Well, in modal logic you cannot, as the basis of a premise alone, assume something is metaphysically possible, because then it HAS to be possible, which is where all these problems are coming from. Metaphysical claims ARE special in modal logic for this reason.

But to be honest, I'm not particularly familiar with modal logic, so I could just be mentally masturbating here; quite messy, clearly. You'll have to find someone more knowledgeable than me on this. I finally found these two YouTube videos in my history, they give a better rundown of my point than I have:

(December 5, 2013 at 10:40 am)MindForgedManacle Wrote: Well, in modal logic you cannot, as the basis of a premise alone, assume something is metaphysically possible, because then it HAS to be possible, which is where all these problems are coming from. Metaphysical claims ARE special in modal logic for this reason.

But to be honest, I'm not particularly familiar with modal logic, so I could just be mentally masturbating here; quite messy, clearly. You'll have to find someone more knowledgeable than me on this. I finally found these two YouTube videos in my history, they give a better rundown of my point than I have:

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I don't think this is true, because it would expose a fatal flaw in modal logic that Kripke and co missed out on.

I mean, if you're saying metaphysical claims are qualitatively different, then what in the world do you hang that on exactly? What ABOUT metaphysical claims necessitates special treatment?

I'm assuming of course, when you say it HAS to be possible, you mean "it's necessarily possible." If I'm right, then there might be a misuse of S5 because possibility does not lead to necessary possibility in modal logic to my knowledge.

But even assuming it does, the problem can immediately be circumvented by merely denying the premise.

So given

1) "It is possible that P."

If this leads to problems, you can say "it's only epistemically possible that P" or simply deny the truth of the premise, ie "It is impossible that P."

But I'll have a look at the videos and tell you what I think. It's really cool that there's someone here who knows something about this stuff.

Well, with me 'knows something about this' is more like 'has a fuzzy recollection of something like this, maybe'. :p A philosophy-centric forum may generate better informed folk on this topic. I recommend this one: http://onlinephilosophyclub.com/forums, since I go there every once in a while.

Anyhow, it isn't a flaw with modal logic per se, just in a particular application of it. As I said in my last post, it can't be assumed as metaphysically possible as the basis of a premise alone. That's why people have tried to prepend supporting arguments for the first premise. Logical systems are made to be used certain ways, and transgressing the intentions of their usages will likely make issues like these inevitably crop up.

I'm curious as to whether this view you hold is held by anyone else. Did you think of it yourself, or did you find it in your reading?

No, I didn't come up with this. I remember first coming across it by the uploader of those 2 YouTube videos I posted, and in a blog post by a graduate philosophy student on it
(http://www.uncrediblehallq.net/2011/12/1...fway-good/). I later went through Plantinga's original paper on his MOA and he seemed to conclude with what the aforementioned people did: The his argument alone cannot establish it's conclusion:

Plantinga Wrote:But obviously this isn't a proof; no one who didn't already accept the conclusion, would accept the first premise. The ontological argument we've been examining isn't just like this one, of course, but it must be conceded that not everyone who understands and reflects on its central premise -- that the existence of a maximally great being is possible -- will accept it. Still, it is evident, I think, that there is nothing contrary to reason or irrational in accepting this premise. What I claim for this argument, therefore, is that it establishes, not the truth of theism, but its rational acceptability. And hence it accomplishes at least one of the aims of the tradition of natural theology.

I disagree, but his paper seems to contain a few instances where he references this problem of it only working if you can establish the first premise outside of this argument.