The examined life — from the Presocratics who asked what the world is made of, through Plato and Aristotle, the Hellenistic schools, and the Alexandrian synthesis, to Spinoza, Kant, and the Scottish tradition that made common sense a philosophical position.
The philosopher of flux. Everything flows; you cannot step into the same river twice. Fire is the fundamental element, and the logos — the hidden rational structure of the universe — governs all change through the unity of opposites. He wrote in aphorisms and despised the mob.
Can help you study: Flux, fire, the logos, the unity of opposites, and the Presocratic foundations of Western metaphysics.
The philosopher of being. What is, is. What is not, cannot be thought. Against Heraclitus, he argued that change is illusion and reality is one, eternal, and unchanging. His poem established the Way of Truth and the Way of Seeming — a distinction that philosophy has never resolved.
Can help you study: Being and non-being, monism, the impossibility of change, the Way of Truth, and the Eleatic challenge to common sense.
The laughing philosopher and co-founder of atomism. Nothing exists except atoms and void — everything else is opinion. He proposed a materialist account of the universe that anticipated modern physics by two millennia.
Can help you study: Atomism, materialism, the void, the distinction between convention and reality, and the Presocratic origins of science.
The philosopher who wrote nothing and changed everything. His method — the elenchus — proceeds by question and refutation until the interlocutor discovers their own ignorance. This composite draws on Plato, Xenophon, and Aristophanes.
Can help you study: The Socratic method, the examined life, elenchus, aporia, the daimonion, and the Socratic problem.
The early dialogues — Apology, Euthyphro, Crito, Meno — where Socrates asks questions rather than builds systems. The method is everything: define the concept, test it, discover it fails, try again.
Can help you study: The early dialogues, Socratic definition, the Apology, virtue and knowledge, and the method of question and refutation.
The masterwork. The Republic asks what justice is and answers with a theory of the soul, of knowledge, of education, and of the state. The Cave, the Divided Line, the philosopher-king.
Can help you study: The Republic, justice, the theory of Forms, the cave allegory, the tripartite soul, education, and the philosopher-king.
The dialogues of love, beauty, and the soul’s immortality. The Symposium traces love from bodily desire to the vision of Beauty itself. The Phaedo argues for immortality. The Phaedrus gives love wings.
Can help you study: Eros, the Symposium, the soul’s immortality, the Phaedo, beauty, and the ascent from particular to universal love.
The self-critical Plato. In the Parmenides he attacks his own theory of Forms. In the Sophist he wrestles with non-being. In the Timaeus he builds a cosmology. In the Laws he redesigns the state without the philosopher-king.
Can help you study: The late dialogues, the self-critique of the Forms, cosmology, the Sophist, the Laws, and Plato’s final philosophy.
The inventor of formal logic and the philosopher of being qua being. The Categories, Analytics, and Metaphysics — the tools for distinguishing valid from invalid inference and for asking what it means for anything to exist.
Can help you study: The syllogism, the categories, substance and accident, the four causes, being qua being, and the foundations of Western logic.
The philosopher of the good life. The Nicomachean Ethics argues that happiness is activity of the soul in accordance with virtue, a mean between extremes. The Politics, Rhetoric, and Poetics complete the picture.
Can help you study: Virtue ethics, the golden mean, eudaimonia, practical wisdom, the political animal, rhetoric, and the Poetics.
The naturalist philosopher. De Anima asks what the soul is: the form of a living body. The Physics analyses change, place, and time. The biological works classify the animal kingdom with a precision unmatched for two thousand years.
Can help you study: The soul as form, hylomorphism, natural philosophy, teleology, biological classification, and the relationship between physics and metaphysics.
The philosopher of pleasure — but not excess. True pleasure is the absence of pain and the company of friends. His atomist physics eliminated the fear of death and the gods. He lived in a garden with his companions.
Can help you study: Epicurean ethics, ataraxia, atomism, the tetrapharmakos, friendship, the fear of death, and philosophy as medicine for the soul.
Epicurean philosopher whose works were buried by Vesuvius at Herculaneum and are being recovered from carbonised papyri. He taught that frank criticism between friends is the highest form of care.
Can help you study: Epicureanism, frank criticism, the Herculaneum papyri, ancient aesthetics, and the relationship between philosophy and poetry.
Born a slave. His Discourses and Enchiridion teach one principle: some things are up to us and some are not. Until you understand that distinction, you will be enslaved by what you cannot control.
Can help you study: Stoic ethics, the dichotomy of control, the Enchiridion, freedom, and the argument that philosophy is a way of life.
Roman emperor who wrote the Meditations — a private journal never meant for publication. Night after night on military campaign he reminded himself that equanimity is possible even in the face of ingratitude, betrayal, and death.
Can help you study: The Meditations, Stoic practice, equanimity, impermanence, duty, and the discipline of private philosophical reflection.
The last great Pyrrhonian sceptic. His Outlines of Pyrrhonism argues that for every argument there is an equal and opposite argument, and the response is suspension of judgement — which paradoxically produces tranquillity.
Can help you study: Pyrrhonian scepticism, suspension of judgement, the ten modes, equipollence, and the sceptical path to tranquillity.
The founder of Neoplatonism. His Enneads describe a universe emanating from the One through Intellect and Soul into matter, and the soul’s return journey upward through contemplation. He shaped Christian, Islamic, and Jewish theology for a millennium.
Can help you study: The One, emanation, the Enneads, the soul’s ascent, Neoplatonism, and the relationship between Greek philosophy and monotheistic theology.
The philosopher who read Moses through Plato. His allegorical commentaries on Genesis interpret every detail as encoding philosophical truths. He created the method of allegorical reading that shaped Christian and Islamic theology.
Can help you study: Allegorical method, the synthesis of Hebrew scripture and Greek philosophy, the Logos, and the origins of philosophical theology.
The systematic Philo. His Exposition of the Law presents Moses as the greatest lawgiver, philosopher, and king. He wrote for a Greek-speaking audience to show them what they were missing.
Can help you study: The Exposition of the Law, Moses as philosopher-king, the Decalogue, the contemplative life, and Jewish apologetics in Greek.
Philo the political witness. He went to Rome to plead before Caligula for the survival of Alexandria’s Jewish community. Caligula was renovating his villa and barely looked at them. Philo came back and wrote it down.
Can help you study: The Embassy to Gaius, the pogrom in Alexandria, Against Flaccus, political testimony, and the experience of speaking truth to indifferent power.
Dutch lens-grinder, excommunicated from the Amsterdam synagogue at twenty-three, who wrote the Ethics in geometric form — definitions, axioms, propositions, proofs. God is Nature. Freedom is understanding necessity. There is one substance and everything is a mode of it.
Can help you study: Substance monism, God or Nature, the geometric method, freedom as understanding necessity, the Ethics, and the most radical metaphysics of the early modern period.
German philosopher who never travelled more than ten miles from Königsberg and restructured all of Western philosophy. The Critique of Pure Reason (1781) established that the mind actively structures experience. The categorical imperative grounds morality in reason alone.
Can help you study: The three Critiques, the categorical imperative, the synthetic a priori, transcendental idealism, the limits of knowledge, and the Copernican revolution in philosophy.
The world’s only consulting detective. His method — observation, deduction, the elimination of the impossible — is philosophy applied to crime. He can identify a man’s profession from his hands and his history from his shoes.
Can help you study: Deductive reasoning, observation, the elimination of the impossible, forensic method, and the application of logic to practical problems.
Holmes’s chronicler and the sounding board against which deduction becomes visible. He asks the questions the reader would ask, in the order the reader would ask them.
Can help you study: Logic, the Socratic role of the intelligent questioner, general troubleshooting, and the art of making genius comprehensible.
Irish-born philosopher who taught at Glasgow and argued that we have a moral sense as real as sight. It perceives benevolence as naturally as the eye perceives light. His formula — the greatest good for the greatest number — was later taken up by the utilitarians.
Can help you study: Moral sense theory, benevolence, the greatest happiness, aesthetic perception, and the Scottish origins of utilitarian thought.
Scottish philosopher whose radical empiricism demolished every certainty that philosophy had built. Causation is custom. The self is a bundle of perceptions. Reason is the slave of the passions. The is-ought gap has never been crossed.
Can help you study: Empiricism, scepticism, the is-ought gap, causation, the problem of induction, the passions, and the most powerful philosophical critique of certainty ever written.
Professor of Moral Philosophy at Glasgow. Before the Wealth of Nations he wrote the Theory of Moral Sentiments (1759), grounding morality in sympathy — the ability to enter imaginatively into another’s situation — and the impartial spectator.
Can help you study: Moral sentiments, sympathy, the impartial spectator, the relationship between moral philosophy and political economy, and the Scottish Enlightenment.
Scottish philosopher who refused to accept that the table is not real simply because Hume had an argument. Common sense is not naive — it is the foundation on which philosophy itself stands. His critique of Hume founded the Common Sense school.
Can help you study: Common sense philosophy, direct realism, the critique of Hume, first principles, and the argument that philosophy cannot contradict what everyone knows to be true.
Scottish philosopher and poet who wrote the Essay on the Nature and Immutability of Truth (1770) against Hume’s scepticism. He argued that truth is self-evident to the honest mind and that cleverness without moral seriousness is dangerous.
Can help you study: Common sense, the defence of truth against scepticism, moral aesthetics, and the Scottish Enlightenment critique of Humean philosophy.
Scottish philosopher who analysed taste and genius. His Essay on Taste (1759) won the prize over Hume’s entry, and his Essay on Genius (1774) analysed the creative process as the power to combine ideas that others keep separate.
Can help you study: Taste, genius, aesthetic philosophy, the creative process, and the Scottish Enlightenment analysis of imagination.
Edinburgh professor whose Lectures on Rhetoric and Belles Lettres (1783) was the standard rhetoric textbook in British and American universities for a century. Style is the dress of thought — but the dress must fit the body.
Can help you study: Rhetoric, style, the sublime, belles lettres, taste, and the Scottish tradition of systematic rhetoric.
Scottish minister and philosopher whose Philosophy of Rhetoric (1776) grounded persuasion in the psychology of the audience. The end of rhetoric may be to enlighten, to please, to move, or to influence — and the means must match the end.
Can help you study: The philosophy of rhetoric, evidence, testimony, persuasion, and the psychological foundations of argument.
Scottish judge, philosopher, and polymath whose Elements of Criticism (1762) established aesthetic theory as a science grounded in human nature. The principles of taste are as discoverable as the principles of morals.
Can help you study: Elements of criticism, aesthetic theory, taste as science, law, and the Scottish Enlightenment analysis of beauty and judgement.