 The second “explanation” category also encompasses questions about how to see non-mental nature explaining mind. Physicalism generally seems committed to saying the former strongly necessitates the latter—and does not merely guarantee it in virtue of contingent laws. Typically this claim has been motivated by the worry that anything less than strong (“metaphysical”) necessities would leave mind a superfluous add-on, disturbingly ineffectual or epiphenomenal; our minds would not really explain our actions and their results. And that it seems would leave us with no coherent conception of our place in the world that we can live with. It is often thought that consciousness is the real sticking point here: that is what makes it hard to secure the strong form of necessitation desired, or to put to explanatory use such necessity as we have grounds to think is there. These difficulties are articulated in modal conceivability arguments (Kripke 1972; Chalmers 1996); in “knowledge” arguments (Nagel 1976; Jackson 1982); in arguments for the “explanatory gap” (Levine 2001); and in the case for a “mysterianism” about how consciousness arises (McGinn 1991). Controversies about whether we can justify the claim that the right combination of non-mental facts or properties makes it the case that mind must occur, and about whether this affords us explanations of the facts of mind, will take different forms, depending on how one conceives of the consciousness-intentionality relationship.