Natural Law (lex naturalis) — A body of moral and legal principles held to be valid by nature or by reason, independently of their enactment by any human authority. The idea has roots in the Greek distinction between physis and nómos and was developed by the Stoics, for whom the logos governing the cosmos is also the norm of human conduct. Cicero (On the Republic, III, 33) describes it as right reason in agreement with nature, universal and unchanging. In the Christian tradition, Thomas Aquinas (Summa Theologiae, I-II, q. 91, a. 2) defines it as the participation of the rational creature in God’s eternal law, and its first precept (q. 94, a. 2) is that good is to be done and pursued and evil avoided; the other precepts derive from natural human inclinations, such as the preservation of life and life in society. In modernity, Grotius (On the Law of War and Peace, 1625) defends a rationalist version that would hold even if God did not exist, and Locke ties to the state of nature a law of nature guaranteeing life, liberty, and property. Natural-law theory, which affirms a necessary connection between law and morality, is opposed by legal positivism: H. L. A. Hart (The Concept of Law, 1961) rejects that thesis but admits a “minimum content of natural law” grounded in elementary facts of the human condition. Philosophical criticisms include Hume’s objection to moving from “is” to “ought” and the charge that human nature is historically variable. See Thomas Aquinas, Cicero, Locke, H. L. A. Hart, and justice.
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