In contrast to empiricist and rationalist traditions, existentialism proposes an orderless world, vaguely hostile, where people choose their character and goals, have an obligation only to be "authentic," and may only observe the truth (reality) in moments of anxiety. In this program, world-renowned author and professor Bryan Magee and University of California, Berkeley, philosopher Herbert Dreyfus trace the roots of existentialism from Edmund Husserl’s School of Phenomenology, to his pupil Martin Heidegger’s theories of das Sein, the threefold structure of activity, authenticity, and nihilism. Dreyfus relates the philosophies of both men to present-day schools of thought. A BBC Production. (48 minutes)