  Aristotle solves the separability problem with a kind of fictionalism. The language and practice of mathematicians is legitimate because we are able to conceive of perceptible magnitudes in ways that they are not. The only basic realities for Aristotle remain substances, however we are to conceive them. A primary characteristic of substances is that they are separate. Yet we are able to speak of a triangle, a finite surface, merely the limit of a body, and hence not separate, as if it were separate (hôs kekhôrismenon). It is a subject in our science (in our discourse in the science). The mental and logical mechanism by which we accomplish this is the core of Aristotle's strategy in diffusing platonisms.