The Ontological Argument Key Proponents and Critics
Anselm's argument begins with defining God as "a being than which nothing greater can be conceived." If God exists only in our minds, he can't be truly greatest - as something existing in reality would be greater. Therefore, for God to be the greatest conceivable being, He must exist in reality, not just in our thoughts. Anselm believed God's existence is a necessary truth rather than a contingent one.
Gaunilo challenged this reasoning with his famous "perfect island" counterargument. He proposed imagining "an island than which no greater island can be conceived." Following Anselm's logic, this perfect island must exist in reality - revealing the structural flaw in the argument. Anselm responded that islands are contingent beings (dependent on other things), while God alone possesses necessary existence.
Descartes supported Anselm, defining God as "the supremely perfect being" who must possess all perfect attributes, including existence. He argued that denying God's existence is as contradictory as imagining "a mountain without a valley" - it simply cannot be done. Meanwhile, Kant strongly opposed this view, arguing that existence is not a predicate (characteristic) that adds to a definition. To say "God exists" adds nothing to our understanding of God's essence.
Remember this! The ontological argument is deductive rather than inductive. This means if all its premises are true, the conclusion must be true - offering potential certainty rather than just probability.