Ontological Argument

The Ontological Argument

Definition and Basics

Ontological Argument is a priori argument for the existence of God.
It’s rooted in Anselm’s belief that God is ‘that than which nothing greater can be conceived’.

Anselm’s Ontological Argument

Anselm argued that God exists, as existence is a predicate of a supremely perfect being.
He also stated that God must exist in reality, rather than just in the mind.

Gaunilo’s Critique

Gaunilo proposed a critique towards Anselm’s ontological argument, applying Anselm’s reasoning to prove the existence of the Perfect Island, which he believed was absurd.

Descartes’s Ontological Argument

Descartes reinforced the ontological argument, suggesting that existence cannot be separated from the nature of a supremely perfect being.
According to Descartes, just as we cannot separate a mountain from a valley, we cannot think of God without thinking of him as existing.

Kant’s Critiques

Immanuel Kant argued that existence is not a predicate but a presupposition.
Kant also presented his version of the ontological argument – the transcendental dialectic, which critiques all attempts to prove the existence of God using pure reason.

Alvin Plantinga formulated the modern modal version of the ontological argument.
In this argument, the existence of a maximally great being is possible in some possible world, thus exists in all possible worlds, which includes our own.