Positive Law versus Natural Law

Consider two measuring tapes. One is the tape your tailor uses: made by a manufacturer, marked in the units of your country, sometimes slightly wrong, and replaceable at will. The other is the idea of true length itself, the standard against which every tape is checked. Positive law is the tailor's tape: real, usable, made by people, and sometimes mistaken. Natural law is the true standard it is meant to match. This note gives the definitions and the history of the two ideas, from Greece to the twentieth-century revival. The modern theoretical debate between natural law theory and legal positivism (Hart, Fuller, Raz, Finnis, Dworkin) is the subject of Note 55, and the natural law school as a whole is covered in Note 9.

Figure: Natural law as the higher standard that measures positive law, the law the State actually lays down, and the two answers when they conflict

1. The Two Defined

Positive law is particular to a time and place, the product of human will, changeable by the same will, and backed by the power of the State. It exists as a fact, whether or not it is just. Natural law is held to flow from the nature of man, of things or of God, to be discoverable by reason, and to bind all people. Traditionally it was described as eternal and unchanging. That description needs qualification: Stammler argued that only the form of natural law, the ideal of just law, is constant, while its content must change with the conditions of each society. His phrase natural law with a variable content made the idea usable in a world of changing societies.

2. Greece and Rome

The distinction is as old as Western legal thought. In Sophocles' Antigone, the heroine defies King Creon's edict forbidding burial of her brother, appealing to the unwritten and unfailing laws of the gods: the first dramatic clash of natural and positive law. Aristotle distinguished natural justice, which has the same force everywhere, from legal (conventional) justice, which depends on enactment. The Stoics taught that reason pervades the universe and that man, as a rational being, should live according to nature.

Rome turned these ideas into a legal structure. The jus civile was the law of Roman citizens. The jus gentium was the law common to all peoples, developed as Rome dealt with foreigners (a praetor for foreigners was created in 242 BC); Gaius identified it with what natural reason establishes among all men. The jus naturale was, in Ulpian's famous phrase, that which nature has taught all animals. Cicero's definition in De Re Publica, quoted above, carried Stoic natural law into the Roman and later the Christian world.

3. The Middle Ages: Augustine and Aquinas

St Augustine wrote that a law that is not just does not seem to be a law at all, the source of the maxim lex iniusta non est lex. St Thomas Aquinas quoted Augustine and built the most complete medieval system in the Summa Theologiae.

For Aquinas, human law derives its force from natural law, either as a conclusion from it (do not kill) or as a determination of details it leaves open (which side of the road to drive on). A human law that conflicts with natural law is not law but a perversion of law. Yet Aquinas was cautious: an unjust law may still be obeyed to avoid scandal or disorder. This nuance is often missed.

4. The Secular Turn: Grotius and the Social Contract

Hugo Grotius, in De Jure Belli ac Pacis (1625), made natural law independent of theology. Natural law, he said, would have validity even if we should concede (etiamsi daremus) that there is no God. It rests on man's rational and social nature, and on it Grotius founded the law of nations, earning the title father of international law.

The same premise, a state of nature and a contract, yielded absolutism, liberalism and democracy. That flexibility is both natural law's strength and the ground of the positivist complaint that it can justify anything.

5. Blackstone, Bentham and the Nineteenth-Century Decline

Blackstone, in his Commentaries on the Laws of England (1765 to 1769), declared that the law of nature, dictated by God, is superior in obligation to any other, and that no human law contrary to it is valid. Bentham attacked him in A Fragment on Government (1776) and elsewhere: talk of a law of nature merely dresses up personal opinion, and natural rights were, in his phrase from Anarchical Fallacies, 'nonsense upon stilts'. Austin gave the positivist position its classic statement: the existence of law is one thing, its merit or demerit another.

In the nineteenth century natural law went into decline. The historical school (Savigny) traced law to the spirit of each people rather than to universal reason; analytical positivism (Austin) identified law by its source; utilitarianism replaced natural rights with calculations of utility; and the rise of empirical science made appeals to a law of nature look unscientific. Codification and the sovereignty of Parliament completed the eclipse.

6. The Twentieth-Century Revival

Several forces revived natural law: the relativism of Stammler's variable content and Kohler's view that law must fit the civilisation of each age; the horror of Nazi law, the Nuremberg trials and Radbruch's post-war formula (Note 51); and the Universal Declaration of Human Rights (1948), which restated natural rights as human rights. In theory the revival produced Fuller's procedural natural law, the inner morality of law in eight principles (The Morality of Law, 1964; Note 65), and John Finnis's Natural Law and Natural Rights (1980). Finnis identified seven basic goods: life, knowledge, play, aesthetic experience, sociability (friendship), practical reasonableness and religion, pursued according to requirements of practical reasonableness. Hart's own minimum content of natural law (Note 55) shows how far even a positivist accepted part of the tradition.

7. How They Differ

8. The Indian Constitutional Journey

Indian constitutional history reads as a slow move from a positivist to a natural rights reading of fundamental rights.

9. Frequently Asked Questions

Q. Is natural law really unchanging?
A. The classical tradition said so, as Cicero's definition shows. Stammler qualified it: the ideal of just law is constant, but its content varies with the conditions of each society, hence natural law with a variable content.

Q. What is the difference between jus gentium and jus naturale?
A. Jus gentium was the law common to all peoples, applied by Rome in dealings with foreigners. Jus naturale was the law of nature, in Ulpian's phrase what nature has taught all animals. Gaius tended to identify jus gentium with natural reason.

Q. Why did natural law decline in the nineteenth century?
A. Because the historical school, analytical positivism and utilitarianism all rejected a universal law of reason, and the rise of empirical science made it look unscientific. Bentham's attack on Blackstone and Austin's separation of law's existence from its merit were decisive.

See also: Note 9 (natural law school), Note 11 (analytical positivism), Note 55 (natural law versus legal positivism: the modern debate), Note 65 (Hart versus Fuller), Note 78 (natural versus legal rights).