Follow @shmsdetroit

The Natural Law: "Written Upon Our Hearts"

by Dr. Mark Latkovic

God's universal standard of right and wrong is rooted in our human nature and knowable through reason and a well-formed conscience.

Let's face it. On the subject of morality, our world is really confused. Virtue is vice and vice is virtuealthough we don't use the language of virtue and vice much anymore. But we do talk a lot about rights. (Oh do we talk about rights!) That's not always a bad thingby no mean—particularly when we link rights with duties. But the Catholic Church also has had guardianship of an older language: the language of natural law.

Unfortunately, the terms "nature" and "law" aren't looked at favorably these days. When our secular culture hears law, they primarily hear "no." When they hear nature, they hear only "environment."

But the Church uses these terms in a much different sense in her moral teaching, even if that teaching may involve a firm noeven an absolute noto a particular evil such as abortion or euthanasia.

What is Natural Law?

When she speaks of "natural law," the Church indicates to us that it is a moral law whose principles pertain to free human nature. This is the same law that St. Paul said God has "written in our hearts" (cf., Rom 2:15).

So natural law is both a "supernatural" reality and a "natural" one. St. Thomas Aquinas indicates this twofold character when he defines natural law as "nothing else than the rational creature's participation of the eternal law" (Summa Theologiae, I-II, Q. 91, a. 2). By eternal law, St. Thomas means God's wise and loving plan for all of his creation. Thomas also calls it "Divine Providence."

Natural law, then, is our way of sharing in God's own governance of the world by means of human reason. Put another way: God has made all men and women with a particular natureone that can both reason and willand, when reasoning about practical matters, we can look at our actions and ask, "Is this act in accord with the highest moral standard of all: that of God's eternal law?"

Moral Right from Moral Wrong

Here's where man's moral conscience comes in. It is intimately related to natural law in that it mediates God's law to our minds. Without conscience, we wouldn't even be able to know what God's law is.

This is why conscience is best understood as our basic awareness of moral truth and not as a gut feeling or a mysterious inner voice. It of course includes our feelings (we are bodily beings after all), but ultimately it's a rational judgment about what is (or was) right or wrong to do. The reason we must always follow the dictates of our conscience is due to its "proximate" character: it is our final and best assessment of what is morally good and bad.

But conscience can err! It doesn't always tell us correctly what the demands of God's law are. So we must form it with proper care.

Applies to All and Everywhere

There is an objectivity and universality to natural law because of its grounding in human nature. Thus it applies to all persons without exception and, at least in theory, provides a common reference pointRev. Martin Luther King thought it didfor all persons to talk about morality. In his 1963 "Letter from a Birmingham Jail," King, echoing Aquinas, brilliantly applied natural law theory to the evil of segregation: "An unjust law is a human law that is not rooted in eternal law and natural law."

Not even cultureor creed or country or color, for that matterprovides an exception to the natural law; although it may condition the way we understand and follow it. It is, moreover, a permanent feature of the created moral order by which all men can be held accountable for their deeds, including those who do not know the revealed law of God.

As St. Paul teaches, "For when the Gentiles who do not have the law by nature observe the prescriptions of the law, they are a law for themselves even though they do not have the law. They show that the demands of the law are written in their hearts, while their conscience also bears witness and their conflicting thoughts accuse or even defend them on the day when, according to my gospel, God will judge people's hidden works through Christ Jesus." (Rom 2:14-16)

The Ten Commandments are a wonderful expression of this universality. They are reallyand this might sound strange to our ear—the precepts of the natural law as revealed to us by God (cf., Catechism of the Catholic Church, nos. 1955, 2070-2071). This means that these commandments can be known by unaided human reason. Just because something is scripturally-based doesn't mean that we can't come to know it through reason, too. But God has also revealed his law so that we can have certitude about morality in a fallen world and, cooperating with his grace, attain union with him in heaven.

Violating the Law

All human law must be in conformity with the natural law, or at least not be contrary to its precepts. The first consequence of violating its precept—even before any harm is done to human goods and human dignityis the bad effect this has on our own moral character: we become a person who is evil by doing evil. In religious language, we "sin," either venially or mortally.

This is why we need to develop the moral virtues. For it is one thing to know the natural law, but another thing altogether to carry out its demands. Prudence, justice, temperance, and fortitude enable us to do precisely that.

"Covenant with Creative Wisdom"

"But this is the covenant I will make with the house of Israel after those days, says the LORD. I will place my law within them, and write it upon their hearts; I will be their God, and they shall be my people" (Jer 31:33).

We hear an echo of this text from the prophet Jeremiah in Paul's words about the exigencies of the law inscribed on men's hearts. I think it was because of this passage from Jeremiah that one of my former teachers, Carlo Cardinal Caffarra (now the Archbishop of Bologna), called the natural law the "covenant with Creative Wisdom." But as we have seen, it's not a covenant without content!

No. The natural law contains not only general principles such as "do good, avoid evil," "love God and your neighbor as yourself," but more specific precepts such as we find in the Decalogue (e.g., "Thou Shalt not Kill"), as well as precepts that are known only by those we recognize as extremely wise and prudent persons (e.g., saints).

Pointing Back to Christ

Fr. Livio Melina, the Italian moral theologian, argues: "The natural law and the law revealed through the old covenant show themselves to be partial foreshadowings and prophecies of the living and personal law' that is Christ. The natural law and the commandments of the old covenant have their original locus in the Christic totality wherein they find their foundation and their definitive hermeneutic, insofar as they are brought to completion in love, the fullness of the law."

When presented this way, natural law points ultimately to Jesus Christ and his fulfillment of the old (Mosaic) law; that is, it points to his New Law of Love (cf., Catechism of the Catholic Church, nos. 1965-1970). The Catechism teaches that this New Law is "the grace of the Holy Spirit given to the faithful through faith in Christ [no. 1966] . . . The entire Law of the Gospel is contained in the new commandment' of Jesus, to love one another as he has loved us" [no. 1970; cf., Jn 15:12; 13:34].

Our world needs the moral truths of the natural law. It even more desperately needs the New Law of Christ.

Dr. Mark Latkovic

Dr. Mark Latkovic is professor of moral and systematic theology at Sacred Heart.

Stay connected with Sacred Heart. Sign up for our monthly newsletter.


Sacred Heart Major Seminary is a Christ-centered Catholic community of faith and higher learning committed to forming leaders who will proclaim the good news of Christ to the people of our time. As a leading center of the New Evangelization, Sacred Heart serves the needs of the Archdiocese of Detroit and contributes to the mission of the universal Church.