In this chapter I will review how James got from his earlier position, which so readily fit the scientific and skeptical tenor of his age, to his later position, and I will indicate how the views he began to articulate by the mid-1870s became central to the doctrines he presented in his magisterial Principles of Psychology (1890) and in his subsequent work in psychology and philosophy. Along the way I will make it clear that even before 1872, when he was attending lectures and doing physiological research in Harvard\u27s Medical School, James was a deeply engaged advocate of philosophy, which he was determined to advance through a thorough yet critical understanding of the biological foundations of human thought, feeling, and action. He vie...