The Ontological Argument

The Ontological Argument is unique among the arguments for God's existence because it is a priori — it does not rely on evidence from the world but instead attempts to prove God's existence through reason and logic alone. The argument claims that the very concept of God entails God's existence — that it is logically impossible for God not to exist. This lesson examines the classical formulations by Anselm and Descartes, the major objections from Gaunilo and Kant, and the modern modal versions that have given the argument new philosophical life.

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Anselm's First Form (Proslogion 2)

St Anselm of Canterbury (1033–1109) presented the first version of the ontological argument in his Proslogion (1077–1078). His argument can be reconstructed as follows: