Anselm of Canterbury, a Benedictine monk who was appointed Archbishop of Canterbury in 1093, composed a well-known ontological proof for the existence of God, which appears in this work of his. It reads as follows:
"Therefore, Lord, who grant understanding to faith, grant me that, in so far as you know it beneficial, I understand that you are as we believe and you are that which we believe. Now we believe that you are something than which nothing greater can be imagined.
Then is there no such nature, since the fool has said in his heart: God is not? But certainly this same fool, when he hears this very thing that I am saying - something than which nothing greater can be imagined - understands what he hears; and what he understands is in his understanding, even if he does not understand that it is. For it is one thing for a thing to be in the understanding and another to understand that a thing is.
For when a painter imagines beforehand what he is going to make, he has in his understanding what he has not yet made but he does not yet understand that it is. But when he has already painted it, he both has in his understanding what he has already painted and understands that it is.
Therefore even the fool is bound to agree that there is at least in the understanding something than which nothing greater can be imagined, because when he hears this he understands it, and whatever is understood is in the understanding.
And certainly that than which a greater cannot be imagined cannot be in the understanding alone. For if it is at least in the understanding alone, it can be imagined to be in reality too, which is greater. Therefore if that than which a greater cannot be imagined is in the understanding alone, that very thing than which a greater cannot be imagined is something than which a greater can be imagined. But certainly this cannot be. There exists, therefore, beyond doubt something than which a greater cannot be imagined, both in the understanding and in reality. "
One of the assumptions one has to make beforehand to be able to follow the 'logic' of Anselm's assertions, appears to be that one has to accept the assertion that being able to conceive of something also somehow causes that thing to exist.
Where Anselm says:And certainly that than which a greater cannot be imagined cannot be in the understanding alone.
this is of course true in the sense that a thing one can conceive of, does exist in one's mind or imagination, but I don't follow the logic that simply because you can think of something, means that it must exist outside of human imagination, in an objective reality. I can conceive of the idea of a fairy, but does that mean that fairies really exist?
Gaunilo of Marmoutiers illustrated the apparent illogical aspects of some of the aspects of Anselm's argument in his analogy of The Lost Island.
My own version of Marmoutier's parody of Anselm's argument, in order to point out the first fallacy in Anselm's argument would be:
Just because I can conceive of a hairball greater than a hairball I can conceive of... - well, in actual fact, I cannot conceive of a hairball greater than the greatest hairball I can conceive of, so to some extent Anselm's logic fails, but Anselm does see that there is indeed a paradox in this respect, since he does mention the paradox: " But certainly this cannot be."
However, his conclusion: There exists, therefore, beyond doubt something than which a greater cannot be imagined, both in the understanding and in reality. "
is not logical.
Although I cannot conceive a hairball greater than the greatest hairball I can conceive of, I can conceive of the possibility of there being a hairball greater than the greatest hairball I can conceive of. One can follow the logic of the argument if you see that Anselm might mean that there could conceivably be something so great, so perfect that you cannot conceive of it. So, if he is saying that "God" is so great, so inconceivable, so unknowable, so immense, so vast, so complex, so perfect, that the human mind cannot conceive of it, then this is indeed an assumption that cannot be faulted, since nobody has managed to disprove such an assumption yet.
Yet, Anselm goes one step further, and concludes that, just because humans can conceive of the actual existence of a being or entity so great, so inconceivable, so unknowable, so immense, so vast, so complex, so perfect, that the human mind cannot conceive of it, that such an entity must by inference then actually exist. If you analyze this end-result of Anselm's contortions, this is actually the conclusion that he arrives at, isn't it?
But Anselm doesn't manage to prove that this conclusion, this assertion, is true, just as I cannot prove that just because I can conceive of the idea that an incredibly complex, incredibly secret incredibly mysterious mermaid, one so mysterious and complex that I cannot even conceive of her, really exists just because I can imagine she could possibly exist.
Looking at the "reality is greater than conception" aspect of Anselm's argument: If a hairball existed in reality, rather than just in my imagination, it would per se be a greater hairball than if it only existed in my imagination, because a hairball that exists in reality as well as in my imagination, rather than just in my imagination alone, would automatically be a greater, more perfect hairball simply due to the fact that it actually exists.
I find it hard to conceive of the veracity of the argument that a hairball that exists in reality is a greater, or a more perfect or a better hairball than the best hairball that I can possibly conceive of.
In fact, I can conceive of a hairball that has multifaceted iridescent colours, that crackles and pops and bounces up and down of it's own volition, and can even whistle "Oh Ye Christian Soldiers" in 3 octaves; - but does that then necessarily mean that if such an exact hairball existed, it would be greater than the one in my imagination?
I suppose it would be possible for such a hairball to exist, but I don't see how it must necessarily exist just because I can conceive of it, and I don't follow that if the exact same hairball existed in reality , that it would be greater than the hairball in my imagination. It might be more useful than if it was only in my imagination, as far as usefulness of hairballs go, but in which sense would it be greater? It wouldn't be more perfect, since it would be the exact same hairball (we are now examining the assumption that a 'real' thing is inherently and per se "greater than" the exact same imagined thing).
It might be 'greater' in the sense that because I can see it and touch it, it gives me greater sensory pleasure. If the imagined thing was a banana, I could eat it, so the assumption holds true for bananas. But does it hold true for hairballs? Or for a piece of dandruff?
Would it hold true for "God"? Inasmuch as the quality of a god that is greater than the one that can be imagined is concerned, it would certainly be true, and here Anselm uses a little trick, because if something that is greater than we can imagine exists, then of course that thing would be greater than the one we imagined, because we imagined it would be greater but it would not be greater by virtue of the fact that it exists, but by virtue of the fact that it must be - according to the argument - already a greater one than what we can conceivably imagine of.
Anselm makes a tiny jump there - he doesn't prove that just the fact of existence alone is greater than the exact same imagined thing - he uses a trick to make the imagined thing be a thing that is beyond what can be imagined. So, in fact you didn't imagine it, because - according to the argument - you couldn't imagine it.
But if it was exactly the same god that I imagined in my imagination, would just the fact that that same God existed in reality make him/it greater? I don't think Anselm manages to prove this conclusively.
Anselm's "proof" does have some value, in that it causes one to ponder on the concept of "God". If God existed, what would God be? Anselm seems to give a workable answer to this question, being: " God is that than which nothing greater can be conceived of".
The terminology "greater" could be construed in a few ways: "more perfect", "more powerful" and the ultimate end of the spectrum would imply " that which is all-encompassing", or "that which is being" "or "that which is necessary for being" .
If one reads the rest of Anselm's work, which consists largely of prayers, one gets the impression that Anselm seeks to establish for himself the nature of God. He mentions that he seeks God, and one would assume this seeking to be a seeking both of reason and of faith, of intellect and emotion. As I've already mentioned, in his eagerness to find God, Anselm makes certain jumps in logic, and makes base assumptions that is not necessarily grounded in empirical truth -neither does he in any way prove these assumptions on which he builds a priori arguments.
However, does not even Plato and Aristotle (who influenced Anselm) do this? It would seem that most paradigms presented by philosophers in the course of history, are built upon certain assumptions - of which acceptance is essential towards accepting the logic of the rest of the argument.
Ultimately though, Anselm's argument is not successful enough to hold up against critical scrutiny, since a few of the assumptions he bases his argument on, seem illogical and unproven.