Most students of human rights trace the origins of the concept of human rights to ancient Greece and Rome, where it was closely tied to the doctrines of the Stoics, who held that human conduct should be judged according to, and brought into harmony with, the law of nature. A classic example of this view is given in Sophocles’ play Antigone, in which the title character, upon being reproached by King Creon for defying his command not to bury her slain brother, asserted that she acted in accordance with the immutable laws of the gods.

In part because Stoicism played a key role in its formation and spread, Roman law similarly allowed for the existence of a natural law and with it—pursuant to the jus gentium (“law of nations”)—certain universal rights that extended beyond the rights of citizenship. According to the Roman jurist Ulpian, for example, natural law was that which nature, not the state, assures to all human beings, Roman citizens or not.

It was not until after the Middle Ages, however, that natural law became associated with natural rights. In Greco-Roman and medieval times, doctrines of natural law concerned mainly the duties, rather than the rights, of “Man.” Moreover, as evidenced in the writings of Aristotle and St. Thomas Aquinas, these doctrines recognized the legitimacy of slavery and serfdom and, in so doing, excluded perhaps the most important ideas of human rights as they are understood today—freedom (or liberty) and equality.

The conception of human rights as natural rights (as opposed to a classical natural order of obligation) was made possible by certain basic societal changes, which took place gradually beginning with the decline of European feudalism from about the 13th century and continuing through the Renaissance to the Peace of Westphalia (1648). During this period, resistance to religious intolerance and political and economic bondage; the evident failure of rulers to meet their obligations under natural law; and the unprecedented commitment to individual expression and worldly experience that was characteristic of the Renaissance all combined to shift the conception of natural law from duties to rights. The teachings of Aquinas and Hugo Grotius on the European continent, the Magna Carta (1215) and its companion Charter of the Forests (1217), the Petition of Right (1628), and the English Bill of Rights (1689) in England were signs of this change. Each testified to the increasingly popular view that human beings are endowed with certain eternal and inalienable rights that never were renounced when humankind “contracted” to enter the social order from the natural order and never were diminished by the claim of the “divine right of kings.”

The modern conception of natural law as meaning or implying natural rights was elaborated primarily by thinkers of the 17th and 18th centuries. The intellectual—and especially the scientific—achievements of the 17th century (including the materialism of Hobbes, the rationalism of Descartes and Leibniz, the pantheism of Spinoza, and the empiricism of Bacon and Locke) encouraged a distinctly modern belief in natural law and universal order and, during the 18th century—the so-called Age of Enlightenment, inspired by a growing confidence in human reason and in the perfectibility of human affairs—led to the more comprehensive expression of this belief. Particularly important were the writings of Locke, arguably the most important natural-law theorist of modern times, and the works of the 18th-century thinkers known as the philosophes, who, centred mainly in Paris, included Montesquieu, Voltaire, and Jean-Jacques Rousseau. Locke argued in detail, mainly in writings associated with the English Glorious Revolution (1688–89), that certain rights self-evidently pertain to individuals as human beings (because these rights existed in the hypothetical “state of nature” before humankind entered civil society); that chief among them are the rights to life, liberty (freedom from arbitrary rule), and property; that, upon entering civil society, humankind surrendered to the state—pursuant to a “social contract”—only the right to enforce these natural rights and not the rights themselves; and that the state’s failure to secure these rights gives rise to a right to responsible, popular revolution. The philosophes, building on Locke and others and embracing many and varied currents of thought with a common supreme faith in reason, vigorously attacked religious and scientific dogmatism, intolerance, censorship, and social and economic restraints. They sought to discover and act upon universally valid principles governing nature, humanity, and society, including the inalienable “rights of Man,” which they treated as a fundamental ethical and social gospel.

Not surprisingly, this liberal intellectual ferment exerted a profound influence in the Western world of the late 18th and early 19th centuries. Together with the Glorious Revolution in England and the resulting Bill of Rights, it provided the rationale for the wave of revolutionary agitation that swept the West, most notably in North America and France. Thomas Jefferson, who had studied Locke and Montesquieu, gave poetic eloquence to the plain prose of the 17th century in the Declaration of Independence proclaimed by the 13 American colonies on July 4, 1776:

We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the Pursuit of Happiness.

Similarly, the marquis de Lafayette, who won the close friendship of George Washington and who shared the hardships of the American Revolution, imitated the pronouncements of the English and American revolutions in the Declaration of the Rights of Man and of the Citizen of August 26, 1789, proclaiming that “men are born and remain free and equal in rights” and that “the aim of every political association is the preservation of the natural and imprescriptible rights of man.”

In sum, the idea of natural rights, forebear to the contemporary notion of human rights, played a key role in late 18th- and early 19th-century struggles against political absolutism. It was, indeed, the failure of rulers to respect the principles of freedom and equality that was responsible for this development.

The idea of natural rights was not without its detractors, however. In the first place, because it was frequently associated with religious orthodoxy, the doctrine of natural rights became less attractive to philosophical and political liberals. Additionally, because they were conceived in essentially absolutist terms, natural rights were increasingly considered to conflict with one another. Most importantly, the doctrine of natural rights came under powerful philosophical and political attack from both the right and the left.

In England, for example, conservative political thinkers such as Edmund Burke and David Hume united with liberals such as Jeremy Bentham to condemn the doctrine, the former out of fear that public affirmation of natural rights would lead to social upheaval, the latter out of concern lest declarations and proclamations of natural rights substitute for effective legislation. In his Reflections on the Revolution in France (1790), Burke—a believer in natural law who nonetheless denied that the “rights of Man” could be derived from it—criticized the drafters of the Declaration of the Rights of Man and of the Citizen for proclaiming the “monstrous fiction” of human equality, which, he argued, serves but to inspire “false ideas and vain expectations into men destined to travel in the obscure walk of laborious life.” Bentham, one of the founders of utilitarianism, was no less scornful. “Rights,” he wrote,

is the child of law; from real law come real rights; but from imaginary laws, from “law of nature,” come imaginary rights.…Natural rights is simple nonsense; natural and imprescriptible rights (an American phrase)…[is] rhetorical nonsense, nonsense upon stilts.

Agreeing with Bentham, Hume insisted that natural law and natural rights are unreal metaphysical phenomena.

This assault upon natural law and natural rights intensified and broadened during the 19th and early 20th centuries. John Stuart Mill, despite his vigorous defense of liberty, proclaimed that rights ultimately are founded on utility. The German jurist Friedrich Karl von Savigny, England’s Sir Henry Maine, and other “historicalist” legal thinkers emphasized that rights are a function of cultural and environmental variables unique to particular communities. The English jurist John Austin argued that the only law is “the command of the sovereign” (a phrase of Hobbes). And the logical positivists of the early 20th century insisted that the only truth is that which can be established by verifiable experience and that therefore ethical pronouncements are not cognitively significant. By World War I there were scarcely any theorists who would defend the “rights of Man” along the lines of natural law. Indeed, under the influence of 19th-century German idealism and parallel expressions of rising European nationalism, there were some—the Marxists, for example—who, though not rejecting individual rights altogether, maintained that rights, from whatever source derived, belong to communities or whole societies and nations preeminently.