Abstract: In this talk, I’ll reflect on the role of worlds—both possible worlds and impossible worlds—both in the semantics of various kinds of languages and logics, and in broader issues in metaphysics. I will argue that, given very modest assumptions concerning the role of worlds in semantics, that any defender of possible worlds in such a role should be equally comfortable with impossible worlds.

However, this argument for impossible worlds does not transfer straightforwardly to logically impossible worlds. So, in the second part of the talk I will consider what we might say, for (or against) properly logically impossible worlds.