But what is natural law? And what do we make of the fact that natural law can be and has been claimed as the moral basis for virtually everything – including slavery, racism, and the Nazi genocide of the Jews? Since I’ve started this blog a number of people have written me to ask me just this question. What is natural law?

When Evangelicals think about natural law they often imagine cerebral intellectuals attempting to use reason and logic to invent or try to prove moral principles. They are appropriately skeptical of such exercises. With a little ingenuity and skill, the intellectually self-confident can defend just about any moral conclusion on the basis of reason. Catholics in the tradition of Thomas Aquinas might take natural law to some very conservative conclusions, but the Enlightenment launched us in a liberal trajectory that has taken us far to the left of anything recognizable to Aquinas. As cynics point out, reason alone does not confirm the most basic principles, such as human dignity or equality, which depend on theological affirmations regarding the creation of human beings in the image of God.

Reformed theologians can be quick to jump on the bandwagon. Given human depravity and sin, natural law is not a reliable epistemology (i.e., means of moral knowledge). All it does is to render human beings accountable to God (i.e., Paul’s argument in Romans 1). It has little constructive value for human life.

On the other hand, as theologians like David VanDrunen have demonstrated, the older Reformed tradition actually followed Thomas Aquinas in finding an important role for natural law. To be sure, Calvin and others emphasized that natural law has no power to save. Only the gospel of Christ – special revelation – can do that. But when it came to political and social moral practices these theologians could often wax eloquently about the achievements and wisdom of pagan philosophers like Plato and pagan societies like ancient Rome. And Calvin repeatedly affirmed that all truth comes from the Holy Spirit, wherever it is found.

But what is natural law? And what do we make of the fact that natural law can be and has been claimed as the moral basis for virtually everything – including slavery, racism, and the Nazi genocide of the Jews? Since I’ve started this blog a number of people have written me to ask me just this question. What is natural law?

This is not the focus of my work, and I have no scholarly response prepared. VanDrunen is currently working on a book that articulates a biblical theology of natural law, and I think it will be quite good. It will certainly move the discussion forward. For now, however, I want to make a few points about what natural law is, what it isn’t, and why it is useful in our current cultural context.

First, contrary to popular belief, natural law is not first and foremost a process of reasoning or a means of attaining moral knowledge. It is, rather, the objective moral order of creation as designed by God. It exists whether or not any human beings understand it or can attain to it, and whether or not human theories of natural law have any correspondence to it. It is inherently covenantal, in that it expresses the moral relationship God has created between himself and human beings, among human beings, and between human beings and the rest of creation. As an objective standard built into creation, it is distinct from positive human law (i.e., laws humans have established whether consistent with natural law or not) as well as from revealed divine law as recorded or written (i.e., the Torah, the Ten Commandments, the New Testament), although the latter is always consistent with and often includes much of the natural law.

Second, knowledge of the natural law does not necessarily depend on reason or logic because it is written on the human heart (Romans 2). In that sense it is often intuitive, expressed by human beings in their social and political interactions whether they are aware of it or not. Human beings can suppress some of the principles of natural law (i.e., that God should be worshiped or human life preserved) but they can never consistently suppress all of it (i.e., that human life should be preserved and the flourishing of social order promoted). Evidence of natural law is found in what philosophers and theologians used to call the law of nations – the universal or near universal practices of human beings that are essential to social survival. But intuition, reason, experience, science, and special revelation all provide some evidence of the natural law; none of them reveal it independently, or fully.

Third, although there are areas in which contemporary modern society flagrantly ignores natural law, there are also numerous commitments of the liberal West that express its enduring moral relevance. Such expressions include much of the content of the United Nations’ Universal Declaration of Human Rights, as well as other similar charters, and they also include some of the principles found in more overtly religious documents like the American Declaration of Independence. The moral authority of these documents, even in societies like the United States that feature significant political, cultural, and moral divisions, indicate the widespread acceptance of a natural moral order, however we might disagree about what that order looks like in practice.

Finally, the primary role of natural law in contemporary American political and civil society is not to solve our political disputes or even to adjudicate between our conflicting arguments. In a perfect world, of course, natural law would achieve such ends, but as the critics rightly point out, in the world we have human depravity and sin is simply too great to warrant such optimism. The primary role of natural law is therefore not to serve as a means to moral knowledge but as a basis for moral conversation. By speaking in terms of natural law – or in terms of language of rights and responsibilities, liberty and equality, justice and peace – we testify to the fact that as human beings we are moral creatures obligated to live together according to standards of mutual accountability, order, and basic justice. We acknowledge that although we might often disagree on very important things, we also agree on many important things. We recognize that we have the ability to work through our disagreements in a manner conducive of at least a modicum of peace and justice, and that therefore we should not be in a constant state of war.

What happens if we reject natural law? What happens if we simply appeal to our personal preferences, our religious convictions, or to the revealed standard that our religious community uniquely affirms to be the word of God? We lose all common ground. We see the breakdown of conversation. Politics becomes nothing more than a power struggle. Government loses its moral authority in the eyes of its subjects. There becomes no reason why my neighbor (or enemy) should listen to me when I seek to persuade him that a certain principle or practice is morally essential to our common good.

There is much more that could be said, but perhaps this is a good start. Natural law will certainly not solve all of our problems. But we cannot do without it.

Matthew J. Tuininga is a doctoral candidate in Ethics and Society at Emory University, holds an MDiv from Westminster Seminary California and is licensed to preach in the United Reformed Churches in North America. He blogs at Christianity in America, where this article first appeared; it is used with permission.