  Thomas Aquinas’ account of human positive law treats the central case of government as the self-government of a free people by the rulers and institutions which that people has appointed for that purpose, and the central case of law is the co-ordination of willing subjects by law which, by its public character (promulgation), clarity, generality, stability and practicability, treats those subjects as partners in public reason (Summa Theologiae I-II q. 90 a. 4c; q. 95 a. 3c; q. 96 a. 1; q. 97 a. 2). For he defines law as universal (in the logician’s sense of “universal”) practical propositions conceived in the reason of the ruler(s) and communicated to the reason of the ruled so that the latter will treat those propositions, at least presumptively, as reasons for  action—reasons as decisive for each of them as if each had conceived and adopted them by personal judgment and choice.