ABSTRACT
From the thirteenth through the sixteenth centuries, European philosophers were preoccupied with using their newfound access to Aristotle’s metaphysics and natural philosophy to develop an integrated account, hospitable to Christianity, of everything that was thought to exist, including God, pure nite spirits (angels), the immaterial souls of humans, the natural world of organic objects (plants, animals, and human bodies), and inorganic objects. This account included a theory of human mentality. In the sixteenth and early seventeenth centuries, rst in astronomy and then, later, in physics, the tightly knit fabric of this comprehensive medieval worldview began to unravel. The transition from the old to the new was gradual, but by 1687, with the publication by Isaac Newton (1642-1727) of his Principia Mathematica, the replacement was all but complete. Modern physical science had fully arrived, and it was secular. God and angels were still acknowledged. But they had been marginalized. Yet, there was a glaring omission. Theorists had yet to expand the reach of the new science to incorporate human mentality. This venture, which initially was called “moral philosophy” and came to be called “the science of human nature,” became compelling to progressive eighteenth-century thinkers, just as British empiricism began to seriously challenge an entrenched Cartesian rationalism.
