The Enlightenment - also called the Age of Reason - was an intellectual and philosophical movement that flourished primarily in Europe and the Atlantic world during the 17th and 18th centuries, roughly spanning the period from the mid-1600s to the early 1800s. It is characterized by an emphasis on reason, individual liberty, skepticism of traditional authority (particularly ecclesiastical and monarchical), natural rights, empirical inquiry, and the belief that human progress is achievable through rational thought and education. The movement gave rise to foundational ideas in modern liberal democracy, science, economics, and political philosophy, and its principles are embedded in documents such as the United States Declaration of Independence, the French Declaration of the Rights of Man and of the Citizen, and many subsequent constitutional frameworks.

The Enlightenment emerged from earlier intellectual developments including the Scientific Revolution, the Renaissance, and the Protestant Reformation, each of which contributed to eroding the monopoly of the Catholic Church and hereditary aristocracy over knowledge and legitimacy. Key precursors include Francis Bacon's empiricism, René Descartes' rationalism, and Isaac Newton's demonstration that the natural world operates according to discoverable, universal laws. These developments encouraged thinkers to apply similar methods to questions of morality, governance, and society. The movement was not uniform; historians distinguish between national variants - the Scottish Enlightenment (Hume, Smith, Ferguson), the French philosophes (Voltaire, Rousseau, Diderot), the German Aufklärung (Kant, Lessing), the English tradition (Locke, Newton), and the American Enlightenment (Franklin, Jefferson, Madison) - each with distinct emphases and conclusions.

Several ideas recur across Enlightenment thought, though thinkers often disagreed sharply about their implications:

• Reason - The capacity for rational thought was held to be the primary means by which humans could understand nature, organize society, and evaluate moral claims, displacing revelation and tradition as ultimate authorities.
• Natural rights - Thinkers such as John Locke argued that individuals possess inherent rights - to life, liberty, and property - that exist prior to and independent of government.
• Social contract - Political legitimacy was increasingly grounded in the consent of the governed rather than divine right, a position developed variously by Hobbes, Locke, and Rousseau.
• Secularism - While many Enlightenment figures were deists rather than atheists, the movement pushed religious authority out of the center of public life and made it subject to rational critique.
• Progress - A broad optimism that human knowledge and social conditions could improve over time through reason, education, and institutional reform.
• Toleration - Particularly in matters of religion and conscience, thinkers argued that coercion was both unjust and counterproductive.

A full account of the Enlightenment's origins, major figures, national variations, and reception falls outside the scope of this article. See Enlightenment - History for a detailed treatment.

The Enlightenment is the subject of substantial historical and philosophical debate. Some scholars argue it was a unified project with coherent commitments to rationalism and liberalism; others hold that it was a loose family of overlapping and often contradictory tendencies. Postcolonial and critical theorists argue that Enlightenment universalism is said to have masked Eurocentric assumptions and provided ideological cover for colonialism and racial hierarchy - a position contested by those who argue the movement's principles are self-undermining of such hierarchies. Some religious thinkers argue the Enlightenment's secularism produced a moral vacuum that has weakened Western civilization, while secular critics hold it did not go far enough. The relationship between the Enlightenment and later revolutionary violence - especially the French Revolution's Reign of Terror - remains debated, with some attributing the Terror partly to Enlightenment rationalism and others arguing it represented a betrayal of core Enlightenment commitments. See Enlightenment - Debate for a structured treatment of these disagreements.

There is broad scholarly consensus that the Enlightenment was a historically significant intellectual movement that shaped modern liberal, democratic, and scientific institutions. Historians disagree about its precise boundaries, internal coherence, and normative legacy. Consensus status: not yet established.

• Classical Liberal Viewpoint - The Enlightenment represents the intellectual foundation of individual rights, limited government, and free markets; its core commitments remain valid and underappreciated.
• Conservative Viewpoint - The Enlightenment contributed valuable insights but also unleashed a destructive rationalism that eroded tradition, religion, and social bonds, culminating in ideological excess.
• Religious Viewpoint - Enlightenment secularism misidentified reason as self-sufficient and produced a moral framework without adequate foundation; some religious thinkers see it as a source of modern nihilism.
• Postcolonial Viewpoint - Enlightenment universalism was implicated in colonial projects and racial hierarchy, and its claims to neutrality obscure particular European interests.
• Progressive Viewpoint - The Enlightenment's emancipatory ideals were genuine but incomplete; fully realizing them requires extending rights and recognition to historically excluded groups.
• Counter-Enlightenment Viewpoint - A tradition of thinkers from Hamann and Herder to 20th-century critics argued that Enlightenment rationalism suppresses particularity, community, and human complexity.
• Marxist Viewpoint - The Enlightenment is understood as the ideological expression of rising bourgeois interests, whose emancipatory rhetoric was inseparable from the material conditions of early capitalism; its universalism is seen as obscuring class relations.

• Enlightenment - History
• Enlightenment - Debate
• Scientific Revolution
• Social Contract
• Natural Rights
• Declaration of Independence
• French Revolution
• Liberalism
• Secularism

1. Israel, Jonathan. Radical Enlightenment: Philosophy and the Making of Modernity 1650-1750. Oxford University Press, 2001.
2. Porter, Roy. The Enlightenment. Palgrave, 2001.
3. Gay, Peter. The Enlightenment: An Interpretation. 2 vols. Knopf, 1966-1969.
4. Outram, Dorinda. The Enlightenment. 3rd ed. Cambridge University Press, 2013.
5. Kant, Immanuel. “Beantwortung der Frage: Was ist Aufklarung?” Berlinische Monatsschrift, 1784. (English: “An Answer to the Question: What Is Enlightenment?”)
6. Pagden, Anthony. The Enlightenment: And Why It Still Matters. Random House, 2013.
7. Muthu, Sankar. Enlightenment Against Empire. Princeton University Press, 2003.