Peter Boghossian on The ontological argument
Boghossian regards the ontological argument as a word game that confuses conceptual possibility with actual existence.
Boghossian treats the ontological argument as exhibit A in his case that sophisticated-sounding reasoning can lead people astray. The argument defines God as the greatest conceivable being, asserts that existence is greater than non-existence, and concludes that God must exist. Boghossian regards this as definitional sleight of hand — you cannot define anything into existence, no matter how carefully you construct the definition.
His epistemological critique is characteristically practical. He asks proponents of the ontological argument: does this argument actually change anyone's mind? Has anyone come to believe in God because of it? If not — and in his experience, no one has — then its role is not persuasion but rationalization. It provides a veneer of logical respectability to a belief held on entirely different grounds.
Boghossian also points out that the argument works equally well for any 'greatest conceivable' entity — the greatest conceivable island, the greatest conceivable pizza, the greatest conceivable evil being. If the logical form of the argument is valid, it proves too much. If the parodies fail, then the argument's supporters need to explain why it works for God but not for anything else, and the explanations offered typically beg the question.
“You cannot think something into existence. If the ontological argument worked, we could define our way to any conclusion we liked.”