In “The Model of Rules I,”1 Ronald Dworkin argues that judges are often bound by principles that do not derive their authority from having been formally promulgated by a judge or legislature in accordance with a rule of recognition. But, on Dworkin’s view, the existence of such principles is inconsistent with positivism’s pedigree thesis, according to which propositions are legally valid solely in virtue of having been promulgated in accordance with a rule of recognition. Thus, Dworkin concludes that positivism is false.