Martha Nussbaum in Dissent:
Before we approach the issue of same-sex marriage, we must define marriage. But marriage, it soon becomes evident, is no single thing. It is plural in both content and meaning. The institution of marriage houses and supports several distinct aspects of human life: sexual relations, friendship and companionship, love, conversation, procreation and child-rearing, mutual responsibility. Marriages can exist without each of these. (We have always granted marriage licenses to sterile people, people too old to have children, irresponsible people, and people incapable of love and friendship. Impotence, lack of interest in sex, and refusal to allow intercourse may count as grounds for divorce, but they don’t preclude marriage.) Marriages can exist even in cases where none of these is present, though such marriages are probably unhappy. Each of these important aspects of human life, in turn, can exist outside of marriage, and they can even exist all together outside of marriage, as is evident from the fact that many unmarried couples live lives of intimacy, friendship, and mutual responsibility, and have and raise children. Nonetheless, when people ask themselves what the content of marriage is, they typically think of this cluster of things.