ANSELM'S ONTOLOGICAL ARGUMENT FOR THE EXISTENCE OF GOD

An ontological argument is one that relies on a priori assumptions about the nature of an object's existence.  In 1078, Anselm of Canterbury proposed in his Proslogion his proof of God's existence.

First, he defined God as "that than which nothing greater can be conceived".

Thus defined, he argued that since we can conceive Him as such, this God must exist in our minds.

Now, things can exist in our minds and they can also exist in reality.

Things are greater if they exist both in our minds as well as in reality rather than in our minds only.

If God exists only in our minds, and not in reality, then God would not be the greatest Being; because another hypothetical being which may exist both in our minds and in reality would have been greater than God.

But, as already defined, God is the greatest Being ever conceived. So, God must necessarily exist both in our minds as well as in reality.

Therefore, God must exist!

Well, how convincing is that? I think the best way to evaluate it is to present a similar, but counter ontological argument below:

A COUNTER ONTOLOGICAL ARGUMENT

This argument was apparently formulated many centuries ago to refute Anselm's proof of the existence of God.

It goes something like this:

Ok, let's accept Anselm's definition of God as "that than which nothing greater can be conceived".

Part of that greatness would be because He created the Universe.

God can create the Universe either with Himself also existing in the Universe or without Himself existing in the Universe.

But a God who could create a Universe without Himself even existing in that Universe would be greater than a God who requires to exist in that Universe in order to create it.

Yet, God is the greatest Being. So, He should create the Universe without Himself existing  in it.

Therefore, God does not exist!