Defining the Sciences

Taking Almagest 1.1 as the starting point of this study, as it functions as an epitome of Ptolemy's general philosophical system, this chapter argues that the metaphysics Ptolemy presents when differentiating the three theoretical sciences—physics, mathematics, and theology—is Aristotelian, though not Aristotle's. They do not derive directly from Aristotle's Metaphysics but from his greater corpus. Ptolemy appropriates aspects of Aristotle's metaphysics and epistemology to construct his own. Ptolemy adapts criteria from Aristotle's broader corpus to distinguish the objects of the sciences and, by extension, the sciences themselves. Whether and how an object is perceptible determines whether it is studied by physics, mathematics, or theology. An imperceptible object, the Prime Mover, is studied by theology, special sensibles are studied by physics, and common sensibles are studied by mathematics.