 Second, it is difficult to define physicalism, and in particular to ensure that it is not trivial (see entry on  physicalism).  Clarifying the thesis of physicalism involves circumscribing what counts as “physical”, just as individualism involves clarifying what counts as “individualistic”. If the physical entities are to be a non-social “base” that exhaustively determines the social, then it is required that the social not be included in that base. (See sections  3.2  and  3.3  on the separation of the social from the nonsocial.) Clarifying physicalism likewise requires clarifying what dependence relation various facts are taken to stand in, with regard to the physical. Are social facts, for instance, taken to be physical facts? To supervene on physical facts? To be exhaustively grounded by physical facts? (See  section 2.3.1  for analogous considerations in interpreting individualism.)