- Wittgenstein, Ludwig, 1889-1951 (13)
- Logical positivism (2)
- Adorno, Theodor W., 1903-1969 (1)
- Belief and doubt--History--20th century (1)
- Ernst, Paul, 1866-1933--Influence (1)
- Fichte, Johann Gottlieb, 1762-1814 (1)
- Goethe, Johann Wolfgang von, 1749-1832--Influence (1)
- Philosophy, Modern (1)
- Skepticism--History--20th century (1)