Abstract

To avoid reification of prime matter, or the indeterminate, yet determinable, substrate underlying all change, many readers of Aristotle have identified this per se unknowable “stuff” with its functional identity, i.e., as a conceptual placeholder of the sum of formal potencies abstracted from concrete particulars.Despite the appeal of this reduction, a case will be made in reference to Siger of Brabant’s Metaphysics for the irreducibility of prime matter. This entails granting an extra-formal reality to prime matter beyond its functional role as a correlate passively receiving forms imparted by an agent without contributing anything of this own.