Inclusionism and the Problem of Unmarried Husbands

I discuss a modification of Lewisian modal realism called ‘inclusionism’. Inclusionism is the thesis that some worlds contain other worlds as proper parts. Inclusionism has some attractive consequences for theories of modality. Josh Parsons, however, has raised a problem for inclusionism: the problem of unmarried husbands. In this paper I reply to this problem. My strategy is twofold: first I claim, pace Parsons, that it is not clear why the inclusionist cannot avail herself of an obvious solution to the problem; and second, I argue that even if there is no available solution, the same problem also afflicts Lewis’ original theory. Therefore, even if the problem remains unsolved, we have not been given any reason to think that an inclusionist version of Lewisian realism is worse than the original.