system
Given the following post, respond as if you're commenting on Reddit:
human
What’s logically wrong with the ontological argument?

Perhaps one of the simplest arguments for the existence of god is the ontological argument. I’ve tried to sum up the argument as I understand it.


1. God is defined to be the greatest thing possible
2. We have an idea of God, i.e. he exists in our minds
3. It is greater to exist in reality and the mind than only to exist in the mind
4. God must therefore exist in reality, else there could be a greater thing, which is not possible by definition


It’s a simple argument, and it feels like something is obviously logically wrong, though I can’t quite pin it down. I know about how this same argument can show a perfect “anything” can exist, but to me, this only shows the argument is wrong, not why it’s wrong. I’d also like to just take idea number 3 for granted, as obviously if you refute that, the argument crumbles, but that doesn’t seem to be the real incorrect logic that is enabling the argument.

I think that perhaps the problem can be attacked from this point where if something could exist, it doesn’t have to exist, but even then I’m not too sure, so I think I need some guidance just to make things clear.

Can I get an explanation on the logical problems of the argument?
gpt
If you rewrite 4. as follows, perhaps you can see the issue:

"4. God - *if* he were to exist - must therefore exist in reality, else there could be a greater thing, which is not possible by definition".

To explicate a little: you can provide a definition of God in which, in order to 'fit' said definition, he must be said to exist. But this will not prove that he *does* exist; only that, were 'the greatest thing possible' to exist, it would indeed, well, have to exist. But this still remains conditional (you can't change modalities from possibility to actuality). Basically: the ontological argument (as presented anyway) builds existence into the definition, but from a definition it cannot follow that said entity *actually* exists. Only that, to put it bluntly, *if* it were to exist, it must exist.

As for the argument, the slight-of-hand that shifts the modality from potential to actual existence is in line 2, where God is said to 'exist' in our minds. Leaving aside the ambiguity of what that could mean, at best, what 'exists' in the mind is still yet the possibility of God, but not God itself, whose existence - in any register - is precisely what remains to be proved.