A minimal commitment of physicalism has long been thought to be "Necessitation": The thesis that any minimal physical duplicate of the actual world is a duplicate simpliciter of the actual world. However, in recent years, Necessitation has come under attack by "contingent physicalists" claiming that physicalism does not require the metaphysical necessitation of all facts about the world by the world's physical facts. In this paper, I argue that, without Necessitation, there is no principled and systematic way to distinguish between physicalism and anti-physicalism. I discuss, and ultimaltey reject, two proposals for how to distinguish contingent physicalism from anti-physicalism.
