Here's a telling remark by Taylor on the passage I quoted yesterday. You can find within it the germ of the solution I'd wish to propose.
Aristotle has so far said nothing whatever on how the ethical mean is determined. Hence, despite the 'then' [ἄρα] which introduces the definition, the definition is not derived as a whole from the previous discussion. All that that discussion has established is that the mean in feelings and actions is feeling and acting to the right extent, neither too much nor too little. The questions 'What counts as too much or too little?' and 'How does one recognize what is too much and too little?' have not been raised.I agree with that almost entirely. What I don't agree with is what Taylor next says:
He now asserts that the mean state is determined by reason: namely, the reason by which the person of practical wisdom would determine it. For elucidation we must now turn to VI.I, 1138b18-34, where he returns to this question.To my mind an interpretation of a passage Aristotle is likely not to be correct if for elucidation one absolutely must turn to another book far away.
(Burnet once wrote that he was untroubled by this difficulty because "the theory of logos or orthos logos belongs to the Academy (koinon kai hupokeisthw 1103b 32) and was, of course, familiar to Aristotle's audience" ("On the Meaning of Logos in Aristotle's Ethics", Classical Review 1914). Yet to me this consideration has little weight because Aristotle is developing his theory of virtue as positioned between two vices in opposition to received views. Note in any case that Burnet implicitly agrees that some special proviso needs to be in place to justify interpreting in this way.)
But that's all I can say today... Apologies to Mokawi!