Terrible Atheist Argument #1

[Vincenzo Vinny G.]

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.