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)

The relationship between faith and reason can seem complicated, but is not contradictory. I admit when I was in college, I went to the Newman Center with the same agenda. It seemed there were two camps on campus: the Christians and the thinkers. I went to the priest to find out if it were necessary to choose between the two, which I was not at all comfortable doing.

The priest pointed me toward something wonderful—the rich Catholic intellectual tradition. I learned a valuable teaching from Vatican I: there can be no contradiction between faith and reason, since God is the author of both. Faith and reason spring from the same created reality and are in this sense mutually dependent on divine revelation. This may sound strange, since we think of revelation as a mysterious process involving heavenly apparitions and miraculous unfoldings. Yet talk to a researcher uncovering a new principle concerning the way time operates, or how the human brain functions. Revelation is a word not inconsistent with that scientific seeker’s experience.

If something is discovered to be true, therefore, it cannot be an obstacle to faith. Faith must expand to admit what is true. This explains why the same church that once condemned Galileo’s teachings as a threat to religious belief had to apologize and restore Galileo’s integrity as a Catholic thinker in the long run. God is truth, and truth cannot deny itself.

Needless to say, it would have been better if church leaders hadn’t rejected Galileo to start with! Frequently the obstacle to embracing truth is our faith in our own fallible perception, rather than faith in God.  It takes courage to remain open to the possibility that we’re wrong in our present opinions, comprehension, and vision. More recent popes have viewed science as a partner in the quest for truth rather than an adversary to religious faith.

Two positions are unhelpful to those who think and believe. One is fideism, the other rationalism. Fideism imagines that all truth drops from heaven unaided by human activity. Moral principles are to be accepted and incorporated without nuance, reflection, or relationship to other avenues of knowledge. Fideists don’t want to argue, they just want to imbibe right principles. Rationalists believe all truth can be apprehended and judged by human reason alone. Religious ideas improvable by scientific means are deemed irrelevant if not invalid.

Scriptures: Job 38:1—42:6; Psalm 8; Isaiah 55:6-9; John 1:1-4; 14:6; Romans 12:2; 1 Corinthians 13:9-12; Hebrews 11:1; 1 John 1:1-4

Books: The Bible and Science: Longing for God in a Science-Dominated World – Vincent M. Smiles (Collegeville, MN: Liturgical Press, 2011)

Science vs. Religion: What Scientists Really Think – Elaine Howard Ecklund (New York; Oxford University Press, 2010)