It would be a bit much to expect people to sign on to what might be called “apodictic mysterianism”–the thesis that this or that is certainly a permanent mystery (say, consciousness). This seems like claiming infallible insight into the open future of knowledge. But mysterianism doesn’t need to be that strong: more reasonable is “probabilistic mysterianism”–such and such is probably a mystery. Weaker still is the doctrine that it is epistemically possible that mysterianism is true: for all we know, X is a mystery–we don’t know it’s not a mystery. Let’s call this modal mysterianism. My question is how many people are willing to sign on to that doctrine. Instead of two or three mysterians (me, Chomsky, and possibly Pinker) we might get dozens or hundreds. Not that I think we are limited to modal mysterianism; indeed, I think apodictic mysterianism is true in some areas–some things can be known with certainty to be unknowable. We can’t know the exact temperature of a particular volume of air on a particular day two billion years ago. Nor can we ever know what it was like to be a member of some extinct species of mollusc. The question is who is certain that all problems can be solved by the human mind.