Comments Elsewhere

Richard: Put in more intuitive terms, we can ask: could our world have turned out in any possible way?

Sure. In fact, I’d wager that it’s necessarily true that our world could have turned out in any possible way, provided that you’re not equivocating on the sort of modality you’re talking about in between the “could” and the “possible.” After all, any way that our universe could not have turned out to be is (ipso facto) an impossible, not a possible, “way.”

To put it another way, isn’t your question here just equivalent to asking whether the world could have turned out in any way it could have turned out, or whether it’s possible for the world to have turned out in any possible way?

Richard: Or are some possibilities so extreme that they could only be realized by a different underlying universe?

I don’t think I know what this even means. What would it mean to have a numerically (not just qualitatively) different universe from the one we’ve got? I can conceive of things going quite differently in this universe, but I really have no idea what I’m supposed to imagine about this numerically distinct, alien world that would make it something other than the world we’re in, under different circumstances. (If they are numerically distinct, could they both be actual at once? If not, why not? But if so, doesn’t that conflict with the condition of totality?)

Alex Skiles: Whether or not property P is essential to object x itself has to do with whether or not x has P in all possible worlds. But possible worlds aren’t the sorts of things that can have properties in other possible worlds.

I don’t see why they wouldn’t be. If there are statements that are true of possible worlds, (e.g. that in at least one of them I went to bed instead of writing these remarks), then that seems like a good prima facie reason for saying that those statements are actual, i.e., are among the states of affairs that constitute the actual world. But if you accept that, then you accept applying predicates to worlds within other possible worlds (e.g. that the world in which I go to bed has, in this the actual world, the property of having been accessible for me).

Of course, you could deny the prima facie case, and argue either (a) that modal facts aren’t in any possible world, but float outside (over? under?) any possible world; or (b) that there aren’t really any facts about possible worlds at all. But the sort of transworld realm of facts required for (a) seems to undermine the idea of possible worlds as total; and to assert (b) just seems to be to give up on possible worlds as anything other than a useful fiction.