Philosophy: Biographies
- Rudolf Christoph Eucken
- Rudolf Hermann Lotze
- Saint Thomas Aquinas
- Samuel Alexander
- Samuel Clarke
- Sidney Hook
- Simone Weil
- Sir Alfred Jules Ayer
- Sir Karl Raimund Popper
- Sir William Hamilton
- Socrates
- Soren Aabye Kierkegaard
- Speusippus
- Spinoza
- Stephanus of Alexandria
- Strato of Lampsacus
- Susanne Knauth Langer
- Thales
- Theodor Wiesengrund Adorno
- Theophrastus