Question I've been wrestling with this problem for some time. My question concerns the concept of 'possibility'. When one says that something is possible, they are saying that something might be but may not be as well. There is an uncertainty. And of course whatever it is cannot both be and not be at the same time. Now, when we say that something is 'not possible', we are saying that something is not and cannot be. There is no uncertainty and the term as used does not seem to be a true negation as is usually meant when the term 'not' is used. What confuses me, is that in when actually trying to negate the concept of possibility, such as when saying 'not possible', aren't we on the one hand saying that 'that which might be' is not, and on the other hand that 'that which may not be' is not as well, and therefore is (or could be)? What may be is not and/or what may not be is. Saying that something is not possible, in this sense, is the same as saying that it is possible, thus making the negation of the concept meaningless. Is this confusion brought about do to a language or linguistic imperfection or peculiarity or just bad logic and fuzzy thinking on my part. Or does the dual nature of the concept of possibility (the uncertainty of either x or y) make negating it meaningless, so that there is always only the possible. I'm confused.

Accepted:
April 12, 2016

Comments

I don't think there's a deep

I don't think there's a deep puzzle here, as I hope I can explain.

The kind of possibility that stems from uncertainty is usually called "epistemic possibility," often signaled in English by "may" or "might," as in "There may [or might] be life on other planets." We're far from certain that there isn't life on other planets, so there may [for all we know] be life on other planets: life on other planets is an epistemic possibility for us. There are other kinds of possibility, such as metaphysical possibility, but I think the general point I'll make applies to all of them.

To deny possibility in this sense, to say that some state of affairs S isn't epistemically possible for someone, is roughly to say that he/she is certain that S doesn't obtain, or at least he/she knows that S doesn't obtain (if knowledge doesn't require certainty). So I'd say that, right now, my own non-existence is epistemically impossible for me, because I know (indeed, I'm certain) that I exist, for the reason Descartes gives in the second of his Meditations. By contrast, my non-existence is epistemically possible for someone who's never met or heard of me: for all that person knows, I don't exist.

Importantly, to say that my own non-existence is epistemically impossible for me is not to say that there's an epistemic possibility that I know doesn't obtain. Rather, it's to say that my own non-existence isn't an epistemic possibility, for me, in the first place. I deny that I might, for all I know, not exist right now. I can deny my own non-existence without having to regard it as an epistemic possibility, i.e., as something that might obtain.

I hope that helps.