 Exclusive positivists offer two main arguments for stopping at social sources. The first is due to Raz (1994: 201–37) and has to do with law’s role in practical reasoning (for criticism see Perry 1989, Waluchow 1994, Coleman 2001, Dworkin 2002, Kramer 2004 and Himma 2019). Although law does not necessarily have legitimate authority, Raz suggests it lays claim to it, and can intelligibly do so only if it is the kind of thing that could have legitimate authority. It may fail, therefore, in certain ways only, for example, by being unjust, pointless, or ineffective. But law cannot fail to be a candidate authority, for it is constituted in that role by our political practices. According to Raz, practical authorities mediate between subjects and the ultimate reasons for which they should act. Authorities’ directives should be based on such reasons, and they are justified only when compliance with the directives makes it more likely that people will comply with the underlying reasons that apply to them. But they can do that, he suggests, only if is possible to know what the directives require independent of appeal to those underlying reasons. If law were to incorporate the moral standards to which it refers it would no longer be able to play this mediating role; identifying the law would require identifying the reasons underlying it. Because the nature of law is partly determined by its role in giving practical guidance, Raz concludes, there is theoretical reason for stopping at source-based considerations.