In Book IX of the Nichomachean Ethics, Aristotle continues his discussion of the attributes of friendship. Where he discussed the kinds and nature of friendship in the earlier book; however, in this book he deals with the moral and social obligations of friendship, in keeping with the ethical concerns of the book. Instead of dealing with the attractions and qualities that make the association with another person “good, pleasant or useful,” he discusses the ways in which an already established friendship make certain requirements of people, and distinguishes the kinds of friendship which no longer require the performance of these duties. Aristotle begins with the question of “How to measure what friends owe to one another.” He continues to make the distinction between good, pleasant and useful in friendship, of course. He points out that an unequal friendship based on different motives (combinations of the above three desires), can be dissolved when one party ceases to get any satisfaction out of the relationship. The example he gives is of two lovers, one of whom no longer feels any pleasure in the other. Aristotle says that such friendships are doomed because they rely not on what the other person is, but on what they have to offer. He repeats his belief that only a friendship based on an appreciation of the good character of each party can outlast mere pleasure or usefulness:
...when friendship is based on character, it does last, as we have stated, because it is friendship for its own sake, (in which each partner is loved for what he is.) (Aristotle, The Nichomachean Ethics, p. 245-6)
Any relationship based on an exchange of “services rendered” is bound to lead eventually to the dissatisfaction of one of the parties, and thus to the end of the friendship. A further problem can arise when there are conflicting obligations in the way of friendship; as we have seen, the Greek concept of “phila” involves many more kinds of relationships than simple friendship. The ethical authority Aristotle uses here is the figure of the father, who may perhaps stand in the way of friendship, a relationship with a doctor or a soldier. Aristotle argues that it is best to judge the obligations of friendship by the nature of that friendship, rather than to try to be all things to all people and fail to please any: “We must also try to render what is appropriate to kinsmen, fellow tribesmen, fellow citizens, and every other person, and compare what each is entitled to in terms of the closeness of his relation to us and in terms of his excellence or usefulness.” (Aristotle, The Nichomachean Ethics, p. 250)
This may seem to be a rather political version of friendship, but if you think about it for a minute it is also a version of the idea, “Render unto Caesar what is Caesar’s and to God what is God’s.” Aristotle approaches the problem of dissolving friendships in an equally practical manner: when one or the other of the partners in a friendship loses the quality which we appreciated in him, then it is justifiable to break off the friendship. It is all a question of honesty and of good intentions:
“So, when a person has erroneously assumed that the affection he got was fro his character, though nothing in his friends conduct suggested anything of this sort, he has only himself to blame. But when he has been deceived by his friend’s pretense, he has every right to complain against the deceiver.” (Aristotle, The Nichomachean Ethics, p. 251)
Aristotle applies the same standard to a relationship which is based on qualities that change (say a friend that remains mentally a child), but warns that we should continue to treat such a person as an old friend. At this point in book IX, Aristotle turns to a different aspect of the question of friendship, that of self-love. This is a complicated question, since as Aristotle points out, a certain element of friendship is always self-love, and in a way