There is a unique argument by William J. Haun at First Things on why those who believe in limited government should oppose expanding the definition of marriage to include same-sex couples. It sounds counter-intuitive, but it is not. Haun says that, “The new basis of marriage, same-sex marriage advocates tell us, is not procreation or sexual difference, but love. For them, the personal promises husbands and wives make to each other is the government’s only reason to license (or not license) a marital relationship.” The state, says Haun, has a compelling reason to define marriage as the union of one man and one woman for the purpose of reproduction. However, official recognition of relationships rooted in love is not much of a limiting principle and serves no over-rising national or social interest; doing so would open the state to giving its imprimatur to all kinds of relationships. If the state did not legally sanction every possible loving relationship (brothers, close friends) says Haun, granting legal recognition to homosexual couples  would “expand government so as to discriminate in favor of relationships with sex partners versus relationships without sex partners.” It is a very interesting libertarian argument against same-sex marriage; whether or not libertarians would find it persuasive is another matter.