Natural Law Theory: From Aquinas to Finnis

Natural law theory holds that the validity of positive, human-made law is bound up, in some way, with morality — that there are objective standards of justice and human good, accessible to reason, against which enacted law can and should be measured. Its classical formulation belongs to Thomas Aquinas (1225–1274), who in the Summa Theologiae (Prima Secundae, questions 90–97, composed c. 1265–1274) defines law generally as "an ordinance of reason for the common good, made by him who has care of the community, and promulgated," and distinguishes four types: eternal law (God's rational plan for the universe), natural law (the rational creature's participation in the eternal law, graspable by unaided reason), human law (positive law enacted by political authorities), and divine law (revealed in scripture). Aquinas's most consequential and most quoted claim is that "lex iniusta non est lex" — an unjust law is not really a law at all, but rather "a species of violence" — a formula usually rendered as the maxim that an unjust law is no law. Crucially, Aquinas does not conclude that unjust enactments simply vanish or may never be obeyed; in question 96, article 4, he argues that a human law conflicting with the natural law binds in conscience only weakly, if at all, though disobedience must still be weighed against the risk of civil disorder (scandal), a qualification often lost in later, more polemical summaries of the position.