Europe · c. 1650–1800
What Was the Enlightenment?
The Enlightenment was an intellectual movement, roughly 1650 to 1800, arguing that reason and evidence — rather than inherited authority, revelation or tradition — should decide questions about nature, government and morality. Its practical output is everywhere in modern politics: separation of powers (Montesquieu), government by consent and natural rights (Locke), popular sovereignty (Rousseau), religious toleration (Voltaire), and market economics (Adam Smith). It fed directly into the American and French Revolutions. It also carried contradictions its critics have pressed ever since: thinkers who wrote about universal human rights while defending slavery, empire, or the exclusion of women — and a confidence in reason that later critics blamed for new forms of domination.
Key facts
- Kant's answer to "What is Enlightenment?" (1784) gave it a motto: Sapere aude — dare to know — and defined it as emergence from a self-imposed inability to think without someone else's guidance.
- Its infrastructure was social, not academic: salons often hosted by women, coffeehouses, learned journals, and the great Encyclopédie of Diderot and d'Alembert (1751–72), 28 volumes designed to put all knowledge in reach and quietly undermine authority while doing it.
- Montesquieu's separation of powers (1748) was written for a French audience and adopted almost verbatim by the framers of the U.S. Constitution.
- It was not uniformly anti-religious. Many figures were deists — accepting a creator knowable through nature rather than revelation — and some were devout; the target was clerical political power more than belief itself.
- The contradictions are documented, not invented by later critics: several leading figures wrote racial hierarchies into their work, colonial systems expanded during the period, and Mary Wollstonecraft had to write A Vindication of the Rights of Woman (1792) because the rights being declared were not being extended to her.
- Its political test case cut both ways: the French Revolution claimed Enlightenment authority and produced both the Declaration of the Rights of Man and the Terror — which is the core of the argument about the movement that has run ever since.
The argument at its centre
One move underlies the whole movement: that claims should be judged by evidence and reasoning available to anyone, rather than by the authority of who makes them. Newton's physics was the model — a small set of mathematical laws, testable, explaining the heavens without appeal to purpose or scripture. If nature worked that way, the thought went, so might politics and morality.
Locke supplied the political version late in the seventeenth century: government exists by the consent of the governed to protect pre-existing natural rights, and a government that violates them may legitimately be replaced. Montesquieu supplied the engineering — divide power between legislature, executive and judiciary so that no part can dominate. Rousseau pushed further and more ambiguously, locating sovereignty in the general will of the people, an idea that has served both democracy and its authoritarian imitations. Voltaire made toleration a campaign, intervening in judicial scandals with a polemicist's fury. Smith argued that prosperity emerges from decentralised self-interest under rules rather than from state direction.
How ideas travelled without a university
The Enlightenment happened largely outside official institutions, and that shaped it. Its venues were salons — regular gatherings, many organised and led by women such as Madame Geoffrin and Madame du Deffand, where aristocrats and writers met on unusually level terms — along with coffeehouses, corresponding societies, and a booming trade in periodicals, pamphlets and banned books smuggled past censors.
Its monument was the Encyclopédie: 28 volumes edited by Diderot and d'Alembert between 1751 and 1772, with thousands of articles on crafts, sciences and ideas, and a technique of subversion by cross-reference — an innocuous entry pointing the reader to a dangerous one. It was suppressed, resumed, and sold across Europe. The point of the project was that knowledge should be collected, systematised and made available, which is a political claim disguised as a reference work.
Consequences, and the argument that never closed
The political payoff came fast. The American Declaration of Independence in 1776 is Locke's argument in a public document, and the U.S. Constitution is Montesquieu's design in institutional form. France's Declaration of the Rights of Man and of the Citizen in 1789 states natural rights as founding law. Slavery came under sustained intellectual attack for the first time on universalist grounds, and abolition movements grew directly out of Enlightenment language — used against Enlightenment thinkers who had defended the trade.
That is where the enduring dispute sits. Defenders point out that the tools used to expose the movement's hypocrisies — universal rights, evidence, argument — are the movement's own, and that abolition, women's suffrage and secular law all advanced by wielding them. Critics reply that the period's confidence in reason and progress also licensed scientific racism, colonial administration justified as civilising, and, in the Terror, killing in the name of virtue. Adorno and Horkheimer made the sharpest version of the charge in 1944, arguing that instrumental reason turns into domination. The honest summary is that the Enlightenment gave the modern world both its emancipatory vocabulary and some of the machinery used against it — and that the debate is not a footnote to the period but its most active legacy.
Frequently asked questions
What is the Enlightenment in simple terms?
The argument that questions about nature, government and morality should be settled by reason and evidence anyone can examine, rather than by tradition, revelation or the authority of rank. Practically, it produced the case for separation of powers, government by consent, natural rights, religious toleration and freedom of the press — the vocabulary most modern constitutions still use.
Was the Enlightenment against religion?
Not uniformly. Its sharpest attacks were on the political power of established churches and on claims that could not survive scrutiny, but many leading figures were deists who accepted a creator knowable through nature, and some were sincerely devout. Voltaire campaigned against clerical injustice, not against God. Outright atheism was a minority position even within the movement.
What are the main criticisms of the Enlightenment?
Two recur. First, hypocrisy: thinkers proclaimed universal rights while defending slavery and empire and excluding women, which Mary Wollstonecraft attacked in 1792. Second, that its faith in reason and progress enabled new kinds of domination — scientific racism, colonial 'civilising' projects, and the French Revolution's Terror. Defenders answer that the critique itself is made with Enlightenment tools.
Sources & further reading
This article was written from the published record. Every link below was checked and is live:
- Stanford Encyclopedia of Philosophy — Enlightenment
- Project Gutenberg — Adam Smith, The Wealth of Nations (1776)
- Wikipedia — Age of Enlightenment
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