Brian considers the normativity of law within the framework of legal positivism, noting that the very idea of it has been understood differently by different authors. He proposes that we analyse the concept in terms of reasons for action, that such reasons must be something more than prudential reasons, that the proper question is whether law gives us reasons for actions of the relevant type that we would not have without law, and that Hume’s law makes this task difficult for legal positivists. He considers consequentialist justifications for the normativity of law proposed by Hobbes and Hume, Kelsen’s theory of the basic norm, Postema’s claim that the rule of recognition is a coordination convention, Shapiro’s planning theory of law, and Enoch’s triggering account, concluding that these accounts are all problematic in different ways. He observes that some authors see it as a specifically legal normativity that is neither moral nor prudential, while others conceive of it as moral normativity; he concludes that the former alternative needs elaboration and justification, while the latter is difficult to establish from within the legal positivist tradition.

Bix considers that Joseph Raz might not be willing to accept that legal positivism is a theory, or stance, that is sufficiently well-defined to be captured in a few main tenets, thinking of it rather as a tradition of legal thinkers held together in a rather loose way. Bix focuses his discussion on Raz’s version of the social thesis, the so-called sources thesis, according to which all law is source-based, in the sense that the existence and content of the law is determined using exclusively factual (social) considerations. Bix considers Raz’s two main arguments in support of the sources thesis – the argument from authority and the argument from different functions – as well as certain objections to these arguments put forward by other legal philosophers.