<metaphysics, theologia rationalis> an attempt to prove the existence of god by a priori reasoning from the content of the concept of god. As formulated by Anselm, the ontological argument begins with a notion of "that than which nothing greater can be conceived.". Anything that satisfies this concept must exist in reality as well as in thought (since otherwise it would be possible to conceive something greater-one that really exists); hence, god exists. Descartes endorsed a different version of this argument, and Spinoza also relied upon it, but Kant rejected it because of the unintelligibility of comparing the relative greatness of real and merely possible beings. A form of the argument that emphasizes god's possession of the attribute of necessary existence has been defended in recent decades. Recommended Reading: Anselm of Canterbury: The Major Works, ed. by Brian Davies and G. R. Evans (Oxford, 1998); Alvin Plantinga, God, Freedom, and Evil (Eerdmans, 1978); and The Ontological Argument, from St. Anselm to Contemporary Philosophers, ed. by Alvin Plantinga (Anchor, 1989).
[A Dictionary of Philosophical Terms and Names]
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