AP European History

## Learning Outcomes

- Explain how the Scientific Revolution shaped Enlightenment thinking
- Identify how philosophes applied reason to government, religion, economics, and social life
- Recall major thinkers, including **Locke**, **Voltaire**, **Montesquieu**, **Rousseau**, **Diderot**, and **Adam Smith**
- Distinguish between different Enlightenment approaches to reform and authority
- Understand how print culture, salons, and the Republic of Letters spread Enlightenment ideas
- Analyse how Enlightenment thought both challenged traditional authority and had clear limits

## AP European History Syllabus

For the AP European History, you are expected to understand how Enlightenment thinkers applied reason to society, with a focus on the following syllabus points:

- Know that the Enlightenment was an **18th-century** movement that extended methods associated with the Scientific Revolution into human affairs
- Identify the role of **philosophes** in using reason to criticise absolutism, religious intolerance, and inherited privilege
- Explain how **Locke** developed ideas of natural rights, government by consent, and the right of rebellion
- Understand how **Montesquieu** argued for **separation of powers** in _The Spirit of the Laws_ (**1748**)
- Recognise **Voltaire** as a critic of religious intolerance and defender of freedom of thought
- Explain the significance of **Diderot’s Encyclopédie** in organising and spreading Enlightenment knowledge
- Understand how **Rousseau** connected political legitimacy to the **general will** and popular sovereignty in _The Social Contract_ (**1762**)
- Identify how thinkers such as **Adam Smith** applied reason to economics and how **Mary Wollstonecraft** extended Enlightenment criticism to women’s rights

## Test Your Knowledge

_Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, look more closely at that area during your revision._

1. How did the Scientific Revolution influence Enlightenment thought?
2. What did philosophes want to reform in European society?
3. Name two Enlightenment thinkers and explain what each criticised or proposed.
4. How did the _Encyclopédie_ help spread Enlightenment ideas?
5. Why is it inaccurate to say that all philosophes believed the same thing?

## Introduction

The Enlightenment was one of the defining intellectual developments of **18th-century Europe**. For AP European History, the key idea is not just that people valued reason. It is that thinkers began to argue that the same habits of mind used to study nature could also be used to improve **human society**. If Newton could explain motion and gravity through discoverable laws, then perhaps government, religion, economics, and education also followed patterns that reason could examine and reform.

This is why the phrase “philosophes applied science to society” matters. It describes a transfer of method. Enlightenment thinkers did not usually become laboratory scientists. Instead, they borrowed the confidence, skepticism, and search for general laws associated with the Scientific Revolution and applied them to questions such as: What gives rulers authority? Why should one church dominate public life? Can economic life run better with less state interference? Are social inequalities really natural?

> **Key Term: philosophe**
> An Enlightenment thinker, especially prominent in 18th-century France, who applied reason and critical inquiry to society, politics, religion, and economics.

### From natural laws to social laws

The Enlightenment grew out of the intellectual changes of the **17th century**. The Scientific Revolution had weakened the old habit of accepting inherited authority simply because it was old. Figures such as **Francis Bacon** promoted empiricism and observation, while **René Descartes** urged people to doubt assumptions and test ideas through reason. **Newton’s Principia** (**1687**) was especially important because it seemed to prove that the universe operated according to rational, discoverable laws.

Enlightenment thinkers asked a bold follow-up question: if nature is ordered by laws, could society be studied in the same way?

This did not mean every Enlightenment writer used experiments in a strict scientific sense. The point was broader. They used comparison, criticism, observation, and logical argument to examine social institutions. In other words, they treated monarchy, churches, legal systems, and economies as human creations that could be judged and improved, not as fixed parts of an eternal order.

> **Key Term: Enlightenment**
> An 18th-century intellectual movement in which thinkers used reason to analyse and reform society, politics, religion, and economics.

A common exam mistake is to describe the Enlightenment as simply “people believed in science.” That is too vague. The stronger answer is that the Enlightenment extended the reasoning habits of the Scientific Revolution into **human affairs**.

A clear cause-and-effect chain looks like this:

- The Scientific Revolution challenged reliance on ancient authority
- Thinkers gained confidence that reason could uncover laws
- Enlightenment writers applied that confidence to society
- Traditional political and religious authority came under criticism
- Reform, toleration, and new theories of rights became more persuasive
  > **Test Tip:** In SAQs and LEQs, use the phrase “applied methods associated with the Scientific Revolution to human society” rather than just saying “they liked science.” That earns clearer causation.

### Political thought: rights, consent, and limits on power

The political side of the Enlightenment was one of its most important legacies. Here, the best starting point is **John Locke** (**1632–1704**). For AP Euro, Locke is safest treated as an **early Enlightenment thinker**. He argued that human beings possess natural rights to **life, liberty, and property**. Government exists by consent and through a **social contract**, not simply by divine right. If rulers violate those rights, the people may resist.

> **Key Term: natural rights**
> Rights believed to belong to human beings by nature, not because a ruler grants them.
>
> **Key Term: social contract**
> The idea that government is based on an agreement between rulers and the governed.

Why was this so radical? Because it challenged absolutism at its root. Under divine-right monarchy, kings ruled because God had supposedly placed them above subjects. Locke instead argued that legitimate government depended on the people. That idea later shaped constitutionalism in Britain and beyond.

Locke also linked reason to human equality in another way. His idea of the mind as **tabula rasa**, or blank slate, suggested that people were shaped by experience rather than born with fixed intellectual rank. This supported stronger arguments for education and against inherited assumptions about superiority.

**Montesquieu** (**1689–1755**) pushed political analysis in a different direction. In _The Spirit of the Laws_ (**1748**), he argued for **separation of powers**. Rather than placing all authority in one ruler or one body, government should divide power into branches so each can restrain the others.

> **Key Term: separation of powers**
> The division of government authority into separate branches so that no single part can dominate.

Montesquieu thought he saw this principle in Britain, though his interpretation was not fully accurate. For AP purposes, the key point is that he used comparative political analysis to ask how governments could prevent tyranny. This is exactly what “applying science to society” looked like in politics: observing systems, identifying patterns, and recommending structures that would reduce abuse of power.

**Rousseau** (**1712–1778**) added a more radical dimension. In _The Social Contract_ (**1762**), he argued that sovereignty rested in the **general will** of the people, not in the king. Unlike Montesquieu, Rousseau had little faith that modest constitutional adjustment alone would solve inequality or dependency. He focused on how a political community could create freedom through collective self-rule.

> **Key Term: popular sovereignty**
> The principle that political authority comes from the people.

Rousseau is often grouped with other philosophes, but students should not flatten the differences. Locke stressed individual rights and limited government. Montesquieu stressed balanced institutions. Rousseau stressed collective sovereignty and the general will. All three challenged old authority, but not in the same way.

### Religion, toleration, and secular criticism

Religion was another major target of Enlightenment criticism. This does not mean all philosophes were atheists. Many were **deists**, believing that God created the universe but did not intervene in daily life. Their point was that religion should be consistent with reason, not based on coercion, superstition, or blind obedience.

**Voltaire** (**1694–1778**) is the clearest example. Influenced by his time in England, he admired greater religious toleration and freer public discussion than existed in France. He attacked clerical abuse, fanaticism, and judicial persecution. The **Calas affair** helped make him famous as a public critic of intolerance: he fought to expose the injustice of a Protestant wrongly convicted in Catholic France.

Voltaire’s **Treatise on Toleration** (**1763**) made religious toleration a practical issue, not just an abstract principle. He argued that persecution weakened society and violated reason. In exam answers, link Voltaire directly to criticism of religious intolerance and defence of freedom of thought.

> **Key Term: religious toleration**
> Acceptance of the right of people to hold and practise different religious beliefs.

**David Hume** (**1711–1776**) went further. He doubted revealed religion and argued that miracles lacked empirical proof. Hume matters because he shows that Enlightenment criticism of religion could move beyond reforming the church toward questioning the basis of belief itself.

Yet even here, avoid overstatement. The Enlightenment did not simply destroy religion. It changed the terms of debate. Religious belief became more private, and organised religion had to defend itself against public criticism in new ways.

> **Test Tip:** If a prompt asks how Enlightenment thinkers challenged traditional authority, pair one political example with one religious example. For instance: Locke against divine-right monarchy, and Voltaire against religious intolerance.

### Knowledge, print culture, and reforming society

Some philosophes did not mainly propose one political system. Instead, they tried to reorganise knowledge itself. **Denis Diderot** (**1713–1784**) is central here. His **Encyclopédie**, published from **1751**, aimed to gather and organise human knowledge in a rational form.

> **Key Term: Encyclopédie**
> A major Enlightenment reference work edited by Denis Diderot that organised knowledge and spread critical ideas across Europe.

Why was this project so important? First, it reflected the Enlightenment belief that knowledge could be systematised. Second, it spread practical and critical ideas to a wider reading public. Third, it challenged old hierarchies by taking artisans’ and workers’ skills seriously alongside elite learning.

That matters because applying science to society was not only about abstract philosophy. It was also about making useful knowledge available and showing that improvement could come from understanding how things actually work. Diderot’s attention to tools, crafts, and production suggested that societies become better through informed, rational organisation.

The spread of such ideas depended on communication networks. The **Republic of Letters** connected writers across borders. **Salons**, often hosted by elite women, gave philosophes places to debate. Print shops and expanding reading publics helped ideas travel far beyond one city.

> **Key Term: Republic of Letters**
> The international network of writers and thinkers who exchanged Enlightenment ideas through letters and print.

This is important for AP themes such as **Objective Knowledge and Subjective Visions** and **States and Other Institutions of Power**. Ideas mattered more because they circulated more widely. A criticism written in Paris could influence readers in Scotland, Prussia, or the American colonies.

Economic thought also changed. **Adam Smith** (**1723–1790**) applied reason to commerce in _The Wealth of Nations_ (**1776**). He criticised **mercantilism** and argued that economic life worked better when individuals could pursue exchange with less state interference. His idea of the **invisible hand** suggested that markets could regulate supply and demand without constant government direction.

Smith shows that Enlightenment reform was not only constitutional or anti-clerical. It also involved asking whether economies should be managed by old privilege, monopolies, and tariffs, or by freer exchange.

### Limits, exclusions, and why the Enlightenment was not fully equal

The Enlightenment expanded arguments for liberty and reform, but it had real limits. Many philosophes criticised absolutism without supporting mass democracy. Montesquieu preferred mixed government, not popular rule. Voltaire admired enlightened monarchs more than crowds. Even Locke, who wrote about liberty, did not extend freedom consistently to enslaved people.

Women also reveal the limits clearly. Elite women helped spread Enlightenment ideas through salons, but many male thinkers did not support equal rights for women. **Rousseau**, for example, argued for different roles and education for men and women.

The clearest extension of Enlightenment reasoning to gender inequality came from **Mary Wollstonecraft** (**1759–1797**). In _A Vindication of the Rights of Woman_ (**1792**), she argued that if reason is universal, women should also receive education and civic rights. Her critique exposed a contradiction at the heart of the movement: many men praised reason and equality while excluding half the population.

This is a strong evaluation point for essays. The Enlightenment helped create modern ideas of rights, but it did not apply them consistently. That makes arguments about continuity and change much stronger. Traditional authority was challenged, but hierarchy did not disappear.

You can frame that as:

- **Change:** more criticism of absolutism, intolerance, and inherited privilege
- **Continuity:** many thinkers still accepted monarchy, class hierarchy, slavery, or male dominance

That balanced judgement is stronger than saying the Enlightenment simply “brought freedom.”

## Key Point Checklist

_This article has covered the following key knowledge points:_

- The Enlightenment was an **18th-century** movement that applied reason to society as the Scientific Revolution had applied reason to nature
- Philosophes used criticism, observation, and logic to study government, religion, economics, and social organisation
- **John Locke** argued for natural rights, government by consent, and the right of rebellion
- **Montesquieu** proposed **separation of powers** in _The Spirit of the Laws_ (**1748**)
- **Rousseau** argued in _The Social Contract_ (**1762**) that sovereignty rested in the general will of the people
- **Voltaire** criticised religious intolerance and clerical abuse and defended freedom of thought
- **Diderot’s Encyclopédie** organised knowledge and spread Enlightenment criticism across Europe
- **Adam Smith** applied rational analysis to economics and attacked mercantilism in _The Wealth of Nations_ (**1776**)
- The Enlightenment spread through salons, print culture, and the **Republic of Letters**
- Many philosophes supported reform, but not all supported democracy or full equality
- Enlightenment thought challenged traditional authority but still excluded many groups, especially women
- **Mary Wollstonecraft** extended Enlightenment ideas to women’s rights in **1792**

## Key Terms and Concepts

- philosophe
- Enlightenment
- natural rights
- social contract
- separation of powers
- popular sovereignty
- religious toleration
- Encyclopédie
- Republic of Letters


The Enlightenment - Philosophes applied science to society