6.2.3 The Ontological Argument for the Existence of God


By the end of this section you will discover:

  • The nature of an ontological argument.
  • Anselms famous ontological argument and attempts to refute it.
  • Strenghts and weaknesses of the ontological proof for God.

Ontos” is the Greek word for “foundation, “being,” or “existence.” An ontological argument then attempts to prove the existence of God by exploring the concept of being.  The ontological argument is unusual in that it has no empirical premises at all; God is not called upon as an explanation for anything. Rather, God’s existence is proven by reflection on the concept of God itself.

Anselm & the Argument for God: Crash Course Philosophy #9

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Statue of Anselm, Archbishop of Canterbury, from the exterior of Canterbury Cathedral
Anselm (1033-1109)

The argument’s first proponent was Anselm of Canterbury (1033-1109). It’s a familiar idea that God is great, the greatest, in fact, so great one cannot think of anything greater. Anselm draws on this familiar idea in his Proslogion. There, Anselm characterizes God as “a being than which nothing greater can be conceived. In more modern language, Anselm is saying that God is the greatest conceivable being, that it is part of the concept of God that it is impossible to conceive of any being greater than God.

It seems that existence is greater than nonexistence. So, if we conceive of God as nonexistent, then we can conceive of something greater than God: e.g., [an existing] shoe, a flea. But God is the greatest conceivable being, so our assumption of God’s nonexistence must have been false, and God must exist.

Another way of putting this is that Anselm anticipates Hume’s objection that no being’s existence is necessary (since any being’s nonexistence can be conceived without contradiction). Anselm insists that in this case the idea of God, properly understood, does give rise to contradiction if we suppose his non-existence. “The being which must exist does not exist” seems like a contradiction.

From the outset, the ontological argument has had difficulties heaped upon it. For one thing, although it may seem intuitively right that existence is greater than nonexistence, what does “greater” mean? Better than? Preferable to? More real than? A satisfying characterization is hard to find.

Another early objection comes from Gaunilo of Marmoutier (994-1083), who makes the satirical suggestion of an island that is the greatest island that can be conceived. If such an island is to be greater than, say, Corsica, it must exist. Must we then say that such an island exists? Surely not. The difficulty raised by Gaunilo is that it seems that the predicate of existence can be bolted onto any concept illicitly.

A predicate is an attribute or characteristic of a thing.

A contingent being is a being that could logically not exist as well as exist. This applies to everything in the physical universe.

A necessary being is a being that cannot “not” exist. It must exist.

Anselm responds, however, that his argument applies uniquely to the greatest being that can be conceived (not a given, limited kind of being like an island), since although the imagined island would indeed be greater if it existed, it is not part of the concept of anything except the greatest being that can be conceived that it be greater than everything else, and so for it alone can we infer its existence from its concept.

A similar response is that contingency is part of the concept of an island (or dog, or horse, or any other specific, limited kind of being which we are acquainted with), so that a necessarily existing island would simply be a contradiction. Only with the non-specific concept of “a being” in general would contingency not just be included in the concept.

The most historically influential criticism of the ontological argument, however, comes from Immanuel Kant (1724-1804). In his Critique of Pure Reason, Kant argues that existence is not a predicate (Kant 1781). Think about the concept of a banana. We can attribute certain predicates to it, such as “yellowness” and “sweetness.” As time goes by, we might add further predicates to the concept, e.g., “nutritional potassium source.” Now think about what happens to the concept of a banana when you suppose that bananas exist. It seems that the concept is not changed at all. To say something exists is not to say anything about the concept of it, only that the concept is instantiated in reality. But if existence cannot be part of a concept, then it cannot be part of the concept of God and cannot be found therein by any sort of analysis.

Kant’s argument was widely taken to be calamitous to the ontological argument. However, in the 1960s, the argument was rejuvenated, in a form that (perhaps) avoids Kant’s criticism, by Norman Malcolm (1911-1990). Malcolm suggests that although existence may not be a predicate, necessary existence is a predicate. As contingent beings, we are the sort of things that can come into and go out of existence. But if God exists, then he is a necessary being rather than a contingent being. So, if he exists, he cannot go out of existence. This is a predicate God enjoys, even if existence per se is not a predicate (Malcolm 1960). Intuitively, “indestructibility” and “immortality” are predicates that alter the concept of a thing.

Another modern version of an Anselmian ontological argument is offered by Lynne Rudder Baker (1944-2017). Baker’s version avoids the claim that existence is a predicate (as well as several other traditional difficulties). Instead, Baker notes that individuals who do not exist have mediated causal powers, that is, they cause effects but only because individuals who do exist have thoughts and beliefs about them: Santa Claus has the mediated causal power to get children to leave cookies out for him, children who themselves have unmediated causal powers. In short, to have unmediated causal powers is intuitively greater than having mediated causal powers, so given that God is the greatest being that can be conceived of, God must have unmediated causal powers, and so he must exist (Baker 2013).

A final difficulty that we may mention for these three theistic proofs is whether they prove the existence of …the God of classical theism … — which it is the concern of most theistic philosophers to do. The teleological argument may show a designer, which corresponds tolerably well to the creator-hood of God but seems to fall short of showing God’s other attributes, like omnibenevolence. Similarly, the world-cause or necessary being purportedly shown by the cosmological and ontological arguments may seem far distant from a personal God who is interested in our affairs. One theistic response is that these arguments may work in combination, or be supplemented by the evidence of revelations, religious experiences, and miracles…, or we may be able to find ways in which one divine attribute implies the others. Bear in mind also that there are many less well-known theistic arguments beyond these three traditional ones… (Ibid, Hunt, in Branson, Introduction to Philosophy, Philosophy of Religion, Chapter 2: Reasons to Believe–Theoretical Arguments).

Taking it to the Streets…

Find 6-8 people who identify as theists and believe in God. Ask them to explain their reasons for their belief. Take note of their answers. What commonalities do you notice among the responses? Which response stands out to you as the strongest? Which response is the weakest?
Ask these same people the following question and take note of their responses:
“If you wanted to prove the existence of God, how would you go about it? What do you think is the best way to prove the existence of God without appealing to scripture?”
Again, take note of any commonalities in people’s answers. Which approaches to proving God’s existence are most common? Are there any unique approaches in your responses? What role do reason and evidence play in people’s ideas of how to prove God?
In any of your responses did you notice aspects of the Cosmological, Teleological or Ontological arguments being utilized? Did any of your respondents really struggle to answer these questions or seem incapable of providing answers? Why do you think that might be?

Strengths and Weaknesses of the Ontological Argument.

A strength of an a priori argument is that as a deductive argument if you accept the premises then the conclusion must be true as it is logically necessary. Thus, God must, by definition, exist. To accept as true on the one hand that God is ‘that than which no greater can be conceived and then to say that God doesn’t exist is to make a logical error.

Also, the argument avoids the objections to cosmological arguments that infer (weakly) from a part to the whole and from the universe to something outside the universe.

However, scientists would have trouble with the notion of a necessarily existing thing. For them, necessary existence is not a coherent concept as existence can only be contingent.

Also, there seems to be no reason that perfection entails existence. In fact, it might be argued that existence adds limits to the idea of perfection. Such an idea, if it must exist, cannot, therefore “not exist.” A limitation?

We can use Anselm’s logic to prove the existence of all kinds of things that don’t actually exist – leprechauns, unicorns—only the concept exists. So, by this logic, the Ontological argument only shows us ideas, it does not prove actual existence.

The argument in no way establishes the existence of a personal being or of the Biblical God.



Works Cited

CrashCourse. Anselm & the Argument for God: Crash Course Philosophy #9. YouTube, YouTube, 4 Apr. 2016, https://www.youtube.com/watch?v=FmTsS5xFA6k&list=PLUHoo4L8qXthO958RfdrAL8XAHvk5xuu9&index=9&t=217s. Accessed 12 Apr. 2022.

Ealdgyth. “Anselm statue canterbury cathedral outside.” Wikimedia Commons, Wikimedia Commons, 31 May 2010, https://commons.wikimedia.org/wiki/File:Anselmstatuecanterburycathedraloutside.jpg. Accessed 12 Apr. 2022.


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PPSC PHI 1011: The Philosopher's Quest by Daniel G. Shaw, Ph.D. is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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