David Hume
Gene Kim
René Descartes
John Locke
John Stuart Mill
Peter L. Berger
Elias M. Awad
Immanuel Kant
Michael Polanyi
Donald Hislop
Richard David Precht
Gabriel Marcel
Gregory Bateson
Karl Popper
Henri Bergson
B. R. Hergenhahn
Jean Piaget
Bertrand Russell
Gottfried Wilhelm Leibniz