The concepts, the people who argued them, and the texts they argued in.
In the libraryRawls's 1971 systematic statement of justice as fairness, developing the original position thought experiment, the two principles of justice, and the framework that revived political philosophy as a major analytic subfield.
Hume'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.
Aristotle's distinction between what a thing is now and what it is capable of becoming. Change is a potential being actualised, which is what lets change be real without requiring that something come from nothing.
Scottish moral philosopher and political economist (1723–1790), professor at Glasgow and confidant of David Hume, whose Theory of Moral Sentiments grounded ethics in sympathy and whose Wealth of Nations founded the modern discipline of political economy, providing the framework within which commercial society has been understood for two centuries.
The philosophical study of beauty, art, and taste.
Acting against your own better judgment — knowing the better course and taking the worse one, which Socrates argued is impossible and everyone else has observed constantly.
Scottish-American moral philosopher (1929–2025) whose After Virtue, Whose Justice? Which Rationality?, Three Rival Versions of Moral Enquiry, and Dependent Rational Animals constructed the most influential late twentieth-century case for the recovery of an Aristotelian-Thomistic tradition of moral reasoning against the fragmentation of modern moral discourse.
The French-Algerian writer and philosopher whose work on the absurd, revolt, and the limits of revolutionary politics made him the canonical philosophical voice of mid-century European disenchantment and one of the few twentieth-century writers to receive the Nobel Prize for fundamentally philosophical work.
French 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.
Marx's concept naming the structural condition under capitalism in which workers are estranged from the product of their labor, from the activity of labor, from their species-being, and from other workers.
Plato'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.
The Stoic doctrine of loving fate — actively accepting whatever happens as the working of cosmic logos, rather than merely tolerating it.
Aquinas's account of how a word like good or wise can be said of God and of a creature: neither in the same sense, which would make God a being among beings, nor in unrelated senses, which would make theology empty, but in related senses with one primary.
The 20th-century tradition characterized by formal precision, linguistic clarity, piecemeal problem-solving, and close engagement with logic and the sciences.
Introduced Mind as the ordering principle of the cosmos, and was prosecuted for saying the sun is a burning stone.
The 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.
The third Milesian, who proposed air as the origin of everything and supplied a mechanism for how it becomes other things.
The 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.
The Stoic doctrine of freedom from passion — not the absence of feeling, but the absence of the disturbing emotions that arise from mistaken judgments about what is good and bad.
Plato'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.
The Greek term for productive perplexity — the recognition, often arrived at through dialectical questioning, that one does not in fact know what one thought one knew.
The 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.
Plato's most consequential student, who systematized philosophy, founded biology, invented Western formal logic, and gave virtue ethics its canonical form.
The 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.
The Hellenistic ideal of mental tranquility — the settled, undisturbed state of soul that Epicureans and Skeptics took to be the goal of philosophy.
Hegel'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.
The North African bishop whose synthesis of Christianity and Neoplatonism became the foundation of Latin Christian theology and shaped the metaphysical inheritance of the medieval West.
The existentialist value of being what one is in the deepest sense — living from one's own freedom and recognition of finitude rather than from inherited roles, social conformity, or self-deception.
Commentaries on Aristotle that transmitted Aristotelian philosophy to medieval Europe, and the argument that philosophy and revelation cannot conflict.
The distinction between essence and existence, the argument from contingency to a necessary being, and the Canon of Medicine.
Sartre's name for the mode of consciousness that flees its own freedom by treating itself as a fixed thing rather than the open activity it actually is — self-deception that requires simultaneously knowing and not knowing the same thing.
The 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.
Sartre's 1943 major work of phenomenological-existentialist philosophy, developing systematic analyses of consciousness, freedom, bad faith, interpersonal experience, and the structures of human existence.
Heidegger'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.
The Pre-Socratic opposition between what is stable and what changes — Parmenides holding that only unchanging being is real and Heraclitus that everything flows. Most later metaphysics is an attempt to hold both without contradiction.
Heidegger'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.
A set of beliefs held together so that each is supported by the others. The system, not the individual belief, is what meets evidence — which is why disconfirming one claim rarely changes anything, and why systems are abandoned socially rather than refuted.
English moral philosopher (1929–2003), Cambridge Knightbridge Professor and Oxford White's Professor of Moral Philosophy, whose Problems of the Self, Moral Luck, Ethics and the Limits of Philosophy, Shame and Necessity, and Truth and Truthfulness defended a humanistic moral philosophy against both the Kantian deontological and the utilitarian-consequentialist traditions.
The 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.
French 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.
The late-antique Roman philosopher whose Consolation of Philosophy, written while awaiting execution, became one of the most-read texts in the medieval West, and whose translations and commentaries on Aristotle were the principal source for Latin scholastic logic for seven centuries.
The 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.
Luther'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.
Hume'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.
Marx's three-volume major theoretical work of systematic political economy, analyzing the structure, dynamics, and internal contradictions of capitalist society.
Kant's formulation of the moral law as an unconditional principle of action — act only on that maxim which you can will to be a universal law — the foundational doctrine of deontological ethics.
The relation by which one event or state brings about another — contested from Aristotle's four causes to Hume's skepticism.
Explained the appearance of design without a designer, which reshaped philosophy as much as biology.
The American polymath who founded pragmatism with the 1878 paper How to Make Our Ideas Clear, made fundamental contributions to formal logic and semiotics, and produced one of the most original philosophical bodies of work in the nineteenth century — most of it published only after his death.
Canadian philosopher (b. 1931) whose work bridges analytic and continental traditions, whose Sources of the Self (1989) and A Secular Age (2007) are major works of philosophical history, and whose essays on multiculturalism and the politics of recognition have shaped late twentieth- and early twenty-first-century political theory.
The systematic intellectual tradition built around Christian revelation, integrating Scripture, the Church Fathers, and inherited Greek philosophy into a coherent account of God, world, and the human person.
Roman statesman and orator (106–43 BCE) whose philosophical dialogues — De Officiis, De Finibus, De Natura Deorum, Tusculan Disputations — created a Latin philosophical vocabulary, preserved the systems of Hellenistic schools otherwise lost, and shaped every subsequent Western reception of Greek thought.
Augustine's vast late work in twenty-two books on history, politics, and theology, interpreting human history as the unfolding of two intermingled communities oriented respectively to God and to self.
Descartes's foundational principle — cogito ergo sum, 'I think, therefore I am' — the indubitable certainty of the thinking subject's existence, recovered through systematic doubt as the foundation of modern philosophy.
The epistemic posture of holding beliefs as functionally coherent and provisionally adequate without claiming demonstrative certainty — the alternative to both dogmatic conviction and skeptical paralysis.
Augustine'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.
Subjective experience itself; the 'hard problem' is explaining why physical processes give rise to it.
The family of a posteriori arguments for God's existence that proceed from observed features of the world (motion, causation, contingency) to a first cause or necessary being, developed across Aristotelian, Islamic, Thomist, and Leibnizian versions.
Husserl's late masterpiece composed in the shadow of Nazi Germany that substantially develops the analysis of the life-world and treats the natural sciences as having lost contact with their grounding in pre-theoretical lived experience.
The 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.
Kant'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.
A Greek school holding that virtue alone is good and is reached by living according to nature — refusing wealth, status and convention as sources of anxiety rather than security.
Argued that consciousness is not what it seems to be, and that the appearance of a unified inner theatre is itself what needs explaining.
Named the hard problem of consciousness and argued that explaining function leaves experience untouched.
The Scottish empiricist whose analysis of causation, induction, and the self produced some of the most consequential skeptical arguments in modern philosophy.
Aristotle's treatise on the soul as the form of a living body, analyzing the faculties of nutrition, sensation, and intellect across plants, animals, and human beings.
Choosing when the probabilities of the outcomes are not known. Frank Knight (1921) separated this from risk, where they are: risk can be priced and insured, uncertainty cannot, and on Knight's account profit is the return for bearing the second.
Averroes's late-twelfth-century juridical defense of philosophy from within Islamic legal categories, arguing that systematic rational inquiry is religiously obligatory for those qualified and laying out the doctrine of interpretation that reconciles philosophical conclusions with scriptural authority.
Reasoning in which the conclusion cannot be false if the premises are true. That guarantee is bought at a price: a deduction adds nothing that was not already in the premises, which is why it can never establish a new fact about the world.
Dewey's 1916 systematic statement of progressive education theory, treating schools as miniature democratic communities and education as the cultivation of dispositions for inquiry-based participation rather than transmission of fixed content.
The 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.
Duty-based ethics: actions are right or wrong in themselves, regardless of consequences. Most associated with Kant.
The thesis that every event is the necessary outcome of prior causes.
Reasoning conducted through opposition — by question and refutation, or by the development of a position through its own contradictions. Aristotle distinguished it from demonstration precisely: dialectic argues from what is commonly held, demonstration from what is true and primary.
The 1947 work by Horkheimer and Adorno composed during their wartime California exile, developing the thesis that the Enlightenment project of emancipation through reason has produced its own opposite in the dominance of instrumental rationality and the culture industry.
Hume'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.
The Greek philosopher whose ostentatious rejection of conventional propriety produced the canonical exemplification of Cynic philosophy and whose anecdotes have made him one of the most-recognized single figures from the ancient philosophical tradition.
Foucault's 1975 genealogical history of the European penal system that analyzed the transformation from the spectacle of public execution to the disciplinary techniques of the modern prison, developing the concepts of discipline, surveillance, and the Panopticon.
Descartes's 1637 short methodological work, the first major French-language philosophical treatise, containing the famous cogito argument and the four rules of method.
The doctrine that God has no parts of any kind — not physical, not metaphysical — so that God's attributes are not components God possesses but are identical with God and with each other. It is what keeps God from being a being among beings.
Aristotle's doctrine that each moral virtue lies as a mean between two vices — one of excess and one of deficiency — found by practical wisdom in the particular situation.
The view that mind and matter are fundamentally different kinds of thing, so mental states are not simply physical states of the body.
The 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.
Anglo-Irish statesman, orator, and political thinker (1729–1797) whose Reflections on the Revolution in France founded modern conservative political thought, whose decades in Parliament addressed American, Indian, and Irish questions with sustained moral seriousness, and whose theory of the political tradition shaped Anglo-American conservatism from the nineteenth century to the present.
The Moravian-German philosopher who founded the phenomenological tradition, developed the method of bracketing (epoché) and transcendental phenomenology, and shaped twentieth-century continental philosophy more decisively than any other single figure.
The 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.
The 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. Everything turns on whether the novelty is in our description or in the world.
The 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.
The 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.
The thesis that knowledge derives primarily from sensory experience.
The tradition holding that all genuine knowledge originates in sense experience; the mind starts as a blank slate that experience writes on.
Epictetus's handbook of Stoic ethics, compiled by his student Arrian as a short, portable distillation of the longer Discourses.
The Stoic philosopher, born a slave, whose Discourses and Enchiridion are the most rigorous surviving applications of Stoic ethics to daily life.
A 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.
The Greek philosopher who founded Epicureanism in his Athenian Garden, developed a comprehensive philosophy integrating atomist physics with hedonistic ethics, and produced one of the most influential ethical traditions of the ancient world.
Greek for knowledge in the strict sense — what is known rather than merely believed. Plato required belief to be tethered by an account; Aristotle reserved the term for demonstrative knowledge of what cannot be otherwise, distinguishing it from craft and practical wisdom.
The study of knowledge — what it is, how we get it, and the limits of what can be known.
The principle that people are in some fundamental respect to be treated as equals — and the long argument about which respect, since equality in one dimension usually produces inequality in another.
Locke's foundational work of modern empiricism, in four books, arguing against innate ideas and developing the doctrine that all knowledge derives from sensation and reflection.
The 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.
Nietzsche'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.
The systematic study of right action, good character, and the structure of moral claims.
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.
The Greek term for a life that has gone well taken as a whole — usually rendered happiness, which is misleading. Eudaimonia is an assessment of a life's course, not a mood, and Aristotle held it consists in activity of the soul in accordance with virtue.
Existence precedes essence: humans must create meaning in a universe that doesn't supply it.
The 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.
German 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.
The relationship between religious belief and rational justification — fideism, evidentialism, and everything between.
Karl Popper's criterion for scientific status: a theory is scientific if it forbids something, so that a statable observation would refute it.
The idea that events are fixed in advance and will arrive regardless of what anyone does — distinguished from determinism, in which your actions are themselves causes.
Kierkegaard's 1843 pseudonymous work on Abraham, the binding of Isaac, the teleological suspension of the ethical, and the nature of faith — the founding text of religious existentialism.
Aquinas's five arguments for the existence of God in Summa Theologiae Ia q.2 a.3, proceeding from observed features of the world (motion, causation, contingency, gradation, order) to a first principle that everyone calls God.
The structure that makes something the kind of thing it is. Plato treated forms as perfect patterns existing apart from the world; Aristotle treated form as the organizing principle inside a particular thing.
Frege's 1884 informal statement of the logicist program, arguing that arithmetic is reducible to logic and providing the conceptual foundation for the formal derivation later attempted in the Grundgesetze.
Aristotle's doctrine that every thing or event has four kinds of explanation — material, formal, efficient, and final — and that complete understanding requires grasping all four.
English Lord Chancellor and philosopher (1561–1626) whose Novum Organum proposed inductive natural philosophy against the Aristotelian-Scholastic tradition, whose Great Instauration projected an encyclopedic scientific reform, and whose programmatic vision shaped the founding of the Royal Society and the institutional form of modern science.
Founding the Franciscan order on voluntary poverty, and the Canticle of the Creatures.
The capacity to have done otherwise, or — on the competing account — to act from one's own will without external constraint. Which definition you take decides the whole dispute, because determinism threatens the first and leaves the second untouched.
The German philosopher and philologist whose late nineteenth-century works on morality, religion, art, and the will to power produced one of the most influential and most contested philosophical bodies of work in modern thought.
The open question argument and the naturalistic fallacy in ethics; the defence of common sense against scepticism.
English analytic philosopher (1919–2001), Wittgenstein's literary executor and translator, professor at Cambridge after Wittgenstein and Anscombe's own Oxford career, whose Intention (1957) founded modern philosophy of action and whose 1958 essay Modern Moral Philosophy initiated the late-twentieth-century revival of virtue ethics and reshaped Anglophone moral philosophy.
The German polymath philosopher and mathematician whose Monadology developed a metaphysics of simple substances and whose work in logic, mathematics, and the principle of sufficient reason shaped both rationalist philosophy and modern logic.
The German Idealist philosopher whose dialectical system attempted to articulate the unfolding of absolute spirit through history, nature, and consciousness as a single rational structure.
The study of decisions where the outcome depends on what other people choose, and everyone knows the others are reasoning the same way.
The Anglo-Irish bishop and philosopher whose subjective idealism — esse est percipi, to be is to be perceived — took empiricism to its most radical conclusion: there are no material substances, only ideas and the minds that perceive them.
The post-Kantian movement (~1781–1840) that took the mind's role in constituting experience to its limit — making consciousness, spirit, or absolute reason the fundamental reality.
The French philosopher whose individual work on Nietzsche, Spinoza, Bergson, and difference, together with his collaboration with Felix Guattari on Anti-Oedipus and A Thousand Plateaus, produced one of the most distinctive bodies of late-twentieth-century continental philosophy.
The classical concept: a maximally great being. Arguments for and against constitute much of philosophy of religion.
Sophist and rhetorician who argued that nothing exists, and that if it did, nobody could know or communicate it.
The German mathematician and philosopher whose 1879 Begriffsschrift invented modern predicate logic, whose attempt to derive arithmetic from logic founded the analytic philosophy of mathematics, and whose theory of sense and reference founded the analytic philosophy of language.
Kant's 1785 short foundational work of moral philosophy, presenting the categorical imperative and the structure of autonomous rational will in their most concise and accessible form.
German-Jewish political theorist (1906–1975) who fled Nazi Germany, became one of the major American public intellectuals of the postwar period, and produced in The Origins of Totalitarianism, The Human Condition, and Eichmann in Jerusalem the most influential analyses of mass politics, action, and the banality of evil written in the twentieth century.
German philosopher (1900–2002), Heidegger's student and later interlocutor, whose Wahrheit und Methode (1960) developed philosophical hermeneutics into a comprehensive theory of understanding that grounded twentieth-century reflection on interpretation across philosophy, theology, history, jurisprudence, and the human sciences.
French philosopher (1859–1941), professor at the Collège de France and Nobel laureate in Literature (1928), whose major works — Time and Free Will, Matter and Memory, Creative Evolution, The Two Sources of Morality and Religion — elaborated a philosophy of duration, intuition, and creative evolution that shaped early twentieth-century French thought and was the dominant philosophical reference in French intellectual life before being eclipsed by phenomenology and existentialism.
The Pre-Socratic philosopher of Ephesus who held that everything is in flux, that opposites are unified in their tension, and that an underlying logos orders the whole.
The German-American philosopher who joined the Frankfurt Institute in exile, developed a synthesis of Freud and Marx in Eros and Civilization, produced the canonical New Left critique of advanced industrial society in One-Dimensional Man, and became the most publicly visible Frankfurt School thinker.
Peirce's 1878 Popular Science Monthly paper containing the founding statement of the pragmatic maxim and the central methodological proposal of the pragmatist tradition.
The view that reality is fundamentally mental — that what exists is minds and their contents, and the physical world depends on being perceived or thought.
The structural process of rebuilding the self after a load-bearing belief system has collapsed, treated not as a cognitive update but as a re-architecting of the framework through which selfhood and meaning are organized.
A system of beliefs and assumptions that presents a particular social arrangement as natural or inevitable, and which the people holding it usually do not experience as a position at all.
The Königsberg philosopher whose Critical philosophy redrew the map of metaphysics, epistemology, and ethics, and whose work organized nearly all subsequent Continental thought.
Reasoning from observed cases to a general claim or to an unobserved case. It is how every empirical conclusion is reached, and it is not truth-preserving — true premises can give a false conclusion without any error in the reasoning.
The applied-epistemology distinction between beliefs absorbed pre-reflectively from one's culture and beliefs deliberately taken up after examination, with consequences for how each kind is held, defended, and revised.
Anglo-Irish novelist and moral philosopher (1919–1999), Oxford fellow and tutor, whose moral philosophy defended a Platonic conception of attention to the good against the prevailing analytic moral theory of the postwar period and whose twenty-six novels are among the major achievements of twentieth-century English fiction.
Hume's observation that moral writers regularly slide from descriptive (is) claims to normative (ought) claims without justifying the inference — sometimes called Hume's Law or the naturalistic fallacy.
Latvian-born British philosopher and historian of ideas (1909–1997), Oxford professor and founding president of Wolfson College, whose essay Two Concepts of Liberty (1958) shaped postwar liberal political theory and whose essays on Russian thought, the Counter-Enlightenment, and value pluralism made him one of the most influential public philosophers of the second half of the twentieth century.
The tradition of rational philosophical inquiry within the Islamic world that preserved and substantially developed the Greek inheritance, produced its own major synthesis through al-Fārābī, Avicenna, and Averroes, and transmitted Aristotle to medieval Europe.
Bonaventure's 1259 short work organizing the six-stage ascent of the mind to God, modeled on the six-winged seraph that Francis of Assisi had seen at La Verna, and integrating Augustinian theology with the Franciscan contemplative tradition.
The French-Algerian philosopher who founded deconstruction, transformed the study of writing and the metaphysics of presence, and produced one of the most influential bodies of late-twentieth-century continental philosophy across philosophy, literature, law, and the broader humanities.
Genevan-born philosopher, novelist, composer, and educational theorist (1712–1778) whose Social Contract reframed political legitimacy in terms of the general will, whose Discourse on Inequality argued that civilization had corrupted natural human freedom, and whose Émile founded modern educational theory.
The French philosopher, novelist, and playwright whose Being and Nothingness gave existentialism its most systematic philosophical formulation and whose public-intellectual career defined the mid-twentieth-century figure of the engaged philosopher.
Founder of utilitarianism and of the principle that actions are right as they tend to promote happiness.
French Reformed theologian and reformer of Geneva (1509–1564) whose Institutes of the Christian Religion is the most systematic theological work of the Reformation, whose biblical commentaries cover most of the New and much of the Old Testament, and whose Geneva model of disciplined Reformed Christianity shaped Presbyterian, Reformed, and Puritan traditions for the following centuries.
The American philosopher who developed pragmatism into a systematic philosophy of inquiry, experience, education, and democracy across more than seventy years of continuous publication — the most institutionally consequential American philosopher of the twentieth century.
The English philosopher whose Essay Concerning Human Understanding founded modern empiricism and whose Two Treatises of Government provided the philosophical foundation of liberal political theory.
The American philosopher whose A Theory of Justice (1971) revived political philosophy as a major analytic subfield and whose subsequent work on political liberalism and the law of peoples produced the most influential single body of work in twentieth-century English-language political theory.
Irish philosopher and translator (c. 815–877) at the court of Charles the Bald, whose Latin translations of Pseudo-Dionysius and other Greek theologians transmitted Eastern Christian thought to the medieval Latin West and whose Periphyseon constructed the most ambitious philosophical theology of the early middle ages.
The English philosopher, economist, and reformer whose work on utilitarian ethics, the philosophy of liberty, the logic of inductive reasoning, and the subjection of women shaped Victorian and modern liberal thought.
The fourth canonical Gospel, distinguished from the Synoptics by its high Christology, its Logos prologue, and its sustained appropriation of Greek philosophical vocabulary into Christian revelation.
Giving each what is due — the Roman formula, suum cuique tribuere. Every substantive dispute is about what determines the due: merit, need, agreement, entitlement by history, or the outcome parties would accept without knowing their own position.
The German philosopher and sociologist who led the second generation of the Frankfurt School, developed the theory of communicative action and discourse ethics, and remains the most institutionally influential living German philosopher.
The German philosopher, economist, and revolutionary whose materialist transformation of Hegelian dialectic and analysis of capitalism produced one of the most influential intellectual frameworks of the modern era.
Proposed falsifiability as what separates science from everything else, and argued that theories are tested rather than proved.
Traditionally defined as justified true belief; problematized by Gettier and beyond.
German-American political philosopher (1899–1973), University of Chicago professor and author of Natural Right and History, Persecution and the Art of Writing, Thoughts on Machiavelli, and many other works, whose esoteric hermeneutic and reading of classical and medieval political philosophy founded the Straussian school of political philosophy.
Seneca's 124 surviving philosophical letters to his friend Lucilius, the most extensive and accessible body of practical Stoic ethical writing in the Roman corpus.
Freedom from interference (negative) or capacity to act (positive); the axis of modern political debate.
The study of valid inference — the rules by which conclusions follow from premises.
Husserl's two-volume 1900-1901 work that founded the phenomenological tradition by reversing his earlier psychologism and establishing the structures of meaning and conceptual content as the proper objects of a rigorous descriptive science.
Greek for word, account, ratio or reason. In Heraclitus it is the intelligible order the cosmos runs on; in Stoicism the rational principle pervading matter; in John's prologue it is identified with a person. The same term carries all three, which is why it is so often equivocated.
The Roman poet whose six-book hexameter poem De Rerum Natura is the most comprehensive surviving exposition of Epicurean philosophy and the principal channel through which Epicurean thought reached the Renaissance and modern world.
The Austrian-British philosopher whose two distinct phases — the picture theory of the Tractatus (1921) and the language-games of the Philosophical Investigations (1953) — each defined a distinct period of twentieth-century analytic philosophy.
Andalusian-born rabbinic codifier, physician, and Aristotelian philosopher (1138–1204) whose Mishneh Torah systematized the entire halakhic tradition and whose Guide for the Perplexed offered the deepest medieval Jewish engagement with Greek and Arabic philosophy.
Roman emperor (161–180 CE) and Stoic practitioner whose private notebooks, the Meditations, are the most influential single text in the practical Stoic tradition.
Built the capabilities approach, and argued that emotions are judgements rather than interruptions of reason.
The German philosopher whose Being and Time (1927) reframed the central question of Western philosophy as the question of the meaning of being, and whose later work pursued the same question through a sustained meditation on language, technology, and the history of metaphysics.
German Augustinian friar and theologian (1483–1546) whose 1517 protest against indulgences began the Reformation, whose German Bible translation shaped the development of modern German, and whose theological doctrines of justification by faith, the bondage of the will, and the priesthood of all believers founded Lutheran Protestantism and reshaped Western Christianity.
The substantial philosophical and political tradition founded by Marx and Engels that takes the analysis of historical material conditions, class structure, and economic production as the foundation of social theory and political practice.
Hegel's analysis in Phenomenology of Spirit IV of the struggle between two self-consciousnesses for recognition — a foundational text for subsequent philosophy of recognition, Marxist analysis, and post-colonial thought.
The view that everything that exists is physical, so mental states are states of the brain and nothing further is required to explain them.
The French philosopher whose Phenomenology of Perception (1945) made the lived body the central category of phenomenology, produced the major French systematic phenomenological work of the century, and shaped twentieth-century theories of embodiment, perception, and political agency.
The German philosopher and social theorist who founded the program of critical theory at the Frankfurt Institute for Social Research, co-authored the Dialectic of Enlightenment with Adorno, and shaped the entire trajectory of twentieth-century critical social theory.
Marcus Aurelius's private philosophical notebooks, twelve books of Stoic reflections composed during the later years of his reign as Roman emperor.
Descartes's foundational work of modern philosophy, six meditations developing the method of systematic doubt, the cogito, and the reconstruction of knowledge from indubitable foundations.
German Dominican theologian, master of the University of Paris, and preacher (c. 1260–1328) whose Latin Tripartite Work attempted a comprehensive Scholastic synthesis and whose German sermons on the soul's union with God in the divine ground founded the Rhineland mystical tradition and were partially condemned by Pope John XXII in 1329.
The branch of philosophy that asks what fundamentally exists and what its nature is.
Aristotle's foundational treatise on being qua being, substance, causation, potentiality and actuality, and the unmoved mover — the work that gave Western metaphysics its name and most of its categories.
The French philosopher and historian whose archaeological and genealogical investigations of madness, medicine, the prison, and sexuality produced the most influential single body of work in late-twentieth-century continental philosophy.
Invented the essay, and revived ancient scepticism in a form that set the problem Descartes tried to answer.
The question of how mental states relate to physical states — Descartes' dualism inaugurated the modern version.
Leibniz's 1714 short systematic statement of the mature metaphysics, presenting reality as composed of infinitely many simple, indivisible substances (monads) coordinated through pre-established harmony.
The problem that our moral judgments of people depend heavily on factors they did not control, which sits badly with the principle that we are assessed only on what is up to us.
The view that moral claims are true only relative to a culture or framework, so there is no standpoint from which one moral code can be judged better than another.
The Greek term for story, myth, or narrative — contrasted across the philosophical tradition with logos as a distinct mode of conveying truth.
Kripke's 1980 book based on the January 1970 Princeton lectures that revived essentialist metaphysics, developed the causal-historical theory of reference, and produced the framework of necessary a posteriori and contingent a priori truths.
The doctrine that there is a moral law accessible to human reason, grounded in human nature and the rational structure of reality, distinct from but related to divine command and positive law.
The discipline that seeks to establish or defend claims about God's existence, nature, and providence using reason alone, without appeal to revelation or sacred text.
The late-antique revival of Plato that built a hierarchical metaphysics from the One down through Intellect and Soul, profoundly shaping Christian, Islamic, and Jewish theology.
Florentine diplomat whose Prince and Discourses founded modern political realism.
German cardinal, mathematician, and philosopher (1401–1464) whose Of Learned Ignorance applied Neoplatonic apophatic theology to the limits of human knowledge of God, whose conciliar diplomacy between Council of Basel and the Greek union shaped the late medieval church, and whose cosmology of the centerless infinite universe anticipated Copernicus, Galileo, and Bruno.
Aristotle's foundational treatise on virtue, practical wisdom, friendship, and the structure of the good human life — the work that gave Western virtue ethics its canonical form.
The denial that life has objective meaning, or that moral claims have any ground outside human invention. Nietzsche treated it less as a doctrine to be argued for than as a historical condition to be survived — what remains once the inherited framework stops holding weight.
The view that only particular things exist, and that general terms are names we apply to things that resemble each other rather than labels for real shared entities.
The principle that entities should not be multiplied beyond necessity — where two explanations account equally well for the evidence, prefer the one with fewer commitments. A rule for choosing between theories, not a claim that the world is simple.
Derrida's 1967 founding work of deconstruction, developing the analysis of the Western metaphysics of presence through the critique of the privileging of speech over writing and introducing the concept of différance.
Nietzsche's 1887 work of three essays analyzing the historical and psychological sources of moral judgment, organized around the contrast between aristocratic and slave moralities.
The family of a priori arguments for God's existence that proceed from the concept of God alone, originating with Anselm's 1078 Proslogion and continuously contested across the rationalist, Kantian, and contemporary analytic traditions.
The study of being qua being — what it means for anything to exist.
Alexandrian Christian scholar (c. 185–254) whose Hexapla, On First Principles, biblical commentaries, and Contra Celsum constituted the first systematic Christian intellectual project, integrating Platonist metaphysics with biblical theology and producing a controversial speculative system later condemned in part but never displaced as a foundational reference.
The Christian doctrine that human nature is wounded by inherited disorder transmitted from the fall of Adam, leaving the will divided against itself and unable consistently to will the good without grace.
Thomas Kuhn's term for a scientific revolution that replaces the whole framework — the questions, methods and standards — rather than adding to what was known.
The Pre-Socratic philosopher of Elea whose poem On Nature argued that being is one, eternal, indivisible, and unchanging — the founding statement of Western metaphysics and the framework against which subsequent Greek philosophy defined itself.
Plato's term for the relation between a particular and the Form it shares in — the thing that makes a beautiful object beautiful. It is the load-bearing member of the theory of Forms and the part Plato himself could not make work.
French philosopher (1913–2005), professor at Strasbourg, Paris-Sorbonne, Paris-Nanterre, and the University of Chicago, whose hermeneutical phenomenology engaged Freud, structuralism, biblical exegesis, and analytic philosophy to produce comprehensive philosophical anthropologies of will, evil, language, narrative, selfhood, memory, and recognition.
What makes someone the same person over time, despite continuous change in body, memory and character — and what, if anything, that sameness consists in.
Medieval logician who located morality in intention, and whose position on universals settled the dispute for a century.
Applied utilitarian reasoning to animals and global poverty, and followed the arguments to conclusions most people reject.
Plato's dialogue on the immortality of the soul, set on the day of Socrates's execution and containing the first systematic statement of the Theory of Forms.
The twentieth-century tradition that takes the rigorous description of the structures of conscious experience — not its empirical psychology but its essential structures — as the foundation of philosophy.
Hegel's 1807 foundational work tracing the dialectical development of consciousness through successive shapes from sense-certainty through absolute knowing.
Allegorical interpretation of scripture and the doctrine of the Logos as intermediary between God and the world.
Wittgenstein's posthumous 1953 masterwork developing the account of meaning as use, the analysis of language as practice organized into language-games, and the famous private language argument.
Aristotle's name for practical wisdom — the trained capacity to perceive what a particular situation calls for and to act on it well.
The Athenian philosopher who turned Socrates's questioning into a comprehensive philosophical system and founded the institution that taught it for nine centuries.
The tradition holding that reality is grounded in abstract, eternal Forms grasped by reason — with the visible world as a participating shadow of the real.
The third-century philosopher who founded Neoplatonism, systematizing Plato's thought into a hierarchical metaphysics of emanation from the One that shaped Christian, Islamic, and Jewish theology for over a thousand years.
Aristotle's short treatise on tragedy, epic, and the principles of literary composition — the founding work of Western literary theory.
Aristotle's foundational treatise on the political community, the varieties of constitutions, and the relation between political life and human flourishing.
A device for making claims about necessity and possibility precise: a proposition is possible if it holds in some world, necessary if it holds in all. Whether the worlds are real or merely a way of speaking is the dispute.
The body of French thought that accepted structuralism’s insight that meaning is relational and rejected its assumption that systems are stable, closed or analyzable from outside.
James's 1907 book, from eight public lectures — the most readable statement of pragmatism, and the one whose loose formulation of truth gave its critics everything they needed.
The American tradition holding that the meaning of a concept lies in its practical consequences, and the truth of a belief in its capacity to work — to help us cope, predict, and act.
The Greek thinkers of the sixth and fifth centuries BCE who replaced mythic explanation with natural philosophy and gave Western thought its starting categories — matter, principle, change, being.
Leibniz's principle that nothing happens without a sufficient reason why it should be so rather than otherwise — the central methodological commitment of his rationalism and one of the most contested principles in modern metaphysics.
What makes two things that share all their properties two things rather than one. The candidates are matter, position, a primitive thisness, or nothing at all — and each answer commits you to a different account of what a particular is.
The situation where each person is better off defecting whatever the other does, so both defect and both end up worse than if they had cooperated.
The apparent inconsistency between the existence of suffering in the world and the existence of an omnipotent, omniscient, perfectly good God — the most-discussed single argument against theism, with major formulations from Epicurus through Hume and the contemporary analytic literature.
Hume's argument that inductive inference — from observed cases to unobserved ones — cannot be rationally justified without circularity, and yet underlies most of what counts as empirical knowledge.
Athenian Neoplatonist (412–485) whose Elements of Theology presented a systematic deductive theology of the One, the Henads, the Intellect, and the Soul, whose extensive commentaries on Plato shaped late antique Platonism, and whose works transmitted through Pseudo-Dionysius and the Liber de Causis defined medieval Christian and Islamic metaphysics.
The best known of the Sophists, and the source of the claim that man is the measure of all things.
Anonymous late fifth- or early sixth-century theologian (fl. c. 500) writing under the pseudonym of the Athenian convert of Paul (Acts 17:34), whose Corpus Areopagiticum integrated Proclean Neoplatonism with Christian doctrine, founded systematic apophatic theology in the Christian West, and shaped medieval mysticism and Scholastic angelology.
The Greek philosopher who founded Pyrrhonian skepticism through the practice of suspending judgment on matters that cannot be settled by appearances, producing the tradition that Sextus Empiricus would later systematize.
The Pre-Socratic philosopher and religious teacher whose Pythagorean movement combined mathematical inquiry, ascetic practice, and the doctrine of the transmigration of souls, and whose influence on subsequent philosophy and mathematics has been continuous through the Western tradition.
The felt qualities of experience — the particular redness of red, the specific character of a pain — and the part of the mind that physical description seems least able to capture.
The thesis that reason, not experience, is the primary source of substantive knowledge.
The early modern tradition (Descartes, Spinoza, Leibniz) holding that substantive knowledge of the world is available through reason alone, independently of experience.
The view that something exists independently of our minds, beliefs or language — used of the external world, of universals, of moral facts and of scientific entities, with a different dispute in each case.
The French philosopher and mathematician whose Meditations on First Philosophy and method of systematic doubt founded modern philosophy by relocating its starting point in the certainty of the thinking subject.
Plato's encyclopedic dialogue on justice, the soul, education, the ideal city, and the philosophical knowledge required to govern it.
Claims a person holds that others are obliged to respect — and a dispute about whether such claims exist prior to law or are created by it.
Author of Anarchy, State, and Utopia and the libertarian reply to Rawls.
The American philosopher and logician whose technical contributions to modal logic (Kripke semantics) and whose Naming and Necessity (1980) revived essentialist metaphysics in analytic philosophy, transforming the philosophy of language, mind, and metaphysics.
The medieval method of philosophical and theological inquiry through structured disputation — stating a thesis, marshaling objections, giving a determination, responding to each objection.
The set of procedures by which science produces and tests claims — and a subject of dispute, since no single account describes what scientists across fields actually do.
Roman statesman, dramatist, and Stoic philosopher whose Letters to Lucilius and moral essays are the most readable surviving introduction to practical Stoic ethics.
The Greek philosopher and physician whose surviving works are the principal source for Hellenistic skepticism and the canonical statement of the Pyrrhonian framework systematized through the ten modes, the five modes, and the eight modes against cause.
The French philosopher, novelist, and feminist whose The Second Sex (1949) reshaped twentieth-century thought about gender and whose existentialist ethical writings developed the framework of situated freedom and ambiguity.
The position that knowledge is unattainable or radically uncertain — from Pyrrho to Descartes' demon.
The tradition of suspending judgment where evidence does not settle a question — Pyrrhonism seeking tranquillity through balanced arguments, Academic skepticism arguing that nothing can be known.
The idea that political authority is grounded in (hypothetical) agreement among the governed — Hobbes, Locke, Rousseau, Rawls.
The Athenian philosopher who turned philosophy from cosmology to the examined life — and was executed by the city he refused to stop questioning.
Fifth-century BC Greek teachers of rhetoric and argument who taught for a fee, and who first argued that law and custom are human conventions rather than natural facts.
The Hellenistic philosophy that virtue is the only true good and that flourishing comes from aligning with nature and accepting what's outside our control.
The Greek-then-Roman tradition holding that virtue is the only good, the cosmos is rationally ordered, and human flourishing comes from aligning your will with what is.
The approach holding that meaning arises from relations within a system rather than from the elements themselves, applied first to language and then to myth, kinship and culture.
What a thing fundamentally is, as against the properties it happens to have. Aristotle's ousia is the bearer that persists through change; Descartes defined it as what needs nothing else in order to exist, and Spinoza showed that definition admits exactly one instance.
Spinoza's metaphysical doctrine that there is one and only one substance — infinite, self-caused, identical with God or Nature — of which everything else is a mode.
Aquinas's earlier and more apologetic Summa, in four books, addressing Christian doctrine to readers (Muslims, Jews, pagans) who do not share its scriptural premises.
Aquinas's vast unfinished masterwork of systematic theology, comprising over three thousand articles structured as Scholastic disputations and constituting the most ambitious single work of Christian theology in the Western tradition.
Aristotle's three-line deductive argument form (e.g., All M are P; All S are M; therefore All S are P).
Plato's dialogue on the nature of love (eros), structured as a sequence of seven speeches at an Athenian drinking party that culminate in Socrates's ascent to the Form of Beauty.
Kant's central epistemological category: knowledge that is both synthetic (extending what is known beyond the analysis of concepts) and a priori (independent of experience for its justification).
The Danish philosopher and theologian whose pseudonymous works on anxiety, despair, faith, and the existing individual founded the existentialist tradition and reshaped Christian theology.
The empiricist doctrine that the human mind at birth contains no innate ideas or principles, originating with Aristotle and given its canonical modern statement by Locke in 1689.
Explanation by reference to ends or purposes — saying what something is for, rather than only what caused it.
The end or purpose for the sake of which a thing exists or acts. In Aristotle it is one of the four causes and the one that explains why a process runs as it does; modern science expelled it from physics and biology has spent a century finding substitutes.
Carthaginian Latin Christian writer (c. 155–220) who composed the first major body of Latin Christian literature, established the Latin theological vocabulary later adopted by Augustine and the Council of Nicaea, and whose later turn to the Montanist movement put him outside the catholic mainstream while his earlier work shaped it permanently.
The Milesian thinker of the early sixth century BCE conventionally regarded as the first Western philosopher — the originator of the Greek tradition of natural philosophy through his claim that water is the source and substance of all things.
The existentialist (especially Camusian) concept naming the gap between the human desire for meaning and the universe's silence on the question — the fundamental human condition once consolatory frameworks have collapsed.
A three-page paper from 1963 showing that a belief can be true, and justified, and still obviously not knowledge — because the justification and the truth can come apart by luck. It ended a definition that had stood since Plato.
The text whose opening identified its subject with the logos of Greek philosophy, making Christian theology a subject for philosophical argument.
Camus's 1942 philosophical essay on the absurd, opening with the famous claim that there is but one truly serious philosophical problem (suicide) and developing the substantial ethic of lucid revolt that became the canonical mid-century articulation of the absurdist response to a post-religious condition.
Every hour you spend produces something and somebody ends up owning it. Twelve principles for reading any decision by what it builds and who holds it.
Russell's 1912 introduction to philosophy, written for a general audience, that established the British analytic approach to questions of knowledge, perception, induction, universals, and the limits of human cognition.
De Beauvoir's 1949 foundational work of modern feminist philosophy, systematically analyzing the historical, biological, psychoanalytic, economic, and lived dimensions of women's situation as 'the Other' of the male subject.
A novel dramatising the absurd through a narrator condemned as much for his refusal to perform expected feeling as for the killing he commits.
James's 1902 Gifford Lectures: a typology and analysis of religious experience treated empirically rather than doctrinally, organized around case material from autobiography and devotional literature and arguing for the experiential reality and pragmatic fruits of religion independent of theological commitment.
Leibniz's principle that no two distinct things can share every property — if they are indiscernible, they are one. Its converse, that identical things share all properties, is uncontroversial. The principle itself is not.
The oldest question in Western metaphysics: how a world of many changing things can also be one intelligible order. Nearly every major position in the tradition is an answer to it, which is why it looks like a theme rather than a problem.
If every plank of a ship is replaced one at a time, is it the same ship? And if the old planks are reassembled, which of the two is? The puzzle isolates what identity over time could consist in when nothing material persists.
One grain of sand is not a heap, and adding one grain never turns a non-heap into a heap — yet a million grains is a heap. The argument is valid, the premises look true, and the conclusion is false, which is what makes vagueness a genuine problem.
The properties the scholastics held belong to everything that exists — being, unity, truth and goodness — which are not kinds of thing but the same thing considered under different aspects. They cut across every category, which is what transcendental means.
The attempt to reconcile the existence of an all-good, all-powerful God with the existence of evil and suffering.
The German philosopher, sociologist, and musicologist who co-authored the Dialectic of Enlightenment with Horkheimer, produced the canonical works of Frankfurt School critical theory in his own name (Negative Dialectics, Aesthetic Theory, Minima Moralia), and shaped twentieth-century continental philosophy as the most substantial individual theorist of the first generation.
Plato's claim that abstract, perfect Forms are more real than the changing particulars that participate in them.
The Dominican friar whose synthesis of Aristotelian philosophy and Christian theology became the dominant intellectual framework of late-medieval Catholicism and the standard reference of Catholic philosophy ever since.
English philosopher (1588–1679) whose Leviathan grounded political authority in the rational consent of self-interested individuals, established the modern social-contract tradition, and provided the most rigorous early-modern statement of materialist metaphysics in English.
Argued that science proceeds by long stable periods punctuated by revolutions that replace the framework itself.
Asked what it is like to be a bat, and argued that objective description leaves something out.
Nietzsche's philosophical poem-novel in four parts, composed 1883–1885, presenting the figure of Zarathustra teaching the death of God, the übermensch, the will to power, and eternal recurrence.
Plato's late cosmological dialogue, presenting the construction of the cosmos by a divine craftsman (the Demiurge) ordering pre-existing chaos according to the eternal Forms.
Wittgenstein's 1921 treatise organized as numbered propositions developing the picture theory of meaning and ending with the famous injunction that what cannot be spoken about must be passed over in silence.
The pattern where a shared resource is depleted because each user gains the full benefit of taking more while the cost is spread across everyone.
Kant's metaphysical position: appearances are transcendentally ideal (depending on the structures of cognition) but empirically real; things in themselves, independent of cognition, are not knowable.
The central Christian doctrine that the one God exists as three coequal, coeternal persons (Father, Son, and Holy Spirit), articulated at the Councils of Nicaea (325) and Constantinople (381) and continuously contested across the patristic, medieval, and modern theological traditions.
A set of cases where diverting a runaway trolley kills one person instead of five, designed to isolate why the permissibility of causing harm changes with how the harm comes about.
What it is for a claim to correspond to, cohere with, or work in reality.
Properties shared by many particulars; the central problem dividing realists, nominalists, and conceptualists.
Duns Scotus's claim that being must mean exactly the same thing when said of God and of creatures, with the difference lying in what is added — infinite or finite — because otherwise no argument from the world to its source can avoid equivocating.
The view that the right action maximizes overall well-being or pleasure — Bentham and Mill's signature contribution.
The substantial moral and political tradition founded by Bentham and developed by Mill that takes the maximization of aggregate well-being or happiness as the substantial foundation of moral and political evaluation.
The deliberate building of a personal value system after the inherited framework has ceased to be load-bearing, treated as an intentional act of construction rather than discovery or inheritance.
A stable disposition to act, feel and perceive well — Aristotle's hexis, acquired by practice rather than instruction. Virtue is not a rule followed or an intention held but a settled state of character that makes the right action reliable.
An approach centered on character traits (virtues) rather than rules or outcomes — rooted in Aristotle, revived by Anscombe and MacIntyre.
The American philosopher whose work in logic, philosophy of language, and epistemology shaped the second half of twentieth-century analytic philosophy more deeply than any other single figure, especially through Two Dogmas of Empiricism (1951) and Word and Object (1960).
The German-Jewish critic and philosopher whose essays on art, history, language, and Paris produced one of the most distinctive bodies of twentieth-century writing — a Frankfurt School affiliate whose work has shaped cultural studies, the philosophy of history, and the contemporary engagement with mass culture.
Nietzsche's contested doctrine that the fundamental drive of all living things — and on the most ambitious reading of all reality — is the will to expand, intensify, and overcome itself.
The American philosopher and psychologist whose work across pragmatism, the psychology of consciousness, religious experience, and radical empiricism made him the most influential single American philosophical voice of the late nineteenth and early twentieth centuries.
The English Franciscan philosopher whose nominalism, methodological parsimony, and theological voluntarism made him the most influential late-medieval scholastic and a major preparatory figure for early-modern empiricism.
The founder of Stoicism, who established his school at the Painted Stoa in Athens around 300 BCE and shaped the entire subsequent philosophical tradition that took its name from the building.
The paradoxes of motion and plurality, constructed to defend Parmenides by showing that the alternative is worse.
A set of arguments designed to show that motion and plurality lead to contradiction, written in defense of Parmenides. They are not puzzles to be waved away — each one isolates a genuine difficulty about infinity that took two thousand years to state.
Khorasanian 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.
Persian 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.