From Richard Rorty, “Human Rights, Rationality and Sentimentality”:
"If one follows Baier's advice one will not see it as the moral educator's task to answer the rational egotist's question "Why should I be moral?" but rather to answer the much more frequently posed question "Why should I care about a stranger, a person who is no kin to me, a person whose habits I find disgusting?". The traditional answer to the latter question is "Because kinship and custom are morally irrelevant, irrelevant to the obligations imposed by the recognition of membership in the same species". This has never been very convincing, since it begs the question at issue: whether mere species membership is, in fact, a sufficient surrogate for closer kinship. Furthermore, that answer leaves one wide open to Nietzsche's discomfiting rejoinder: That universalistic notion, Nietzsche will sneer, would only have crossed the mind of a slave – or, perhaps, the mind of an intellectual, a priest whose self-esteem and livelihood both depend on getting the rest of us to accept a sacred, unarguable, unchallengeable paradox.
A better sort of answer is the sort of long, sad, sentimental story which begins "Because this is what it is like to be in her situation – to be far from home, among strangers", or "Because she might become your daughter-in-law", or "Because her mother would grieve for her". Such stories, repeated and varied over the centuries, have induced us, the rich, safe, powerful, people, to tolerate, and even to cherish, powerless people – people whose appearance or habits or beliefs at first seemed an insult to our own moral identity, our sense of the limits of permissible human variation."