Socrates (470–399 BCE) — ethics, questioning, Socratic method

Plato (427–347 BCE) — forms, justice, ideal state

Aristotle (384–322 BCE) — logic, science, virtue ethics

Confucius (551–479 BCE) — ethics, family, social harmony

Niccolò Machiavelli (1469–1527) — political realism

Francis Bacon (1561–1626) — scientific method

René Descartes (1596–1650) — rationalism, “I think, therefore I am”

Thomas Hobbes (1588–1679) — social contract, Leviathan

Baruch Spinoza (1632–1677) — pantheism, ethics

John Locke (1632–1704) — empiricism, liberalism

Gottfried Leibniz (1646–1716) — monads, optimism

David Hume (1711–1776) — empiricism, skepticism

Jean-Jacques Rousseau (1712–1778) — social contract, human freedom

Immanuel Kant (1724–1804) — categorical imperative, critique of reason

Georg Hegel (1770–1831) — dialectics, history as progress

Arthur Schopenhauer (1788–1860) — pessimism, will to live

John Stuart Mill (1806–1873) — utilitarianism, liberty

Karl Marx (1818–1883) — materialism, class struggle

Friedrich Nietzsche (1844–1900) — will to power, eternal recurrence

William James (1842–1910) — pragmatism, psychology

Ludwig Wittgenstein (1889–1951) — language, logic

Martin Heidegger (1889–1976) — being, existentialism

Jean-Paul Sartre (1905–1980) — existentialism, freedom

Simone de Beauvoir (1908–1986) — feminism, existential ethics

Michel Foucault (1926–1984) — power, knowledge, institutions

Hannah Arendt (1906–1975) — totalitarianism, political theory

Noam Chomsky (1928– ) — linguistics, political philosophy