“Ways Things Can’t Be,” Notre Dame Journal of Formal Logic, 38 (1997) 583–596 (published in 1998).
I show that the believer in possible worlds can have impossible worlds for free, as classes of possible worlds. These do exactly the job of ways that things cannot be, and they model the simple paraconsistent logic LP. This motivates a semantics for paraconsistent logic that even a classical logician can love.