Natural law, then, remains as indispensable for Christians today as it was for the many centuries in which it held a central role in Christian ethics. As Protestants, however, we cannot retrieve natural law without allowing Scripture to remain the final authoritative norm of our teaching. 

How should we then live? So Francis Schaeffer famously asked in his 1973 book and subsequent video series. The question has certainly had renewed urgency over the past two years, as Christians around the world have confronted the for-us-unprecedented (although not so much for our ancestors) moral and political challenges of navigating a global pandemic, and accompanying public health measures. How should we love our neighbors? By mask-wearing and vaccinating? By moving worship services and schools online or carrying on as normal? And by what standard should we evaluate the many answers proffered by TV personalities and public authorities?

For many Christians, the answer is quick and easy: “By Scripture, of course.” But a few minutes’ reflection will be enough to leave us scratching our heads in puzzlement. For Scripture, clearly, has very little to say on the subject of public health emergencies, and only the most general principles about how we should conduct ourselves in the face of such complex moral and legal demands. The same, we may soon realize, goes for hundreds of moral and political—and indeed ecclesiastical—decisions that we are called upon to make in the course of carrying out our vocations. If we assume that Scripture has all the answers, we are quickly bound to be disappointed. And if we say, sensibly enough, that we need to “apply Scriptural principles” to particular cases, this simply raises the question of how we identify and apply such principles? How do we engage in moral reasoning?

The answer, for generation after generation of Christian theologians and ethicists, was “natural law.” But the idea of natural law fell on hard times among twentieth-century Protestants, under pressure from Barth, fundamentalism, and modernism. It’s high time we recover it if we’re to navigate the profound moral challenges of our day with integrity.

From one standpoint, the idea that there is such a thing as natural law should be pretty uncontroversial. Everything in nature was created by God, who determined what it was and how it was meant to act. Just as a human inventor can tell you how a tool is meant to work, how to keep it in good working order, and how it’s liable to break if you don’t, so God, being a God of order rather than chaos, impressed upon all of his creatures the way they were meant to work. This is what we still often call “the law of nature” or “the laws of nature.” But man too is a creature, and as such is also subject to the law of his nature, which determines how we are meant to act and how we shouldn’t, what kinds of behaviors will achieve good results and which ones will end in brokenness. At the intersection of human nature and the natures of the rest of the world, we find natural law, the moral principles that distinguish wise and successful living from foolish and disastrous actions: sow and reap in preparation for winter, eat and drink in moderation, marry and remain faithful, honor the aged.

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