The Enlightenment

Explore how the Age of Reason transformed European thought through rationalism, individual rights, and challenges to traditional authority.

AP European History

What Was the Enlightenment?

The Enlightenment was an intellectual and cultural movement that swept across Europe during the 17th and 18th centuries. Thinkers known as philosophes championed the power of reason, science, and individual liberty to improve human society.

Intellectual Roots of the Enlightenment

Scientific Revolution

Copernicus, Galileo, and Newton demonstrated that the natural world followed discoverable laws, inspiring confidence in reason.

Renaissance Humanism

The rediscovery of classical texts and focus on human potential laid groundwork for secular inquiry.

Reformation Legacy

Protestant challenges to papal authority showed that established institutions could be questioned and reformed.

Why the Enlightenment Still Matters

Enlightenment ideas directly shaped the modern world. Concepts like natural rights, separation of powers, and religious tolerance became the foundation of democratic constitutions, including those of the United States and France.

Core Principles of Enlightenment Thought

1

Reason: Human reason, not faith or tradition, is the primary source of knowledge and authority.

2

Natural Rights: All individuals possess inherent rights to life, liberty, and property that no government may violate.

3

Progress: Through science and education, humanity can continuously improve its condition.

4

Skepticism of Authority: Political and religious institutions must justify themselves through reason, not tradition.

The Major Thinkers and Their Ideas

Locke vs. Hobbes: The Social Contract

	John Locke	Thomas Hobbes
Human Nature	Basically good; born as blank slate	Selfish and brutish
State of Nature	Mostly peaceful	"Nasty, brutish, and short"
Purpose of Government	Protect natural rights	Maintain order at all costs
Ideal Government	Limited, consent of governed	Absolute monarchy
Right to Revolt?	Yes: if rights violated	No: chaos is worse

The Encyclopedie: Knowledge for All

Edited by Denis Diderot and Jean le Rond d'Alembert, the Encyclopedie (1751-1772) was a 28-volume compendium that aimed to collect and spread all human knowledge. It became the Enlightenment's most ambitious publishing project.

71,818

Articles written by over 140 contributors across every field of knowledge

Censored

Banned by the French government and the Pope for challenging religious authority

Enlightened Despotism: Reform from Above

Some monarchs adopted Enlightenment ideas to strengthen their states while preserving their own power. These rulers are called enlightened despots.

Frederick II

Prussia: Religious tolerance, reformed the justice system, promoted education. Called himself "first servant of the state."

Catherine II

Russia: Corresponded with Voltaire, expanded education, but expanded serfdom after the Pugachev Rebellion.

Joseph II

Austria: Abolished serfdom, granted religious freedom, but reforms were reversed after his death.

Key Events of the Enlightenment Era

1687

Newton's Principia

Established universal laws of motion and gravity, proving nature follows rational laws

1690

Locke's Two Treatises

Argued for natural rights and the right to revolution against unjust government

1748

Montesquieu's Spirit of the Laws

Proposed separation of powers into executive, legislative, and judicial branches

1751

Diderot begins the Encyclopedie

Massive compendium aiming to spread Enlightenment knowledge to the public

1762

Rousseau's Social Contract

"Man is born free, and everywhere he is in chains": popular sovereignty and general will

1776

American Declaration of Independence

Applied Lockean natural rights theory to justify revolution against Britain

1789

French Revolution begins

Declaration of the Rights of Man enshrined liberty, property, and popular sovereignty

How to Analyze Enlightenment Sources

1

Identify the core principle: Is the author arguing for reason, natural rights, progress, or institutional reform?

2

Determine the target: What institution or idea is being challenged: the Church, monarchy, aristocratic privilege, or traditional knowledge?

3

Consider the audience: Was this meant for elites in salons, the general public, or a specific monarch?

4

Trace the influence: Connect the argument to later events: the American Revolution, French Revolution, or modern democracies.

5

Note the limits: Did the thinker extend these rights to all people, or exclude women, enslaved persons, and the lower classes?

Worked Example: Locke and the American Revolution

Locke (1690): "The state of nature has a law of nature to govern it, which obliges every one: and reason, which is that law, teaches all mankind... that being all equal and independent, no one ought to harm another in his life, health, liberty, or possessions."

1

Core principle: Natural rights exist before government. Reason is the law of nature.

2

Target: Absolute monarchy: rulers who claim authority beyond protecting natural rights.

3

Influence: Jefferson adapted Locke's "life, liberty, property" to "life, liberty, pursuit of happiness" in 1776.

Worked Example: Voltaire and Religious Tolerance

Voltaire, Treatise on Tolerance (1763): "What is tolerance? It is the prerogative of humanity. We are all steeped in weaknesses and errors: let us forgive each other's follies: it is the first law of nature."

1

Core principle: Religious tolerance is a natural human duty, not a government concession.

2

Target: The Catholic Church and state-enforced religious conformity in France.

3

Limits: Voltaire championed tolerance but held anti-Semitic views, showing Enlightenment ideals were inconsistently applied.

Worked Example: Rousseau and the General Will

Rousseau, The Social Contract (1762): "Each of us puts his person and all his power in common under the supreme direction of the general will; and in a body we receive each member as an indivisible part of the whole."

Common Mistakes on the AP Exam

✕ All Philosophes Agreed

Enlightenment thinkers disagreed sharply. Voltaire favored enlightened monarchy; Rousseau championed direct democracy. Locke trusted property owners; Wollstonecraft fought for women's inclusion.

✕ Enlightenment = Democracy

Many philosophes did not advocate democracy. Voltaire and many others preferred enlightened absolutism over rule by the masses.

✕ Universal Application

Most Enlightenment "universal" rights were limited in practice to propertied European men. Slavery, colonialism, and gender inequality persisted.

Summary: Key Thinkers at a Glance

Thinker	Key Idea	Major Work	Legacy
Locke	Natural rights, social contract	Two Treatises	U.S. Declaration
Voltaire	Free speech, religious tolerance	Candide, Letters	1st Amendment
Montesquieu	Separation of powers	Spirit of the Laws	U.S. Constitution
Rousseau	General will, popular sovereignty	Social Contract	French Revolution
Wollstonecraft	Women's rights, equal education	Vindication	Feminism

Question 1 of 5

Which Enlightenment thinker is most directly associated with the idea of separation of powers into executive, legislative, and judicial branches?

Montesquieu proposed the separation of powers in The Spirit of the Laws (1748). This concept directly influenced the structure of the U.S. Constitution. Locke focused on natural rights, Voltaire on free speech, and Rousseau on popular sovereignty.

Question 2 of 5

Speaker A: "People are naturally selfish and violent. Without a strong sovereign to impose order, life would be a war of all against all. Citizens must surrender their freedoms to an absolute ruler in exchange for security."

Speaker B: "Humans are born free and rational. Government exists only to protect our natural rights to life, liberty, and property. When a government fails in this duty, the people have the right to replace it."

▼ Tap to read passage

Speaker A and Speaker B would most likely disagree about which of the following?

Speaker A (Hobbes) argues people must surrender freedoms to an absolute ruler, with no right to resist. Speaker B (Locke) argues the people can replace a government that fails to protect their rights. Both accept a social contract, so the core disagreement is over the right to revolution.

Question 3 of 5

The term "enlightened despot" best describes a ruler who:

Enlightened despots like Frederick the Great, Catherine the Great, and Joseph II implemented reforms such as religious tolerance and legal reform, but never surrendered their absolute authority. They used Enlightenment ideas to strengthen the state, not to create democracy.

Question 4 of 5

Which of the following best explains why Diderot's Encyclopedie was considered dangerous by the French monarchy and the Catholic Church?

The Encyclopedie was dangerous because it democratized knowledge: written in French (not Latin), it made scientific, philosophical, and critical ideas accessible to literate citizens. By promoting reason over faith and questioning Church teachings, it undermined the authority of both the monarchy and the Catholic Church.

Question 5 of 5

Mary Wollstonecraft, A Vindication of the Rights of Woman (1792): "I do not wish [women] to have power over men, but over themselves... It is time to effect a revolution in female manners: time to restore to them their lost dignity: and make them, as a part of the human species, labour by reforming themselves to reform the world."

▼ Tap to read passage

Wollstonecraft's argument most directly challenges which assumption held by many Enlightenment thinkers?

Wollstonecraft used Enlightenment logic against the philosophes themselves. If reason is universal, she argued, then excluding women from rational education and natural rights contradicts the Enlightenment's own principles. She did not reject the Enlightenment but demanded it live up to its claims of universality.