Does an argument against haecceitism on the basis of PII fare any better within an ersatz view of possible worlds? It’s tough to say. As noted in Section One, different versions of ersatzism deliver different verdicts about whether possible worlds are qualitatively indiscernible from one another. For example, if one holds that all propositions are qualitatively indiscernible, an unrestricted application of PII will cause broad problems for such a view—e.g., by ruling out the existence of more than a single possible world. On other ersatzist views, according to which possible worlds have distinctive qualitative characters even while they represent maximal possibilities that differ haecceitistically, PII will not rule out a commitment to haecceitism. In light of these consequences, PII would need to be applied, not to the possible worlds of the ersatzist, but, rather, to the possibilities they represent. And, of course, if the ersatzist denies that there are maximal possibilities that differ without differing qualitatively, they reject haecceitism. But, since the relevant principle used to undercut haecceitism is not, strictly speaking, PII regarding objects or worlds but instead possibilities, it is unclear whether it merely collapses into the straightforward denial of haecceitism. A worry, then, is that the version of PII that suffices to undercut haecceitism is so close to the thesis of anti-haecceitism that any argument that proceeds from such a principle merely begs the question. In addition, it is unclear if such a principle can be plausibly motivated without leading to objectionable modal commitments by requiring one to reject the kinds of possibilities that Black (1952) notes. (On the case for Black-style possibilities involving qualitatively indiscernible objects, see Adams (1979: 17–19).)