Footnote on Contingent Perdurantism
Perhaps I was wrong when I said that those who claim that perdurantism is contingent think that things could undergo intrinsic change without having temporal parts. I've just reread Haslanger's and Lewis' remarks, and these appear to be compatible with the view that only things that don't change might endure. For example, Lewis only mentions the possibility that the spatial parts of a spinning sphere might persist by enduring. And maybe those parts don't ever change their intrinsic properties. Probably even the entire sphere doesn't, because if you copy a particular sphere stage and rotate the copy by 180 degrees, you still have an exact intrinsic duplicate of the original stage. This would explain why Lewis doesn't announce a big change of view, because he always accepted that some special entities, namely universals, might endure.
My only complaint then is that this doesn't turn perdurantism into a contingent theory of intrinsic change (rather than persistance). And I still find it difficult to understand how extended things could lack parts.