Here's some more clarification or furtrher obfuscation for my MCCC Philosophy of Religion students.
On Plantinga's modal version of the ontological argument.
It's possible that there is a world in which SpongeBob exists. This modal statement, as true, is necessarily true. Which means: It is impossible that SpongeBob not exist in that world.
Now consider this: It is possible that there is a world in which a maximally great Being exists. Modally, this statement is necessarily true. Which means: It is impossible that a maximally great Being does not exist in that possible world.
But "maximal greatness" means: a maximally excellent being that exists in every possible world. Now we have this:
It is impossible that a maximally excellent Being that exists (by definition of "maximal greatness") in one possible world does not exist in every possible world.
Our world is a possible world.
Therefore God exists.
