 Stalnaker (1996) argues that, whilst there is nothing wrong in admitting impossible worlds, not much explanatory work can be expected from them. For instance, if one takes worlds as sets of propositions, then one cannot then analyze propositions as sets of worlds. But the same point can be made against any account of possible worlds (such as Adams’s) that takes them to be maximally consistent sets of propositions. And, just as ersatz possible worlds needn’t be constructed in this way, nor need ersatz impossible worlds. Impossible worlds have found many uses in the recent literature, as we have abundantly seen. So we don’t find Stalnaker’s worry convincing.