The Disposition of Recapitulation

DESCARTES' ONTOLOGICAL ARGUMENT FOR

GOD'S EXISTENCE

In the fifth Meditation, Descartes provides a version of the so-called Ontological Argument for God's existence, that is, an argument which attempts to derive the existence of a supremely perfect being from the very nature of the concept of a perfect being, or, in other words, from the definition of a supremely perfect being. The argument is fairly simple:

(1) I have a clear and distinct idea of a supremely perfect being.

(2) Existence is a perfection.

(3) Existence is inseparable from supreme perfection indeed, supreme perfection cannot be clearly and distinctly thought of without thereby thinking of existence.

(4) In having a clear and distinct idea of a supremely perfect being, I have a clear and distinct idea of an existing supremely perfect being.

Let us now consider. Normally, if I have a clear and distinct idea of something of a particular sort, it does not automatically follow that a thing of that sort exists, that is, I can, with consistency, think that no being of that sort exists. But given (4), I cannot suppose that a supremely perfect being does not exist, since existence is part of the essence of such a being and, hence, existence belongs to the content of what I am thinking of. Thus, given (4), we can infer,

(5) A supremely perfect being exists.

Objections to Descartes' Ontological Argument

Kant's Objection. Every real predicate expresses a property or attribute of something, that is, a definite "way" that a thing is or can be. Thus, to think of something X as having a given property is certainly different from thinking of X without that property. Now the term 'exists' is not a real predicate corresponding to a property or determination of a subject. It does not add anything to the concept of the subject but, rather, "posits" the subject. Thinking of a hundred thalers is no different from thinking of an existing hundred thalers so far as the content of what my thought goes. That is, existence is no further determination, no additional feature, which can be added to what is already thought. Moreover, one certainly think a concept C without positing it, that is, without thinking or asserting that "there is a C" or "a C exists" (thus, when I think the concept of unicorn). When one does say that "a C exists" then one is positing an object which is external to C itself. Descartes' premise (2) is false. Consequently, from the mere concept of a supreme being, we cannot obtain knowledge that there exists such a supreme being.

One Reply to Kant. What is better: the conception of your spending Spring Break in the Bahamas or your actually spending Spring Break in the Bahamas? What would you rather have in your pocket: a merely imagined hundred thalers or an existing hundred thalers? The answer to these questions is clear. This shows that the concept of existence or actuality can add something to a thing, namely, value. That is, existence certainly seems to be something positive, and proof of this is that existence is generally preferred to non-existence. So, while I can conceive of something being a unicorn without conceiving it as existing, how could I conceive of something being perfect without conceiving of it as existing?

Descartes' Reply (in his replies to the first and second sets of objections).

While I can conceive of a thing without conceiving of it as existing, perhaps it is true that when I conceive of a thing I think of it as possibly existing. But there is a difference between possible existence and necessary existence, and when I conceive of God I conceive of God as existing necessarily since only by existing necessarily would God have the independence that is a mark of a supremely perfect, infinite, complete being. Hence, the second premise of the argument should be understood as proceeding in this fashion:

(2') Necessary existence is a perfection.

(3') Necessary existence is inseparable from supreme perfection.

(4') In having a clear and distinct idea of a supremely perfect being, I have a clear