 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 through friendship, in which one’s friend acts as a kind of mirror of one’s self. Hence, a flourishing life is possible only through the epistemic access friendship provides. Second, Cooper’s Aristotle claims that the sort of shared activity characteristic of friendship is essential to one’s being able to engage in the sort of activities characteristic of living well “continuously” and “with pleasure and interest” (310). Such activities include moral and intellectual activities, activities in which it is often difficult to sustain interest without being tempted to act otherwise. Friendship, and the shared values and shared activities it essentially involves, is needed to reinforce our intellectual and practical understanding of such activities as worthwhile in spite of their difficulty and the ever present possibility that our interest in pursuing them will flag. Consequently, Cooper concludes, the shared activity of friendship is partly constitutive of human flourishing. Similarly, Biss (2019) argues along Kantian lines that friendship and the sort of trust friendship involves, are a central and necessary part of the pursuit of moral self-perfection.