The doctrine of the natural law is as old as philosophy. Just as wonder,1 according to Aristotle, lies at the beginning of philosophy, so, too, is it found at the beginning of the doctrine of natural law.
In the early periods of all peoples the mores and laws, undifferentiated from the norms of religion, were looked upon as being exclusively of divine origin. The order according to which a people lives is a divinely instituted order, a holy order. This is true of the ancient Greeks, among whom all law was stamped with the seal of the divine. It likewise holds good for the early Germans: their law bore in the primitive period a distinctly sacred character. Nor is it any less true of the Roman people, whose legal genius enabled its law twice to become a world law.2 For among the Romans, too, law in the earliest times was divine law. Moreover, even the later period, when the Romans had already hit upon the distinction between strictly sacred law (fas) and profane law (ius), still afforded clear evidence of the sacred origin of Roman law: the pontifices remained the dispensers and custodians of the law until Roman legal reason emancipated itself from this secret law of the priests.
This theological cast of all primitive law has two characteristics. Such law is essentially unchangeable through human ordinances, and it has everywhere the same force within the same cultural environment.
The idea of a natural law can emerge only when men come to perceive that not all law is unalterable and unchanging divine law. It can emerge only when critical reason, looking back over history, notes the profound changes that have occurred in the realm of law and mores and becomes aware of the diversity of the legal and moral institutions of its own people in the course of its history; and when, furthermore, gazing beyond the confines of its own city-state or tribe, it notices the dissimilarity of the institutions of neighboring peoples. When, therefore, human reason wonderingly verifies this diversity, it first arrives at the distinction between divine and human law. But it soon has to grapple with the natural law, with the question of the moral basis of human laws. This is at the same time the problem of why laws are binding. How can laws bind the conscience of an individual? Wherein lies, properly speaking, the ethical foundation of the coercive power of the state’s legal and moral order? Closely connected with these problems is the question of the best laws or best state, a matter which from the time of Plato has engaged the attention of nearly all exponents of the great systems of natural law. Before long, however, a related idea made its appearance. This was the view that the tribal deities are not the ultimate form of the religious background of reality. For if an eternal, immutable law obliges men to obey particular laws, behind the popular images of tribal deities exists an eternal, all-wise Lawgiver who has the power to bind and to loose.3
It is quite understandable, then, that the philosophical conception of the natural law should have made its first appearance in the area of Western culture among the ancient Greeks. This dynamic people was endowed with a penetrating critical intelligence, with an early maturing consciousness of the individual mind, and with great power of political organization. Indeed, Western political philosophy likewise originated in this gifted people.
It is a remarkable fact that at the very beginning of the Greek philosophy of law (or rather of the laws), and therewith of the natural law, a distinction came to light which has survived down to the present time, a distinction between two conceptions of the natural law. One is the idea of a revolutionary and individualistic natural law essentially bound up with the basic doctrine of the state of nature as well as with the concept of the state as a social unit which rests upon a free contract, is arbitrary and artificial, is determined by utility, and is not metaphysically necessary. The other is the idea of a natural law grounded in metaphysics that does not exist in a mythical state of nature before the “laws,” but lives and ought to live in them—a natural law which one would fain, though somewhat ineptly, style conservative. It is further significant that the notion of God as supreme Lawgiver is intimately connected with the latter conception. Both of these tendencies are already plainly visible in the first Sophists and in Heraclitus, the great forerunner of Plato.
Heraclitus of Ephesus (cir. 536–470 B.C.) is famous for his thesis that “all things flow; nothing abides.” But this ceaseless changing of things led him directly to the idea of an eternal norm and harmony, which exists unchangeable amid the continual variation of phenomena. A fundamental law, a divine common logos, a universal reason holds sway: not chance, lawlessness, or irrational change. Natural occurrences are ruled by a reason that establishes order. Man’s nature as well as his ethical goal consists, then, in the subordination or conformity of individual and social life to the general law of the universe. This is the primordial norm of moral being and conduct. “Wisdom is the foremost virtue, and wisdom consists in speaking the truth, and in lending an ear to nature and acting according to her. Wisdom is common to all. … They who would speak with intelligence must hold fast to the (wisdom that is) common to all, as a city holds fast to its law, and even more strongly. For all human laws are fed by one divine law.”4 The laws of men are but attempts to realize this divine law. Wherefore, declares this conservative aristocrat, the people ought not to resist the laws, which to him are the embodiment of the divine law. On the contrary, “the people ought to fight in defense of the law as they do of their city wall.”5 Thus in the diversity of human laws (not beyond them) there flashed upon Heraclitus the idea of an eternal law of nature that corresponds to man’s reason as sharing in the eternal logos. The variety of human laws does not exclude the idea of the natural law. For through the contingency and diversity of human laws rational thought perceives the truth of the eternal law, whereas sense perception—the eye and the ear—notices only what is different and unlike. With Heraclitus, the “Obscure Philosopher,” the thinker who speaks in obscure symbols, the idea of the natural law for the first time emerged as a natural, unchangeable law from which all human laws draw their force.
Heraclitus’ doctrine had a practical aim. It was intended to stress the value of the laws and their binding force against the fickleness of the uncritical masses. Prone to novelties of all kinds and woefully lacking in powers of discrimination, the masses were subject to capricious fluctuations of opinion. They thus fell easy prey to the demagogy of the Sophists.
It is no easy matter to judge the Sophists fairly. For one thing their teachings have come down to us in a very fragmentary form and are known to us chiefly from the dialogues of Plato, their great adversary. Moreover, as popular orators with a leaning toward demagogy, they were fond of oversimplified slogans and paradoxical statements. This earned for them, among posterity, the sinister reputation of philosophical ropedancers, rationalistic revolutionaries, and contemners of the law. For this reputation Plato has been particularly responsible. But this judgment is, to say the least, far too harsh. That the Sophists had of necessity to appear to the Greeks as revolutionary rationalists is explained, on the one hand, by their reckless criticism of contemporary social institutions and their cynical skepticism in political matters, and, on the other, by the high esteem in which their opponents held the laws and the polis, or city-state.
Their laws were the pride of the citizens of the Greek polis, and the Sophists were mostly foreigners. Heraclitus had looked upon the laws as equal in worth to the walls of the city. The philosophers spoke of the nomoi, or laws, with the greatest respect: the peoples who had no polis were to them barbarians. Hence it happened, too, that Socrates, despite his distinction between what is naturally right and legally right, pronounced the laws of Athens to be “right” without qualification. The citizens, consequently, were under obligation to obey them, even as he also obeyed them to the bitter end. For Plato likewise the laws of Athens were for the most part something inviolable. He regarded the social order founded upon them as good, even if capable of improvement; never did he term it bad. Therefore to these aristocrats in political outlook as well as in thought, the social criticism of the Sophists necessarily passed not only for an attack upon the foundations of a particular order of a particular polis, but also for a malicious assault upon the right order of the polis itself.
Moreover, in point of fact the Sophists had much in common with the revolutionary natural-law ideas of the eighteenth-century Enlightenment, especially with Rousseau’s doctrine and its reckless criticism of existing society. In the case of the conservative natural law (if one wishes to speak of a political tendency) the distinction between natural and positive law served to justify and improve