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Metaphysics
What there is: substance, cause, time, identity, possibility.
- A Treatise of Human NatureHume's 1739–1740 first major work, in three books, attempting to apply the experimental method to the human mind — the most ambitious early statement of British empiricism.Books
- Act and potencyAristotle's distinction between what a thing is now and what it is capable of becoming.Concepts
- al-FarabiKhorasanian philosopher (c. 870–950) commonly regarded as the founder of Arabic-Islamic Aristotelianism, whose commentaries on Aristotle and original works of political philosophy, logic, and metaphysics established the Arabic falsafa tradition and supplied the framework Avicenna would systematize.FiguresMedieval
- al-GhazaliPersian Ashʿarite theologian, jurist, and Sufi (1058–1111) whose Tahāfut al-Falāsifa challenged the rationalist program of Avicenna and whose Iḥyāʾ ʿUlūm al-Dīn became the most influential work of Sunni piety, reshaping the relationship of philosophy, theology, and mystical practice in Islam.FiguresMedieval
- Alexis de TocquevilleFrench aristocrat, magistrate, and political writer (1805–1859) whose Democracy in America (1835, 1840) and The Old Regime and the Revolution (1856) produced the deepest nineteenth-century analyses of the transformation of European and American societies by the equalizing logic of democracy.Figures19th Century
- Allegory of the CavePlato's famous image in Republic VII of prisoners chained in an underground cave, mistaking shadows for reality — the canonical illustration of the soul's ascent from ignorance to knowledge.ConceptsClassical Greek
- AnaximanderThe second Milesian philosopher, whose doctrine of the apeiron (boundless) introduced abstract metaphysical thinking into the Western tradition and whose cosmology proposed substantively novel ideas about the structure of the universe and the evolutionary origin of living things.FiguresPre-Socratic
- AnaximenesThe third Milesian, who proposed air as the origin of everything and supplied a mechanism for how it becomes other things.Figuresc. 586–526 BC
- Anselm of CanterburyThe Italian-born Benedictine theologian and Archbishop of Canterbury whose ontological argument for God's existence and account of the atonement shaped the entire subsequent medieval tradition.FiguresMedieval
- ApologyPlato's account of Socrates's defense speech at his 399 BCE trial in Athens, the foundational text on the relation between philosophy and the political community that condemns it.Books
- AristotelianismThe tradition founded by Aristotle: forms are immanent in things, knowledge starts with observation, ethics aims at virtuous activity, and reality is best studied through its causes and ends.TraditionsClassical Greek
- Arthur SchopenhauerThe German philosopher whose World as Will and Representation developed the post-Kantian metaphysics of the irrational Will as ultimate reality, integrated Western philosophy with Buddhist and Hindu thought, and shaped Nietzsche, Wittgenstein, Wagner, Tolstoy, Freud, and the broader European cultural engagement with pessimism and the unconscious.Figures19th Century
- AufhebungHegel's technical term for the dialectical movement that simultaneously negates, preserves, and elevates a position into a higher synthesis — the central operation of dialectical thinking.Concepts19th Century
- AverroesCommentaries on Aristotle that transmitted Aristotelian philosophy to medieval Europe, and the argument that philosophy and revelation cannot conflict.Figures1126–1198
- AvicennaThe distinction between essence and existence, the argument from contingency to a necessary being, and the Canon of Medicine.Figuresc. 980–1037
- Baruch SpinozaThe Dutch-Jewish philosopher whose Ethics applied geometrical method to substance, mind, and freedom and concluded that there is only one substance, identified with God or Nature.FiguresEarly Modern
- Being and becomingThe Pre-Socratic opposition between what is stable and what changes — Parmenides holding that only unchanging being is real and Heraclitus that everything flows.Concepts
- Being and NothingnessSartre's 1943 major work of phenomenological-existentialist philosophy, developing systematic analyses of consciousness, freedom, bad faith, interpersonal experience, and the structures of human existence.Books
- Being and TimeHeidegger's 1927 foundational work, the major philosophical event of the twentieth century in continental philosophy: a systematic phenomenological analysis of Dasein as the entry point into the question of the meaning of being.Books
- Being-toward-DeathHeidegger's analysis of human existence as essentially structured by its relation to its own coming death — the recognition of which is what makes authentic existence possible.Concepts20th Century
- Bertrand RussellThe British philosopher, mathematician, logician, social critic, and public intellectual whose work in the foundations of mathematics, the philosophy of language, and the broader analytic tradition shaped twentieth-century philosophy more than any other single figure.Figures20th Century
- Blaise PascalFrench mathematician, physicist, and Jansenist Catholic apologist (1623–1662) whose Pensées presented Christianity as the only adequate account of human contradiction, whose wager argument introduced decision theory to natural theology, and whose Provincial Letters established modern French prose.FiguresEarly Modern
- BonaventureThe Italian Franciscan whose Augustinian-Neoplatonist synthesis was the major thirteenth-century theological alternative to Aquinas's Aristotelian framework, and whose Itinerarium Mentis in Deum is the canonical Franciscan mystical theology.FiguresMedieval
- Bondage of the WillLuther's 1525 treatise replying to Erasmus's Diatribe on Free Will, arguing that the human will after the Fall has no power in matters of salvation and that salvation is wholly the work of divine grace — a foundational text of Reformation theology and a major position in the long debate over freedom and grace.Books
- Bundle TheoryHume's account of the self (and, by extension, of objects) as a bundle of perceptions held together by relations of resemblance and causation rather than by an underlying substance.ConceptsEnlightenment
- CausationThe relation by which one event or state brings about another — contested from Aristotle's four causes to Hume's skepticism.Concepts
- Charles DarwinExplained the appearance of design without a designer, which reshaped philosophy as much as biology.Figures1809–1882
- ConfessionsAugustine's autobiographical and philosophical work in thirteen books, the founding text of Western autobiography and one of the most influential single works in Latin Christian thought.Books
- Critical TheoryThe twentieth-century tradition founded by the Frankfurt School Institute for Social Research that integrates Marxist analysis, Hegelian dialectic, Freudian psychoanalysis, and Weberian sociology into a critical theory of contemporary society.Traditions20th Century
- Critique of Pure ReasonKant's foundational work of Critical philosophy, demonstrating that the mind contributes structuring conditions (space, time, the categories) to all possible experience, and establishing the limits of theoretical knowledge.Books
- David ChalmersNamed the hard problem of consciousness and argued that explaining function leaves experience untouched.Figuresb. 1966
- David HumeThe Scottish empiricist whose analysis of causation, induction, and the self produced some of the most consequential skeptical arguments in modern philosophy.FiguresEnlightenment
- DemocritusThe Pre-Socratic philosopher who developed atomism with his teacher Leucippus, producing the substantial framework that the substantial Hellenistic Epicurean tradition would inherit and that substantial twentieth-century physics would vindicate in modified form.FiguresPre-Socratic
- DeterminismThe thesis that every event is the necessary outcome of prior causes.Concepts
- Dialogues Concerning Natural ReligionHume's posthumously published 1779 dialogue, the most rigorous critique of natural theology in the philosophical tradition, presenting and analyzing the major arguments for God's existence through three philosophical characters.Books
- Discourse on MethodDescartes's 1637 short methodological work, the first major French-language philosophical treatise, containing the famous cogito argument and the four rules of method.Books
- Duns ScotusThe Scottish Franciscan whose technical revisions to the dominant Thomist framework — the univocity of being, the formal distinction, the primacy of the will, the haecceity of individuation — produced the major Franciscan alternative to Thomism in late-medieval and early-modern scholasticism.FiguresMedieval
- EmanationThe Neoplatonic account of how multiplicity comes from unity: the One overflows necessarily and without diminishing, as a source radiates light, producing a descending order of reality rather than creating it by an act of will.Concepts
- EmergenceThe claim that a whole has properties its parts lack, and that those properties are not simply a convenient summary of what the parts are doing.Concepts
- Emmanuel LevinasThe French-Lithuanian philosopher whose work recentered phenomenology on the ethical encounter with the Other, made ethics first philosophy, and produced one of the most distinctive philosophical projects of the postwar period.Figures20th Century
- EmpedoclesThe Pre-Socratic philosopher whose four-element cosmology shaped Western natural philosophy for two thousand years, and whose substantial poetic-philosophical works (Physics and Purifications) substantially integrated cosmological speculation with religious-ethical doctrine.FiguresPre-Socratic
- EmpiricismThe tradition holding that all genuine knowledge originates in sense experience; the mind starts as a blank slate that experience writes on.TraditionsEarly Modern
- EnchiridionEpictetus's handbook of Stoic ethics, compiled by his student Arrian as a short, portable distillation of the longer Discourses.Books
- EpictetusThe Stoic philosopher, born a slave, whose Discourses and Enchiridion are the most rigorous surviving applications of Stoic ethics to daily life.FiguresRoman
- EpicureanismA Greek school holding that pleasure — understood as freedom from pain and mental disturbance — is the highest good, reached through simple needs, friendship and the removal of fear.Traditions307 BC – 3rd century AD
- Essence and ExistenceThe metaphysical distinction, developed by Avicenna and Aquinas, between what a thing is (essence) and the fact that it is (existence) — with the corollary that only in God are essence and existence identical.ConceptsMedieval
- Eternal RecurrenceNietzsche's doctrine that every moment of existence will recur infinitely many times, identically — functioning both as a thought experiment testing one's relation to life and (on the strongest reading) as a cosmological claim about the structure of time.Concepts19th Century
- Ethics (Spinoza)Spinoza's 1677 major work, structured geometrically (definitions, axioms, propositions, demonstrations) and developing a comprehensive metaphysics, philosophy of mind, theory of the emotions, and account of human freedom from a small set of opening assumptions.Books
- ExistentialismThe mid-20th century philosophy that insists existence precedes essence — we are not what we are because of some fixed nature, but because of what we choose to make of ourselves.Traditions20th Century
- F.W.J. SchellingGerman Idealist philosopher (1775–1854) whose early Naturphilosophie and System of Transcendental Idealism completed the Kantian-Fichtean project from the side of nature, whose middle-period Identity Philosophy proposed an absolute identity of nature and spirit, and whose late Positive Philosophy at Berlin (1841) opened existentialist themes that shaped Kierkegaard, the late Schelling himself, and twentieth-century continental thought.Figures19th Century