Natural Law, in ethical philosophy, theology, law, and social theory, a set of principles, based on what are assumed to be the permanent characteristics of human nature, that can serve as a standard for evaluating conduct and civil laws. Natural law is considered fundamentally unchanging and universally applicable. Because of the ambiguity of the word nature, the meaning of natural varies. Thus, natural law may be considered an ideal to which humanity aspires or a general fact, the way human beings usually act. Natural law is contrasted with positive law, the enactments of civil society.
II CLASSICAL THEORIES
The ancient Greek philosophers were the first to elaborate a doctrine of natural law. In the 6th century bc, Heraclitus spoke of a common wisdom that pervades the whole universe, “for all human laws are nourished by one, the divine”. Aristotle distinguished between two kinds of justice: “A rule of justice is natural that has the same validity everywhere, and does not depend on our accepting it or not; a rule is legal [conventional] that in the first instance may be settled in one way or the other indifferently.” The Stoics, especially the philosopher Chrysippus of Soli, constructed a systematic natural law theory. According to Stoicism, the whole cosmos is rationally ordered by an active principle, the logos, variously named God, mind, or fate. Every individual nature is part of the cosmos. To live virtuously means to live in accord with one’s nature, to live according to reason. Because passion and emotion are considered irrational movements of the soul, the wise individual seeks to eradicate the passions and consciously embrace the rational life. This doctrine was popularized among the Romans by the 1st-century bc orator Cicero, who gave a famous definition of natural law in his De Republica: “True law is right reason in agreement with Nature; it is of universal application, unchanging and everlasting; it summons to duty by its commands, and averts from wrongdoing by its prohibitions … There will not be different laws at Rome and at Athens, or different laws now and in the future, but one eternal and unchangeable law will be valid for all nations and for all times.” In the Corpus Juris Civilis a compilation and codification of Roman legal material prepared in 534 under Emperor Justinian I, a jus naturale is acknowledged, but there is no assertion that natural law is superior to positive law and no vindication of human rights (slavery, for example, was legal).
III CHRISTIAN CONCEPTIONS
Christians found the natural law doctrine of the Stoics quite compatible with their beliefs. St Paul spoke of Gentiles who do not have the Mosaic law doing “by nature what the law requires” (Romans 2:14). The 6th-century Spanish theologian St Isidore of Seville affirmed that natural law is observed everywhere by natural instinct; he cited as illustrations the laws ordaining marriage and the procreation of children. Texts from Isidore cited at the beginning of Decretum by the Italian scholar Gratian (c. 1140), the canon law textbook of the Middle Ages, stimulated extensive discussion among the scholastics. The teaching of St Thomas Aquinas on the natural law is the most widely known. In his Summa Theologiae (Summary Treatise of Theology, 1265-1273) Aquinas called the rational guidance of creation by God the “Eternal Law”. The Eternal Law gives all beings the inclination to those actions and aims that are proper to them. Rational creatures, by directing their own actions and guiding the actions of others, share in divine reason itself. “This participation in the Eternal Law by rational creatures is called the Natural Law.” Its dictates correspond to the basic inclinations of human nature. Thus, according to Aquinas, it is possible to distinguish good from evil by the natural light of reason.
IV MODERN THEORIES
The Dutch jurist Hugo Grotius is considered the founder of the modern theory of natural law. His definition of natural law as that body of rules which can be discovered by the use of reason is traditional, but in raising the hypothetical argument that his law would have validity even if there were no God or if the affairs of human beings were of no concern to God, he effected a divorce from theological presuppositions and prepared the way for the purely rationalistic theories of the 17th and 18th centuries. He thus departed from scholasticism in his methodology if not in his content. A second innovation of Grotius was to view this law as deductive and independent of experience: “Just as the mathematicians treat their figures as abstracted from bodies, so in treating law I have withdrawn my mind from every particular fact” (De Jure Belli ac Pacis; On the Law of War and Peace, 1625).
The German jurist Samuel von Pufendorf, the first to hold a chair of natural law in a German university, more fully developed the concept of a law of nature. The 17th-century English philosophers Thomas Hobbes and John Locke proposed an original state of nature from which a social contract arose and combined this theory with that of natural law. Locke’s doctrine that nature had endowed human beings with certain inalienable rights that could not be violated by any governing authority was incorporated in the American Declaration of Independence.
In the 19th century a critical spirit dominated discussions of natural law. The existence of a natural law was generally regarded as unprovable, and it was largely replaced in legal theory by utilitarianism, formulated by the English philosopher Jeremy Bentham as “the greatest happiness of the greatest number”, and by legal positivism, according to which law is based simply on “the command of the ruler”, in the phrase of the English jurist John Austin.
The atrocities committed by Nazi Germany during World War II revived interest in a higher standard than positive law. The United Nations (UN) Charter declared the “faith” of that organization in human rights, and on December 10, 1948, the UN General Assembly adopted the Universal Declaration of Human Rights, which, however, is more a moral pronouncement than a legally enforceable treaty. See also Ethics.