An Introduction to the Literature of Natural Law and Natural Rights, Part One: Natural Law

An essential aspect of classical liberal or libertarian theory is its emphasis on the moral dimension in human interaction, specifically, its focus on the principle of justice. This is expressed by the principle of natural rights, which in its distinctively libertarian form is usually formulated as “self-ownership” or “self-proprietorship.” Of course, to defend adequately a theory of self-ownership (or any theory of justice) requires that one’s moral theory be based on objective facts in some fashion. This attempt to ground values in facts, to derive rationally what “ought” to be from what “is,” has been for centuries the major task of natural law moral theory.

In approaching the subject of natural law (we shall take up natural rights in Part Two), we are confronted with several problems, including the meaning of “natural law” itself. This term is often beset with ambiguity, and it more accurately denotes a general approach to moral theory than a particular moral doctrine. It is not an easy task to isolate a definition of “natural law” to which all of its defenders would subscribe.

For example, A. P. d’Entrèves, in his excellent introductory work, Natural Law (2nd ed., London: Hutchinson, 1970, p. 17), contends that “there is really not one tradition of natural law, but many.” The supposed continuity between the medieval and modern concepts of natural law “is mainly a question of words.” Similarly, Francis Oakley and Elliot Urdang, “Locke, Natural Law, and God;” (Natural Law Forum no. 11 [1966], p. 99), criticize those scholars who “project a spurious unity upon the disparate natural law theories current in the middle ages.” It is improper “to speak of the classical and Christian and . . . of the medieval natural law theory.”

Some scholars, on the other hand, stress the common themes uniting natural-law philosophers. Paul Sigmund, in Natural Law in Political Thought (Cambridge: Winthrop, 1971, p. x), detects in natural-law theory a confidence “in the ability of human reason to deal with moral problems.” Implicit within a natural-law approach, argues Leo Strauss in Natural Right and History (Chicago: University of Chicago Press, 1953, p. 2), is a reliance upon “a standard with reference to which we are able to judge of positive right.”

The contemporary Aristotelian philosopher Henry Veatch, in For an Ontology of Morals (Evanston: Northwestern University Press, 1971, pp. 118, 41), regards natural-law ethics as “an attempt to give a factual status to values.” The “hallmark of a natural-law ethics,” argues Veatch in this important book, “is that norms and values are held to be based or grounded in nature, and that in virtue of norms thus having a natural status, as over against being merely man-made, it is possible to claim a rational basis for ethics.”

Finally, Leonard Krieger, writing on “Kant and the Crisis of Natural Law” (Journal of the History of Ideas 24 [1965], p. 194), pinpoints in natural law the desire “to connect the fundamental principles of reality with the fundamental principles of action—in other words, knowledge with morality . . . In short, natural law involved a description of reality in terms of laws which became prescriptive for men.”

The novice who wishes to trace his way through the historical maze of natural law theories will find the previously cited books by A. P. d’Entrèves and Paul Sigmund quite helpful. Also recommended is Francis H. Eterovich, Approaches to Natural Law, From Plato to Kant (New York: Exposition, 1972). This provides a well-organized summary of natural-law history that the beginning student will appreciate.

Other general overviews, though less satisfactory in some respects, include the following: Edward S. Corwin, The “Higher Law” Background of American Constitutional Law (Ithaca: Cornell University Press, 1955 [originally published in the Harvard Law Review, 1928–9]); Heinrich A. Rommen, The Natural Law (St. Louis: Herder, 1947); John C. H. Wu, Fountain of Justice: A Study in the Natural Law (New York: Sheed and Ward, 1955); and Charles G. Haines, The Revival of Natural Law Concepts (New York: Sheed and Ward, 1955). For an interesting survey of natural law and its contemporary critics see Henry Veatch, “Natural Law: Dead or Alive?” (Literature of Liberty vol. 1, no. 4 [1978]). A good selection of writings on natural law is Brendan F. Brown (ed.) The Natural Law Reader (New York: Oceana, 1960).

Because natural law was for many centuries the dominant approach to moral and political philosophy, the history of natural law is often synonymous with the development of moral and political theory. Here, of course, there is an abundance of literature to choose from. The reader will find that surveys written by Catholic scholars, or by other historians and philosophers generally sympathetic to the Aristotelian-Thomistic tradition, are usually the most sensitive to the natural-law aspects of moral and political philosophers. Hence scholarly journals such as The American Journal of Jurisprudence (formerly Natural Law Forum), The Thomist, and The New Scholasticism contain many articles on the theory and history of natural law. These journals, along with Journal of the History of Ideas, should be perused for their specialized studies.

A History of Philosophy, the multi-volume classic by the Catholic philosopher and historian Frederick Copleston, (Garden City, N.Y.: Doubleday, 1962, rev. ed.), is a solid reference work that no serious student should be without. Another Catholic scholar, Vernon J. Bourke, has given us a valuable two-volume History of Ethics (Garden City, N.Y.: Image Books, 1970). The standard text by George Sabine, A History of Political Theory (New York: Henry Holt, 1950), is a justly acclaimed introduction, but Sabine is far less sympathetic to the natural-law tradition than either Copleston or Bourke.

The origins of a systematic approach to natural-law ethics may be traced to the early Greek philosophers, especially to Plato and Aristotle. John Wild’s Plato’s Modern Enemies and the Theory of Natural Law (Chicago: University of Chicago Press, 1953), is a spirited defense of the natural-law theories of Plato and Aristotle, although it is questionable whether Wild successfully rescues Plato from the charge of totalitarian sympathies (leveled by Karl Popper, among others). A brief but illuminating discussion of natural law in Greek philosophy is found in Harry A. Wolfson, Philo (Cambridge: Harvard University Press, 1947, II:169–180).

Of course, there is never any substitute for the original classics; and the reader of Aristotle’s Nicomachean Ethics (ed. by W. D. Ross The Works of Aristotle, volume 9 [Oxford: Clarendon Press, 1925]) will be treated to one of the best and most influential treatises on moral philosophy ever written.

The Stoic conception of natural law, which was to exert a profound influence on later philosophers, is discussed in Maryanne C. Horowitz, “The Stoic Synthesis of the Idea of Natural Law in Man: Four Themes” (Journal of the History of Ideas, vol. 35, no. 1 [1974], pp. 3–16). Cicero played a major role in disseminating Stoic ideas of natural law during the Roman Republic, and one finds two of his works quoted widely by subsequent writers on natural law: De re publica (On the Commonwealth) and De legibus (On the Laws), translated in “Bohn’s Classical Library” (London: Bell and Daldy, 1872). The following excerpt from On the Commonwealth (p. 360) is among the most famous passages on natural law ever written:

“True law is right reason conformable to nature, universal, unchangeable, eternal, whose commands urge us to duty, and whose prohibitions restrain us from evil. . . . This law cannot be contradicted by any other law, and is not liable either to derogation or abrogation. Neither the senate nor the people can give us any dispensation for not obeying this universal law of justice. It needs no other expositor and interpreter than our own conscience. It is not one thing at Rome, and another at Athens; one thing to-day, and another to-morrow; but in all times and nations this universal law must for ever reign, eternal and imperishable.”

Natural law was a pervasive theme in medieval philosophy, but there was serious disagreement among philosophers and theologians of this period concerning the precise nature and status of natural law precepts. In a class by itself is the magisterial work by R. W. and A. J. Carlyle, A History of Medieval Political Theory in the West, originally published from 1903 to 1936 in 6 volumes (Edinburgh and London: William Blackwood, 1950). These volumes devote a good deal of space to the idea of natural law, and their scope is greater than indicated by the title (they cover the period from Cicero to the late sixteenth century). A good selection of readings with incisive commentary is Ewart Lewis, Medieval Political Ideas, 2 volumes (New York: Cooper Square, 1974).

If there is a weakness in the Carlyle volumes, it is an inadequate appreciation of the influence of canon law in forging medieval notions of natural law. This is rectified in the superb writings of Walter Ullmann. See, for example, “The Canonists and Natural Law” in Medieval Papalism (London: Methuen, 1949, pp. 38–49); and Ullmann’s Law and Politics in the Middle Ages (Ithaca: Cornell University Press, 1975), which also discusses the impact of Roman law on medieval thought. The same author has given us perhaps the finest introduction to medieval political theory (though his interpretation is by no means uncontroversial) in A History of Political Thought: The Middle Ages (Baltimore: Penguin Books, 1974). A student of Ull-mann’s, Brian Tierney, has also produced some first-rate work. Relevant to our theme here is “Natura Id Est Deus: A Case of Juristic Pantheism?” (Journal of the History of Ideas vol. 24, no. 3 [1963], pp. 307–22). This article explores various meanings of natural law within the medieval tradition.

Two works by the great German scholar Otto Gierke are indispensable for the medieval and early modern period. Political Theories of the Middle Ages originally appeared in German in 1881 and was later translated by Frederic Maitland (Cambridge: Cambridge University Press, 1900); and Natural Law and the Theory of Society, 1500 to 1800 made its first appearance in 1913 (one volume edition trans. by Ernest Barker, Cambridge: Cambridge University Press, 1950). Gierke, it should be noted, was a Hegelian who belonged to the German historical school, so he was hostile to the rise of individualism and natural rights that grew from the natural-law tradition. But Gierke’s scholarship and arresting generalizations far outweigh his bias and critical remarks.

The greatest influence on medieval thought before Thomas Aquinas was St. Augustine (354–430). Although Augustine believed in natural law, he so emphasized the corrosive effect of original sin on man’s natural faculties (including reason), that pure natural law was relegated to the distant past of prelapsarian man (i.e., before the fall). Thus, among the evils condemned by natural law in a state of innocence were slavery and government; but Augustine defended both institutions as decreed by God as a punishment and remedy for sin. A good treatment of this subject is Herbert A. Deane, The Political and Social Ideas of St. Augustine (New York: Columbia University Press, 1963). A critical treatment of the Augustinian tradition is found in Herschel Baker, The Image of Man (New York: Harper Torchbooks, 1961). In the same vein, with a fascinating discussion of the revival of the Augustinian emphasis on sin during the Protestant Reformation and its deleterious effect on natural-law theory, is a neglected book by Robert Hoopes, Right Reason in the English Renaissance (Cambridge: Harvard University Press, 1962).

Christian Europe saw a revival of Aristotelianism in the twelfth century (sometimes called “The Renaissance of the Twelfth Century”), and two great figures emerged in the thirteenth century who attempted to integrate Aristotle into the Christian tradition. The first was Albert the Great, who is discussed in Stanley B. Cunningham, “Albertus Magnus on Natural Law” (Journal of the History of Ideas, vol. 28, no. 4 [1967], pp. 479–502).

The other student of Aristotle was Thomas Aquinas, who was to have a tremendous impact on philosophy for centuries afterwards. Aquinas (who studied under Albert the Great) diverged from Augustine in that he assigned less importance to the effect of sin on man’s nature and thus made possible the revival of a natural-law ethics which was not so closely tied to supernatural revelation. The “principles of which nature is constituted,” wrote Aquinas in his monumental Summa Theologica (N.Y.: McGraw Hill, 1964–76, vols. 1–60), “and the properties that flow from them . . . [are] neither destroyed nor diminished by sin.” It is very possible, as Walter Ullmann has maintained, that we owe to Aquinas the revival of political philosophy as an autonomous discipline.

There are many books and articles on Thomas Aquinas. The beginning student will benefit from D. J. O’Connor, Aquinas and Natural Law (London: Macmillan, 1968); and Vernon J. Bourke, “Is Thomas Aquinas a Natural Law Ethicist?” (The Monist vol. 58, no.1 [1974], pp. 52–66). More advanced is Thomas Gilby, The Political Thought of Thomas Aquinas (Chicago: University of Chicago Press, 1958). A good anthology with a useful introduction is A. P. d’Entrèves (ed.), Aquinas: Selected Political Writings (Oxford: Basil Blackwell, 1954).

Aquinas paved the way for an autonomous secular moral theory by maintaining (to oversimplify somewhat) not that the precepts of natural law are right because God wills them, but that God wills them because they are right. A reaction against this view arose in the fourteenth century with William of Ockham (or Occam), who argued that the rightness of natural law is rooted in the will of God (voluntarism), thus denying to the precepts of natural law an independent foundation. Ockham’s development of voluntarism was to play a significant role during the Reformation, with Luther and Calvin aligning with the voluntarist camp against the Catholic defenders of natural law. Francis Oakley has written extensively on medieval voluntarism; especially recommended is his The Political Thought of Pierre d’Ailly: The Voluntarist Tradition (New Haven: Yale University Press, 1964). Unlike many commentators who treat voluntarism as an abandonment of natural law, Oakley sees it as a variant within a broader natural-law framework. For a succinct treatment of Ockham’s political theory, see E. F. Jacob, “Ockham as a Political Thinker” in Essays in the Conciliar Epoch (Manchester: Manchester University Press, 1963, pp. 85–105).

As we enter the modern era, especially in the sixteenth and seventeenth centuries, ideas of natural rights begin to emerge as a current within the natural-law tradition. This is the subject we shall explore in Part Two.

George Smith is a Fellow of the Institute for Humane Studies and is the author of several books and articles on Freethought, the political thought of Herbert Spencer, and education. He is currently working on a book, coauthored by Jack High, on Education and Liberty: The Separation of School and State. He resides in Los Angeles.