The classic ontological argument

[Modern Atheism]

The flaw in this argument is actually pretty simple: "Existence" is not just another property/attribute of a thing that makes it "greater" than another thing without "existence". Thats outright silly.

But, all things being equal, isn't something that exist in reality greater than something that does not?

[Paleophyte]

There is a thread about the modal ontological argument, but not about the classical one. Here is the original ontological argument as formulated by Sain Anselm: 

By definition, God is the greatest being that can be conceived of.

By whom? Seems like treacherous theological ground to limit your deity to the cognitive faculties of the mortals that grovel beneath it.

But if God did not exist in reality, we could imagine a being that had all the other properties of God but that also existed in reality, and this being would be greater than God.

Umm.. No. If God exists only in our imaginations then this other critter, which also exists only in our imaginations, isn't any better. The rest of this argument fails from there on down.

It's just a bunch of theists playing make-believe and adding words like "modal" and "ontology" to make it seem legit.

[Ahriman]

I would argue in support of the idea that something that exists is necessarily greater than something that does not exist. My imaginary girlfriend is definitely not as good as a real girlfriend would be.

[The Grand Nudger]

In anselms understanding it's not a binary proposition of things which do and do not exist.  God, to be god, must not only exist, it must not only have the greatest this and that other thing, it must also..tautologically, have the most existence.  Anselms argument, reduced to it's most essential terms, is that nothing can have more existence than the thing that has the most existence, therefore god must exist.  It was a theist, kant, who offered the definitive modal criticism of anselms formulation - stating that existence is not a real predicate.  You cannot have "more" of a thing which is not an actual quantity.  Kant argued that there were at least two modalities.  One that concerns the truth of judgements, and another that concerns the existence of things.  By taking a set of assertions that, for generosity and brevity's sake, we'll accept as true about one modality, and forming a conclusion about a wholly different one, anselm made the forced error of invalidating his own argument for god.  Forced, in this case, because there is no other way to premise this argument from within the confines of christian neoplatonism without making such an error.  

The church subsequently abandoned it and neoplatonism like a common altar boy.

[Deesse23]

The flaw in this argument is actually pretty simple: "Existence" is not just another property/attribute of a thing that makes it "greater" than another thing without "existence". Thats outright silly.

But, all things being equal, isn't something that exist in reality greater than something that does not?

No, existence is a precondition to having any attributes. Comparing existing things with nonexisting ones is a category error. Who was the better detective: Sherlock Holmes or Eliot Ness? Well, Sherlock Holmes never was a detective, since he never existed. He is an imaginary figure, just like an imaginary god with whatever imaginary attributes you want to attribute it with. But one thing is sure: You dont get to attribute "existence" to anything with the kind of dishonest mental masturbation the ontological argument shows to be.

All this ontological arguments tries is to put real things into the same box with imaginary things, and then pretend to be able to pull one of these things randomly out. By the same logic, i could pull out an existing pink unicorn (which is "greater" than an imaginary one, right?). If there was actual evidence for a god actually existing, none of this BS would be required to do.

[The Grand Nudger]

Concepts exist, and can have attributes, but telling me that a thing has x y and z attributes and also exists tells me nothing new about the concept of the thing - which does exist by virtue of it's mere proposition and which is what it is and has those attributes proposed regardless of whether or not it's instantiated in the real world (or is even a logical proposition). Rules that pertain to the truth of judgements do not always pertain to the existence or state of existence of things (and vv). This is a fancy way of saying, among other things, that it's possible for us to have good reasons to believe in things which do not exist, and good reason to disbelieve in things that do. It also means that what we may apprehend as a good reason from one category or modality is a uniquely bad one in another. This is why some people perceive such arguments to be compelling. The list of logical fallacies is an ongoing accounting of human cognitive ticks. The platonists tried to handle this with their ideas about the four or five essential elements, kant called it modality, and in the 40's it became category.

[Thumpalumpacus]

I would also say that you just cant just define something into existence. If the mere definition of something implies that it exists, then you really can't use this definition in an argument to prove its existence. That would be circular logic.

This is the essential flaw of these sorts of arguments. Imagination does not convey reality.

I can actually imagine a better god: one who not only created the Universe, but has no need to threaten humans with Hell in order to compel belief. It follows that my god is more merciful and forgiving, and therefore more perfect.

By their own logic, my imaginary god must exist -- and being more perfect than theirs, must be pre-eminent.

[Thumpalumpacus]

I would argue in support of the idea that something that exists is necessarily greater than something that does not exist. My imaginary girlfriend is definitely not as good as a real girlfriend would be.

You clearly have never had to dig through a pile of shoes in the closet looking for your slippers.

[Paleophyte]

I would argue in support of the idea that something that exists is necessarily greater than something that does not exist. My imaginary girlfriend is definitely not as good as a real girlfriend would be.

I'd argue that "something that does not exist" is a contradiction of terms. In order to be "something" it must exist. Your imaginary girlfriend exists, if only in your imagination. Ditto unicorns, dragons, pixies, and giants. I'd ask for a list of things that you think don't exist but simply writing them down would cause them to exist. Married bachelors, square circles, and other paradoxes don't exist because they aren't anything. They're tortured words that can't describe anything rational and when you try to imagine one you quickly find out that you can't. "Something that doesn't exist" may well fall into this category.

About now is when the theologist typically amends this to include "exists in reality", as if mental states weren't real, at which point I take a quick look at every definition of the Abrahamic god in the last few thousand years and after reading through a lot of "intangible", "unknowable", "undetectable", "ineffable", ad nauseum I'm left wondering what they mean by "reality".

[Angrboda]

I think some argue that conceiving and imagining are different, that conceiving implies possibility while imagining does not. It's an interesting twist, but not particularly persuasive.