 A question closely related to this question of the value of friendship is that of what justifies my being friends with this person rather than with someone else or no one at all. To a certain extent, answers to the question of the value of friendship might seem to provide answers to the question of the justification of friendship. After all, if the value of friendship in general lies in the way it contributes (either instrumentally or constitutively) to a flourishing life for me, then it might seem that I can justify particular friendships in light of the extent to which they contribute to my flourishing. Nonetheless, this seems unacceptable because it suggests—what is surely false—that friends are  fungible.  (To be fungible is to be replaceable by a relevantly similar object without any loss of value.) That is, if my friend has certain properties (including, perhaps, relational properties) in virtue of which I am justified in having her as my friend (because it is in virtue of those properties that she contributes to my flourishing), then on this view I would be equally justified in being friends with anyone else having relevantly similar properties, and so I would have no reason not to replace my current friend with someone else of this sort. Indeed, it might even be that I ought to “trade up” when someone other than my current friend exhibits the relevant friendship-justifying properties to a greater degree than my friend does. This is surely objectionable as an understanding of friendship.