1. Ancient
   1. Pre-Socratic cir. 585-450 BCE
      1. Milesian
         1. Thales
            1. System
            2. thales.doc
         2. Anaximander
            1. System
            2. Aperion
         3. Anaximenes
            1. System
            2. anaximines.doc
      2. Pythagoreans
         1. Pythagoras
            1. System
         2. Philolaus
         3. Alcmaeon
         4. Archytas
      3. Heraclitus
         1. System
            1. heraclitus.doc
      4. Eleatic School
         1. Parmenides
            1. System
            2. parmenides.doc
         2. Zeno of Elea
         3. Melissus of Samos
         4. Xenophanes
            1. System
            2. xenophanes.doc
      5. Pluralists
         1. Empedocles
         2. Anaxagoras
      6. Atomists
         1. Leucippus
         2. Democritus
         3. Metrodorus
      7. Pherecydes
      8. Sophists
         1. Gorgias
         2. Protagoras
         3. Antiphon
         4. Prodicus
         5. Hippias
         6. Thrasymachus
         7. Callicles
         8. Critias
         9. Lycophron
      9. Diogenes
   2. Hellenistic
      1. Metrodorus the Younger
      2. Arcesilaus
      3. Archimedes
      4. Clitomachus
      5. Peripateticism
         1. Theophrastus
         2. Strato
         3. Alexander of Aphrodisias
      6. Cyrenaicism
         1. Aristippus of Cyrene
      7. Epicureanism
         1. Epicurus
         2. Metrodorus of Stratonicea
         3. Zeno of Sidon
         4. Philodemus
         5. Lucretius
      8. Stoicism
         1. Zeno of Citium
         2. Chrysippus
         3. Posidonius
         4. Cleanthes
         5. Epictetus
      9. Neo-Pythagoreanism
         1. Apollonius of Tyana
         2. Numenius of Apamea
      10. Neo-Platonism
          1. Plotinus
          2. Porphyry
          3. Iamblichus of Chalcis
      11. Pyrrhonism
          1. Pyrrho
          2. Aenesidemus
          3. Timon
      12. Cynicism
          1. Antisthenes
          2. Diogenes of Sinope
          3. Menippus
          4. Crates of Thebes
          5. Demetrius
      13. Philo of Larissa
      14. Philo of Alexandria
      15. Agrippa
      16. Platonism
          1. Speusippus
          2. Carneades
          3. Antiochus of Ascalon
          4. Xenocrates
          5. Plutarch
   3. Classical Greek
      1. Socrates
      2. Euclid of Megara
      3. Plato
      4. Aristotle
      5. Stilpo
2. Medieval
   1. Augustine
   2. Boethius
   3. John Scottus Eriugena
   4. Maimonides
   5. Roger Bacon
   6. Anselm of Canterbury
   7. Peter Abelard
   8. Thomas Aquinas
   9. John Duns Scotus
   10. William of Ockham
3. Renaissance
   1. Mirandola
   2. Erasmus
   3. Machiavelli
   4. Thomas More
   5. Paracelsus
   6. Copernicus
   7. Montaigne
4. Early Modern
   1. Francis Bacon
   2. Rene Descartes
   3. Hobbes
   4. Henry More
   5. Arnauld
   6. Malebranche
   7. Benedict Spinoza
   8. Lady Anne Conway
   9. John Locke
   10. Gottfried Leibniz
   11. Berkekey
   12. Wolff
   13. Rousseau
   14. Immanual Kant
   15. Bentham
   16. Schiller
   17. Malthus
5. 19th Century
   1. Johann Fichte
   2. Friedrich Schelling
   3. GWF Hegel
   4. Arthur Schopenhauer
   5. Kierkegaard
   6. Nietsche
   7. Peano
   8. Durkheim
   9. William James
   10. Pareto
   11. Veblen
6. Contemporary
   1. Husserl
   2. Moore
   3. Otto
   4. Ferdinand Saussure
   5. Dewey
   6. Bertrand Russell
   7. Alfred North Whitehead
   8. Santayana
   9. Heidegger
   10. Godel
   11. Gramsci
   12. Popper
   13. Horney
   14. Gilbert Ryle
   15. Wittgenstein
   16. Ayn Rand
   17. Quine
   18. Chomsky
   19. Derrida
   20. John Searle
   21. John Rawls