The structure of definitions in Aristotle, according to Christian Pfeiffer (and me)
Complexity is both a sufficient and necessary condition of definability: every complex is definable and only complex entities can be defined. But what is a complex entity? Obviously, an entity is complex if it is not simple, i.e., it must contain more than one component. This is what Pfeiffer calls the complexity constraint. Complexity is a necessary condition, but not a sufficient one, for complex entities are not mere pluralities (as, for example, heaps of objects – an example that both Pfeiffer and me favor): they have unity. In other words, they are not just complex, but complex entities . Thus, complex entities are things that satisfy both the complexity and unity constraints. Now, how do we define these complex things? Assume the simplest of complex entities: an ordered pair AB . It is complex, thus it must be definable. According to Aristotle (according to Pfeiffer) is to say that it is the sequence of A and B in that order. Here, it is very easy to identify t...