Americanization of Natural Law: A Historical Perspective

The role and significance of natural law in the twenty-first century are the same as they have always been: namely, to constitute a moral order favorable to the existence and flourishing of human beings in the world. Within the framework of laws of nature that govern the physical environment, natural law is a historically known and time-honored philosophical system that has regard for human beings in particular. Furnishing means of thinking and acting through the faculty of practical reason, natural law enables humans to thrive in ways consistent with the kind of being they are.

Natural law presents itself as a comprehensive account of human existence and provision. Insofar as age and generation—temporality and secularity—are properties of the world, natural law recognizes memory and historical reflection as essential features of human experience. Accordingly, to understand its role in secular society we are permitted, if not required, to take into account the historical dimension of natural law. This means recognizing the existence of natural law in history without historicizing it—without assuming, that is, that its meaning is exhausted by consideration of the changing historical contexts in which natural law texts are written.¹

Controversy over the meaning of natural law throughout history parallels its apparent indispensability in political rhetoric and moral discourse since ancient times. A threshold difficulty is to explain what is "natural" and what "law-ful" about natural law thinking. In this context, the idea of nature means essence, form, kind, or category. Concerned mainly with ethics and morality, it has reference primarily to mental-intellectual rather than physical-biological features of human existence. The element of law in the equation refers to the binding and obligatory character of natural law principles. Further to define its basic meaning, it is pertinent to observe that although always subject to challenge by doubters and skeptics, until the early twentieth century natural law was recognized as a theory of objective moral reality.²

If natural law is an objective moral order for human flourishing, its enforcement might be assumed to be in some sense necessary and irresistible, comparable to the ordering of the physical world. An approximation of the idea of self-enforcement is expressed in descriptions of natural law as "the law written on the human heart," and as the reasoning faculty of "common sense" by which human beings distinguish right from wrong. In fact, the need constantly to recur to the natural law in a more explicit theoretical sense suggests the imperfectness of these means. Nevertheless they help to clarify the fact that, taken on its own terms as an objective moral order existing outside the mind and will of human beings, natural law implicates, if it does not depend upon, the personal responsibility of the individual for his or her actions.³

Natural law is the study of being, existence, what is. An advance beyond primitive religious speculation about the cosmos, it emerged when critical reason observed changing customs, laws and conventions in human society. Natural law inquiry sought to identify the unchanging and essential basis of the positive rules that regulated social organization. Natural law was the "moral reflex of the metaphysical order of the universe," disclosed to human reason by the gods of antiquity or the Hebraic and Christian God in the creation of the world.⁴

To the extent that it requires recognition through human reason, the efficacy of natural law is always subject to qualification and challenge from human willfulness. This problem is historically illustrated in the conflict between Platonism and Sophism in fifth-century Greek philosophy, and between nominalism and realism in twelfth-century European philosophy. The metaphysical realism of natural law, in part no doubt because of its dependence on human nature, is always at risk of producing its positivist opposite or alternative. As approaches to moral reasoning, both natural law and positivism have intellectual appeal and lend themselves to a wide range of practical applications.⁵

With the advent of modernity in the scientific revolution of the seventeenth century, the natural law tradition was relegated to premodern intellectual standing. Cartesian rationalism shifted philosophical investigation from the ontological...