People can look at non-conforming behaviour in two ways: either the person is acting immorally or the moral theory that condemns the behaviour is mistaken. To choose the former is to reflect a confidence in the existing moral theory, while choosing the latter is evidence that moral theory for that particular behaviour is wrong. This point says a lot about the link between the descriptive and evaluative enterprises of law. The development of basic moral principles, which draws from moral intuition, (...) is a similar process when it comes to developing social practices, which in turn draw from human behaviour. Legal positivism has contributed much to clarifying the kind of social facts that characterize legal systems, specifically the kind of normative claims that legal systems typically make. Legal positivism provides much of the descriptive front. This chapter is motivated by an interest in reconciling the normative claims of law with the claims that moral philosophers believe can be justified. (shrink)