The Stanford Encyclopedia of Philosophy entry for “Ontological Arguments” has the following:

St. Anselm claims to derive the existence of God from the concept of a being than which no greater can be conceived. St. Anselm reasoned that, if such a being fails to exist, then a greater being—namely, a being than which no greater can be conceived, and which exists—can be conceived. But this would be absurd: nothing can be greater than a being than which no greater can be conceived. So a being than which no greater can be conceived—i.e., God—exists.


Question: Exactly who is doing the conceiving?

Answer 1, us:
Does Anselm mean a being than which no greater can be conceived by us? If so, that seems to set a rather low bar for God. Yes, we use words like omnipotent, omniscient, and omnibenevolent. And those words impress who? Us.

We are the descendants of hominids who a few hundred thousand years ago were living in trees. Why should we believe that the greatest possible being we can conceive in any way corresponds to some supreme reality?

I mean, does anyone seriously think that we are the very best that the entire vast and ancient universe has to offer? Maybe, just maybe, there are intelligent beings somewhere who are not destroying their environment. Who never kill each other; no history of massacres and wars. Who care about each other. Who provide excellent public services for all: free education, free medical care, adequate food and clothing for all. If so, I’d call them a notch or two hundred above us. But a supreme reality, if one exists, would probably be beyond their ability to conceive, perhaps totally unlike what they can conceive. How much more so does that apply to us?

Answer 2, God:
Or does Anselm mean a being than which no greater can be conceived by God? If so, wouldn’t that mean that God is unable to do something, i.e., cannot conceive of a being greater than himself? I can conceive of a being greater than myself. But God cannot conceive a being greater than himself?

So, we seem to get to a question similar to “Can God make a rock so heavy that he can’t lift it?” Our question is: Can Anslem’s God conceive of a being greater than himself? If not, then he’s not omnipotent and, so, not the greatest being. If yes, then Anslem’s God fails to fulfill Anslem’s own definition.

To sum up: If Anslem means no greater can be conceived by us, then I’d say he’s setting the bar too low. If Anslem means no greater can be conceived by God, then no God can satisfy the definition. We get the opposite of an infinite regress. Here, we go infinitely forward. God1 conceives of a God greater them himself, God2. So, God1 ceases to be God and God2 becomes God. Now, the process repeats ad infinitum.

P.S. Another objection to Anslem’s argument is the vagueness of “greatest.” Is God the greatest deceiver? The greatest liar? The greatest sadist? Anslem obviously means the greatest in all the “good” qualities, but this brings up the question: how do we know what is good? If we’re trying to prove God, as Anslem is, we cannot use what we are trying to prove to define goodness. We have to prove God exists before we can use God to define goodness. But if goodness is undefined in Anslem’s argument, then his argument seems to leave the possibility that God is the greatest deceiver.