 When H.L.A. Hart revived legal positivism in the middle of the 20th century (Hart 1958, 2012), he did it by criticizing and building on Austin’s theory: for example, Hart’s theory did not try to reduce all legal rules to one kind of rule, but emphasized the varying types and functions of legal rules; and Hart’s theory, grounded partly on the distinction between “obligation” and “being obliged,” was built around the fact that some participants within legal systems “accepted” the legal rules as reasons for action, above and beyond the fear of sanctions. Hart’s “hermeneutic” approach, building on the “internal point of view” of participants who accepted the legal system, diverged sharply from Austin’s approach to law.