Well i have been having a discussion with a theist and he has just brought up the modal ontological argument.  I have now  done some research on modal logic and have sites marked to further educate myself on it, but i am still way to new to it to have any clue whether my argument holds water or not, and i would really apreciate some help.

the argument he used goes like this
"1. It is possible that a maximally great being exists.
2. If it is possible that a maximally great being exists, then a maximally great being exists in some possible world.
3. If a maximally great being exists in some possible world, then it exists in every possible world.
4. If a maximally great being exists in every possible world, then it exists in the actual world.
5. If a maximally great being exists in the actual world, then a maximally great being exists.
6. Therefore, a maximally great being exists."- him

to which, after very little research i replied with


 "Now the modal ontological argument is not proof of anything .The modal ontological argument applies a string of logic but fails to test the logic. If the same string of logic can be used to come to an opposite conclusion, then the logic has been disproven through contradiction.

1) It is possible that a maximally great being does not exist.
2) If it is possible that a maximally great being does not exist, then a maximally great being does not exist in some possible world.
3) If a maximally great being does not exist in some possible world, then a maximally great being does not exist in any possible world.
4) If a maximally great being does not exist in every possible world, a maximally great being does not exist in the actual world.
5) If a maximally great being does not exist in the actual world, then a maximally great being does not exist.
6) Therefore maximally great being does not exist.

This uses the exact same logic to reach an opposite conclusion that is at odds with the original conclusion. This proves that the logic of the MOA is completely faulty and as such, illogical."-my reply

To which he replied


 "The issue I hold  that you does not effectively deny the rationality of there existing God. Here I would re-enter the absence of evidence ,does not, = evidence of absence argument. Due to the nature of the atheist's presuppositional base for the arguments against the existence of God, it undermines the evidences that are provided for the existence of God because to say there is no evidence for the existence of God suffices to say that the atheist's knows all possible proofs that God exists, which is logically absurd. This is what I meant with my ontological argument as a preface for the evidence of absence. There is enough rational proof for the existence of God and that's where Plantinga's argument comes into play. Philosophically, it is possible. Yes, you can flip the logic but I don't believe that's sufficient enough to prove the argument holistically false.  The difference here is I am saying that a maximally great being is necessarily possible and not simply possible. The reason for providing Plantinga's argument in the first place is because I am meaning to exhibit that there are no logical objections to the maximally great being unless the objector can prove that to be false. Rendering us back to premise 1. that it is possible. " - hes reply


Now this is where i am at the moment. now form my limited understanding it seems the major problem with this argument is that it uses two different meanings for the word possibility and only gets away with this argument by confusing them. the one type of possibility has to do with something that is either true or false but which the laws of logic cannot say one way or the other  . such as the possibility england will win tomorrows rugby match.
The other possibility seems to be a logical possibility, something that has always been either true or false and always will be either true or false and so then has to be neccesarily true or false. and the only reason we can call it a possibility is because we do not have the answer yet.
Now this is what i have come up with so far to answer back to what he replied just  and i would like to know if it is valid or not


 "  what i am  saying is that this  argument proves nothing. lets us  replace god with some other proposition which is possible and  if true is neccaserily true for all possible worlds  , but that we do not know the answer to. lets call it (x) and (x)=  the statement that the 12 billionth and first digit of pi is a 7. now we dont know the answer so it is possible that (x) is true  , and if true in any world it would be true in all worlds,so  if true it is neccaseraly true. now i will use your exact same argument
1. It is possible that (x) is true
2. If it is possible that(x) is true , then (x) is true  in some possible world.
3. If (x) is true in some possible world, then it true in every possible world.
4. If (x) is true  in every possible world, then it true in the actual world.
5. If (x) is true  in the actual world, then (x) is actualy true
6. Therefore, (x) must be true

Now we do not need to know the actual answer to be able to say this does not prove (x) is true. yes it is possible (x)  true, there is a 1/10 chance it is, but this does not prove it is true and we do not need to be able to prove  (x) is untrue to be able to say this does not prove anything."


Now this seems fine to me and the only objection i can think of is if , in modal logic, it is possible for worlds to exist where logical and mathematical truths are not true any longer. ie if there is a world where 2+2=563 or something

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1. It is possible that a greatest cross-eyed squirrel exists.
2. If it is possible that a greatest cross-eyed squirrel exists, then a cross-eyed squirrel-lizard exists in some possible world.
3. If a cross-eyed squirrel exists in some possible world, then it exists in every possible world.
4. If a cross-eyed squirrel exists in every possible world, then it exists in the actual world.
5. If a cross-eyed squirrel exists in the actual world, then a cross-eyed squirrel-lizard exists.
6. Therefore, a cross-eyed squirrel exists.

"Being" is a kind of placeholder word, and an adjective can't really apply until "being" is instantiated. I say this because what is "great" for a toad is bound to be different than what "great" means for a poet, a geographical area, or a best-selling novel.

My point is, you can't really get very far with undefined terms like "great" and "being." You need to instantiate them first. Once you do that (or, more precisely, ATTEMPT to do that), you see that the argument is a crock.

Definitions-schmefinitions. Just take a look at why there's no short-cut: http://www.paul-almond.com/ModalOntologicalArgument.htm

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