Hi Mad Fool, I think the OP deals with the limits of your imagination rather than the existence of God.
It may be that I can't imagine anything tastier than a hotdog. This implies that a hotdog exists, but not that it is the tastiest thing out there - except in respect to my knowledge and perception of foods.
I like that you are trying to reason it out though.

My favourite response to the ontological argument is an attack against the uniqueness of the entity it conjures into being.

(1) An entity X has property P.
(2) If X did not exist, then it would not have property P.
(3) X exists. (1,2, modus tollens)
P is typically 'greater than that which cannot be conceived' and X is god.

You can adjoin any set of properties to X, so long as P is among them X exists if the argument is valid. The argument is invalid anyway since (1) quantifies over the space of entities existentially. So (1) is equivalent to: there is a being Y such that Y = X and Y has property P, and a sub statement (there is a being Y such that Y=X) is exactly what the argument seeks to demonstrate, so it is circular.

edit: you don't even NEED 2 to conclude 3 from 1 with the quantifier.

The argument is invalid anyway since (1) quantifies over the space of entities existentially. So (1) is equivalent to: there is a being Y such that Y = X and Y has property P, and a sub statement (there is a being Y such that Y=X) is exactly what the argument seeks to demonstrate, so it is circular. — fdrake

Yes, this is exactly right. I've had this argument twice with another forum member. To predicate (truly or falsely) of an object does not show that the object is within your domain of discourse, but presupposes that it is.

There is a sort of epistemic variant that is worthwhile:
1. Something is perturbing the orbits of these asteroids.
2. If there were a planet of a certain mass there, it would do that.
3. ?
Well, you don't get to conclude anything. (2) gives you an abductive hypothesis to investigate, but you still need to investigate.

1. God is the greatest being imaginable [premise] — TheMadFool

Premise 1 is reasonable. — TheMadFool

Really. Why?
The definition in 1 is loaded by containing a hidden premise that there is an idea of a being that can be imagined that is greater than any other idea of a being that can be imagined. Why should that hidden premise be true?

The reason needs to be something that works in that case but not in the following case:

Premise: X is the greatest integer

What might such a reason be?

4. If God doesn't exist then I can imagine a being greater than God (a greatest being who exists) [premise] — TheMadFool

If God does not exist, then you CAN'T imagine a thing greater than god. For a comparison in real terms, both comparands must exist. So you can't imagine a thing greater than god, or lesser than god, or in any way related to god. Because it is a given (as per the condition) that god does not exist.

You mean to say ''god is the greatest being imaginable'' contains the claim ''god exists''?

That makes sense in predicate logic. After all:

1. God is the greatest being imaginable

Statement 1 translates as (Ex)(Gx & Ix) where Gx = x is god and Ix = x is the greatest being imaginable. Existence is, it appears, presumed in statement 1.

Here's what I think...

Predicate logic fails to capture the full content of the Ontological argument. The Ontological argument moves from existence in imagination to existence in reality. So, the TOP depends on the distinction between existence in imagination and existence in reality. This crucial distinction can't be made in predicate logic. The existential quantifier, (Ex), is restricted to reality.

So, your critique fails to adequately refute the Ontological argument.

Please read above.

Really. Why?
The definition in 1 is loaded by containing a hidden premise that there is an idea of a being that can be imagined that is greater than any other idea of a being that can be imagined. Why should that hidden premise be true? — andrewk

It's reasonable to say ''God is the greatest being imaginable'' because God is defined as such and agrees with our conception of what a God must be.

If God does not exist, then you CAN'T imagine a thing greater than god. — szardosszemagad

If existence is ''better'' than nonexistence, then I can imagine a God that exists which would be greater than one that doesn't exist.

Predicate logic fails to capture the full content of the Ontological argument. The Ontological argument moves from existence in imagination to existence in reality. So, the TOP depends on the distinction between existence in imagination and existence in reality. This crucial distinction can't be made in predicate logic. The existential quantifier, (Ex), is restricted to reality.

Honestly I think the ambiguity in the domain of quantification is the essential feature of the argument. You want there to be a single way in which something can be said to exist, collapsing the distinction between an imagined perfect entity and a real perfect entity - and if the argument is right, that's exactly what happens.

The distinction you draw absolutely is not in the argument's favour, since 'God exists in the imagination' is supposed to show through some property that 'God exists in reality', it may be that predication of 'is the greatest being imaginable' or like sentences is only a predicate of strictly imaginary entities... And really that's what's supposed to be so strong about the argument - you can go from supposedly minimal assumptions about imaginary entities and properties and deduce the existence of an entity. But if you would like to predicate God in a manner that makes God strictly imaginary that makes the existence of God a moot point.

You're right. There's something wrong in relocating an imaginary x, no matter how great or perfect, into the real world. I think this is a good refutation.

1. God is the greatest being imaginable
2. If God doesn't exist then God isn't the greatest being imaginable
Therefore (modus tollens)
3. God exists

Your refutation applies to premise 2 and is a good one. I too think premise 2 is false because it's equivalent to: If God is the greatest being imaginable then God exists. This is illicit, according to you, and I agree. We can't imagine things into existence, can we????

I think it's appropriate to imagine things into existence so long as there's not a unique sense of what it means to exist. EG, Gods are myths, chairs are actual, the abstract concept of golf is something else...

It's reasonable to say ''God is the greatest being imaginable'' because God is defined as such — TheMadFool

In the same sense that it's reasonable to say that 'X is the greatest integer', or perhaps 'Fred is the fattest ten-foot tall man', or 'Nemo is the smallest talking fish' because they are defined as such.

Your golf example isn't actually a relocation of an imaginary thing into the real world. It's a case of marrying thought with matter. It isn't imagining something into existence.

It isn't reasonable to say "X is the greatest integer" because there is none. Also, it's unreasonable to say "Fred is the fattest ten-foot tall man" because we know human's can't achieve 10 feet heights.

There's nothing wrong, as you say, in defining God as the ultimate being - the possessor of superlative qualities. Where is the inconsistency in this definition?

There's nothing wrong, as you say, in defining God as the ultimate being - the possessor of superlative qualities. Where is the inconsistency in this definition? — TheMadFool

Because saying 'Define God to be the greatest imaginable being' is equivalent to the following sequence of statements:

1. There exists an idea X of a being such that:
a. X can be imagined by at least one human, and
b. for any Y that is an idea of a being, if Y can be imagined by at least one human, then either Y=X or X is greater than Y

2. If statement 1 is true then we label the idea X whose existence is asserted by 1, as 'God'.

Statement 1 is an assertion.
Statement 2 is a definition that only operates if statement 1 is true.

So unless statement 1 is true, we do not even have a definition of 'God'.

And no argument has been supplied to indicate why we should accept statement 1 as true. Indeed, my intuition says very strongly that it is not true - that for any imaginable great being, one can imagine a greater one.

1. There exists an idea X of a being such that:
a. X can be imagined by at least one human, and
b. for any Y that is an idea of a being, if Y can be imagined by at least one human, then either Y=X or X is greater than Y

2. If statement 1 is true then we label the idea X whose existence is asserted by 1, as 'God'. — andrewk

I can, presumably others too, imagine a greatest possible being - omnipotent, omniscient, omnibenevolent - one greater than which can't be imagined. So, (a) and (b) are true, making assertion 1 true.

Is that not sufficient to make 1 true?

That's precisely what I intended. All of those words denote things which, at face value, exist in different ways.

If God does not exist, then you CAN'T imagine a thing greater than god.
— szardosszemagad

If existence is ''better'' than nonexistence, then I can imagine a God that exists which would be greater than one that doesn't exist. — TheMadFool

taken out of context, any proposition can be falsified.

My point is meaningless without the context I put it in. You don't have the right to take it out of context and manipulate it to your whimsy. You are committing a Strawman fallacy.

You can't argue like that in a proper philosophy forum.

I therefore reject your argument, Mad Fool.

That's A.

B. is that you made a new proposal, in the new context which you placed the question in. That proposal is pending on a condition, which is

If existence is ''better'' than nonexistence, — TheMadFool

This is a condition which is not proven or supported by argument pro or con. So your argument is meaningless at best.

Heidegger's answer is to look back into the history of the metaphysical idea of being, noting that it used to be that what a being is, is that which is actual, and is not non-existent. The measure is (my paraphrase) efficacy. What is efficacious is actual. Ideas are efficacious.

As to St. Anselm, it's argued that he was in a sense preaching to the choir, in that he wasn't proving that God existed, but rather the idea of God was an absolute presupposition of his - and any Christian's - thinking. That is, that his argument presupposed the existence of the God whose existence he was supposedly trying to establish, or prove. If it were an attempt at a proof, this begging-the-question would be a fatal flaw. Because he wasn't, it isn't.

Is that not sufficient to make 1 true? — TheMadFool

No, because I can imagine a being greater than yours.

Sequences of divine entities are like the rationals, incomplete and thus irreal. *badumtisch*

This is a condition which is not proven or supported by argument pro or con — szardosszemagad

I agree. That existence is better than nonexistence is questionable. How about if we look at this from the perspective of life as a whole. It's surely better that an omnibenevolent being exists than not exists. Do you agree? If yes, then existence of such a being is positively better than nonexistence.

No, because I can imagine a being greater than yours. — andrewk

You can imagine a being greater than God, who's omnipotent, omnibenevolent and omniscient? Can you describe such a being?

If it were an attempt at a proof, this begging-the-question would be a fatal flaw. — tim wood

Can you clarify where the argument goes wrong?

You can imagine a being greater than God, who's omnipotent, omnibenevolent and omniscient? Can you describe such a being? — TheMadFool

Of course not! If it were describable in mere human words, that would hardly be very impressive, would it?

You can imagine a being greater than God, who's omnipotent, omnibenevolent and omniscient? Can you describe such a being? — TheMadFool

Omnipotent, omnibenevolent, omniscient, and sexy. That, of course, proves that God must be a woman.

As I said before, this term "greater" is so unclear as to be vacuous. Spell out the actual properties and you'll see that your argument doesn't work.

I'll try to make it clearer.

1. God is defined as the greatest being imaginable
2. The greatest being imaginable is imagined to have the properties of omnipotence, omniscience, and omnibenevolence.
3. If nothing exists that has the properties of omnipotence, omniscience, and omnibenevolence then ...?

Your argument wants to end the 3rd premise with "I can imagine a being greater than God (a being who exists)". The problem is that this contradicts both premises 1 and 2. It contradicts premise 1 because you're saying that you can imagine a being greater than the greatest being imaginable, and it contradicts premise 2 because you're saying that the greatest being imaginable is imagined to exist, which wasn't included in the initial description of the greatest being imaginable.

Now, let's reconsider the argument with this new description of the greatest being imaginable (which includes the notion of existence):

1. God is defined as the greatest being imaginable
2. The greatest being imaginable is imagined to have the properties of omnipotence, omniscience, and omnibenevolence and to exist.
3. If nothing exists that has the properties of omnipotence, omniscience, and omnibenevolence then ...?

How do we end the third premise? With "I can imagine a being greater than God (a being who exists)"? Leaving aside the continued fact that this contradicts premise 1, there is no difference between the God you imagine and this greater-than-God being you imagine; in both cases you imagine a being to be omnipotent, omniscient, omnibenevolent, and to exist.

Responding to the OP,

The ontological proof works well for the God of philosophy or of the Quran. There is no other beside Him, the almighty, all merciful, all wise kind of God. Which happens to be kinda of God I think is most plausible. The proof may not with absolute certainty establish that God must exist, but it's definitely informative as to His nature.

But Anselm who wrote this proof was Christian. Plato in his Republic, before Jesus was born of course, makes a powerful argument I think. God is perfectly good and cannot be higher. To change at all would only make Him less and being good He would not do that. He also has no need of deception and deceiving one about God is the greatest evil. Therefore, Gods do not incarnate. Because incarnation would be a change of state. I always find it funny that Paul says (in a quote evangelicals love) that God never changes yet the whole Torah and New Testament split is all about a change from an old convenant to a new convenant in which Gos's method of revelation and relationship with man is fundamentally changed. If God is perfect in the Torah then he can't change and he can't incarnate. If he isn't perfect in the Torah, then He's not God.
There is a way out that Jesus, the Logos, existed in the Torah and since the beginning. John 1. But then isn't Jesus then go from non-incarnate to incarnate to effectively non-incarnate again. (A body in heaven is not here on earrh, we can't visit him so it's not a real incarnation).
I think you can have a incarnate God made man but then you can't have an ontologicaly perfect God. The incarnation destroyed the idea of perfect, that's the point. God becomes man and becomes sin.

Responding to OP as well.

I believe you are correct. I don't understand Anselm's psychology behind his statements.

Just because you can imagine a flavor of ice cream that's better than all others doesn't mean that there isn't a better one out there. What's to say someone hasn't conceived of something better that suits their needs?

'Better' is a subjective term anyways.

Of course not! If it were describable in mere human words, that would hardly be very impressive, would it? — andrewk

:D You have a point. Let's go with your ''greatest being'' then. Surely you agree that this particular being, that which can't even be described, is the greatest being imaginable. So, assertion 1 is true.

As I said before, this term "greater" is so unclear as to be vacuous. Spell out the actual properties and you'll see that your argument doesn't work. — Michael

What's the problem with ''greater''? Take power, knowledge and benevolence and maximize them into omnipotence, omnscience and omnibenevolence. It doesn't look that problematic to me.

You're saying the argument is circular. Anyway, here's another version that, hopefully, brings out the main point of the argument:

1. God is the greatest being [imaginable]
2. If God is the greatest being [imaginable] then God must exist
Therefore,
3. God must exist

The above is as clear as I can get. The argument is circular too, as you said. There is no assumption of existence in premise 1; God is in the imagination. The problem I see is in premise 2. How does something in the imagination become real?

(Y)

'Better' is a subjective term anyways. — MountainDwarf

Well, we can come to a consensus. In fact that's what's happened with omniscience, omnibenevolence and omnipotence.

1. God is the greatest being [imaginable]
2. If God is the greatest being [imaginable] then God must exist
Therefore,
3. God must exist — TheMadFool

The second premise is false when we include the term "imaginable".

Am I stronger than Superman because I exist, or is he stronger than me because he's imagined to have the strength to move planets? Am I richer than Scrooge McDuck because I exist, or is he richer than me because he's imagined to be worth billions of dollars?

The strongest person imaginable doesn't exist and the richest person imaginable doesn't exist. So there's no contradiction in claiming that the most powerful person imaginable doesn't exist, that the most knowledgeable person imaginable doesn't exist, and that the kindest person imaginable doesn't exist.

That an omnipotent, omniscient, and omnibenolvent thing can be imagined is not that an omnipotent, omniscient, and omnibenevolent thing exists.

You can't define into existence a thing with superlative properties.

Well, we can come to a consensus. In fact that's what's happened with omniscience, omnibenevolence and omnipotence. — TheMadFool

Definitely. Have you seen the Youtube video with the Professor from MIT on the problem of evil?

To me, the ontological argument for god is reminiscent of Cantor's "diagonal arguments" for the existence of uncountably large sets. This is because neither arguments are really 'arguments' in the sense of reaching a conclusion analytically via an independent process of logical deduction. Both in logical "proofs of god", and in logical "proofs of uncountable sets", the convention of syntactical deduction does not represent the intended meaning of the arguer, who isn't drawing a conclusion deductively, but is inventing his conclusion and expressing it using novel syntax and inventing additional rules of deduction to relate it to his premises.

Surely you agree that this particular being, that which can't even be described, is the greatest being imaginable. — TheMadFool

No, because this morning I imagined a being that is 10% greater than the one I imagined yesterday.