The Ontological Argument - valid or debunked?

[wiploc]

We know that there's something wrong with that logic because it can "prove" that gods do not exist just as easily as it "proves" that they do:

Premise 1: It's possible that a 'maximally great being' does not exist. 
Premise 2: If it's possible that a maximally great being does not exist, then a maximally great being does not exist in some possible world.
Premise 3: If a maximally great being does not exist in some possible world, then it does not exist in every possible world. 
Premise 4: If a maximally great being does not exist in every possible world, then it does not exist in the actual world. 
Premise 5: Therefore a maximally great being does not exist in the actual world.
Premise 6: Therefore a maximally great being does not exist.
Conclusion: Therefore God does not exist.

This second version is exactly as strong as the first version, yet it proves the exact opposite.  Any argument that proves both X and not-X is worthless.  In the scales of persuasion, its weight is zero.

We know, therefore, that the MOA (modal ontological argument) is worthless, absolutely refuted. 

Which brings us to P1.   

We're talking about necessary gods, gods that don't exist at all unless they exist in all possible worlds.  Can a god like that exist in some possible worlds? 

No.  Certainly not. 

We know that some possible worlds are godless.  We know this because of the definition of "possible world."  A possible world is any world without contradictions.  If a world doesn't have square circles or married bachelors, or anything other logical contradiction, then it is a possible world. 

There's nothing contradictory about godless worlds, so they are by definition possible. 

But a god existing in a godless world would be a contradiction, an impossibility.  Therefore, no god can exist in all possible worlds.  

Since P3 establishes that the god we are discussing, the god of the modal ontological argument, does not exist in any possible world unless it exists in all of them, it follows that this god does not exist in any possible world. 

Therefore, P1 is false. 

I'm sorry, but it makes no sense that this defeats the argument. What is the difference between Premise 1 and Premise 1'?

Premise 1: It's possible that a 'maximally great being' exists.
Premise 1': It's possible that a 'maximally great being' does not exist. 

So the real difference is in P4' (P2' and P3' are definitionally true). 

Premise 4: If a maximally great being exists every possible world, then it exists in the actual world. 
Premise 4: If a maximally great being does not exist in every possible world, then it does not exist in the actual world. 

When you apply the modal logic "if something is necessary in one possible world then it is necessary in all possible worlds" to a negative such as P4', you are saying it is necessary that something does not exist. Isn't that saying the same thing as a maximally great being is logically impossible? So to support P4', you are back to having to show that a greatest conceivable being is not logically possible--which was the original challenge of the original argument. 

I'm not sure what you're trying to say.  But I'll take a guess, and you can tell me if I'm wrong. 

Well, actually, first I want to deal with the bit about the "greatest conceivable being."  I think that's a complete change of topic.  But you say it is the original challenge of the original argument, so I went back to the OP.  I don't see that subject in the OP.  So I had my computer search the OP for "greatest conceivable being" and it didn't find it.  So I had it search for "conceivable," and it didn't find that either.  I wonder if you aren't confusing two different threads? 

Okay, back to what I think you may be talking about: 

Premise 4: If a maximally great being does not exist in every possible world, then it does not exist in the actual world.

"A maximally great being does not exist in every possible world" can be read in two different ways.  Thank you for pointing that out, if you did. 

Interpretation 1: In every possible world, the MGB does not exist; there is no possible world in which the MGB exists.  

Interpretation 2: There is at least one possible world in which the MGB does not exist. 

Feel free to use interpretation 1.  That is supported, proven, by the preceding premises.  It is consistent with the meaning of the preceding premises.  It is consistent with the meaning of the original (non-parody) version of the argument.  And it is the meaning that I intended when I wrote the parody. 

Note also that using interpretation 2 doesn't help your case.  If there is even one possible world in which a necessary being does not exist, then that necessary being does not exist at all, in any possible world.  In which case, no surprise, it does not exist in the actual world. 

So, regardless of which interpretation you use,  the result doesn't change:  Therefore god does not exist.