Beginning with the principles of the Renaissance and the Modern Scientific Revolution, this chapter focuses on the "crisis of authority" which is historically understood to have called for a new methodology to found a "new philosophy." Just as René Descartes' philosophy was understood to have met the criteria of the "new philosophy," so too it accomplished a shift from a Theo-centric to an Ego-centric understanding of psychology and established new problems as foundational for psychology, such as, the "mind-body problem." After examining multiple principles introduced throughout Early Modern philosophy regarding these foundational problems for Early Modern psychology, the principles and distinctions to emerge from Immanuel Kant's transcendental philosophy are discussed as of critical importance in the history of Western psychology.