Anselm's Ontological Argument

The evidences for the existence of God that we've considered in this series of arguments for the existence of God so far have all been a posteriori—proofs in which the reasoning has been from the effect to the cause. The ontological argument follows the opposite, a priori, method. Just as in geometry we argue a priori from the nature or essence of the figure, as expressed in its definition, to its various properties, so certain thinkers have sought to argue from the nature of God to the fact of His existence. God, it must be remembered, exists necessarily. To exist belongs to His very essence. In this He differs from all finite things. Their existence is contingent. Their natures can be expressed in concepts, whether they exist or not, and the concepts throw no light on the question of their existence. However, if we could arrive at a knowledge of the Divine essence, we couldn't represent it thus apart from its real existence. Existence isn't something extraneous to its nature as such, but enters into the nature as a necessary constituent. And this it is which has led men to believe that it is possible to argue from the concept of God's nature to His actual existence, precisely as we argue from essence to property. Those who made this attempt failed to realize that though God's nature demands existence, yet our human intellect is incapable of knowing the Divine essence as it is. We're on a lower plane of being, and our powers are proportional to our nature. Of natures that are above us we posses a meager and inadequate knowledge, reached through abstraction and discursive reason. We know something about them, but can't really be said to know them. For this reason, Aristotle made his well-known comparison of the human intellect to the eyes of bats, saying that as bats are blinded by the daylight, but see in the dusk, so man has but a dim and imperfect cognition of the things which in themselves are such as to evoke the clearest knowledge; and that he knows best those sensible objects, which by reason of their material nature are incapable of being apprehended otherwise than obscurely. Yet though the proof, as we will see, is invalid, two thinkers of great eminence—Anselm of Canterbury, who first propounded the argument, and, subsequently, Descartes—have not only regarded it as sound reasoning, but as the most secure of all the demonstrations of God's existence, while Leibniz also gave it his approval. It thus possesses great historical interest, and can't be passed over in silence. Anselm knew that there must be some simple yet cogent argument, demonstrating both that God exists, and that He is the supremely perfect Being in whom all perfections are found. The argument is developed in the first chapters of the work to which Anselm gave the name 'An Address on God's Existence'. It may be thus summarized: The term God signifies that than which nothing greater can be conceived. Even the fool, when he denies the existence of God, has an idea corresponding to the word 'God'; and his idea is what we've just stated. That is, that of a nature than which nothing greater can be conceived. However, a nature which is of this kind is a necessarily existing nature. If it only existed in the mind, we could conceive something greater. That is, a nature so great as not merely to exist in the mind, but to be exigent of real existence as well. God, therefore, exists. Such an argument stated like this is invalid. It is true that a nature conceived as that other than which nothing greater can be thought of, must be conceived as necessarily existing, exists at all. The point at issue is, is there such a nature? Couldn't it be that it is pure imagination? If so, although when we conceive it, we conceive it as self-existent, it won't really exist outside our imagination. Many skeptics have seen no more in the argument than a sophism, and have countered that any person of intelligence could have been deluded into regarding it as a valid argument. Such was the attitude of Anselm's contemporary, the monk Gaunilo of Marmoutiers. He argued that in this way he could prove the existence of a fabled Lost Island, which was supplied with all riches and all conceivable delights. “Let it be granted," he argued, “that the idea of that island is of a land which excels all others, and you must own that my fabulous region exists: for otherwise the idea of some really existing land would excel it.”1 And to this day it is often thought sufficient to dismiss the reasoning in similar fashion. Yet careful consideration might well suggest that one of the most profound intellects of his age wasn't likely to have been misled by a childish fantasy; that there was probably something deeper in the argument than appears at first sight. That this was so, in fact, is shown by Anselm's reply to his critic. He there states definitely that his argument is specific to the infinitely perfect being, and that to apply it to anything finite is to have completely misunderstood its significance. This sheds a new light on Anselm's intention. It is, in fact, evident that a being possessed of infinite perfection must be self-existent. If He receives existence from another, He's dependent on that other, and not infinite at all. In other words, self-existence is part of the essential nature of the infinitely perfect. Now let's assume that there is nothing contradictory in an infinitely perfect nature, and that no impossibility is involved in the idea; that it is capable of actual existence. It follows of necessity that it exists. Here, though not in other cases, possibility implies existence. In all other cases, if we say that a nature is possible, we mean that there is no internal contradiction involved, and that consequently, given an adequate efficient cause, the nature might be realized. But here, as we've seen, there is no question of dependence on an efficient cause. The nature is its own sufficient reason. If it is possible, it exists actually. It would be a contradiction in terms for such a nature to merely be possible—to be capable of existence and yet not to exist actually, since self- existence belongs to its essence. Anselm's real error is in the assumption that an infinite nature involves nothing contradictory, and that its possibility is not open to question. It is one thing to be able to affirm of some essence that we can fully apprehend, that we can see its possibility, but it is another to have to content ourselves with saying, with regard to a nature obscurely and imperfectly known, that we don't detect its impossibility. The latter is our case with regard to the infinite. Our concept of the infinite is negative. It gives us no insight into the essential nature of the one infinite Being, but simply asserts absence of limits. Indeed, that the possibility of an infinite nature isn't immediately self-evident appears from the fact that at the present day some Modernist philosophers and theologians are prepared to maintain the thesis of a finite God. That position leads to all sorts of contradictions, and is incapable of reasonable defense. However, the possibility of an infinite being must be established by logical arguments. And this is done by demonstrating a posteriori that a First Cause exists, and then that He must be infinitely perfect. Since the infinite exists, we know that such a being is possible. It follows from this that the argument fails for the reason which we first gave. Inasmuch as our notion of the infinite doesn't assure us of its internal possibility, we can draw no conclusion other that an infinite nature must be conceived as existing necessarily, if it exists at all. We can't prove that it does exist, since we lack the power to frame an idea of the essential nature of the infinite.

It isn't too much to say that few of Anselm's critics have understood his argument. They think it is sufficient to adopt an illustration employed by Kant, and to say that we can't prove the existence of a hundred dollars from the idea of them, no matter how good the dollars are supposed to be. This refutation of Anselm's argument really misses the point of that this is an effort to discriminate between the idea of God and all other ideas. Gaunilo's objection comes closer to the point than Kant's does. Anselm argued that existence must belong to one idea, though to one only, namely, the idea of that other than which nothing greater can be conceived. To say, as Kant does, that the idea of a hundred dollars doesn't involve their existence, is quite irrelevant, since we can easily conceive greater things than a hundred dollars. On the other hand, Gaunilo's idea of a perfect island was at least the idea of something perfect or complete of its kind. Nothing greater of its kind could be conceived. We can, however, conceive something of a greater kind—perfect of its kind, and of a kind more perfect.

Scotus, and, long afterwards, Leibniz, both put their finger on the weak spot, and pointed out that the argument was inconclusive because the mind can't affirm with certainty that an infinite nature is possible.

Descartes Weighs In
Descartes' version of the argument isn't materially different from that of Anselm. It is worthwhile, how-ever, to see how it takes its place in his system. According to him, the concept of God is an innate idea. He denied, as is well known, what appears to be so evident, that through sense-perception we possess direct cognition of the external world, and held that the direct object of knowledge is always internal and spiritual; that we have no immediate knowledge of anything except the ideas within the soul. These ideas he distinguishes into 'adventitious' and 'innate.'
Adventitious ideas include all particular perceptions. These appear to inform us of the existence of a material world outside us; yet it would be rash to accept their testimony on this point without further guarantee. As innate we must reckon our universal ideas, and all common notions, i.e., axiomatic truths. These can't come from without: no particular impression can be the cause of a universal idea. Are, then, these innate ideas capable of giving us valid knowledge? And if so, what can we gather from them? He answers this question by the application of his criterion of truth, viz., clearness of conception. If the innate ideas are tested by this criterion, it appears that they convey perfectly valid knowledge, but in reference only to possible existence, not to real. The note of possible existence is attached to every nature thus intellectually conceived. Any one of them could be actualized in a real external order of things. Yet there is among them one that differs from the rest—the idea of God. This contains the note, not of possible, but of real existence. It is the idea of a supremely perfect Being, and a Being can't be conceived as supremely perfect unless it is really existent. God, therefore, exists. The argument can be stated thus:
  • Every note which is contained in the clear idea of any nature belongs in fact to that nature.
  • Real (and not merely possible) existence is contained in the clear idea of God.
  • Therefore, God really exists.
In God's existence he finds a satisfactory basis for certainty regarding the reality of an external world. Since adventitious ideas must come from myself, from God, or from an external corporeal world. They don't come from myself, since they come often against my will. They don't come from God, since He wouldn't deceive me. There is, therefore, an external world. The criticism of Anselm's form of the argument is true here. Our idea of the supremely perfect being containing the note of necessary existence isn't obvious in the sense that is necessary for the validity of the reasoning. We can form such ideas of geometrical figures. The intellect knows beyond all doubt that these contain no contradictory elements, and that, therefore, possible existence can be argued, but we have no such certainty regarding the concept of supreme perfection. For all we know, some impossibility might be involved in such a nature. That this isn't the case must be demonstrated. Descartes' contention that the idea isn't gathered from created things, but forms part of the soul's initial endowment, seems to lend some clarity to his conclusion that the idea can't be a figment of our own minds, but must represent objective reality. However, as we've previously pointed out, his whole theory of innate ideas is baseless. The idea of God, the perfect Being, stands in no need of recourse to any such hypothesis. We reach it without difficulty by considering the finite perfections of the created world, and then forming a negative idea, in which perfection is conceived without any limit.

1In Behalf of the Fool, Guanilo's response to Anselms address.