The Ontological Argument of Anselm of Canterbury
Anselm’s Proslogium
Chapter 1: Encouraging the Mind to Contemplate God
… I acknowledge, Lord, and I give thanks that you have created in me this your image, so that I can remember you, think about you and love you. But … my intellect does not measure up to that task… Nor do I seek to understand so that I can believe, but rather I believe so that I can understand. For I believe this too, that “unless I believe I shall not understand” (Isa. 7:9).
Chapter 2: That God Really Exists
Therefore, Lord, you who give knowledge of the faith, give me as much knowledge as you know to be fitting for me, because you are as we believe and that which we believe. And indeed we believe you are something greater than which cannot be thought. Or is there no such kind of thing, for “the fool said in his heart, ‘there is no God'” (Ps. 13:1, 52:1)? But certainly that same fool, having heard what I just said, “something greater than which cannot be thought,” understands what he heard, and what he understands is in his thought, even if he does not think it exists. For it is one thing for something to exist in a person’s thought and quite another for the person to think that thing exists. For when a painter thinks ahead to what he will paint, he has that picture in his thought, but he does not yet think it exists, because he has not done it yet. Once he has painted it he has it in his thought and thinks it exists because he has done it. Thus even the fool is compelled to grant that something greater than which cannot be thought exists in thought, because he understands what he hears, and whatever is understood exists in thought. And certainly that greater than which cannot be understood cannot exist only in thought, for if it exists only in thought it could also be thought of as existing in reality as well, which is greater. If, therefore, that than which greater cannot be thought exists in thought alone, then that than which greater cannot be thought turns out to be that than which something greater actually can be thought, but that is obviously impossible. Therefore something than which greater cannot be thought undoubtedly exists both in thought and in reality.
Chapter 3: That God Cannot be Thought Not to Exist
In fact, it so undoubtedly exists that it cannot be thought of as not existing. For one can think there exists something that cannot be thought of as not existing, and that would be greater than something which can be thought of as not existing. For if that greater than which cannot be thought can be thought of as not existing, then that greater than which cannot be thought is not that greater than which cannot be thought, which does not make sense. Thus that than which nothing can be thought so undoubtedly exists that it cannot even be thought of as not existing.
And you, Lord God, are this being. You exist so undoubtedly, my Lord God, that you cannot even be thought of as not existing. And deservedly, for if some mind could think of something greater than you, that creature would rise above the creator and could pass judgment on the creator, which is absurd. And indeed whatever exists except you alone can be thought of as not existing. You alone of all things most truly exists and thus enjoy existence to the fullest degree of all things, because nothing else exists so undoubtedly, and thus everything else enjoys being in a lesser degree. Why therefore did the fool say in his heart “there is no God,” since it is so evident to any rational mind that you above all things exist? Why indeed, except precisely because he is stupid and foolish?
Chapter 4: How the Fool Managed to Say in His Heart That Which Cannot be Thought
How in the world could he have said in his heart what he could not think? Or how indeed could he not have thought what he said in his heart, since saying it in his heart is the same as thinking it? But if he really thought it because he said it in his heart, and did not say it in his heart because he could not possibly have thought it – and that seems to be precisely what happened – then there must be more than one way in which something can be said in one’s heart or thought. For a thing is thought in one way when the words signifying it are thought, and it is thought in quite another way when the thing signified is understood. God can be thought not to exist in the first way but not in the second. For no one who understands what God is can think that he does not exist. Even though he may say those words in his heart he will give them some other meaning or no meaning at all. For God is that greater than which cannot be thought. Whoever understands this also understands that God exists in such a way that one cannot even think of him as not existing.
Thank you, my good God, thank you, because what I believed earlier through your gift I now understand through your illumination in such a way that I would be unable not to understand it even if I did not want to believe you existed.
In the many subsequent chapters, Anselm deduced God’s nature from his basic definition: his God is creative, rational, omnipotent, merciful, unchangeable, just, eternal, etc.
We turn to Rosen’s commentary.
Gideon Rosen’s Analysis
Anselm’s ontological argument purports to be an a priori proof of God’s existence. Anselm starts with premises that do not depend on experience for their justification and then proceeds by purely logical means to the conclusion that God exists. His aim is to refute the fool who says in his heart that there is no God (Psalms 14:1). This fool has two important features.
- He understands the claim that God exists.
- He does not believe that God exists.
Anselm’s goal is to show that this combination is unstable. Anyone who understands what it means to say that God exists can be led to see that God does exist. On this view, the atheist is not just mistaken: his position is internally inconsistent.
What follows is an attempt to clarify the argument as it is presented in Chapter II of the Proslogium. The argument in Chapter III is rather different, and in some ways more interesting. After you have worked through this[], you might try to produce a similar gloss on the second argument. This will not be easy: the argument is notoriously complicated. But you might find it a useful exercise nonetheless.
A Running Paraphrase of the Argument
Let’s work through the argument as Anselm presents it. Anselm writes:
… we believe that thou art a being than which nothing greater can be conceived.
This is Anselm’s definition. We might paraphrase it as follows:
By “God” we mean an absolutely unsurpassable being, a being that cannot conceivably be improved upon.
As we’ve stressed, you do not need to agree that this is what the word “God” ordinarily means. Treat it as a stipulation. Clearly, if Anselm can establish the existence of a being of this sort, his conclusion would be of immense philosophical and theological significance.
Or is there no such nature, since the Fool has said in his heart, there is no God?
This puts the question: Is there in fact a being with the properties our definition assigns to God?
But, at any rate, this very fool, when he hears of this being of which I speak – a being than which nothing greater can be conceived – understands what he hears, and what he understands is in his understanding; although he does not understand it to exist.
This begins and ends straightforwardly. The fool understands the definition of God but denies that God exists. The first hint of strangeness comes in what seems to be a parenthetical remark: “what he understands is in his understanding.” Anselm apparently proposes to treat the understanding or the mind as if it were a place, and to speak of things existing “in the understanding.” Anselm’s assumption here is that if I understand claims about God, then we may say that God exists in my understanding or in my mind.
For it is one thing for an object to be in the understanding, another to understand that the object exists. For when a painter first conceives of what he will afterwards perform, he has it in his understanding be he does not yet understand it to be, because he has not yet performed it. But after he has made the painting, he both has it in his understanding and he understands that it exists, because he has made it.
Anselm here explains a distinction. It is one thing for an object to exist in my understanding, and another for me to understand it to exist. This is a familiar distinction, even if the terms are not familiar. Ghosts, trolls, flying saucers and the like are all things I can think about. We might say that I have ideas of these things; Anselm says that they exist in the understanding. Anselm’s point is that in general there is a difference between saying that something exists in my understanding and saying that I understand (or believe) it to exist. Trolls exist in my understanding; but I do not understand them to exist.
Hence even the fool is convinced that something exists in the understanding, at least, than which nothing greater can be conceived. For when he hears of this, he understands it. And whatever is understood, exists in the understanding.
Here Anselm applies the distinction he has just drawn to the case of God. The fool understands claims about God. So God – a being than which none greater can be conceived – exists in his understanding. Anselm means this to be an entirely uncontroversial claim.
And assuredly, that than which nothing greater can be conceived cannot exist in the understanding alone: then it can be conceived to exist in reality, which is greater.
Therefore, if that than which nothing greater can be conceived exists in the understanding alone, the very being than which nothing greater can be conceived is one than which a greater can be conceived. But obviously this is impossible.
This is the heart of the argument. The trick is to show that God cannot possibly exist in the understanding alone. Anselm begins by contrasting existing in the understanding with existing in reality. This by itself is not problematic. Trolls exist in the understanding alone; Bill Clinton exists both in the understanding and in reality; and no doubt there are things that exist in reality that do not yet exist in the understanding because no human being has ever managed to frame a thought about them. The picture seems to be as follows:
In the area marked A we have things that exist in the understanding alone; in the area marked B we have things that exist both in the understanding and in reality; and in the area marked C we have things that exist in reality but not in the understanding. (For obvious reasons, we cannot give any concrete examples of the last category.)
At this stage the fool has conceded that God exists in the understanding: so God belongs either in A or in B. Anselm now argues that God cannot exist in the understanding alone. The argument seems to proceed as follows.
- Suppose (with the fool) that God exists in the understanding alone.
- Given our definition, this means that a being than which none greater can be conceived exists in the understanding alone.
- But this being can be conceived to exist in reality. That is, we can conceive of a circumstance in which theism is true, even if we do not believe that it actually obtains.
- But it is greater for a thing to exist in reality than for it to exist in the understanding alone.
- Hence we seem forced to conclude that a being than which none greater can be conceived can be conceived to be greater than it is.
- But that is absurd.
- So (1) must be false. God must exist in reality as well as in the understanding.
This reading of the argument is amply confirmed by the final paragraph:
Therefore, if that than which nothing greater can be conceived exists in the understanding alone, the very being than which nothing greater can be conceived is one than which a greater can be conceived. But obviously this is impossible. Hence there is no doubt that there exists a being than which nothing greater can be conceived, and it exists both in the understanding and in reality.
A Reconstruction of the Argument
This is a useful first pass at the argument. Now let’s go over it and try to isolate its most fundamental assumptions. (I’ll highlight the premises of the reconstructed argument in red.) Remember the argument’s dialectical context. The aim is to refute the fool – or less tendentiously, the rational atheist. So what we want to know about these premises is whether the fool should accept them. There is first the definition:
(a) By “God” we mean “a being than which no greater being can be conceived.”
Then there are some assumptions about the Fool’s understanding.
(b) We understand what it means to speak of a being than which no greater can be conceived. We understand what these words mean.
(c) We can conceive of such a being’s existing in reality.
Anselm now assumes a principle that he clearly regards as trivial.
(d) If we understand what it means to speak of X, then X exists in the understanding.
From (a), (b), and (d) we may now infer:
(e) God exists in the understanding.
(Note: this is not a premise. It is an intermediate conclusion supported by a quick argument from premises we have already accepted.)
Anselm now employs a form of reasoning called reductio ad absurdum. This is a very useful technique. In a proof of this sort, we begin by assuming the opposite of what we want to prove. Then we derive a contradiction or an absurdity from this supposition. And from this we conclude that our original assumption was false. The general form of such an argument is as follows:
Premiss: Suppose p.
Premiss: From p it follows that q.
Premiss: But q is absurd (self-contradictory).
Conclusion: Therefore p is false.
For Anselm the target of his reduction is the proposition that God exists in the understanding alone. So let us suppose that this is the case:
(f) Suppose that God exists in the understanding but not in reality.
From (f) and (c) we may now infer
(g) God in fact exists in the understanding alone, but he may be conceived to exist in reality as well as in the understanding.
At this point Anselm wields what is perhaps his most controversial premise. It is hard to know exactly how to formulate it. But something like the following seems to be what Anselm has in mind.
(h) If something exists in the understanding alone, but can be conceived to exist in reality, then that thing can be conceived to be greater than it actually is.
The idea seems to be: if we compare two things that are alike in all respects except that one exists in the understanding alone and the other exists in reality, then the one that exists in reality is clearly greater, better, more perfect. We will have to discuss the cogency of this assumption in class. But suppose for now that it is granted. We may then argue as follows. From (g) and (h) it follows that
(i) God can be conceived to be greater than it actually is.
But this is absurd. For given our definition (a), this just means that
(j) A being that cannot be conceived to be greater than it is can be conceived to be greater than it is.
From which it follows that our supposition (f) is false. We may therefore conclude
(k) God exists in reality.
Now you should ask: Is this a valid argument as it stands? Are the assumptions plausible? Would the fool be willing to grant them? Would you be willing to grant them? If you think that the argument is not a good one, you are under an obligation to say where it goes wrong. It might go wrong in several places. See how many “mistakes” you can find.
Anselm’s thoughts did not go unchallenged in his day, however. His first major critic was Gaunilo, a monk in the abbey of Marmoutier. Gaunilo’s reply is the only bit of writing we possess by him, which is a shame, because in it we encounter a very perceptive mind, although a radically different one than Anselm’s.
So we return to the 11th century dispute – this time, to the voice of the monk, Gaunilo.
Gaunilo’s “In Behalf of the Fool”
Gaunilo’s subtitle was honorific: “An Answer to the Argument of Anselm in the Proslogium, by Gaunilo, a monk of Marmoutier.”
1. IF one doubts or denies the existence of a being of such a nature that nothing greater than it can be conceived, he receives this answer:
Gaunilo recites Anselm’s argument.
The existence of this being is proved, in the first place, by the fact that he himself, in his doubt or denial regarding this being, already has it in his understanding; for in hearing it spoken of he understands what is spoken of. It is proved, therefore, by the fact that what he understands must exist not only in his understanding, but in reality also.
And the proof of this is as follows. — It is a greater thing to exist both in the understanding and in reality than to be in the understanding alone. And if this being is in the understanding alone, whatever has even in the past existed in reality will be greater than this being. And so that which was greater than all beings will be less than some being, and will not be greater than all: which is a manifest contradiction.
And hence, that which is greater than all, already proved to be in the understanding, must exist not only in the understanding, but also in reality: for otherwise it will not be greater than all other beings.
2. The fool might make this reply:
This being is said to be in my understanding already, only because I understand what is said. Now could it not with equal justice be said that I have in my understanding all manner of unreal objects, having absolutely no existence in themselves, because I understand these things if one speaks of them, whatever they may be?
Unless indeed it is shown that this being is of such a character that it cannot be held in concept like all unreal objects, or objects whose existence is uncertain: and hence I am not able to conceive of it when I hear of it, or to hold it in concept; but I must understand it and have it in my understanding; because, it seems, I cannot conceive of it in any other way than by understanding it, that is, by comprehending in my knowledge its existence in reality.
But if this is the case, in the first place there will be no distinction between what has precedence in time — namely, the having of an object in the understanding — and what is subsequent in time — namely, the understanding that an object exists; as in the example of the picture, which exists first in the mind of the painter, and afterwards in his work.
“God doesn’t exist” doesn’t seem to be contradictory, as it’s at least conceivable.
Finally, that this being so exists that it cannot be perceived by an understanding convinced of its own indubitable existence, unless this being is afterwards conceived of — this should be proved to me by an indisputable argument, but not by that which you have advanced: namely, that what I understand, when I hear it, already is in my understanding. For thus in my understanding, as I still think, could be all sorts of things whose existence is uncertain, or which do not exist at all, if some one whose words I should understand mentioned them. And so much the more if I should be deceived, as often happens, and believe in them: though I do not yet believe in the being whose existence you would prove.
3. Hence, your example of the painter who already has in his understanding what he is to paint cannot agree with this argument. For the picture, before it is made, is contained in the artificer’s art itself; and any such thing, existing in the art of an artificer, is nothing but a part of his understanding itself. A joiner, St. Augustine says, when he is about to make a box in fact, first has it in his art. The box which is made in fact is not life; but the box which exists in his art is life. For the artificer’s soul lives, in which all these things are, before they are produced. Why, then, are these things life in the living soul of the artificer, unless because they are nothing else than the knowledge or understanding of the soul itself?
With the exception, however, of those facts which are known to pertain to the mental nature, whatever, on being heard and thought out by the understanding, is perceived to be real, undoubtedly that real object is one thing, and the understanding itself, by which the object is grasped, is another. Hence, even if it were true that there is a being than which a greater is inconceivable: yet to this being, when heard of and understood, the not yet created picture in the mind of the painter is not analogous.
4. Let us notice also the point touched on above, with regard to this being which is greater than all which can be conceived, and which, it is said, can be none other than God himself. I, so far as actual knowledge of the object, either from its specific or general character, is concerned, am as little able to conceive of this being when I hear of it, or to have it in my understanding, as I am to conceive of or understand God himself: whom, indeed, for this very reason I can conceive not to exist. For I do not know that reality itself which God is, nor can I form a conjecture of that reality from some other like reality. For you yourself assert that that reality is such that there can be nothing else like it.
For, suppose that I should hear something said of a man absolutely unknown to me, of whose very existence I was unaware. Through that special or general knowledge by which I know what man is, or what men are, I could conceive of him also, according to the reality itself, which man is. And yet it would be possible, if the person who told me of him deceived me, that the man himself, of whom I conceived, did not exist ; since that reality according to which I conceived of him, though a no less indisputable fact, was not that man, but any man.
Is God in fact conceivable?
For when it is so conceived, it is not so much the word itself (which is, indeed, a real thing — that is, the sound of the letters and syllables) as the signification of the word, when heard, that is conceived. But it is not conceived as by one who knows what is generally signified by the word; by whom, that is, it is conceived according to a reality and in true conception alone. It is conceived as by a man who does not know the object, and conceives of it only in accordance with the movement of his mind produced by hearing the word, the mind attempting to image for itself the signification of the word that is heard. And it would be surprising if in the reality of fact it could ever attain to this.
Thus, it appears, and in no other way, this being is also in my understanding, when I hear and understand a person who says that there is a being greater than all conceivable beings. So much for the assertion that this supreme nature already is in my understanding.
5. But that this being must exist, not only in the understanding but also in reality, is thus proved to me:
Gaunilo rehearses another piece of Anselm’s argument.
If it did not so exist, whatever exists in reality would be greater than it. And so the being which has been already proved to exist in my understanding, will not be greater than all other beings.
I still answer: if it should be said that a being which cannot be even conceived in terms of any fact, is in the understanding, I do not deny that this being is, accordingly, in my understanding. But since through this fact it can in no wise attain to real existence also, I do not yet concede to it that existence at all, until some certain proof of it shall be given.
For he who says that this being exists, because otherwise the being which is greater than all will not be greater than all, does not attend strictly enough to what he is saying. For I do not yet say, no, I even deny or doubt that this being is greater than any real object. Nor do I concede to it any other existence than this (if it should be called existence) which it has when the mind, according to a word merely heard, tries to form the image of an object absolutely unknown to it.
How, then, is the veritable existence of that being proved to me from the assumption, by hypothesis, that it is greater than all other beings? For I should still deny this, or doubt your demonstration of it, to this extent, that I should not admit that this being is in my understanding and concept even in the way in which many objects whose real existence is uncertain and doubtful, are in my understanding and concept. For it should be proved first that this being itself really exists somewhere; and then, from the fact that it is greater than all, we shall not hesitate to infer that it also subsists in itself.
6. For example: it is said that somewhere in the ocean is an island, which, because of the difficulty, or rather the impossibility, of discovering what does not exist, is called the lost island. And they say that this island has an inestimable wealth of all manner of riches and delicacies in greater abundance than is told of the Islands of the Blest; and that having no owner or inhabitant, it is more excellent than all other countries, which are inhabited by mankind, in the abundance with which it is stored.
Now if some one should tell me that there is such an island, I should easily understand his words, in which there is no difficulty. But suppose that he went on to say, as if by a logical inference: “You can no longer doubt that this island which is more excellent than all lands exists somewhere, since you have no doubt that it is in your understanding. And since it is more excellent not to be in the understanding alone, but to exist both in the understanding and in reality, for this reason it must exist. For if it does not exist, any land which really exists will be more excellent than it; and so the island already understood by you to be more excellent will not be more excellent.”
If a man should try to prove to me by such reasoning that this island truly exists, and that its existence should no longer be doubted, either I should believe that he was jesting, or I know not which I ought to regard as the greater fool: myself, supposing that I should allow this proof; or him, if he should suppose that he had established with any certainty the existence of this island. For he ought to show first that the hypothetical excellence of this island exists as a real and indubitable fact, and in no wise as any unreal object, or one whose existence is uncertain, in my understanding.
7. This, in the mean time, is the answer the fool could make to the arguments urged against him. When he is assured in the first place that this being is so great that its non-existence is not even conceivable, and that this in turn is proved on no other ground than the fact that otherwise it will not be greater than all things, the fool may make the same answer, and say:
Gaunilo insists that first comes proof of existence, then follow the attributes, too. But this inference doesn’t work the other way around.
Moreover, it is said that the non-existence of this being is inconceivable. It might better be said, perhaps, that its non-existence, or the possibility of its non-existence, is unintelligible. For according to the true meaning of the word, unreal objects are unintelligible. Yet their existence is conceivable in the way in which the fool conceived of the non-existence of God. I am most certainly aware of my own existence; but I know, nevertheless, that my non-existence is possible. As to that supreme being, moreover, which God is, I understand without any doubt both his existence, and the impossibility of his non-existence. Whether, however, so long as I am most positively aware of my existence, I can conceive of my non-existence, I am not sure. But if I can, why can I not conceive of the non-existence of whatever else I know with the same certainty? If, however, I cannot, God will not be the only being of which it can be said, it is impossible to conceive of his non-existence.
8. The other parts of this book are argued with such truth, such brilliancy, such grandeur; and are so replete with usefulness, so fragrant with a certain perfume of devout and holy feeling, that though there are matters in the beginning which, however rightly sensed, are weakly presented, the rest of the work should not be rejected on this account. The rather ought these earlier matters to be reasoned more cogently, and the whole to be received with great respect and honor.
Anselm’s Reply to Gaunilo
Since whoever wrote this reply to me is not the fool against whom I wrote in my treatise but instead one who, though speaking on behalf of the fool, is a catholic Christian and no fool himself, I can speak to him as a catholic Christian.
You say – whoever you are who claim that the fool can say these things – that something greater than which cannot be thought of is in the mind only as something that cannot be thought of in terms of some [existent thing known to us]. And you say that one can no more argue, “since a being greater than which cannot be thought of exists in my mind it must also exist in reality,” than one can argue, “the lost island certainly exists in reality because when it is described in words the hearer has no doubt that it exists in his mind.”
I say in reply that if “a being greater than which cannot be thought of” is neither understood nor thought of, nor is it in our understanding or our thought, then God either is not that greater than which cannot be thought of or he is not understood or thought of, nor is he in the understanding or mind. In proving that this is false I appeal to your faith and conscience. Therefore “a being greater than which cannot be thought of” is really understood and thought of and it really is in our understanding and thought. And that is why the arguments by which you attempt to prove the contrary either are not true or what you think follows from them does not follow from them at all.
Moreover, you imagine that although “a being greater than which cannot be thought of” is understood, it does not follow that it exists in our understanding nor does it follow that, since it is in our understanding, it must exist in reality.
I myself say with certainty that if such a being can even be thought of as existing, it must necessarily exist. For “a being greater than which cannot be thought of” cannot be thought of except as having no beginning; but whatever can be thought of as existing yet does not actually exist can be thought of as having a beginning. Therefore “a being greater than which cannot be thought of” cannot be thought of yet not actually exist. Therefore, if it can be thought of, it necessarily exists.
Furthermore, if it can be thought of at all, it must necessarily exist. For no one who denies or doubts the existence of “a being greater than which cannot be thought of” denies or doubts that, if it did exist, it would be impossible for it not to exist either in reality or in the mind. Otherwise it would not be “a being greater than which cannot be thought of.” But whatever can be thought of yet does not actually exist, could, if it did come to exist, not existence again in reality and in the mind. That is why, if it can even be thought of, “a being greater than which cannot be thought of” cannot be nonexistent.
But let us suppose that it does not exist (if it is even possible to suppose as much). Whatever can be thought of yet does not exist, even if it should come into existence, would not be “a being greater than which cannot be thought of.” Thus “a being greater than which cannot be thought of” would not be “a being greater than which cannot be thought of,” which is absurd. Thus if “a being greater than which cannot be thought of” can even be thought of, it is false to say that it does not exist; and it is even more false if such can be understood and exist in the understanding.
I will go even farther. Without doubt whatever does not exist somewhere or at some time, even if it does exist somewhere or at some time, can be thought of as capable of as existing never and nowhere, just as it does not exist somewhere or at some time. For what did not exist yesterday and exists today can be thought of as never existing, just as it is thought of as not having existed yesterday. And what does not exist here but does exist somewhere else can be thought of as not existing anywhere. And it is the same with something some parts of which are absent at times. If that is the case, then all of its parts and thus the thing in its entirety can be thought of as existing never and nowhere.
For if it is said that time always exists and the world is everywhere, it is nevertheless true that time as a whole does not exist forever, nor does the entire world exist everywhere. And if individual parts of time exist when other parts do not, they can be thought of as never existing at all. And just as particular parts of the world do not exist where other parts do, so they can be thought of as never existing at all, anywhere. And what is composed of parts can be broken up in the mind and be nonexistent. Thus whatever does not exist as a whole sometime or somewhere can be thought of as not existing, even if it actually exists at the moment. But “a being greater than which cannot be thought of,” if it exists, cannot be thought of as not existing. Otherwise it is not “a being greater than which cannot be thought of,” which is absurd. Thus it cannot fail to exist in its totality always and everywhere.
Do you not believe that the being of which these things are understood can be thought about or understood or be in the thought or understanding to some extent? For if he is not, then we cannot understand these things about him. If you say that he is not understood or in the understanding because he is not fully understood, say as well that one who cannot look directly at the sun does not see the light of day, which is nothing other than the light of the sun. Certainly “a being greater than which cannot be thought of” is understood and exists in the understanding at least to the extent that these statements about it are understood.
Anselm continues repetitively, eventually noting a key difference between his and Gaunilo’s approach . . .
You often picture me as offering this argument: Because what is greater than all other things exists in the understanding, it must also exist in reality or else the being which is greater than all others would not be such. Never in my entire treatise do I say this. For there is a big difference between saying “greater than all other things” and “a being greater than which cannot be thought of.” If someone says “a being greater than which cannot be thought of” is not something actually existing or is something which could possibly not exist or something which cannot even be understood, such assertions are easily refuted. For what does not exist is capable of not existing, and what is capable of not existing can be thought of as not existing. But whatever can be thought of as not existing, if it does actually exist, is not “a being greater than which cannot be thought of.”
Anselm goes on to present his standard argument that the nonexistence of such a being is inconceivable. Then he adds a key claim.
It is not, it seems, so easy to prove the same thing of “that which is greater than all other things,” for it is not all that obvious that something which can be thought of as not existing is not nevertheless greater than all things which actually exist.
The main argument is followed by philosopher Gideon Rosen’s commentary, which reconstructs Anselm’s logic. Further, a classic response from a Gaunilo, a little-known, fellow Benedictine contemporary of Anselm, is also included.