Natural law is the principle that there are higher truths than those dictated by societies and their institutions. It claims these truths are embedded in the natural order of creation. This tradition originated in the Roman Republic with thinkers like Cicero, who reacted against Aristotle’s fierce support for the state centuries earlier. Aristotle had held that society was justified in subjecting women, slaves, and barbarians since they were incapable of moral judgment. Proponents of natural law held that all humans were moral beings; therefore institutions of subjugation were unjust. It was a radical proposition to take back then!
Natural law adherents admitted that government, while “unnatural,” was a necessary force in society to ensure the protection of the weak from oppression by the strong. Church fathers like Augustine would embrace natural law to express just war theory: that while killing was a moral evil, in certain circumstances it was a necessary action to protect the weak.
For many centuries, natural law was wielded by reformers as much as by conservative factions. In the Middle Ages, however, thinkers began applying these ideas to questions of personal morality as well as to social institutions. Sexual and medical choices were scrutinized according to their biological fittingness. Aquinas was less likely to consider natural law in terms of social systems as Augustine used it.
By the time of the Enlightenment, natural law had bifurcated. Philosophers based the doctrine of universal human rights on its principles and urged political reforms that would incorporate this ideal. Catholic thinkers utilized natural law almost exclusively in terms of personal morality. The Catholic position contrasted the natural design of creation with “the unnatural”—against God’s directive and therefore beyond argument.
Natural law remains a fundamental principle in Catholic moral teaching today. At its best, it admits the existence of universally binding moral principles that all humanity might embrace by reason alone. Yet many modern theologians are uncomfortable with a complete capitulation to a law that admits no conversation with Scripture or expanding church tradition. What’s in and what’s outside the immutable boundaries of natural law continue to be hotly debated.
Scriptures: Genesis chapter 1; Exodus 20:1-17; Psalms 8, 19, 104, 119; Proverbs 1:20—2:22; 9:1-12; Jeremiah 31:31-34; Matthew 5:3-12, 17-20; John 1:1-5, 14; 3:31-36; 14:15-27; Hebrews 8:7-12; 10:16
Books: Searching for a Universal Ethic: Multidisciplinary, Ecumenical, and Interfaith Responses to the Catholic Natural Law Tradition –eds. John Berkman and William Mattison III (Grand Rapids, MI: Eerdmans, 2014)
Catholic Moral Theology and Social Ethics: A New Method – Christina Astorga (Maryknoll, NY: Orbis Books, 2013)