Abstract
Physics I 6 addresses the question of the number of principles and motivates the need for an underlying principle in addition to the contrary ones argued for in chapter 5. Physics I 6 ends in aporia about whether there are two or three principles, an aporia which is resolved with Aristotle’s own account in I 7. This chapter focuses on two issues. First, it explores how Aristotle’s arguments for contrary and underlying principles give rise to the aporia. Second, it discusses Aristotle’s puzzling attitude towards, and use of, materialist views in I 6 and, more generally, in book I. Though Aristotle brings out deep tensions between his own hylomorphic conception and materialism, he also seems to downplay them for the purposes of arguing for an underlying principle. I suggest that this is a result of trying to motivate a hylomorphic conception of natural substance from within a more familiar materialist framework.