Adding existence to the list of God’s attributes does nothing to make God exist. Or so goes the supposedly devastating Kantian rebuff of the ontological argument for the existence of God.
But Anselm* does not assign existence to God by way of predication. His ontological argument simply says that it is greater to exist both in the mind and in reality than to exist only in the mind.
So if we start with the concept of God as it exists in the mind, the concept of God as that than which nothing greater can be thought, then it follows necessarily that God exists in reality, not because we have added something to the concept of God but simply because of what is self-evidently the case: that it is greater to exist in reality and in the mind than merely to exist in the mind. And God is that than which nothing greater can be thought.
This is entailment, not mere predication.
To deny the conclusion that God exists in reality—as the Kantian does with his assertion that all the ontological argument does is add existence as another attribute to the concept of God, so that we are still only talking about a concept—is to fall into contradiction, namely, that God is not God conceptually. That that than which nothing greater can be thought is not that than which nothing greater can be thought.
In other words, Kant’s move leaves us with the analytic conclusion that A =/= A, which is absurd.
Anselm’s argument does no such thing. This is its genius. It crosses the supposed bright line between the analytic and synthetic with seamless logical rigor. It demonstrates that the proper understanding of God entails God’s actual existence.
It is the Kantian’s circular criticism** of the argument that introduces the contradiction. Anselm nowhere argues that he is adding the concept of existence to the list of attributes that make up the concept of God. It is the Kantian who does that, and that is precisely what introduces the analytic contradiction.
So leave aside the fact that the Kantian is mischaracterizing Anselm. We can’t even grant him his objection in principle without it creating a contradiction in the concept of God where none existed before.
If it’s logically impossible that the Kantian objection is valid, then it must not be valid.
Postscript I: The more seriously we take the Kantian rebuff, the worse it seems to get for the Kantian. If adding existence to a concept does nothing to demonstrate the existence of the thing conceived, then what do we make of Kant’s concept of the noumenal realm? Fertile ground for exploration.
Postscript II: Nothing said here is novel in the slightest. In fact, Anselm all but “prebuffs” the Kantian position along these lines in the Proslogion itself. Perhaps he had someone like Kant in mind when he said the following:
Even the Fool, then, is forced to agree that something-than-which-nothing-greater-can-be-thought exists in the mind, since he understands this when he hears it, and whatever is understood is in the mind. And surely that-than-which-a-greater-cannot-be-thought cannot exist in the mind alone. For if it exists solely in the mind even, it can be thought to exist in reality also, which is greater. If then that-than-which-a-greater-cannot-be-thought exists in the mind alone, this same that-than-which-a-greater-cannot-be-thought is that-than-which-a-greater-can-be-thought. But this is obviously impossible.St. Anselm’s Proslogion, Charlesworth, M.J., trans. University of Notre Dame Press, 1965. p. 117.
In other words, to insist that God exists only in the mind is to insist that A =/= A, which is not only an absurdity, but an analytic absurdity.
* There are many variants of the ontological argument. Kant focused his criticism on Descartes’ version rather than Anselm’s. Thus the focus here is on the Kantian reply–how those thinking in the tradition of Kant have treated Anselm.
** Circular because to declaim that existence isn’t a predicate we can ever combine with a subject to show that it exists is to assume that proof of existence arrived at via metaphysical demonstration can never be more than conceptualist, or true only by “relations of ideas” within human minds (to borrow a phrase from Hume). In other words, the Kantian simply assumes that Anselm is wrong, which is of course the very thing he must demonstrate. It’s question begging plain and simple. Elsewhere Kant allows for the truth of synthetic a priori propositions. Why not here? But the deeper problem, of course, is that Kant in his transcendental idealism denies that we can ever have knowledge of things-in-themselves. He is committed from the start to a metaphysical analyticism whereby the doctrine of God can never be more than arrangements of cognitions (or conceptual representations or conventions of language) with no real referent in subject-independent reality.
M. J. Chadworth in his excellent commentary on the Proslogion notes the irony of the Kantian position:
Now Anselm might reply both to Kant and to his modern followers that their objections prove too much, for they do not simply assert that the existence of all the things within our experience is contingent (so that all existential propositions about things within our immediate experience are synthetic), but they go further and claim that it is logically necessary that all existential propositions are synthetic. Thus they are led to maintain paradoxically that it is logically impossible for the proposition ‘God exists’ to be a logically necessary one, and they end by espousing an ‘ontological disproof’ of the existence of God.St. Anselm’s Proslogion, Charlesworth, M.J., trans. University of Notre Dame Press, 1965. p. 75.
So the Kantian doesn’t defeat Anselm’s argument. He just rules out the conclusion as impossible. Where the Kantian’s baseless insistence on a presumed metaphysical analyticism ties him up in a contradiction, Anselm exits gracefully, his conclusion intact.