| The Internet Encyclopedia of Philosophy: Free online encyclopedia. Edited by James Fieser, hosted by the University of Tennessee at Martin. |
| Academy: Description of the philosophical institution founded by Plato, which advocated skepticism in succeeding generations. |
| Active Powers: The capacities of impulse and desire which lead to or determine human action, as described by 18th and 19th century Scottish common sense philosophy. |
| Aenesidemus: Biography of the 1st century philosopher who defended the ten tropes of skepticism. |
| Anaxagoras: Greek philosopher born about 500 BCE, responsible for giving philosophy a home at Athens and the first philosopher to introduce a spiritual principle which gives matter life and form. |
| Anaxarchus: 4th century BCE philosopher of Abdera, from the school of Democritus. |
| Anaximander: Greek philosopher of Miletus, born 611 BCE who thought it unnecessary to fix upon air, water, or fire as the original and primary form of body. |
| Anaximenes: 5th century BCE Greek philosopher of Miletus who regarded 'air' as the primary form of body. |
| Animals and Ethics: Consideration of moral status of non-human animals. |
| Anselm: 11th century English prelate who developed views of atonement and satisfaction which are still held by orthodox theologians. |
| Antisthenes: Athenian philosopher and founder of the Cynic sect who was born around 440 BCE. |
| Aquinas, Thomas: The life and work of the major figure in scholastic philosophy. |
| Aristippus: Description of the life and teachings of the philosopher Aristippus, founder of the Cyrenaic school of philosophy. |
| Aristotle: The life and work of the 4th century BCE Greek philosopher. |
| Augustine: Extensive article on the life and work of the 4th century ecclesiastical author. |
| Bacon, Francis: 16th century philosopher and politician. |
| Bakhtin Circle: School of Russian thought centered on the work of Bakhtin which focused on questions of signification in artistic creation. |
| Beccaria, Cesare: 18th century aristocrat whose work 'On Crimes and Punishments (1764)' inspired reform in the Italian criminal justice system. |
| Behaviorism: Theory in philosophy of mind which maintains that talk of mental events should be translated into talk about observable behavior. |
| Bentham, Jeremy: Extensive article on the 18th century 'founder' of utilitarianism. |
| Berkeley, George: Influential 18th century Irish philosopher. |
| Berlin Circle: Group of academics who gathered round Hans Reichenbach in late 1920s and later joined up with the Vienna Circle. |
| Bolingbroke, Henry St. John: 18th century Tory disciple of Locke. |
| Butler, Joseph: 18th century icon of a highly intellectualized theology. |
| Caird, Edward: Nineteenth century Scottish philosopher who was one of the key figures of the idealist movement that dominated British philosophy from 1870 until the mid 1920s. |
| Capital Punishment: The issue of capital punishment involves determining whether the execution of criminals is ever justified. |
| Carnap, Rudolf: Extensive article about his life and work, by Mauro Murzi. |
| Chinese Room Argument: John Searle's thought experiment is one of the best known counters to claims of artificial intelligence. |
| Chrysippus: Prolific stoic of Soli, and disciple of Cleanthes. |
| Cicero, Marcus Tullius: 1st century BCE Roman orator and philosopher of the New Academy. |
| Cleanthes: Stoic philosopher of Assus in Lydia, disciple of Zeno of Citium. |
| Cudworth, Ralph: 17th century 'Cambridge Platonist' who fought for preservation of religious ideals, including divine illumination. |
| Cumberland, Richard: 17th century critic of Hobbes and the neo-Platonists. |
| Cyrenaics: Description of the Cyrenaic school of philosophy, which flourished from the 5th-3rd centuries BCE. The Cyrenaics were skeptics and hedonists. |
| Damon: 5th century BCE Pythagorean philosopher of Syracuse. |
| Davidson, Donald: Introduction to one of the most significant philosophers concerned with philosophy of mind and action of the 20th/21st century. |
| Deism, English: Explores the deism of Hobbes, Locke, Tindal, and the influence of Hume. |
| Deism, French: The deism of Voltaire and Rousseau. |
| Democritus: 4th century BCE philosopher of Abdera who expanded the atomic theory of Leucippus. |
| Demonax: Philosopher of the second century CE. who tried to revive the philosophy of the Cynic School. |
| Descartes, René: Early modern philosopher who rejected religious authority in the quest for scientific and philosophical knowledge. |
| Dewey, John: Leading light of the 20th century American school of thought known as pragmatism. |
| Diderot, Denis: The most prominent of the French Encyclopedists and one of the leaders of the Enlightenment. |
| Diogenes Laertius: 3rd century biographer of ancient Greek philosophers. |
| Diogenes of Apollonia: Pupil of Anaximenes and contemporary of Anaxagoras in the 6th cn. BCE. |
| Diogenes of Sinope: 4th cn. BCE cynic philosopher of Sinope. |
| Eckhart, Meister: 13th century Dominican mystic who was almost forgotten until Franz von Baader revived his memory in the nineteenth century. |
| Eclecticism: Group of ancient philosophers who sought to reach by selection the highest degree of probability in the search for truth. |
| Egoism, Psychological and Ethical: Maintains that the individual self is the motivating moral force and the end of moral action. |
| Emanation: The theory that all derived or secondary things flow from the primary. |
| Empedocles: 5th century BCE philosopher who combined medical study with Orphic mysticism. |
| Encyclopedists: Group of French philosophers and men of letters who collaborated in the production of the famous Encyclopedie. |
| Epictetus: Eminent Stoic philosopher, born as a slave at Hieropolis in Phyrgia in 55 CE. |
| Epicurus: 4th century BCE materialist, empiricist, and hedonist. One of the major philosophers of the Hellenistic period. |
| Euclides: 4th century BCE native of Megara, and founder of the Megarian or Eristic sect. |
| Evolution: Introduces evolution through the ages, from the ancient Greeks, through Leibniz and Descartes to Darwin and Spencer. |
| Ferrier, James Frederick: The earliest absolute idealist in English philosophy. |
| Fichte, Immanuel Hermann: Aimed to secure a philosophical basis for the personality of God. |
| Fichte, Johann Gottlieb: One of the major figures in German philosophy in the period between Kant and Hegel. |
| Freud, Sigmund: Lenghty article on the father of psychoanalysis who is generally recognised as one of the most influential and authoritative thinkers of the twentieth century. |
| German Idealism: The German reaction to empiricism, including related theories of Kant, Fichte, Hegel and others. |
| God, Western Concepts of: Internet Encyclopedia of Philosophy article on God from Socrates to Nietzsche. |
| Gorgias: Greek sophist and rhetorician, known as "the Nihilist," born in 483 BCE. |
| Greek Philosophy: The philosophical currents of Ancient Greek philosophy are introduced, from the Presocratic philosophers through to Proclus. |
| Hamilton, William: 19th century exponent of the Scottish common-sense philosophy. |
| Hartmann, Karl Robert Eduard Von: 19th century German philosopher who attempted to combine the idea of Hegel with the will of Schopenhauer in 'spiritual monism.' |
| Hölderlin, Johann Christian Friedrich: Examines the poet's role in the development of German Idealism. |
| Hegelians, St. Louis: 19th century group of amateur American philosophers founded and led by William Torrey Harris. |
| Helvetius, Claude Adrien: One of the 18th century Encyclopedists who held the skeptical and materialistic views common to that school of philosophy. |
| Hempel, Carl Gustav: A leading member of logical positivism, the German philosopher died in 1997. |
| Heraclitus: 5th century BCE. Presocratic Greek philosopher. |
| Herbert of Cherbury, Edward: 17th century historian, poet (brother of George), and philosopher. Sought to determine the nature and standard of truth, and conditions of knowledge. Precursor of the philosophy of Common Sense. |
| Hippias: Hippias was a sophist, a contemporary of Socrates, and an enthusiast for universality. |
| Hobbes, Thomas: 17th century British philosopher. Author of Leviathan (1651). |
| Hodgson, Shadworth: Follower of Kant, founder of the Aristotelian Society. |
| Humanism: Brief article on Erasmus and the Italian humanist movement. |
| Hume, David: Enormously influential 18th century Scottish philosopher. Author of Treatise of Human Nature (1739-1740). |
| Husserl, Edmund: Leader of the German phenomenological movement. |
| Huxley, Thomas Henry: 19th century zoologist and advocate of Darwinism. |
| Identity Theory: Form of monistic materialism which maintains that mental states and brain activities are identical. |
| Interventionism: Examines the nature and justifications of interfering with another polity or choices made by individuals. |
| Jacobi, Friedrich Heinrich: 18th century German philosopher, famous for effective criticism of Kant. |
| Just War Theory: Some of those who have attempted to justify war include Aquinas, Grotius, and Pufendorf. |
| Leucippus: 5th century BCE founder of atomism. |
| Locke, John: Article on the life and work of the influential philosopher. |
| Lombard, Peter: French scholastic theologian of the 12th century, influenced by Abelard. |
| Lotze, Rudolf Hermann: 19th century German philosopher who criticised the pantheism of Hegel. |
| Lucretius: Roman poet and advocate of Epicurean philosophy. |
| Menippus: Third century BCE Greek philosopher and satirist. |
| Mill, John Stuart: 19th leader and prophet of utilitarianism, heir to the Hume-Bentham line, and influential force in modern political theory. Author of On Liberty (1859), and Utilitarianism (1863). |
| Moral Luck: Andrew Latus, St. Francis Xavier University, summarizes the discussion between Thomas Nagel and Bernard Williams on the question: Can luck ever make a moral difference? |
| Moral Philosophy: Introduction to ethics, with links to other articles at the IEP. |
| Natural Law: Standards that govern human behavior objectively derived from the nature of human beings. |
| Natural Theology: Used in the eighteenth and nineteenth centuries to describe knowledge of God drawn from nature. |
| Neoplatonism: The revival of Greek philosophy in 3rd century BCE, led by Plotinus and his disciple, Porphyry. Influenced by both Pythagoras and Plato. |
| Ockham, William of: Detailed biography of the 14th century Franciscan. |
| Origen: Father of the early Church, born around 182. |
| Paley, William: 18th century British theologian. |
| Parmenides: Greek philosopher and poet. |
| Peripatetics: Brief history of the Peripatetic doctrines. |
| Plato: Biography and description of the philosophy of Plato. |
| Plotinus: 3rd century CE founder of Neo-Platonism. |
| Poincaré, Jules Henri: 19th century French philosopher of science. |
| Positivism, Legal: Theory that law is manufactured according to certain social conventions. |
| Prodicus: 5th century BCE sophist, possibly a mentor of Socrates |
| Protagoras: Early Greek sophist. |
| Pyrrho: 4th century BCE founder of the Greek school of skepticism. |
| Pythagoras: The 6th century BCE philosopher. |
| Reichenbach, Hans: Leading German philosopher of science, and logical positivist. |
| Renaissance: Brief article on the transition between middle ages and modernity. |
| Rights, Human: A treatment of the origins and development of the theory of human rights, with philosophical analysis, justifications, and criticisms. |
| Roman Philosophy: Short introduction to Roman philosophy from the Internet Encyclopedia of Philosophy. |
| Rousseau, Jean Jacques: 18th century French author of the Social Contract, influential during the French Revolution. |
| Russell's Paradox: Examines self-referential linguistics used to describe properties and sets. |
| Shaftesbury, Earl of: Patron of John Locke |
| Shpet, Gustav: Leading proponent of Russian transcendental phenomenology. |
| Skepticism, Ancient Greek: A description of skepticism in Ancient Greece, led by Pyrrho. |
| Skepticism, Contemporary: Introduction to the current discussion of skepticism. |
| Social Contract Theory: View that morality is based on social agreements that serve the interests of those who make the agreement. |
| Solipsism: The doctrine of the solipsist is that existence means my existence and that of my mental states. |
| Solovyov, Vladimir: 19th century Russian philosopher. |
| Sophists: Teachers of philosophy in Ancient Greece, including Protagoras, Gorgias, Prodicus and Hippias. |
| Spinoza, Benedict: 17th century pantheist, critic of Descartes. |
| Stephen, Leslie: 19th century British academic. |
| Stilpo: 4th century BCE member of the Megarean school. |
| Stirling, James Hutchison: 19th century British Idealist, Hegelian academic. |
| Stoic Philosophy of Mind: Description of the philosophy of Mind of the Stoics, including the relationship between mind and body, perception, action-theory, and emotion. |
| Stoicism: Description of the system of ethics, popular in Ancient Greece, which has physics as its foundation. |
| Symposium: Drinking-parties in Ancient Greece where the guests reclined on couches, and were crowned with garlands of flowers. |
| Synderesis: Scholastic philosophy describes this as the principle in moral consciousness which directs an agent to good. |
| Thales: Detailed biographical essay on the Ancient Greek philosopher. |
| Theophrastus: Philosopher of the Peripatetic school, successor to Aristotle at the Lyceum. |
| Time: Long article about questions of time discussed throughout the history of philosophy. |
| Timon: 3rd century BCE disciple of Pyrrho. |
| Truth: Philosophical theories on the nature of truth, by Bradley Dowden and Norman Swartz. |
| Vienna Circle: Organised the development of logical positivism in the 1920s. Included Carnap, Feigl, Frank, Gödel, Hahn, Kraft, Neurath, Waismann. Popper and Wittgenstein also had association with the Vienna Circle. |
| Virtue Theory: View that morality is the development of or virtues. |
| Voluntarism: Theory that God or the ultimate nature of reality is conceived as some form of will. |
| Warburton, William: 18th century Church of England bishop, and critic of the Deists. |
| Wittgenstein, Ludwig: Detailed essay on the life and work of the 20th century philosopher. |
| Xenophanes: Eleatic school, powerful 6th century BCE critic of polytheism. |
| Xenophon: Pupil of Socrates, who contributed to the record of his life. |
| Zeno of Elea: 5th century BCE Eleatic philosopher. |
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