There are plenty of reasons why we should not confuse same-sex marriage with the real thing.Marriage is a universal and historical institution which serves tremendous social purposes. It regulates human sexuality, and it procures the well-being of any offspring from the sexual union. Thus it is not a mere private matter, but a vitally important social institution.Governments have an overwhelming interest in heterosexual marriage. They have no reason to confer special rights and privileges on oth…