A ristotle on Predication

A predicate logic typically has a heterogeneous semantic theory. Subjects and predicates have distinct semantic roles: subjects refer; predicates characterize. A sentence expresses a truth if the object to which the subject refers is correctly characterized by the predicate. Traditional term logic, by contrast, has a homogeneous theory: both subjects and predicates refer; and a sentence is true if the subject and predicate name one and the same thing. In this paper, I will examine evidence for ascribing to A ristotle the view that subjects and predicates refer. If this is correct, then it seems that A ristotle, like the traditional term logician, problematically conflates predication and identity claims. I will argue that we can ascribe to A ristotle the view that both subjects and predicates refer, while holding that he would deny that a sentence is true just in case the subject and predicate name one and the same thing. In particular, I will argue that A ristotle's core semantic notion is not identity but the weaker relation of constitution . For example, the predication ‘All men are mortal’ expresses a true thought, in A ristotle's view, just in case the mereological sum of humans is a part of the mereological sum of mortals.