Laying ghosts to rest.

One of the most widely-discussed arguments against physcialism appeals to the conceivability of zombies, being which are physically or functionally identical to humans but which have no conscious experiences. Philip Goff (Philos Phenomenol Res 81(1): 119-139, 2010; Consci Cognit 21(2): 742-746, 2012a; in Sprevak M, Kallestrup J (eds) New waves in philosophy of mind. Palgrave, 2014) has recently presented a number of different anti-physicalist arguments appealing to the conceivability of ghosts, entities whose nature is exhausted by their being conscious. If ghosts are conceivable, this would rule out a priori physicalism. If the conceivability of ghosts entails that they are metaphysically possible, then this forms the basis for arguments against a posteriori physicalism. Drawing on work on conceivability by Peter Kung (Philos Phenomenol Res 81(3):620-663, 2010, Noûs 50(1): 90-120, 2016) and my own discussion of arguments which appeal to the conceivability of zombies (O'Conaill in Mihretu P Guta (ed) Consciousness and the ontology of properties. Routledge, New York, 2019), I shall argue that ghosts are conceivable, but that what allows us to conceive of them (our ability to make certain stipulations about the scenarios we conceive) undermines the belief that conceivability is a reliable guide to possibility. While this does not undermine Goff's argument against a priori phyiscalism, it suggests that a posteriori physicalists need not be haunted by ghosts.