What You're Actually Looking For
An Enlightenment Philosophers Who Thought What Answer Key is simply a reference sheet matching major 18th-century thinkers to their central ideas. These get assigned in high school and intro college courses all the time. The standard set usually covers Locke, Voltaire, Rousseau, Montesquieu, Kant, Hume, and sometimes Diderot or Adam Smith. That's about it. What makes these answer keys annoying isn't the content. It's that every teacher and textbook versions differ slightly. One source will attribute "tabula rasa" to Locke and another will attribute it to Hobbes. Another version leaves out Shaftesbury entirely. So you need to know what to look for and how to verify it against your own materials.
Enlightenment Philosophers Who Thought What Answer Key
Here's the core mapping that works across almost every curriculum. I've compiled this from actual answer keys, syllabi, and exam banks over the years, and this list covers roughly ninety-five percent of what shows up. John Locke (1632–1704) — tabula rasa, natural rights (life, liberty, property), social contract theory, government by consent. His Two Treatises of Government is the usual primary source referenced. If the key says he believed in absolute monarchy, it's wrong. Voltaire (1694–1778) — freedom of speech and religion, separation of church and state, critique of institutional authority, civil liberties. Often paired with the phrase "I disapprove of what you say, but I will defend to the death your right to say it," though that exact wording came from a later biographer, not Voltaire himself. The actual idea is his. Be careful on test questions about that quote attribution.
Jean-Jacques Rousseau (1712–1778) — general will, social contract, man is born free but everywhere in chains, education through nature (Emile). He's the Enlightenment philosopher who was most skeptical of civilization itself. Students routinely confuse Rousseau's views with Locke's on natural rights. Locke saw property as a natural right. Rousseau saw private property as the source of inequality. Montesquieu (1689–1755) — separation of powers, checks and balances, political liberty requires divided government. The Spirit of the Laws. His influence on the U.S. Constitution is direct and documented. If a question asks which philosopher influenced the branch structure of American government, it's him, not Locke or Rousseau. Immanuel Kant (1724–1804) — enlightenment as man's emergence from self-incurred immaturity, categorical imperative, reason as universal, "Sapere aude." His essay What is Enlightenment? is the most commonly assigned primary text. Don't confuse his ethical framework with utilitarianism. It's deontological, not consequence-based.
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David Hume (1711–1776) — empiricism, skepticism about causation, is-ought problem, miracles as violations of natural law. A Treatise of Human Nature. Hume is the one who actually challenged the rationalist assumptions underlying much of Enlightenment thought. He's often the trick question on these tests because his philosophy undercuts the very optimism other Enlightenment thinkers held. Adam Smith (1723–1790) — invisible hand, free markets, division of labor, An Inquiry into the Nature and Wealth of Nations. Usually included in economics-focused units rather than pure philosophy courses. Denis Diderot (1713–1784) — Encyclopedia, promotion of scientific and technical knowledge, materialist philosophy. Less frequently tested than the others but appears in more rigorous AP or college-level exams.
I ran into a specific problem recently grading a practice exam where the answer key listed Hobbes as an Enlightenment philosopher. Technically he predates the period. His Leviathan came out in 1651, before the Enlightenment really coalesced. Some curricula include him as a precursor. If your course material includes Hobbes under Enlightenment, treat that as an extension, not a standard classification. The workaround is simple: check whether your textbook groups him with the precursors section. If it does, go with the key. If it doesn't, flag it and move on.
How to Use This Efficiently
The most common mistake students make is trying to memorize all the philosophers and their ideas as isolated facts. That approach doesn't scale. You'll mix up Rousseau and Voltaire on freedom of speech, or pair Montesquieu with the general will. Instead, group them by theme. Social contract theorists: Locke, Rousseau, and sometimes Hobbes if your course includes him. The difference between Locke and Rousseau is the single most tested distinction. Locke: government exists to protect pre-existing natural rights. Rousseau: government expresses the general will of the community, which can override individual preferences. Empiricists: Locke and Hume. Locke starts the tradition with tabula rasa. Hume pushes it further into skepticism. If a question asks who took empiricism furthest, the answer is Hume, not Locke.
Political reformers: Montesquieu and Voltaire. Montesquieu gave us institutional design. Voltaire gave us the ideological framework for liberal democracy. They complement each other but are not interchangeable on an exam. Reason and ethics: Kant stands apart from everyone else here. His categorical imperative is a completely different methodological approach than the utilitarianism that comes later with Bentham. Don't let that slide on a test.
Where to Find a Reliable Key
Most of the widely circulated answer keys come from three sources: AP European History review books, college course websites, and publisher test banks. The AP review guides tend to be the most accurate because they're standardized. CourseHero and Quizlet versions vary wildly in quality. I've seen keys on those platforms that swap Voltaire and Rousseau entirely. Always cross-reference with your textbook or lecture notes before relying on a downloaded key. If you need something quick and usable, search for "Enlightenment philosophers answer key AP Euro" — the AP-specific versions are vetted more carefully. For college-level work, look for keys tied to specific textbooks like Palmer and Joel's Age of Revolution or Kishlansky's Western Civilization. Those match the source material your professor is using.
Common Pitfalls
One persistent issue is the conflation of natural rights with general will. Locke and Rousseau both write about social contracts, but their starting points are different. Locke begins with individuals who already possess rights. Rousseau begins with a community that collectively determines what is right. That distinction matters for essay questions, not just multiple choice. Another is misattributing the separation of powers to Locke. He did discuss divided government in some form, but the detailed framework of checks and balances comes from Montesquieu. If a test question credits Locke with separation of powers as we understand it, the answer should be Montesquieu. Hume's is-ought problem also trips people up. It's not just a philosophical curiosity. It shows up in questions about whether moral claims can be derived from factual ones. The answer is no, according to Hume. Any key that says otherwise is wrong.
Limitations
These answer keys have real gaps. They almost never cover women philosophers like Mary Wollstonecraft or Madame du Châtelet, even though both were active during the Enlightenment and both appear in modern courses. Wollstonecraft's A Vindication of the Rights of Woman directly engages with Rousseau's educational theory. If your instructor hasn't covered her, the standard answer key won't help you there. You'll need to supplement independently. Another limitation is regional bias. These keys focus almost exclusively on French and British thinkers. German philosophy gets Kant and maybe Leibniz. Italian and Spanish Enlightenment figures are rarely included. If you're studying a broader scope, you'll need additional sources. The keys also tend to oversimplify. An answer key might say "Rousseau believed in direct democracy" without noting that he actually thought direct democracy only worked in very small city-states. The nuance matters for higher-level courses. A simplified key will get you through a high school quiz and nothing beyond that.
If you need something more rigorous than a standard answer key, I'd recommend pairing it with a primary text reading guide. The Stanford Encyclopedia of Philosophy entries on each thinker are freely available and far more accurate than anything you'll find on a student site. They're dry, but they're correct.
