 Some traditional physicalist theories conflict with other aspects of Russellian monism. For example, (physicalist) analytic functionalism (Armstrong 1968; Lewis 1966, 1972, 1980) conflicts with the Russellian monist’s denial that structural truths alone a priori entail all phenomenal truths (see the entry  functionalism;  phenomenal truths are truths about consciousness). But other traditional physicalist theories are not similarly disqualified. For example, a posteriori physicalists also deny that structural truths alone a priori entail all phenomenal truths (see the entry  physicalism).  Nevertheless, in their view, there are non-phenomenal properties that can collectively constitute phenomenal properties, perhaps when arranged in the right structure. So, one might wonder why a posteriori physicalism does not qualify as Russellian physicalism.