I understand causal necessity but no so much ontological necessity. Why does it follow that if God exists in any possible world, He must exist in all possible worlds?
Nevermind, I just watched a good video explaining it. Basically, being necessary is considered great, therefor God must have it, therefor God is necessary.But it seems to, as I suspected before, that the idea of a maximally great being hinges on the definition of "great." For example: why is omniscience great? Someone with omniscience can never experience the joy of discovery. I could also say beards are great, therefor God must have a beard. As far as I know, there doesn't seem to be an objective standard of greatness. Of course, I could be wrong.