According to David Chalmers, the conceivability of worlds that
duplicate our physics yet lack consciousness refutes physicalism.  Or
rather, it almost refutes it.  This qualification arises because
“Russellian monism,” characterized roughly as the view that
consciousness is determined by the intrinsic properties of fundamental
physical entities, is consistent with the conceivability of such
worlds. One might think this is good news for the physicalist, but not
Chalmers.  Although he takes Russellian monism to be a highly
appealing view, he claims that many physicalists will reject it as it
“shares the spirit of antimaterialism.”  I think that the loophole in
the conceivability argument is more significant than Chalmers has made
it out to be, for, as I shall argue, Chalmers fails to take into
account a version of Russellian monism, what I refer to as “Russellian
physicalism,” that escapes the conceivability argument, yet is fully
physicalistic.