of something entails that everything which I clearly and distinctly perceive to belong to that thing really does belong to it, is not this a possible basis for another argument to prove the existence of God?

September 24, 1992

One of the goals of Descartes' Meditations on First Philosophy is to prove the existence of God. Descartes argues that a knowledge or understanding of God is essential to a knowledge of all things, for nothing can truly be known unless one is aware of God. By the Fifth Meditation I believe Descartes realizes that he has managed to place himself in a state of ignorance from which he now cannot remove himself without relying on the existence of God to save him, and so he tries to invent yet another argument for God’s existence. Basically Descartes’ position is that he knows, and can come to know, nothing until he can prove the existence of God.

If I ignore the fact that Descartes is going to have to use knowledge, ideas, and information, which by his own admission he cannot know, to prove the existence of God, then all I must do to leave him in a state of perpetual ignorance is disprove his argument. If it is invalid then he knows nothing and can come to know nothing. At first I thought I was never going to be able to do this because I couldn’t find anything wrong with Descartes’ argument. In fact the more I read through it the more I thought I was going to have to argue in favor of an existing God. Even after re-reading the objections and replies to the Fifth Meditation more than several times, I was beginning to feel convinced that there was no mistake in Descartes’ reasoning. Eventually I saw where Descartes went wrong. When I discovered his mistake I not only realized how the argument could be disproved, but I also came to a better understanding of the objections given in the Objections and Replies.

Descartes’ ontological argument for the existence of God begins during an explanation of “the essence of material things.” Before he can adequately explain the material world, he must first confirm the certainty of the ideas entertained by his mind. He begins by mentioning quantities. Descartes believes that measurements and comparisons involving length, width, height, and shape are obvious and undoubtable. They are clearly and distinctly perceived by his mind, so much so that he considers quantifications as more examples of a priori knowledge. But there are other ideas, he continues, that exist only in his imagination and not in the “real” world. These ideas, he believes, are clearly and distinctly perceived by his mind also.

The ideas of geometric shapes, for example, were not invented within his mind. His often repeated symbol is the triangle. The triangle is clearly and distinctly perceived by his mind, even though there may not be any perfect representations of the perfect triangle in the sense-perceived world. There are certain true and immutable facts about the triangle (i.e. the three inside angles cannot exceed the sum of two right angles) which he neither invented nor can refute. The triangle, he reasons, must therefore be something.

“But if the mere fact that I can produce from my thought the image of something entails that everything which I clearly and distinctly perceive to belong to that thing really does belong to it, is not this a possible basis for another argument to prove the existence of God?” (Descartes, p.45). Descartes states that he finds in his mind the idea of a supremely perfect God as certainly as he finds the idea of the triangle. And he finds existence as an innate property of God’s just as certainly as he finds various properties of the triangle to be innate. Since he concluded the triangle must be something, using the same logic he concludes that God must be something. The argument for the existence of God, in fact, is even stronger than the argument for the existence of the triangle.

One of the clearly and distinctly perceived properties of God, says Descartes, is existence. Existence is not, however, an essential property of the triangle. The idea of the triangle exists within the realm of Descartes’ mind only when Descartes entertains the idea of the triangle. God on the other hand not only exists as an idea within Descartes’ mind, but in actuality, simply because Descartes believes existence is essential to the idea of God. God, he asserts, is perfect and contains all of “the perfections.” Descartes considers existence to be among “the perfections” because, he says, if something fails to exist, it is less perfect than if it did exist. Since Descartes considers existence to be a “perfection,” and the idea of God, by nature of its essence, contains all “the perfections,” existence must therefore be a property of the idea of God. Therefore God exists. Descartes’ argument can be seen as follows:

1. My idea of God is the idea of a perfect being
2. Therefore, if God exists, God has all the perfections.
3. If God failed to exist, he would be less perfect than if he existed.
4. Therefore, existence is among the perfections.
5. Therefore, God’s existence is an essential property of God.
6. Therefore, God exists.

(“Three arguments for the existence of God in Descartes’ Meditations”, Ludwig, p. 1)

In this form, Descartes ontological argument for the existence of God is simultaneously easier to understand and harder to refute on the basis of its simplicity, than either of his previous two arguments for God’s existence. Perhaps this is why it took me so long to realize where Descartes had gone wrong. Descartes’ mistake is to treat existence as a property of God’s in the same way that he treats the fact that “the sum of the interior angles cannot exceed the sum of two right angles” as a property of the triangle. When he does this, Descartes falls into the same trap that Socrates does in one of his arguments for the immortality of the soul.

In the ‘Argument from Opposites’ (Grube, pp. 19-21) Socrates equates the properties of being alive and being dead with the property of existence. The mistake here is not easily recognized, but when it is it becomes the crucial point of the entire argument. Existence is not a property. This point is, I think, adequately proven with the “‘The ball is red’ theory” (“Five arguments for the immortality of the soul in Plato’s Phaedo”, Ludwig, p. 2). To say that something does or does not exist is to presuppose that it exists. If something is presupposed to exist, there is no reason to prove its existence. So existence cannot be viewed as a property but rather as a state, without which no other properties can be applied.

The same objection is made by the author of the first of the objections to the Fifth Meditation. He writes, “It is quite all right for you to compare essence with essence, but instead of going on to compare existence with existence or a property with a property, you compare existence with a property… In fact, however, existence is not a [property] either in God or in anything else; it is that without which no [properties] can be present.” (Meditations, pp. 95-6). Now the burden, I believe, is on Descartes to either prove that existence is a property or change his argument, for if this objection is a valid one, then Descartes has not yet proven his fourth premise, the idea that existence is among the properties which make up perfection. In his reply to this objection, Descartes unsuccessfully tries to accomplish the former.

First Descartes argues that existence is a property of the idea of God just as omnipotence and omniscience are properties of the idea of God. Since existence is not a property, as it has been proven, this reply says nothing. He goes farther and says that the concept of ‘necessary existence’ is inherent in the idea of God. He reasons that ‘necessary existence’ is a property of the idea of God because it applies to God’s essence and no other. His reasoning here is that he cannot conceive of the idea of God without also attributing to this idea the property of ‘necessary existence’ which he believes is inseparable from the concept of God. I think he is partly correct, for if an idea is conceived the idea, since it is no longer a nothing, exists. But the idea, nor anything else, has existence. To say this is to consider existence an attainable property, which is not possible. Nothing can achieve existence because to do so would imply that the thing already exists. I think that Descartes is still not addressing the fact that existence cannot logically be thought of as a property. He believes it to be, but he cannot prove it. (Or maybe he knows that it is unprovable and intentionally avoids the issue.) By not proving that existence is a property, this objection, in any form, means nothing to him, so he then concludes that it “has not weakened the force of my argument in the slightest.” (Meditations, p. 97).

Descartes cannot concede that existence is not a property because if he does this then his argument will be invalid. I think the one truth, that existence is not a property, is enough to undermine not only the Fifth Meditation, but his entire philosophy. He claimed that nothing could be known without a knowledge of God, and he has not been able to prove that God exists anywhere beyond the idea of God entertained by his mind, so he is still trapped in a situation in which he can know nothing.