Kant's Objection

Existence is not a Predicate

Immanuel Kant (1724 - 1804), offered what many believe to be a damning critique of Anselm's ontological argument.

Let us return to our discussion of unicorns and God. Anselm has argued that there exists a difference between the concept of "unicorn" as it exists intra-mentally and extra-mentally. If we claim that the "unicorn" is, we are somehow adding to the concept. We are endowing the concept with an additional predicate, i.e. the quality that it is. The point of Anselm's argument is that the predicate of existence can be demonstrated for the concept of "God."

Kant does not agree with Anselm's treatment of existence as a predicate. The concept of "unicorn" is not changed in any way if we claim that it is. Nor is the concept damaged if we claim that unicorns are not. According to Kant,"...we do not make the least addition to the thing when we further declare that this thing is." If existence is not a predicate, then Anselm's argument has not demonstrated any meaningful information.