esmagalhaes wrote:One could think of (3) as short for a longer argument as follows. Either God is both possible and actual, or only possible. If he's only possible, then he could be greater than he is. (The assumption, which I'm willing to grant for the sake of the argument, being that it's better to be actual than just possible.) But that's absurd - he is, as the definition says, the greatest possible being. Therefore, God must be both actual and possible.
The major problem with step (3) is that it is masquerading as a logical proposition separate from the rest of the argument but (as the argument itself demonstrates) is in fact part of the premise. What most versions of the ontological argument boil down to is this:
(1) Let us define God as the greatest possible being.
(2) Greatness includes existence.
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(3) Let us define God as existent.
The conclusion of the ontological argument is usually rendered "God, by definition, exists"; but a more accurate rendering would be "If we define God as existent, then by definition God is existent." The ontological argument is an elaborate way of saying nothing more than that.