One of the Enlightenment’s most outspoken atheists, arguing the universe is purely material (System of Nature).
Controversially argued God and Nature are one and the same (pantheism), applying reason to religion itself.
Early English writer who asked, "If all men are born free, how is it that all women are born slaves?"
Used telescopic observation to support Copernican heliocentrism, clashing directly with the Catholic Church.
Defined Enlightenment as humanity’s escape from "self-imposed immaturity," urging people to "dare to know."
Described universal gravitation and the laws of motion, showing the universe runs on discoverable, rational laws.
Natural rights to life, liberty, and property; government exists by the consent of the governed; the mind begins as a "blank slate."
Doubted everything he could not prove through reason, arriving at "I think, therefore I am" (Cogito, ergo sum).
Markets regulate themselves best through an "invisible hand," with minimal government interference (The Wealth of Nations).
Argued all knowledge comes from sensory experience, and was deeply skeptical of religion and miracles.
Relentlessly satirized the Catholic Church and absolute monarchy; championed freedom of speech and religious tolerance.
People are naturally selfish and need an all-powerful sovereign (Leviathan) to escape a brutish "state of nature."
Argued punishment should be proportional to the crime, and opposed torture and the death penalty.
Argued government power should be split into three separate branches to prevent tyranny (The Spirit of the Laws).
Compiled and edited the Encyclopédie, a massive project to gather and spread rational, secular knowledge.
Society should be governed by the "general will" of the people; "man is born free, but everywhere he is in chains."
Championed the empirical scientific method — observe, experiment, and draw conclusions from evidence.
Argued women are not naturally inferior to men, only denied equal education (A Vindication of the Rights of Woman).