Aristotle and the Uniqueness Thesis

Presenter: Brennan K. McDavid (Ormond College, The University of Melbourne)

This paper explores the question of whether or not Aristotle’s theory of moral knowledge allows for disagreement between moral experts (phronimoi). The issues I consider include: (i) what kinds of things Aristotle treats as evidence that can be relied upon by phronimoi, (ii) whether or not particular features of the phronimos’ psychology ground the rightness of some (or all) actions, and (iii) whether or not the phronimos’ evidence and reasons are publically accessible (i.e. can be accessed by all phronimoi in virtue of their being practically wise, or only by the deliberating phronimos alone). These investigations drive to the heart of Aristotle’s ethical epistemology and shed light on his position regarding the possibility of two epistemic peers people having a meaningful disagreement about what actions ought to be done and why. I conclude that Aristotle thinks disagreement between phronimoi is impossible and that he is committed to what contemporary epistemologists call the Uniqueness Thesis.