Liberalism is a political and philosophical tradition centered on individual liberty, legal equality, consent of the governed, and limits on the power of the state. It emerged from Enlightenment thought in the seventeenth and eighteenth centuries and has since developed into a family of related but sometimes competing traditions, including classical liberalism, social liberalism, and libertarianism. The precise boundaries of “liberalism” are themselves contested-some scholars emphasize free markets and limited government, others emphasize individual rights paired with an active state that secures social and economic conditions for liberty-and these competing framings are addressed in liberalism-debate and related Viewpoint pages.

Liberalism is generally associated with several recurring commitments: protection of individual rights (such as freedom of speech, religion, and association), the rule of law, constitutionally limited government, political equality among citizens, and some form of representative democracy. Liberal thought is commonly traced to thinkers such as John Locke, Montesquieu, and later John Stuart Mill, who argued for natural rights, separation of powers, and constraints on majority rule, respectively.

Since the late nineteenth and twentieth centuries, liberalism has split along several axes. One major division concerns the proper scope of government: classical liberals and libertarians favor minimal state intervention in markets, while social liberals (sometimes called “modern” or “welfare” liberals) support government action to address economic inequality, provide public services, and regulate markets, viewing these as necessary conditions for meaningful liberty. Another axis concerns liberalism's relationship to democracy and pluralism, including debates over how liberal societies should accommodate religious, cultural, and moral diversity. Liberalism is also frequently contrasted with conservatism, socialism, and various forms of nationalism and authoritarianism, though the content of these contrasts varies by national context and historical period. A fuller historical account, including liberalism's development across different countries and periods, is given at liberalism-history.

Contemporary usage of the term “liberal” also varies significantly by country. In the United States, “liberal” often refers to a left-of-center position associated with social liberalism, whereas in much of Europe and elsewhere, “liberal” more often refers to free-market, classical-liberal, or centrist positions. This terminological divergence is a frequent source of cross-national confusion in political discourse.

• Classical liberalism emphasizes individual liberty, private property, free markets, and a limited, constitutionally constrained state, viewing extensive government intervention as a threat to liberty. See liberalism-classical-viewpoint.
• Social liberalism (or welfare liberalism) holds that meaningful individual liberty requires government action to secure education, health care, economic security, and protection from market failures, alongside traditional civil liberties. See liberalism-social-viewpoint.
• Libertarianism, sometimes treated as an extension of classical liberalism, argues for minimal state functions-chiefly defense, courts, and protection of property rights-and substantial skepticism toward most other forms of government intervention. See liberalism-libertarian-viewpoint.
• Ordoliberalism, influential in postwar Germany, holds that markets require a strong legal and institutional framework actively maintained by the state to remain free and competitive. See liberalism-ordoliberal-viewpoint.
• Neoliberalism, a contested and often externally applied label, is associated by critics and some self-described adherents with policies favoring deregulation, privatization, free trade, and reduced state involvement in the economy from the late twentieth century onward. See liberalism-neoliberal-viewpoint.
• Conservative critiques of liberalism argue that its emphasis on individual autonomy weakens tradition, social cohesion, religious authority, or national community. See liberalism-conservative-critique-viewpoint.
• Socialist and Marxist critiques argue that liberalism's formal legal equality masks or legitimizes underlying economic inequality and class power. See liberalism-socialist-critique-viewpoint.
• Communitarian critiques contend that liberalism's individualism undercuts the shared values, traditions, and communal bonds necessary for a healthy society. See liberalism-communitarian-critique-viewpoint.

• Disputes over whether twentieth- and twenty-first-century “neoliberal” economic reforms-such as deregulation and privatization in various countries-represent an authentic extension of liberal principles or a departure from them are addressed at liberalism-neoliberalism-controversy.
• The relationship between liberalism and historical European colonialism, including debates over whether liberal thinkers' support for empire was incidental or constitutive to liberal theory, is addressed at liberalism-colonialism-controversy.

• liberalism-history
• liberalism-debate
• liberalism-classical-vs-social-debate
• Democracy
• Enlightenment
• Conservatism
• Socialism
• Libertarianism

1. John Locke, *Two Treatises of Government* (London: Awnsham Churchill, 1689).
2. Montesquieu, *De l'esprit des lois* [The Spirit of the Laws] (Geneva: Barrillot & Fils, 1748).
3. John Stuart Mill, *On Liberty* (London: John W. Parker and Son, 1859).
4. Edmund Fawcett, *Liberalism: The Life of an Idea*, 2nd ed. (Princeton, NJ: Princeton University Press, 2018).
5. Helena Rosenblatt, *The Lost History of Liberalism: From Ancient Rome to the Twenty-First Century* (Princeton, NJ: Princeton University Press, 2018).