  Might it not be better to say: no legal philosopher need, or should, be a legal positivist?  For law’s dependence upon social facts is fully acknowledged, and also accounted for, in natural law theories of law. And this is not a “concession” by natural law theorists, for their main positions were clearly articulated by Aquinas, many centuries before legal positivism emerged with its challenge to (what it took to be) natural law theory.  Positivist critiques of natural law theory, when they do not rest upon scepticism about the possibility of moral judgment, a scepticism implicitly disavowed in the above passage, rest on misunderstanding of passages from the works of natural law theorists. On such misunderstandings, see Finnis 1980, 23–55; Soper 1992.