Quotes from Frederick Schauer

The act of giving a reason is the antithesis of authority. When the voice of authority fails, the voice of reason emerges. Or vice versa.

See Sean Coyle, "Thomas Hobbes and the Intellectual Origins of Legal Positivism," Canadian Journal of Law and Jurisprudence 16 (2003), 243–270; Mark Murphy, "Was Hobbes a Legal Positivist?," Ethics 105 (1995), 846–873.