The notion of another self (heteros/allos autos) is crucial to Aristotle’s theory of friendship; as indicated by the instances in the Nicomachean Ethics (8.12, 9.4, and 9.9), Aristotle appeals to the notion to show how agents treat friends as they do themselves. I assess two different interpretations of other selfhood, focusing on the first two instances in the Nicomachean Ethics, in 8.12 and 9.4 (I also explore 9.7). The mainstream interpretation takes shared virtue to be definitive of other selfhood; x is virtuous person y’s other self in that x is virtuous. This understanding of Aristotle implies impartiality and a position that falls outside the altruism-egoism distinction. The interpretation I will argue for denies that virtue is necessary for other selfhood and instead takes involvement in one’s own actualization (energeia) as the definitive feature; x is y’s other self in that x is specially involved in y’s actualization. This implies partiality and egoism.
