§ 16 Natural or Moral Law
By natural or moral law is meant the principles of natural right and wrong—the principles of natural justice, if we use the term justice in its widest sense to include all forms of rightful action. Right or justice is of two kinds, distinguished as natural and positive. Natural justice is justice as it is in deed and in truth—in its perfect idea. Positive justice is justice as it is conceived, recognised, and expressed, more or less incompletely and inaccurately, by the civil or some other form of human and positive law. Just as positive law, therefore, is the expression of positive justice, so philosophers have recognised a natural law, which is the expression of natural justice.
This distinction between natural and positive justice, together with the corresponding and derivative distinction between natural and positive law, comes to us from Greek philosophy. Natural justice is φυσικὸν δίκαιον; positive justice is νομικὸν δίκαιον; and the natural law which expresses the principles of natural justice is φυσικὸς νόμος. When Greek philosophy passed from Athens to Rome, φυσικὸν δίκαιον appeared there as justitia naturalis and φυσικὸς νόμος as lex naturae or jus naturale.
This natural law was conceived by the Greeks as a body of imperative rules imposed upon mankind by Nature, the personified universe. The Stoics, more particularly, thought of Nature or the Universe as a living organism, of which the material world was the body, and of which the Deity or the Universal Reason was the pervading, animating, and governing soul; and natural law was the rule of conduct laid down by this Universal Reason for the direction of mankind.
Natural law has received many other names expressive of its divers qualities and aspects. It is Divine Law (jus divinum)—the command of God imposed upon men—this aspect of it being recognised in the pantheism of the Stoics, and coming into the forefront of the conception, so soon as natural law obtained a place in the philosophical system of Christian writers. Natural law is also the Law of Reason, as being established by that Reason by which the world is governed, and also as being addressed to and perceived by the rational nature of man. It is also the Unwritten Law (jus non scriptum), as being written not on brazen tablets or on pillars of stone, but solely by the finger of nature in the hearts of men. It is also the Universal or Common Law (κοινος νόμος, jus commune, jus gentium), as being of universal validity, the same in all places and binding on all peoples, and not one thing at Athens and another at Rome, as are the civil laws of states (ἴδιος νόμος, jus civile). It is also the Eternal Law (lex aeterna), as having existed from the commencement of the world, uncreated and immutable. Lastly, in modern times we find it termed the Moral Law, as being the expression of the principles of morality.
The term natural law, in the sense with which we are here concerned, is now fallen almost wholly out of use. We speak of the principles of natural justice, or of the rules of natural morality, but seldom of the law of nature, and for this departure from the established usage of ancient and medieval speech there are at least two reasons. The first is that the term natural law has become equivocal; for it is now used to signify physical law—the expression of the uniformities of nature. The second is that the term law, as applied to the principles of natural justice, brings with it certain misleading associations—suggestions of command, imposition, external authority, legislation—which are not in harmony with the moral philosophy of the present day.
The following quotations illustrate sufficiently the ancient and medieval conceptions of the law of nature:—
Aristotle.—“Law is either universal (κοινος νόμος) or special (ἴδιος νόμος). Special law consists of the written enactments by which men are governed. The universal law consists of those unwritten rules which are recognised among all men.”45 “Right and wrong have been defined by reference to two kinds of law.... Special law is that which is established by each people for itself.... The universal law is that which is conformable merely to Nature.”46
Cicero.—“There is indeed a true law (lex), right reason, agreeing with nature, diffused among all men, unchanging, everlasting.... It is not allowable to alter this law, nor to derogate from it, nor can it be repealed. We cannot be released from this law, either by the praetor or by the people, nor is any person required to explain or interpret it. Nor is it one law at Rome and another at Athens, one law to-day and another hereafter; but the same law, everlasting and unchangeable, will bind all nations at all times; and there will be one common lord and ruler of all, even God the framer and proposer of this law.”47
Philo Judaeus.—“The unerring law is right reason; not an ordinance made by this or that mortal, a corruptible and perishable law, a lifeless law written on lifeless parchment, or engraved on lifeless columns; but one imperishable, and impressed by immortal Nature on the immortal mind.”48
Gaius.—“All peoples that are ruled by laws and customs observe partly law peculiar to themselves and partly law common to all mankind. That which any people has established for itself is called jus civile, as being law peculiar to that state (jus proprium civitatis). But that law which natural reason establishes among all mankind is observed equally by all peoples, and is for that reason called jus gentium.”49
Justinian.—“Natural law (jura naturalia), which is observed equally in all nations, being established by divine providence, remains for ever settled and immutable; but that law which each state has established for itself is often changed, either by legislation or by the tacit consent of the people.”50
Hooker.—“The law of reason or human nature is that which men by discourse of natural reason have rightly found out themselves to be all for ever bound unto in their actions.”51
Christian Thomasius.—“Natural law is a divine law, written in the hearts of all men, obliging them to do those things which are necessarily consonant to the rational nature of mankind, and to refrain from those things which are repugnant to it.”52
The Jus Gentium of the Roman Lawyers
It is a commonly received opinion, that jus gentium, although identified as early as the time of Cicero with the jus naturale of the Greeks, was in its origin and primary signification something quite distinct—a product not of Greek philosophy but of Roman law. It is alleged that jus gentium meant originally that system of civil and positive law which was administered in Rome to aliens (peregrini), as opposed to the system which was the exclusive birthright and privilege of Roman citizens (jus civile or jus quiritium); that this jus gentium, being later in date than the jus civile, was so much more reasonable and perfect that it came to be identified with the law of reason itself, the jus naturale of the Greeks, and so acquired a double meaning, (1) jus gentium, viz. jus naturale, and (2) jus gentium, viz. that part of the positive law of Rome which was applicable to aliens, and not merely to citizens. That the term jus gentium did possess this double meaning cannot be doubted; but it may be gravely doubted whether the true explanation of the fact is that which has just been set forth. It would seem more probable that jus gentium was in its very origin synonymous with jus naturale—a philosophical or ethical, and not a technical legal term—the Roman equivalent of the κοινος νόμος of Aristotle and the Greeks; and that the technical significance of the term is secondary and derivative. Jus gentium came to mean not only the law of nature—the principles of natural justice—but also a particular part of the positive law of Rome, namely, that part which was derived from and in harmony with those principles of natural justice, and which therefore was applicable in Roman law courts to all men equally, whether cives or peregrini. In the same way in England, the term equity, although originally purely ethical and the mere equivalent of natural justice or jus naturae, acquired a secondary, derivative, and technical use to signify a particular portion of the civil law of England, namely, that portion which was administered in the Court of Chancery, and which was called equity because derived from equity in the original ethical sense.
This, however, is not the place in which to enter into any detailed examination of this very interesting and difficult problem in the history of human ideas.53