In H.L.A. Hart’s now famous Postscript to The Concept of Law,H.L.A. Hart, THE CONCEPT OF LAW 185–86 (2nd ed., 1994). Hereinafter referred to as CL. he embraced the Incorporation Thesis, according to which it is possible for a legal system to have a rule of recognition that incorporates moral criteria of validity.Nevertheless, Hart had some reservations about the Incorporation Thesis. Hart, a skeptic about moral objectivism, believed that the Incorporation Thesis presupposes that moral norms have an objective status and hence conditioned his acceptance of the Incorporation Thesis on the truth of moral objectivism. See Kenneth Einar Himma, Incorporationism and the Objectivity of Moral Norms, 5 LEGAL THEORY 415 (1999), for a discussion of Hart’s worries on this count. In such legal systems, a norm must satisfy certain moral conditions as either a necessary or a sufficient condition for it to be legally valid. According to the Incorporation Thesis, then, the criteria of validity need not consist exclusively of standards that define validity in terms of a norm’s source or pedigree.