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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Aside from the fact that what you just typed is at least semantically incoherent and makes patently false accusations about what I said, your entire critique is self defeating.

You are trying to attack logic with logic. If you succeed, you undermine logic and your argument's logical underpinnings are wrong. Therefore, it fails. If you try to retort with logic, you are admitting that logic is needed to argue, thus admitting your entire argument is wrong. QED

you can't accuse people of ad hominems because that entails formalized logic. Accusing people as such defeats your earlier post attacking logic that Nelson responded to. Also, you can not deconstruct anything without logic because it requires logic to do so. 

"I disagree. I think you are trying to attack the messenger for reasons that I will let the reader observe candidly. This also sounds like an attempt to attack the messenger by implying - or just stating - that the messenger is incapable of logic. Did I misunderstand your statement?"

No, I attacked your nonsensical argument. You confused me saying "you can't use logic (meaning that if your argument is correct, then logic doesnt work)" with me saying "you can't use logic (you have some kind of mental deficiency)." I said the first and am nowhere near big enough of a jerk to say the second to anyone.  I'll repeat my argument again.

"You (meaning your argument) are trying to attack logic with logic. If you (meaning your argument) succeed, you (your argument) undermine logic and your argument's logical underpinnings are wrong. Therefore, it fails. If you (any future use of logic made by another argument) try to retort with logic, you (that argument) are admitting that logic is needed to argue, thus admitting your entire argument is wrong. QED"

I am not saying "you lack the skills use logic". I am saying if your argument succeeds then the entire discipline of logic is wrong. Thus, your argument and any other which uses logic, is also wrong.

Just because someone shows why your argument is abjectly self defeating does not mean they are personally attacking you. I am not conceding anything. I showed that your argument is self defeating because it attacks its own logical underpinnings (as I just restated). I am at a loss if proving an argument is completely wrong is counted as avoiding it.

Also, your other argument is wrong about possible worlds. The point of a possible world is merely to see if something is necessary, possible, or contingent. This is a logical construct, not a physical world. Logicians use this method by stipulating only what is different. If something is like 1+1=2 is true in every possible world, then they would conclude that it is a necessary truth. Since this is a logical testing method, it does not require them to speculate about anything else. Nelson already answered this mischaracterization.

If you would like to learn about this, I recommend the following books:

1. Eric Steinhart's More Precisely

2. Ken Konyndyk's Intro to Modal Logic

3. Brian Chellas' Modal Logic: an Intro

Modal logic is so well accepted that you could pretty much open any college level logic textbook and find a discussion on it. These books are particularly easy to read though.

It should also be noted that modality is a core concept used in computer language, so if your argument is right that possible world semantics don't work, your computer doesn't work. Since your pc works, possible worlds modal logic is correct. Therefore, your argument attacking modal logic is incorrect if you can respond to this post. 

"Ok, no worries about the logic thing, it just sounds to me like you're saying your "opposite number" is incapable of logic."

Where did I say that? LOL

"In reading your post I cannot find anything that addresses my objection at all. It is certainly informative and educational, but I don't see any mention of "definition", "possibility", etc. which is where I think this discussion has landed.

As for the explanation of logic, I'm sorry, but I do not understand where or how you answered my earlier question regarding this digression, if I can call it that:

... how am I attacking logic? Did I say that? Where?"

your entire argument (everything you have said) has been an attack on modal logic, which is the foundation of modern logic. Thus, if you are right, logic (which modality is the foundation to) is wrong.

Also, possible was defined. Something is logically possible if and only if it is not logically impossible (nessecarily false) in any possible state of affairs (a possible world). 

or as dictionary.com put it.

— adj
capable of being described without self-contradiction

"but I think the objection I'm making is yet more slippery than yours."

in philosophy, slipperiness is a really bad thing. it means your argument is vague and vacuous. Thanks for the compliment. 

If you understood what I am saying you would have seen that modality is the foundation to logic and computer science. Thus, you are wrong if you can post a response (computer science and modality would be right if you could and your argument wrong) or if you can even make a successful argument (your argument based on logic would mean that your argument against logic fails. -self defeating). 

Who has made these objections you are talking about? If you do not name them, you are comitting a logical fallacy of appealing to unnamed authority. So who are these physicists who have disproved logic?

well what you mean by those terms is irrelevant. If your arguments are not addressing the terms as they are used by professional logicians then your argument is committing the logical fallacy of straw maning (categorically redefining words to make the opponents case into something they do not mean it to be).

Also, from wikipedia: 

From this groundwork, the theory of possible worlds became a central part of many philosophical developments, from the 1960s onwards – including, most famously, the analysis ofcounterfactual conditionals in terms of "nearby possible worlds" developed by David Lewis and Robert Stalnaker. On this analysis, when we discuss what would have happened if some set of conditions were the case, the truth of our claims is determined by what is true at the nearest possible world (or the set of nearest possible worlds) where the conditions obtain. (A possible world W1 is said to be near to another possible world W2 in respect of R to the degree that the same things happen in W1 and W2 in respect of R; the more different what happens in two possible worlds in a certain respect, the "further" they are from one another in that respect.) Consider this conditional sentence: "If George W. Bush hadn't become president of the U.S. in 2001, Al Gore would have." The sentence would be taken to express a claim that could be reformulated as follows: "In all nearest worlds to our actual world (nearest in relevant respects) where George W. Bush didn't become president of the U.S. in 2001, Al Gore became president of the U.S. then instead." And on this interpretation of the sentence, if there is some nearest world to the actual world (nearest in relevant respects) where George W. Bush didn't become president but Al Gore didn't either, then the claim expressed by this counterfactual would be false.

Today, possible worlds play a central role in many debates in philosophy, including especially debates over the Zombie Argument, and physicalism and supervenience in the philosophy of mind. Many debates in the philosophy of religion have been reawakened by the use of possible worlds. Intense debate has also emerged over the ontological status of possible worlds, provoked especially by David Lewis's defense of modal realism, the doctrine that talk about "possible worlds" is best explained in terms of innumerable, really existing worlds beyond the one we live in. The fundamental question here is: given that modal logic works, and that some possible-worlds semantics for modal logic is correct, what has to be true of the world, and just what are these possible worlds that we range over in our interpretation of modal statements? Lewis argued that what we range over are real, concrete worlds that exist just as unequivocally as our actual world exists, but that are distinguished from the actual world simply by standing in no spatial, temporal, or causal relations with the actual world. (On Lewis's account, the only "special" property that the actual world has is a relational one: that we are in it. This doctrine is called "the indexicality of actuality": "actual" is a merely indexical term, like "now" and "here".) Others, such as Robert Adams and William Lycan, reject Lewis's picture as metaphysically extravagant, and suggest in its place an interpretation of possible worlds as consistent, maximally complete sets of descriptions of or propositions about the world, so that a "possible world" is conceived of as a complete description of a way the world could be – rather than a world that is that way. (Lewis describes their position, and similar positions such as those advocated by Alvin Plantinga and Peter Forrest, as "ersatz modal realism", arguing that such theories try to get the benefits of possible worlds semantics for modal logic "on the cheap", but that they ultimately fail to provide an adequate explanation.)Saul Kripke, in Naming and Necessity, took explicit issue with Lewis's use of possible worlds semantics, and defended a stipulative account of possible worlds as purely formal (logical) entities rather than either really existent worlds or as some set of propositions or descriptions.

[Thanks Greg for suggesting a few introductory books on modal logic. I am getting convinced that it'll be a good thing if I am to gain some basic understanding of this stuff.]

cheers my friend.

Where have you heard it in academia? Show me the source. From what I can tell you just openly dismissed what I pasted for no reason without argument. 

Appealing to authority is not a fallacy. Appealing to illegitimate authority is. Human beings have to appeal to authority everytime they go to the doctor or get their car worked on. Without authority to appeal to, society would crumble. A creationist could retort to you saying that evolution was true is a logical fallacy because you yourself are not a biologist and are appealing to the work of scholars.  If you tried to link them to info they could just dismiss that info out of hand.

Also I find your "appeal to knowledge" curious. Dictionary.com defines knowledge as:

"acquaintance with facts, truths, or principles, as from studyor investigation; general erudition: knowledge of many things.
familiarity or conversance, as with a particular subject orbranch of learning: A knowledge of accounting was necessaryfor the job."

are you suggesting that we have this conversation devoid of facts and investigation?

WTF, I gotta lay down after reading that...lol.

Simply reasoning something into existence without any credible evidence to support that claim (notice I didn’t say no evidence, because there’s plenty of poor “evidence” that gets thrown around) doesn’t make it believable. So, your friend has come to the conclusion, through the use of logic, that such a being does exist. I’d say fine, for the sake of argument, concede the point and ask him to present evidence that supports its existence. This argument alone isn’t proof of existence any more than your counter argument is proof of non-existence. Perhaps you should remind him that most atheists accept the (remote)possibility that some god may exist, but in the absence of convincing/credible evidence, have no reason to believe it.

The type of argument/ discussion you’re engaged in with your friend always seem like a pointless exercise in mental masturbation. Personally, I think the physical act is a more worthwhile pursuit.

Problem with "every possible world": one absolutely possible world would be one which is totally bereft of life of any sort, physical OR spiritual. I think that ***ks up the argument pretty badly right there.

Also, one perpetual problem with all ontological arguments is that whatever that being is is God. Now, is that Jehovah or Allah or Krishna or Ahura Mazda? You see, this is what renders the ontological argument unmoving for so many people, who don't want to be convinced that SOME deity exists, but that THEIR deity exists. That is one thing the ontological argument fails to do miserably.


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