During World War II, he played clarinet and bass drum in a military band in California. During this time, he became interested in philosophy, sparked by W. Somerset Maugham's book The Razor's Edge. After this, he engrossed himself in works by well-known philosophers such as Jacques Maritain, Mortimer J. Adler, Francis Bacon, Plato, René Descartes, and John Locke.[1] After being discharged, he entered a graduate program for philosophy at the University of Chicago, even though he had never formally taken a class on the subject.[2][3] While he was there, he learned more about philosophy from Richard McKeon and Charles Hartshorne, and he received his PhD in 1951.[1]