Although Aquinas developed his theory of law within the context of a Christian world-view, much of what he says remains relevant within modern secular societies. Following on from the Synderesis Rule, Natural Law is based on five primary precepts. Thomas Aquinas was a one of the few philosophers to interpret the theology as a whole distinguishing the difference between theology and philosophy by explaining Law in general in a detailed account and focusing on kinds of law which he classified as Eternal, Human, Divine and Natural law. See xx-xxi for the part, question, article structure of the Summa and the Objections, Sed Contra, Respondeo, and Responses-to-Objections structure of the articles. A just law is a man-made code that squares with the moral law or the law of God. You want to know what natural law is according to St. Thomas Aquinas. Natural Law Theory. It relies on Aquinas' basic understanding that humans innately try to do good and to avoid evil in order to find fulfilment and happiness in life ( Synderesis Rule ). The Natural Law theory is most closely associated with St Thomas Aquinas, who used Aristotle's philosophy and applied it to Christian thinking. Natural law (Latin: ius naturale, lex naturalis) is law as seen as being independent of, and pre-existent to, the positive law of any given political order, society or nation-state. The term “positive law” was put into wide philosophical circulation first by Aquinas, and natural law theories of his kind share, or at least make no effort to deny, many or virtually all “positivist” theses—except of course the bare thesis that natural law theories are mistaken. Natural Law is an absolutist theory most commonly associated with St Thomas Aquinas (1224 -1274). Natural law in the Enlightenment and the modern era. Aquinas's Legacy . And in many ways the issues he raised continue yet to dominate the philosophy of law. An unjust law is a code that is out of harmony with the moral law. Aquinas On Law Read Saint Thomas Aquinas, On Law, Morality and Politics (Hackett), xiii-xxii and 11-83. According to St. Thomas Aquinas in his Summa Theologiae, “natural law” is that law that is imprinted on a creature by God through the nature of that creature. Other Scholastic thinkers, including the Franciscan philosophers John Duns Scotus (1266–1308) and William of Ockham (c. 1285–1347/49) and the Spanish theologian Francisco Suárez (1548–1617), emphasized divine will instead of divine reason as the source of law. To put it in the terms of Saint Thomas Aquinas, an unjust law is a human law that is not rooted in eternal and natural law.