The Ontological Argument for God

Saint Anselm of Canterbury (1033-1109) is famous for what has become known as the “ontological argument” for the existence of God. The argument is usually put forth in syllogistic form as follows:

  1. God is that which no greater can be thought
  2. That which no greater can be thought must exist, not only as an idea, but extramentally (extra nos)
  3. Therefore God exists, not only as an idea, but extramentally

Now, I admit that the argument as stated is less than convincing – for me anyway. Why must this idea (i.e. that which no greater can be thought) correspond to being? We know that thought, generally speaking, has no necessary correspondence to reality (i.e. being), else fairy tales would be an impossibility. We can imagine unicorns, elves, and fairy godmothers, but that does not mean they exist in reality. So why is it that the idea of God, that which no greater can be thought, corresponds to reality? What makes the idea of God different than that of a unicorn, such that the one necessarily exists while the other does not? Frederick Coplestone, S.J., elaborates in his 2nd volume of A History of Philosophy (Doubleday, 1993):

This proof starts from the idea of God as that than which no greater can be conceived, i.e. as absolutely perfect: that is what is meant by God.

Now, if such a being had only ideal reality, existed only in our subjective idea, we could still conceive a greater being, namely a being which did not exist simply in our idea but in objective reality. It follows, then, that the idea of God as absolute perfection is necessarily the idea of an existent Being, and St. Anselm argues that in this case no one can at the same time have the idea of God and yet deny His existence.

Now this is an interesting twist. The last sentence says that one cannot “have the idea of God and yet deny His existence.” So are we saying that the idea does not correspond to objective reality, per se, but only that the idea itself would be contradictory if we did not at the same time believe in its objective existence? This is a valid point and great as far as it goes, but I can’t believe that that is the sum of what Anselm was saying. His argument is, as it is said, an ontological one, not an epistimological one.

The argument seems to only make sense from what Coplestone calls, an “ultra-realist” point of view; the view that universals, or ideas (Plato), are an extramental, objective, and substantive reality in themselve (such that “horseness” is itself an objective substance). Thus God, who is the ultimate idea, must exist because ideas as such have an existence outside of us. However, I am not sure if Anselm was an ultra-realist or, what Coplestone calls, a “moderate-realist” in the vein of Saint Thomas Aquinas. A moderate-realist is one who believes that universals or real and objective, yet deny that universals such as “horseness,” “humanity,” whiteness,” etc. are substantive realities in themselves. The opposing view is that of monism, in which universals are not real in any objective way; i.e. universals are purely subjective constructs of human thought.

Still, this argument for God’s existence seems weak to me. Others have found it quite convincing, and since many people smarter than I have found the argument useful, I will assume that I am missing something. Although, I will note that Aquinas did reject this argument (according to Coplestone), but on what grounds I do not yet know. Perhaps I will know in a couple hundred pages when I reach the section on Aquinas in Coplestone’s A History of Philosophy. In the end, I really do wonder if it is on realist presuppositions that this argument is based and indeed found to be necessary. In other words, if you believe that universals are in some way real and objective, and that the idea of God necessarily entails a belief in His existence, then it naturally follows that God must exist. This is the only way that I can make some sense of the argument, but as with all presuppositions they may be attacked and the argument is thereby undercut at the knees, as it were.

Those are my thoughts, disjointed as they are. If anyone else has any further insight into this “ontological argument” for God’s existence, I would love to hear it. I find it (for lack of a better word) interesting that this argument has been taken as seriously as it has throughout the centuries. As Coplestone notes,

In the ‘modern’ era [the ontological argument] has had a dinstinguished, if chequered career. Descartes adopted and adapted it, Leibniz defended it in a careful and ingenious manner, Kant attacked it. In the Schools it is generally rejected, though some individual thinkers have maintained its validity.


3 Responses to “The Ontological Argument for God”

  1. 1 Mark May 2, 2009 at 11:22 am

    Upon further reflection, the argument makes sense from any realist point of view, not just an “ultra-realist” point of view. For a Christian, universals or ideas can be thought of as subsisting in God, such that one can deny that mankind as such exists as a substance (ultra-realism) yet believe that it does exist in so much as it exists in God.

  2. 2 Eric M. May 4, 2009 at 9:28 pm


    Here are some references that might help in your study of St Anselm:

    Brandon Watson has many good links to St. Anselm articles, including many of Anselm’s works, on his blog.

    There are also good comments on the ontological argument from Watson (, James Chastek ( and Michael Liccione (

  3. 3 Mark May 10, 2009 at 6:30 am

    Thanks for the references, Eric.

    Sorry it took so long to get your comment posted. I didn’t realize WordPress was holding it up for my approval (for a reason I still do not know) until this morning.

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