Ontological Disproof

The ontological argument is said to fail because existence is not a property that can be built into a definition.

Tagged: Arguments against God Metaphysics

The ontological argument reasons from the very concept of God to God's existence: God is defined as the greatest conceivable being, and a being that exists is greater than one that does not, so God must exist. The disproof replies that this reasoning proves too much, since it would also prove the existence of a perfect island or any other perfect thing that can be defined. It also denies the key step: existence is not a property that adds greatness to a concept, but the condition for a concept having an instance at all.

Findlay added a further disproof: a necessary being, one that cannot fail to exist, is itself an incoherent idea, so the concept at the heart of the argument cannot be instantiated.

The Argument in Form

The ontological argument treats existence as a property that makes a being greater.
Existence is not a property, and the same reasoning would prove a perfect island.
A necessary being, as Findlay argued, is itself incoherent.

Conclusion: Therefore, the ontological argument does not establish God's existence.

Proponents and History

Gaunilo, a contemporary of Anselm, offered the perfect island parody, arguing that Anselm's reasoning would prove the existence of the most perfect island conceivable. Kant later argued in the Critique of Pure Reason that existence is not a real predicate and adds nothing to a concept. J. N. Findlay added an ontological disproof, claiming that the idea of a necessary being is itself incoherent, and later critics have continued to press all three lines of attack.

Standard Responses

Anselm replied to Gaunilo that a perfect island is not comparable to a necessary being, since an island is contingent by nature and its perfection has no maximum, while a necessary being, if possible, exists in every possible world. Modern defenders add that modal versions of the argument do not treat existence as a simple predicate but argue from the possibility of a necessary being to its existence. On this view, the parody fails and Kant's point does not touch the modal argument, so the ontological argument must be answered in its modal form.

References

Ontological Arguments (Stanford Encyclopedia of Philosophy) Free / open access
Ontological Argument (Internet Encyclopedia of Philosophy) Free / open access

Related Across the Site

Argument from Non-Belief Argument — The sheer scale of unbelief in the world is said to fit naturalism better than theism.
Cosmological Disproof Argument — Modern cosmology is said to remove the need for a first cause of the universe.
Divine Hiddenness Argument — If God were perfectly loving, reasonable people would not remain without belief; yet many do.
Foreknowledge and Free Will Argument — If God already knows infallibly what each person will do, the future seems fixed and human freedom seems lost.
Omnipotence Paradox / Coherence of Theism Argument — The stone paradox asks whether a God who can do anything can make a stone too heavy for God to lift.
Omnipotence and Omniscience Incoherence Argument — The divine attributes themselves are said to conflict, so that no being could hold them all together.
Ontological Argument Argument — God is the greatest conceivable being, and a being that exists is greater than one that does not, so God must exist.
Problem of Evil Argument — The suffering of the world is said to count against a God who is all-powerful, all-knowing, and perfectly good.

Related Arguments

Ontological Argument — God is the greatest conceivable being, and a being that exists is greater than one that does not, so God must exist.
Cosmological Disproof — Modern cosmology is said to remove the need for a first cause of the universe.
Teleological Disproof — Evolution and natural explanations of fine-tuning are said to remove the need for a designer.