Anselm’s Ontological Argument for the Existence of God and its Value for Apologetics

By John D. Wilsey, PhD. Assistant Professor of History and Christian Apologetics at the J. Dalton Havard School for Theological Studies.

John Wilsey’s article contains many good points, but he arguably seems to persist in a common fallacy about Anselm of reducing his definition of God – as ‘that than which nothing greater (more prefect) can be conceived’ or as ‘that which is greater (more perfect) than anything that can be conceived’ to ‘the greatest conceivable being’ (GCB).  This is something that Hartshorne rightly complains about in his book ‘Anselm’s Discovery’.  Anselm’s ‘one single argument needing no other proof than itself’ is to show the person of faith who seeks understanding what it is that they have faith in, not to prove the existence of God direct via an a priori argument: the argument is actually highly inductive in character. This error of definition is present in a number of the popular text books for P or R – such as the one by Cole and Grey and the one in the access series by Jones, Cardinal and Hayward. SL

For nearly ten centuries, Anselm’s ontological argument for the existence of God has been examined, embraced, debated, debunked, and revised by philosophers and theologians. Luminaries such as Descartes and Leibniz have embraced it. Aquinas, Hume, and Kant rejected it. For many years, Kant’s critique of the argument closed the door on serious consideration of it, but in the twentieth century, the argument experienced a sort of reformulation, thanks to scholars such as Charles Hartshorne and Alvin Plantinga. Early in his scholarly career, even Bertrand Russell saw some value it in. He wrote,

“I remember the precise moment, one day in 1894, as I was walking along Trinity Lane, when I saw in a flash (or thought I saw) that the ontological argument is valid. I had gone out to buy a tin of tobacco; on my way back, I suddenly threw it up in the air, and exclaimed as I caught it: ‘Great Scott, the ontological argument is sound.’”1

The present study will be comprised of three parts. First, Anselm’s ontological argument will be stated and explained. Following the explanation, a survey of historical and contemporary assessments will be addressed in order to introduce the general controversy over Anselm’s argument. Finally, an appraisal of the value of the argument for apologetics will be presented. Although Anselm’s ontological argument has enjoyed little consensus over the centuries as to its legitimacy as a proof for God’s existence, it still has apologetic value because it is able to show the rationality of belief in God. Even though the ontological argument alone cannot prove God’s existence, alongside a posteriori arguments it can be a strong component in a cumulative case apologetic approach.

Explanation of Anselm’s Argument

The ontological argument was first developed by Anselm (AD 1033–1109), an abbot of the monastery at Bec in Normandy who became Archbishop of Canterbury in 1093. He is most famous for his works on the incarnation, the Trinity, and the knowledge of God. Peter Hicks wrote of him, “His key methodology was to present ‘necessary reasons’ for the truths of Christianity, that is, establishing them by rational argument rather than appealing to the authority of revelation.”

When Anselm developed his argument, his goal was to find one conclusive statement that would prove the existence of God, and furthermore, the necessity of God for the existence of all else. Anselm wrote, “I began to ask myself whether one argument might possibly be found, resting on no other argument for its proof, but sufficient in itself to prove that God truly exists, and that he is the supreme good, needing nothing outside himself, but needful for the being and well-being of all things.”3 According to Jasper Hopkins, Anselm meant to show in his one argument “that the existence of beings per aliud requires the existence of one Being per se, which likewise is God.”4 Thus, Anselm proceeds from the concept of God to the existence of God.

An a priori syllogism

Two things are clear, then, from the above description of Anselm’s goal. First, the argument is a priori. Wallace Matson observed that philosophers and mathematicians in particular “are intrigued by the argument because it purports to bridge the gap between the realms of mathematical and factual truths.”5 Second, Russell’s observation that “Anselm’s philosophy is mainly derived from Saint Augustine, from whom it acquires many Platonic elements”6 is clear, especially in Anselm’s belief, for example, that good things require a highest good. These two points of context are valuable when attempting to understand the argument’s meaning and significance.
Anselm did not state his argument in the form of a syllogism, but as a prayer. However, for the sake of convenience, the argument has been presented in syllogistic form by scholars since Anselm’s writing. Stephen Davis’ thorough syllogistic presentation in his work God, Reason and Theistic Proofs will be reproduced here:

1. Things can exist in only two ways—in the mind and in reality.
2. The GCB [greatest conceivable being] can possibly exist in reality, that is, is not an impossible thing.
3. The GCB exists in the mind.
4. Whatever exists only in the mind and might possibly exist in reality might possibly be greater than it is.
5. The GCB exists only in the mind.
6. The GCB might be greater than it is.
7. The GCB is a being than which a greater is conceivable.
8. It is false that the GCB exists only in the mind.
9. The GCB exists both in the mind and in reality.

Clarifications

First, a clarification of terms is necessary. What is meant by “greatest conceivable being”? Anselm’s precise term is “a being than which none greater can be thought.” According to Davis, what Anselm meant was not the greatest being anyone can imagine, but rather, “the greatest being that it is logically possible for any conceiver to conceive of.” So, the term “greatest conceivable being” means that being which is the most perfect being that can be named or defined by any conceiver. That being, thus defined, is God.

Premises through, according to Davis, constitute the fundamental assumptions of Anselm’s argument. In other words, they are necessary to the validity of the rest of the argument. Premise reveals that the argument is a reductio ad absurdum. Thus, Anselm was attempting to prove God’s existence in reality by demonstrating the absurdity of positing the non-existence of God in reality.

Premise must be true if, and are also true. If the GCB exists only in the mind, then a GCB existing in reality would be greater. Beings that exist in reality, as Davis noted, “are more powerful, freer, more able to do things than the mere concepts of those things.” Thus, if the GCB existed only in the mind as an idea, it would not be as great as if it were to exist in reality.
Premise reveals an obvious contradiction in the structure of the argument. Since this is a reductio ad absurdum argument, then there must be a premise that is responsible for creating the contradiction. Looking to premises through, it is clear that if the first four premises are necessary to the argument, then must be the responsible premise for the contradiction. Following the reductio pattern, premise (5) is negated by inserting the phrase “it is false that” in front of it. The result is premise, which leads directly to the conclusion that God truly exists, found in premise.

Thus, Anselm attempts to use rationality as a test for truth on the issue of God’s existence. By using a priori reasoning, that is, reasoning prior to evidence and based solely upon deduction, he hoped to arrive at the existence of God. Many have found much to be enthusiastic about Anselm’s argument. Davis, for example, is convinced that Anselm’s argument is successful in proving God’s existence. He stated,

“The OA [ontological argument] does not supply a sufficient reason why God exists—it only proves that God exists.”

Many others, however, have doubted the strength of the argument. In the next section, the study will consider the responses given to the argument by René Descartes, Immanuel Kant, Alvin Plantinga, and William Rowe. This section is presented in order to introduce the general controversy over Anselm’s argument, and to show that even while it may not have enjoyed consensus as to its efficacy in proving the existence of God, it can still show that belief in God is rational.

Historical and Contemporary Assessments of the Argument

After Thomas Aquinas rejected Anselm’s argument and developed his version of the cosmological argument in the thirteenth century, the ontological argument lay dormant until it was again considered by René Descartes early in the modern period. Descartes (1596–1650) is perhaps most famous for his dictum, Cogito ergo sum. Descartes was a mathematician and a philosopher who believed that it was possible to arrive at absolute certainty from any

perspicuous proposition. Affirming the existence of God was a component in his method for arriving at absolute certainty and he viewed Anselm’s argument with favor. Most of his discussion on the ontological argument can be found in his Meditations on First Philosophy, although it is also referenced in Discourse on Method and The Principles of Philosophy.
Descartes modified Anselm’s argument into a form that is recognizably Cartesian.14 Graham Oppy, in his work Ontological Arguments and Belief in God, rendered Descartes’ version of the ontological argument in the following syllogism:

1. I possess the idea of a supremely perfect being. (Premise)
2. The idea of a supremely perfect being includes the idea of existence—that is, the
   idea that a supremely perfect being exists. (Premise)
3. The idea of a supremely perfect being is the idea of a being with a true and
   immutable nature. (Premise)
4. Whatever belongs to the true and immutable nature of a being may be truly
   affirmed of it. (Premise)
5. Existence belongs to the true and immutable nature of a supremely perfect being.
   (From 2, 3, 4)
6. (Hence) I may truly affirm of a supremely perfect being that it exists. (From i, 5)
7. (Hence) A supremely perfect being exists. (From 6)

For Descartes, existence is necessary for a perfect being. Descartes wrote,

“From the fact that I cannot think of God except as existing, it follows that existence is inseparable from God; for this reason he truly exists.”16

If God did not exist, then He would not be supremely perfect. To be the supremely perfect being, God simply must exist. Descartes explicitly denied that he merely conjured up God’s existence in his mind, thereby imposing something inappropriate upon God. Rather, Descartes claimed, “because the necessity of this thing, namely of the existence ofGod, forces me to entertain this thought; for I am not free to think of God without existence (that is, a supremely perfect being apart from the supreme perfection) as I am free to imagine a horse with or without wings.”

One way that it is recognizably Cartesian is that in proving God’s existence, as in proving his own existence by the cogito ergo sum formula, Descartes uses himself as the starting point

“God, forces me to entertain this thought; for I am not free to think of God without existence (that is, a supremely perfect being apart from the supreme perfection) as I am free to imagine a horse with or without wings.”

Kant’s rejection of the ontological argument

According to Descartes, if God were to lack existence, He would lack an attribute that He must have in order to be supremely perfect. To further illustrate the point, Descartes likened God’s attribute of existence to a triangle’s attribute of consisting of three internal angles. Just as it is impossible to think of a triangle with four sides, it is impossible to think of God, the supremely perfect being, as lacking the attribute of existence.

While Descartes was friendly to the ontological argument, Immanuel Kant (1724–1804) rejected it outright. Davis asserted that Kant possesses the distinction of having raised the most famous and most forceful objection against the ontological argument, which appeared in his Critique of Pure Reason.18 This objection, namely that existence is not a real predicate of being, has as Davis asserted, “attained something like the status of philosophical orthodoxy.”19

In the Critique of Pure Reason, Kant aimed to show that all the traditional proofs for the existence of God fail. In order to show their failure, Kant believed that he needed to start with the ontological proof, since it was a priori and, as Copleston stated,

“The movement of the mind towards God in metaphysics is always guided by the transcendental Ideal of pure reason, which is the goal of its striving.” Frederick Coplestone (20)

Thus, Kant believed that every proof for God’s existence makes use of the ontological argument, and if the ontological argument fails, all other arguments fail as well.

Kant’s critique involves many elements, but fundamentally, his claim was that existence is not a real predicate. To appreciate the meaning of Kant’s critique that existence is not a predicate, it is necessary to differentiate between what he termed a logical predicate from a real predicate. A logical predicate, according to Kant, “may be what you please, even the subject may be predicated of itself.”21 For example, in the statement “A cat is a cat” the subject is predicated of itself. Logical predicates have no bearing upon their subjects. That is, they do not add anything to the meaning of the subject. By contrast, a real predicate is, for Kant, “a predicate which aids in the determination of a thing.”22 Kant said that terms such as “being” and “exists” can never be real predicates because the terms do not add to the notion of their subjects.

Thus, Kant wrote,

“if I take the subject (God) with all its predicates (omnipotence being one), and say: God is, or, There is a God, I add no new predicate to the conception of God, I merely posit or affirm the existence of the subject with all its predicates—I posit the object in relation to my conception. The content of both is the same; and there is no addition made to the conception, which expresses merely the possibility of the object, by my cogitating the object—in the expression, it is—as absolutely given or existing. Thus the real contains no more than the possible.”

God, as He exists in the mind and God, if He were to exist in reality, are equally great. To claim that God is not as great if He only exists in the mind and not in reality is not valid because the notion of existence is not a “real” predicate, it is a “logical” predicate which adds nothing to the subject.

Anselm would perhaps have said that Kant’s definition of a predicate was appropriate for all other beings except God. God, for Anselm, is that than which none greater can be conceived. Even an atheist, when he hears of God, has a conception of God; therefore God exists even in the atheist’s mind. But if God is really the greatest conceivable being, and if God is a necessary being upon which all contingent beings depend for their being, then His non-existence is an absurd concept.

Plantinga’s way out of Kant’s objection

Alvin Plantinga of the University of Notre Dame sought to avoid Kant’s objection altogether. Plantinga, in his work God, Freedom and Evil restated the ontological argument in this way:

1. It is possible that there be a being that has maximal greatness.
2. So there is a possible being that in some world W has maximal greatness.
3. A Being has maximal greatness in a given world only if it has maximal excellence in every world.
4. A being has maximal excellence in a given world only if it has omniscience, omnipotence and moral perfection in that world.
5. There is a possible world in which maximal greatness is instantiated.
6. Necessarily, a being is maximally great only if it has maximal excellence in every world.
7. Necessarily a being has maximal excellence in every world only if it has omniscience, omnipotence and moral perfection in every world.

Plantinga tried to avoid Kant’s critique by defining a being with maximal greatness as having the properties of omniscience, omnipotence and moral perfection. By acknowledging these properties in God, Plantinga sought to avoid the charge that he based his whole argument on the assumption that existence is itself a predicate. Thus, he stated that “a being can’t be omnipotent (or for that matter omniscient or morally perfect) in a given world unless it exists in that world.”

Plantinga considered his argument to be consistent with how Anselm understood the notion of God’s existence. He neither believed that his argument necessitated that God’s existence serve as a predicate nor did Anselm’s. Plantinga wrote,

“Anselm argues that the proposition God exists is necessarily true; but neither this claim nor his argument for it entails or presupposes that existence is a predicate in the sense just explained.”26

Plantinga denied that Anselm was attempting to conceive God into existence because (contra Kant) existence is not an attribute added to a necessary being, though that might be the case for a contingent being. For a contingent being, Plantinga asserted, an object that exists in the mind is logically equivalent to the corresponding object that exists in reality. But this was not Anselm’s view of God. According to Plantinga, “If this were Anselm’s procedure—if he started with some concept that has instances contingently if at all and then annexed existence to it—then indeed his argument would be subject to Kant’s criticism. But he didn’t, and it isn’t.”

Geisler, Rowe and Corduan’s critique of Plantinga

Norman Geisler and Winfried Corduan, in their work Philosophy of Religion found much to admire about Plantinga’s version of the ontological argument, and about his defense of Anselm. However, their critique of Plantinga was two-fold. First, Plantinga presupposes that there is a reality at all. The argument cannot proceed unless the basic assumption that something exists is a necessary truth. To argue this way one must abandon a priori reasoning.

Another critique Geisler and Corduan made against Plantinga was that he made the assumption that the maximally excellent being should be theistically defined. Nothing about Plantinga’s argument, asserted Geisler and Corduan, compelled one to make this assumption. “Why could not perfection be viewed in nonmoral, nonintelligent terms,” they ask.

Plantinga sought to avoid Kant’s venerable and potent critique of the ontological argument, but he could not avoid the stinging critique made by William Rowe of Purdue University. According to Davis, Rowe “succeeds in breaking new ground”29 by critiquing the ontological argument on the basis of the informal fallacy of begging the question. Prior to explaining Rowe’s critique, however, it is necessary to provide his version of the ontological argument:

1. God exists in the understanding.
2. God might have existed in reality (God is a possible being).
3. If something exists only in the understanding and might have existed in reality then it might have been greater than it is.
4. Suppose God exists only in the understanding.
5. God might have been greater than He is. (2, 4, and 3)
6. God is a being than which a greater is possible. (5)
7. The being than which none greater is possible is a being than which a greater is possible.
8. It is false that God exists only in the understanding.
9. God exists in reality as well as in the understanding. (1, 8)

The heart of Rowe’s critique of the argument is that, in granting premise (2), that God is not an incoherent concept, we granted Anselm too much. Rowe wrote,

“Without realizing it, we were in fact granting much more than this. . . . Since Anselm’s concept of God logically cannot apply to some non-existing thing, the only possible objects to which it could apply are possible objects which actually exist.” William Rowe

So how exactly does the argument beg the question, according to Rowe? First, Rowe differentiated two ways of begging the question, the logical and the epistemological ways. The logical way of begging the question, Rowe explained, is when one assumes the conclusion in one of the premises. However, Rowe stated, “when an argument is such that its premises cannot be known independently of its conclusion, the argument begs the question in itself in an epistemological way.”

Rowe was careful not to say that the argument begs the question in the logical way, but rather in the epistemological way. So if, according to Rowe, the argument’s definition of God as the greatest possible being is not incoherent or contradictory—if premise is granted—and that if existence is a great-making quality from premise, then only an existing thing could be God. Davis summarized Rowe stating, “The notion of God cannot logically apply to a non-existing thing, so the only possible objects to which it can apply are existing ones.” So, in order to know the premises of the argument are true, one must know the conclusion to be true. Thus, the argument begs the question in the epistemological way.

Still, Davis disagreed that Anselm’s argument begs the question. He made the point that Anselm’s intention was in fact to produce the conclusion that God exists from his definition of God together with premises and the fact that one may grant more than expected to premise may on the surface be astonishing, but that one should not think that he is guilty of committing a fallacy. Davis wrote, “It might be true that the definition of God together with premises and logically entail that God exists, but that is another matter. This certainly does not show that premise  is ‘virtually equivalent’ to ‘God exists’ or that it ‘amounts to the assertion’ that God exists.”

Certainly many other historical and contemporary assessments of Anselm’s ontological argument could be presented and critiqued, but this would be far beyond the scope of this study. The purpose of presenting these assessments has been to show the controversial nature of the argument, that its conclusions have been widely contested over the course of many centuries. Important flaws in the structure of the argument have been pointed out by thinkers down through the years. But, as shown in the examples above, the complaints against the argument have not proven to be decisive in defeating it. The point here is that, given the weaknesses of the argument revealed by Kant, Rowe and others, Anselm’s goal of formulating one universally agreed upon argument proving that God exists has not been fulfilled. But even if it hasn’t satisfied every thinker on the issue of the existence of God, it can still be useful to show that God’s existence is logical and that belief in Him is rational.

Appraisal of the Value of Anselm’s Argument for Apologetics

Does the argument have anything at all of value to offer? The answer to this question is, certainly. John Hick stated (and one might add that he is no friend of Anselm’s argument) that

“The most valuable feature of Anselm’s argument is its formulation of the Christian concept of God.” John Hick

Anselm developed the final form of monotheism in his definition of God as the being than which no greater can be conceived. Hick summarized the implications of this definition saying, “there is no possibility of another reality beyond him to which he is inferior or subordinate and which would thus be an even more worthy recipient of man’s devotion. . . . Here the religious exigencies that move from polytheism through henotheism to ethical monotheism reach their logical terminus.”37 This is quite an acknowledgement, considering it arrives from an opponent of the argument.

Another element of value the argument offers is that it can be said to provide a rational justification for belief in God. Plantinga asserts that the argument “establishes . . . rational acceptability” for theism.38 Anselm’s argument is brilliantly conceived, and while it has been an object of controversy for many centuries, it has also proved resilient. Furthermore, Brown noted that Karl Barth, in his extensive study of Anselm, concluded that it was a mistake to assume that he intended merely to derive God’s existence purely without appeal to outside authority. Rather, according to Brown, Barth asserted:

“Anselm intended to show that we cannot rationally deny the living God once we know who he is—the most perfect being.” Karl Barth

Brown went further to say that in any consideration of Anselm, it must be remembered that he was not trying to prove God first in order that belief in God might follow. According to Brown, Anselm thought, “it is only when we believe that we are in a position to understand its grounds and significance. In its context the ontological argument seeks to answer the question raised by the Psalms, how it is that the fool can say in his heart that there is no God (Psalms 14:1; 53:1). ”Keeping this context in mind is helpful in understanding what the argument was meant to accomplish in the broader sense.

Conclusion: Why the ontological argument is still useful

Corduan is correct in his assertion that rationality alone cannot serve as a test for truth, “when it comes to such large-scale matters as the existence of God.”41 If the measure for a useful apologetic for God’s existence is that it must stand alone and apart from other apologetic methods, then the ontological argument is not useful. If the measure for a useful apologetic for God’s existence is that it must satisfy everyone it encounters, then the argument fails here also.

But if the measure is that the apologetic argument must be rational, must be consistent with Scriptural teaching, and must fit within a cumulative case for the Christian faith, then it seems that the ontological argument is indeed useful. The argument goes to show the possibility that God’s existence can be arrived at not only through the testimony of Scripture, the evidence of Creation, but also by deduction. The God posited by the argument, namely the greatest conceivable being, is a being that Scripture also posits. It is true that the argument does not conclusively arrive at the God of the Bible, but neither does the argument exclude the God of the Bible. Finally, while the complaint can be made that the ontological argument must at some point be argued cosmologically, the complaint does not take away from the usefulness of the argument. When the ontological argument is set alongside the a posteriori arguments for God’s existence, a cumulative case is made for it—even if the formal purity of the argument might be compromised.

The ontological argument ought not be jettisoned from a cumulative case for God’s existence simply because it has failed to satisfy all those who have considered it. It has endured for nearly a thousand years and it has survived intact the onslaughts of worthy thinkers.

While many of the critiques levelled against the ontological argument are legitimate and worth discussing, the purpose of the argument must be remembered—to give understanding to those who seek to grasp the meaning of the supreme being of God.