Christianity, however, contains three ideas of decisive importance for the present problem: the idea of the supermundane, transcendent, personal God as Lawgiver in the absolute sense, the idea of Christian personality, whose eternal goal transcends the state, the law, and the mores of the polis; and the idea of the Church as the institution charged with the salvation of mankind standing alongside and, in matters of faith and morals, above the will of the state. Such ideas had in the long run to affect the whole problem of natural law: not, indeed, in order to revolutionize it, but to explore it more thoroughly, to strengthen its foundations, and to complete it materially.1
The history of the natural-law idea shows that Christianity took it over at a very early date. Paul, the Apostle of the Gentiles, declares that the natural law is inscribed in the hearts of the heathen, who do not have the Law (of Sinai), and is made known to them through their conscience. It is valid both for pagans and for Jews because it is grounded in nature, in the essence of man. (Cf. Rom. 2:12–16).
The Fathers of the Early Church made use of the Stoic natural law, finding in its principles “seeds of the Word,” to proclaim the Christian doctrine of the personal Creator-God as the Author of the eternal law as well as of the natural moral law which is promulgated in the voice of conscience and in reason. Thus, for instance, we read in St. John Chrysostom (d. 407): “We use not only Scripture but also reason in arguing against the pagans. What is their argument? They say they have no law of conscience, and that there is no law implanted by God in nature. My answer is to question them about their laws concerning marriage, homicide, wills, injuries to others, enacted by their legislators. Perhaps the living have learned from their fathers, and their fathers from their fathers and so on. But go back to the first legislator! From whom did he learn? Was it not by his own conscience and conviction? Nor can it be said that they heard Moses and the prophets, for Gentiles could not hear them. It is evident that they derived their laws from the law which God ingrafted in man from the beginning.”2
The Fathers also took over the Stoic distinction of a primary and a secondary natural law, which they interpreted in a theological sense. They regarded the former as applying to the state of unimpaired nature or innocence, while they assigned the latter, with the coercive authority of the law, with bondage and slavery, to the theological condition of fallen nature. Nature, somehow wounded indeed but not destroyed, is therefore still able fully to recognize the first principles of morality and law. But the conclusions from the first principles, which were also plainly intelligible in the state of unimpaired nature, are now attainable only by means of deductive reasoning, since the practical reason is also weakened. Accordingly law takes on a harsh, compulsory character, and the state bears a sword. But the state as such was not regarded by the Fathers as some sort of consequence of sin. An age ignorant of tradition has been able to take such a view of the state only on the basis of patristic texts torn from their context and because of a want of understanding of the mental outlook of the Fathers.
The Fathers did not attempt to construct a system of ethics and jurisprudence. Their speculative thinking was wholly taken up with elucidating the truths of faith, which were in danger of being swamped in the upsurge of pseudomystical doctrines characteristic of the numerous mystery cults of declining antiquity. In addition, their heavy pastoral duties in the period of persecutions, organization, and evangelization left them little leisure for thorough theoretical treatment of questions of moral and legal philosophy.
St. Augustine (d. 430), it is true, forms an exception, and a very brilliant one. In his extremely fertile mind the ideas of ancient philosophy came once again to life and were worked into the new Christian mentality. His talents and the struggles against the Pelagian and Manichaean heresies, as well as the shattering experience of the breakdown of the Roman Empire, of the earthly city, brought ethico-legal problems home to the great bishop of Hippo.
For Augustine the substantial ideas, which Plato had conceived of as dwelling in a heavenly abode, became thoughts of God. The impersonal world reason of the Stoics became the personal, all-wise and all-powerful God. The purely deistic Nous of Aristotle became the Creator-God who transcends the world, but who continually sustains it through His omnipotence, directs it through His providence, and governs it according to His eternal law. This eternal law was for Augustine identical with the supreme reason and eternal truth, with the reason of God Himself, according to whose laws the inner life and external activity of God proceed and are governed. God’s reason is order, and His law rules this ontological order, the order of being, of essences and values. But since this norm is identical with the immutable, immanent nature of God, it does not stand above Him; it is connatural to Him, and it is as unchangeable as He. No power, no chance event, not even the complete collapse of all things can alter it. No obscure, occult fate is any longer enthroned, as in ancient thought, above the personal God.
Through this law God, so far as He produces external effects, directs, guides, and sustains the universe. God, supreme reason, unchangeable being and omnipotent will: this is oneness in its highest form. But the natural moral law and its component part, the ius naturale, is precisely this divine law with reference to man, so far as the latter participates in the divine law. The eternal law dwells as blind necessity in irrational nature. As oughtness, as norm of free moral activity, it is inscribed in the heart of man, a rational and free being. It appears in the moral, rational nature of man; it is written into the rational soul. There is no soul, however corrupt it may be, in whose conscience God does not speak, if only it is still capable of rational thought. There are human actions, consequently, which are in themselves good or bad. Bad acts are not qualified as such by force of law, but because they are such in themselves: because they constitute a disturbance of the natural order. Thereupon, because they are such, the lawmaker prohibits them under threat of punishment, which thereby obtains its moral justification. Not the will of the earthly lawgiver, but variance with natural reason is the ground of the intrinsic immorality of determinate actions.
The doctrine of natural law was transmitted to the golden age of Scholasticism not only in the works of the Church Fathers but also through the study of Roman law and through the development of canon law. The classical authors of the Corpus iuris civilis, as has been seen, stood in close contact with natural-law thinking. It is not merely in passing that we meet with the natural law in their writings: the natural law is there pronounced valid, unconditionally binding law. Considerably greater, however, was the influence of canon law in the form of Gratian’s Decretum (cir. 1148), especially since during the first period of the flowering of Scholasticism the study of Roman law by theologians was frowned upon and even, for a time, prohibited. Gratian distinguished between ius naturale and the mores. The ius naturale, which is contained in the Law (i.e., the Decalogue) and the Gospel, is of divine origin. It resides in human nature, it is alike in all men, and it has force independently of human statute. Natural rights and duties may indeed have to be more closely defined by positive law, but they stand as a norm and rule above the positive laws. To Gratian the latter were, like customary law or mores, liable to change according to time, place, and people. In short, Gratian merely set forth what tradition had handed down.
As the great philosophical movement of the Middle Ages, Scholasticism,3 approached its peak, the natural-law doctrine attained its most masterly expression. It was carried to speculative heights which have never been surpassed in the centuries that followed. Since then the doctrine of natural law has never wholly perished. Even though it might be neglected in the official academic philosophy which has been dominant in the chairs of the secular universities, and even though at the close of the nineteenth century and at the opening of the twentieth century jurisprudence might pronounce it dead, the natural-law doctrine has ever found a home and tender care among the adherents of the philosophia perennis. These have preserved it even throughout the decades in which legal positivism held fullest sway. Moreover, they carried it over, as Christian natural law, into an environment that is once again more