Acknowledging the reality of natural law, C.S. Lewis claimed in one of his wartime broadcasts, is “the foundation of all clear thinking about ourselves and the universe we live in.” Lewis’s aim in these talks, later published as Mere Christianity (1952), was to offer an ecumenical restatement of Christian belief to a world saturated in nihilism, relativism, and historicism. He chose to go about his task in a “roundabout way” by starting with the experiential reality of what he variously called the “Law of Nature,” “Moral Law,” and the “Rule of Decent Behaviour,” a standard known by reason prior to revelation.

Hadley Arkes, the Edward N. Ney Professor in American Institutions, Emeritus, at Amherst College and founding director of the James Wilson Institute on Natural Rights and the American Founding, nods to Lewis’s project in the title of his most recent book, Mere Natural Law: Originalism and the Anchoring Truths of the Constitution. It is Arkes’s eighth major book and the capstone to a remarkable career that is now in its sixth decade. Arkes’s aim, like Lewis’s, is to draw our attention to truths woven into the fabric of human reason and thus of human experience. For Arkes—in contrast to many of his originalist friends—clear thinking about constitutional jurisprudence begins with acknowledging the reality of the natural