 One response points out that, while the problem of abstracta confronts many different versions of physicalism, it does not arise for supervenience physicalism. After all, since numbers exist in all possible worlds, facts about them trivially supervene on the physical; any world identical to the actual world in physical respects will be identical to it in respect of whether 5+7=12, because any world at all is identical to the actual world in that respect! But the difficulty here is that supervenience physicalism seems, as we saw above, too weak anyway. Indeed, one might think that the example of abstracta is simply a different way to bring out that it is too weak.