 These ideas are exploited in what Chalmers calls ‘Russellian monism’ (a variety of neutral monism). In our world, he suggests, the underlying intrinsic properties might be ‘phenomenal properties, or they might be protophenomenal properties: properties that collectively constitute phenomenal properties when organized in the appropriate way’ (2010: p. 151); while in some other worlds the corresponding intrinsic physical properties did not provide for consciousness. If the intrinsic properties which supposedly provide for our consciousness are nevertheless classified as physical, exponents can deny the possibility of zombies if these are understood to be our ‘full’ physical duplicates. At the same time they can concede the possibility of zombies which duplicate us only in their structural properties. As he points out, this view is ‘a highly distinctive form of physicalism that has much in common with property dualism and that many physicalists will want to reject’ (Chalmers 2010, p. 152; see also Pereboom 2011). One obstacle to counting it as physicalism is that it seems unable to explain why the special intrinsic properties in our world should provide for consciousness, while those which perform the same functions in those other worlds do not: this has to be accepted as a brute fact. 