The Ontological Argument for God

The ontological argument for god’s existence has taken several different forms throughout history, but the most popular version is that of the 11th century philosopher and theologian Saint Anselm of Canterbury. Anselm argued that we can imagine a being which is greater than all else.1 He went on to claim that this being cannot solely exist in the imagination, since an even greater being would be one that exists in reality and is not dependent on our conception of it. This being Anselm labeled “god.” Ontology is the study of being, or existence, and thus an ontological argument strives to get from what god is to that god is – from a definition to existence. However, there are more than a few problems with this way of arguing for the existence of god.

I. Conceiving of Greatness

In Reply on Behalf of the Fool, a monk named Gaunilo challenged Anselm’s ontological argument with what has become known as the ‘perfect island’ analogy. Suppose that someone tells you about a lost island abundant in riches and containing delights beyond your wildest dreams. This island, they say, is more perfect than any island known to humankind. Is it then reasonable to argue, Gaunilo asks, that you cannot doubt the existence of this perfect island, because you can imagine it existing, and it is better to exist in reality than solely in the imagination? If this island only existed in your imagination, it would cease to be the most perfect island.

Gaunilo’s analogy demonstrates one fundamental flaw in Anselm’s argument: there is a big difference between grasping the words behind something and comprehending the full concept itself. While most of us understand what an island is, what riches are, and what else might make an island seem excellent, it’s not altogether clear that we do grasp the idea of the most perfect island. We know the words associated with it, and perhaps we can conceive of a ‘pretty darn perfect’ island, but do we clearly understand the concept itself? If we don’t actually understand the notion of a greatest conceivable being, then Anselm’s argument suffers a fatal blow, since it rests on the presumption that we have this in our understanding.

As Gaunilo explains, it must first be shown that “the hypothetical excellence of this island exists as a real and indubitable fact” before Anselm’s argument can get off the ground.2 Some have objected that Gaunilo’s analogy is unfair because an island possesses no characteristics comparable to god. This objection is special pleading, however, and seems to forget that Anselm speaks of a being upon which greatness is bestowed, and this is not any more suitable for an attribute like greatness than an island is. Such a response also seems to actually support Gaunilo, since his purpose with the analogy was to expose an absurdity. If a perfect island is so easily dismissed, why is a perfect being plausible?

II. Ruling Out the Abrahamic Deity

Another problem with the ontological argument is that it is inapplicable to certain deities. If a religion proposes a god that is inferior to what we might imagine of a supreme being, then it cannot be that said god is the greatest conceivable being. For Judaism, Christianity, Islam, and other monotheistic faiths, it would be blasphemous to think that there might be something greater than god. Yet the Hebrew scriptures report that, in one situation, god was unable to help the Israelites drive an army out of a valley “because they had chariots of iron” (Judges 1:19). In the New Testament, it is written that, due to a lack of faith among the people of his hometown, Jesus “could do no miracles there” (Mark 6:4-6). From the Qur’an, we read of the doctrine of abrogation, where Allah substitutes “better” revelations for older, presumably inferior ones (Surah 2:106).

If I can conceive of a being that can overcome iron chariots, that can work miracles anywhere without a dependence on the faith of followers, and that has no need for abrogation because it provides absolute and unchanging revelations from the start, then I have already conceived of a being greater than the Abrahamic god, which means that Anselm’s argument is inapplicable to Yahweh, Jesus, or Allah. A believer with a more liberal faith might argue that the passages I have referenced are the marks of fallible human authors, not evidence against the greatness of god. But this response fares no better, since I can then say that I can conceive of a greater being that would produce infallible revelations – texts that could not be corrupted by human hands.

One other argument in this vein would be that the most perfect being would be non-intervening. Because perfection means completeness, having nothing to be added or subtracted, a perfect god would create a perfect universe that would need no improvement, no miracles, no revelations, and no interaction at all. This is not the god of Christianity, Islam, or Judaism, though it is a very deistic being. These examples show how imagining god to be the pinnacle of greatness and perfection will exclude certain depictions of god. You may notice that I first use examples of things god cannot do to argue that a greater being could do them, and then I argue that the greatest conceivable being should actually do nothing. This is yet another firm indication of the hazy and unstable ground that Anselm’s argument rests upon with its ideas of a greatest conceivable, or most perfect, being.

III. Kant and Existence

Lastly, Anselm’s argument also suffers from a largely discredited notion of existence. In the 18th century, the German philosopher Immanuel Kant provided a refutation of his own in the Critique of Pure Reason. Kant states that simply defining what god is does not automatically entail his existence. While one might imagine that god has the property of omnipotence or perfection, existence is not a property. If you try to think of a person and a person that actually exists, you will find there is no difference between them, except for the fact that the person who actually exists can be experienced – we can find out about their location, physical properties, lifespan, etc. Existence is what we talk about when we mean that something corresponds to a concept that can be experienced in reality.

Therefore, the question of god’s existence is related to whether our concept of god corresponds with anything in the real world. We say that something exists when we have experience of it in space and time, and although some religious believers may genuinely believe there is evidence of god’s interaction with reality, none of it has been sufficiently demonstrated so far. There are likewise many believers who claim that god is not susceptible to naturalistic investigation, because he exists outside time and space. This idea of existence, I would argue, is incoherent, since existence is tied to experience of the natural world, as just elaborated. But the point is that Anselm attributes existence to his greatest conceivable being as if it were a property.

A further problem is that even if the argument could successfully establish the conceptual necessity of god, it makes an unwarranted leap in assuming metaphysical necessity. While conceptual necessities hold by virtue of their meaning, metaphysical necessities hold by virtue of their relationship to facts in the world. As an example, a bachelor is, by conceptual necessity, an unmarried man, but there is nothing evidently metaphysical that makes or imposes on a bachelor to be an unmarried man. The ontological argument attempts to define god into existence without regard for such distinctions, and this is just one of several reasons for why the argument fails to make a persuasive case.


1. Anselm. (1078) Proslogion. Chapter II
2. Gaunilo. How Someone Writing on Behalf of the Fool Might ReplyAnselm on God’s Existence. Retrieved Sep. 4, 2011.