Friendship, through its shared values and shared activities, reinforces one's intellectual and practical understanding of such activities as worthwhile despite their difficulty.

Yet friendship is not merely instrumentally valuable, as is hinted at by Annis’ claim that “our lives would be significantly less full given the universal demise of friendship” (1987, 351). Cooper (1977b), interpreting Aristotle, provides two arguments for why this might be so. First, Cooper’s Aristotle claims, living well requires that one know the goodness of one’s own life; however, given the perpetual possibility of self-deception, one is able accurately to evaluate one’s own life only throu