Agreeing in Disagreeing

As I've said, Caston proposes an 'activity' reading of the opening of DA 3.2, Johansen a 'capacity' reading. And, whatever their disagreements, they seem agreed that the dispute may usefully be set up in this way, at least initially.

And yet I'm puzzled that that should be so. Johansen in his lecture nicely gave the reason why:

…by saying that Aristotle seeks to account for the soul in terms of its faculties we should by no means take it that his account of the soul is not also about the activities of these faculties. We should remember that the activity of a faculty is definitionally prior to the faculty (dunamis) (DA II.4 415a18-20). Given the definitional priority of activities over faculties, we should therefore expect that his starting point in identifying the faculties of the soul will often be an account of the soul’s activities. This, I shall suggest, exactly what we find in DA III.2: Aristotle here takes his starting point in the activity of perceiving that we see and hear and then asks what is the faculty that explains how we engage in this activity. His answer, I shall argue, is that it is the sense faculties themselves that explain it.

Caston makes a similar point, in connection with he calls a 'moderate capacity reading':

Most translations in fact conform to an extreme capacity reading. But I doubt whether anyone has ever really considered it seriously. Most discussions assume that we perceive that we are seeing on a given occasion (b12); and that it is not sight, but seeing (th=j o)/yewj, b14), that is perceived along with the colour seen. One can make these modifications, moreover, without competely foregoing a capacity reading. The argument's main concern can still be over which capacities are required for such perceptions. All that has changed is that the object of such perceptions will be the activity of these capacities, not the capacities themselves. (767)

Indeed, in book II of DA, Aristotle standardly follows the procedure: identify first the object of a sense; then identify the activity which is the sensing of such objects; and finally define the sense as that faculty or capacity which is thus actualized by objects of that sort. Capacities are correlative with activities: no activity of a certain sort without a capacity, and no capacity except in relation to certain sorts of activities.

Hence, it would seem: if an 'activity' reading were correct, then we should take Aristotle as wishing to infer corresponding capacities from those activities; and if a 'capacity' reading were correct, this could only make sense as understood in relation to corresponding activities.

It seems, then, that you couldn't get a different answer, depending upon which you were focusing on, so that the language of 'activity reading'/'capacity reading' must be masking the true basis of disagreement.