Ontological Argument, The. One of the three traditional arguments for the existence of God. It has had two principal exponents: (1) Anselm in the 11th c., who argued that when we conceive of God we conceive of that than which nothing greater can be conceived (id quo nihil majus cogitari possit) and such a concept of God entails his existence (an argument to which Gaunilo gave the obvious objection that one can think of a perfect island which nevertheless does not exist), and (2) in the 17th c. by Descartes who developed it along somewhat different lines. Both Thomas Aquinas in the 13th c. and Kant in the 18th repudiated it. Hegel defended it. Most modern philosophers have rejected it on grounds similar to Kant's, namely, that existence is not a predicate.

One can add red apples to green apples and come up with a total that makes sense, but one cannot so add imaginary apples to real apples. Nevertheless, several modern philosophers (e.g., Charles Hartshorne and Norman Malcolm) have sought to revive interest in the Ontological Argument. It should he noted that Anselm did not find Gaunilo's objection damaging. He contended that while it applies to a perfect island and indeed to any finite thing (as a "contingent", i.e., a possible kind of being), it does not apply to the one "something" that is the necessary source of all such possible beings. To that "something" we give the name of God. See Cosmological Argument and Teleologoical Argument.

Geddes MacGregor, Dictionary of Religion and Philosophy, New York: Paragon House, 1989