Natural Law versus Legal Realism

A structural engineer asks whether a new flyover meets the standards any bridge ought to meet. A site inspector records what was actually built and where the concrete was skimped. The engineer without the inspector is lost in drawings; the inspector without the engineer has no standard to report against. Natural law asks the engineer's question, what law must be to deserve the name. Realism asks the inspector's, what law actually does. The schools themselves are in Notes 9 and 15; this note explains why they are poles apart, why the gap is smaller than the slogans suggest, and who has tried to bridge it.

Figure: A vertical scale from the ought to the is: natural law at the top as the ideal, positivism and the analytical school in the middle, and legal realism at the bottom as what courts actually do

1. Why They Are Called the Two Poles

The natural lawyer looks above positive law, to principles of reason that give it authority and against which it can be judged; Aquinas held that an unjust law is a corruption of law. The realist looks below it, to the behaviour of judges, juries, police and officials. Positivism sits between, finding law in the valid rules themselves. The figure shows this three-level scale. It is a useful picture, but it can mislead: it suggests realism has no interest in the Ought at all.

Natural law itself is not one theory but a long tradition (Note 9). The classical version (Aristotle, the Stoics, Cicero) found a law of nature in right reason. The medieval version of Aquinas arranged eternal, natural, divine and human law in a hierarchy, with human law valid so far as it is derived from natural law. The modern version of Grotius and the social contract thinkers grounded natural rights in human reason. The twentieth-century revival includes Stammler's natural law with a variable content, Fuller's procedural natural law and Finnis's basic goods. Realists attacked the tradition as a whole, but their criticism bites hardest on the medieval and modern claim to fixed, objectively true moral rules.

2. Correcting the Slogan: Realists and Morality

In 'Some Realism about Realism' (1931), Llewellyn listed among the realists' starting points the temporary divorce of Is and Ought for purposes of study. The key word is 'temporary'. Realists wanted an accurate description of what courts do before deciding what they ought to do, because moral argument built on a false picture of the courts is wasted. Once the facts were known, value judgments were to return. In practice many were reformers: Llewellyn was the chief architect of the Uniform Commercial Code, and Jerome Frank chaired the Securities and Exchange Commission before sitting as a federal appellate judge. The accurate contrast is not 'morality central against morality set aside', but 'morality as part of what law is' against 'morality set aside while we study law, and brought back to reform it'.

3. The Realist Attack on Natural Law

American realism: no brooding omnipresence

Holmes, the forerunner of American realism, dissenting in Southern Pacific Co v Jensen (US Supreme Court, 1917), wrote that the common law is not a brooding omnipresence in the sky but the articulate voice of an identifiable sovereign. Talk of higher law, for Holmes and the realists after him, often hid the real policy choices judges make.

Scandinavian realism: metaphysics must go

Axel Hägerström, founder of the Uppsala school, took as his motto a variation on Cato's refrain: praeterea censeo metaphysicam esse delendam, 'furthermore, I hold that metaphysics must be destroyed'. Value judgments, on his view, are expressions of feeling, not true or false statements, so a natural law claiming objectively valid moral propositions is metaphysics of the purest kind. Alf Ross, in On Law and Justice, put the charge memorably: 'Like a harlot, natural law is at the disposal of everyone.' It has been invoked for absolute monarchy and for revolution alike, and so justifies nothing in particular.

An unexpected common ground

The two poles share one enemy: the formalist picture of law as a closed system of rules from which every answer can be deduced. The realists attacked it by showing that judges make choices the rules do not dictate. Natural lawyers attacked it by showing that when rules run out, judges fall back on principles of justice and reasonableness. They differ on what fills the gap: for the realist it is policy, personality and social pressure; for the natural lawyer it is moral principle. Dworkin's later argument that principles form part of the law itself (Note 19) can be read as taking the realists' description of judging seriously while giving it a natural-law answer.

4. The Natural Law Reply: Fuller

Lon Fuller is the natural link between the poles. He came of age academically when realism dominated American law schools and shared its interest in law as a working, purposive activity. Yet in 'American Legal Realism' (1934) and The Law in Quest of Itself (1940) he criticised both positivism and realism for the same mistake: trying to separate the law that is from the law that ought to be. One cannot describe a purposive activity without reference to what it is for; even the realist who studies what judges 'do' selects facts by reference to what judging is for.

In The Morality of Law (1964) Fuller gave law an inner morality of eight principles: generality, promulgation, non-retroactivity, clarity, non-contradiction, possibility of compliance, constancy, and congruence between official action and declared rule. This procedural natural law answers the realist neatly: congruence concerns exactly the gap between declared rules and what officials do, the gap realism made its subject.

5. Finnis and the Revival

John Finnis, in Natural Law and Natural Rights (1980), rebuilt natural law without a divinely ordered cosmos. He identified seven basic goods (life, knowledge, play, aesthetic experience, sociability or friendship, practical reasonableness, religion) and nine requirements of practical reasonableness. Finnis accepts that law can be described as a social fact; the central case of law, he argues, is the one a practically reasonable person would see as serving the common good. The goods are offered as self-evident features of human flourishing, not metaphysical entities, which partly meets the Scandinavian charge.

6. Classic Statements

7. The Poles Compared

8. The Indian Angle

The natural law side of the Indian story, ADM Jabalpur (1976) and its overruling in Puttaswamy (2017), is treated in Notes 54 and 55. What this comparison adds is the realist reading: the constitutional text did not change between those years; the Court and the political climate did. The case below is an illustration of how both theories read one decision, not a claim that the Court adopted either.

9. Evaluation

Realism is right that higher-law talk can disguise choices, and Ross's remark is a fair warning. Natural law is right that a behavioural account cannot explain why anyone treats law as a reason for action, or how a court can be wrong. After the Second World War, critics charged value-free theories, positivist and realist alike, with having nothing to say against totalitarian legality, and natural law revived. Fuller, and the realists' own reforming purpose, show that description and evaluation are hard to keep apart for long.

Criticisms in brief. Against natural law: its content is contested and has served opposite causes; it slides from what is to what ought to be (Hume's objection); and it gives judges a licence to override enacted law on their own moral views. Against realism: it cannot explain obligation or the judge's own reasoning (Hart's point in Note 59); fact-scepticism, pressed hard, leaves no stable law at all; and Scandinavian non-cognitivism makes it impossible to call even the worst law unjust in any objective sense.

10. Frequently Asked Questions

Q. Did the legal realists reject morality?
A. No. Llewellyn called for only a temporary divorce of Is and Ought for study, so that reform could rest on an accurate picture of the courts. Many realists were active reformers.

Q. Who connects natural law and realism?
A. Lon Fuller. He criticised realism in 1934 and 1940 for separating is and ought, yet shared its interest in how law works, and his inner morality of law (1964) centres on the congruence between declared rules and official action.

Q. Why did the Scandinavian realists reject natural law?
A. Because they held that moral and legal 'oughts' are not objective facts but expressions of feeling, so a law of nature is metaphysics. Hägerström wanted metaphysics destroyed, and Ross argued that natural law can be used to justify any ideology.

See also: Note 9 (natural law school), Note 15 (realist school), Note 54 (positive versus natural law), Note 55 (natural law versus positivism), Note 65 (Hart versus Fuller), Note 70 (American versus Scandinavian realism).