 Evaluative argument is, of course, central to the philosophy of law more generally. No legal philosopher can be only a legal positivist. A complete understanding of law requires also an account of what kinds of things could possibly count as the merits of law (must law be efficient or elegant as well as just?); of what role law should play in adjudication (should valid law always be applied?); of what claim law has on our obedience (is there a duty to obey?); and also the more practical questions of what laws we should have and whether we should have law at all. Legal positivism does not aspire to answer these questions (although cf. Murphy 2014: 88–108 for the argument that the theory has important first-order implications for legal practice). Nonetheless, positivism’s claim that the existence and content of law depends only on social facts does give them shape.