Although numerous books and articles have examined Arnold Schoenberg’s religious thought, fewer have taken a close look at his core philosophical orientation. This chapter explores the composer’s philosophical milieu, musings and influences. Thinkers who began to set new coordinates for the new century sought to abolish the brand of metaphysics that had dominated German philosophy throughout the nineteenth century. While remnants of dialectical metaphysics were still circulating in Schoenberg’s Vienna, the cosmology it presupposed was rapidly fading out of fashion. This chapter traces Schoenberg’s philosophical alignment with the new ‘scientific worldview’ of proto-logical positivist Ernst Mach, his student David Joseph Bach (Schoenberg’s lifelong friend) and Schoenberg’s composition student Robert Neumann, an active member of the Vienna Circle (originally the Verein Ernst Mach).