This note is a reply to margery bedford naylor's "a note on david lewis's realism about possible worlds" ("analysis", ja 1986, 28-29). naylor asks why, if we accept david lewis's argument for real possible worlds ("counterfactuals", blackwell, 1973, 84), we should not accept an analogous argument for impossible worlds. i argue that the latter argument is invalid on the modal realist account of possibility and thus has no force for an adherent of lewis.
Sharlow, M. F. (1988). Lewis’s Modal Realism: A Reply to Naylor’s “a Note on David Lewis’s Realism About Possible Worlds.” Analysis, 48 13–15.