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.

“Nonsense upon stilts”: the critics of natural rights

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.

The persistence of the notion

Although the heyday of natural rights proved short, the idea of rights nonetheless endured. The abolition of slavery, the implementation of factory legislation, the rise of popular education and trade unionism, the universal suffrage movement—these and other examples of 19th-century reformist impulses afford ample evidence that the idea was not to be extinguished, even if its a priori derivation had become a matter of general skepticism. But it was not until the rise and fall of Nazi Germany that the idea of human rights truly came into its own. Many of the gruesome atrocities committed by the Nazi regime had been officially authorized by Nazi laws and decrees, and this fact convinced many that law and morality cannot be grounded in any purely idealist or utilitarian or other consequentialist doctrine. Certain actions, according to this view, are absolutely wrong, no matter what the circumstances; human beings are entitled to simple respect, at least.

Today the vast majority of legal scholars and philosophers—particularly in the liberal West—agree that every human being has, at least in theory, some basic rights. Indeed, except for some essentially isolated late 19th-century and early 20th-century demonstrations of international humanitarian concern, the last half of the 20th century may fairly be said to mark the birth of the international as well as the universal recognition of human rights. In the charter establishing the United Nations, for example, all member states pledged themselves to take joint and separate action for the achievement of “universal respect for, and observance of, human rights and fundamental freedoms for all without distinction as to race, sex, language, or religion.” In the Universal Declaration of Human Rights, representatives from many cultures endorsed the rights therein set forth “as a common standard of achievement for all peoples and all nations.” And in 1976 the International Covenant on Economic, Social and Cultural Rights (ICESCR) and the International Covenant on Civil and Political Rights (ICCPR), each approved by the UN General Assembly in 1966, entered into force and effect. Together with the Universal Declaration and their additional protocols, these documents came ultimately to be known as core elements of the “International Bill of Human Rights.”