In the current argument over the question of gay marriage, both sides focus on their respective moral and even constitutional claims. But when the battle is pitched on those rather elevated and abstract grounds, the pro-heterosexual factions are at a big disadvantage, drowned out by the gay cohorts, who claim, not without justice, that their constitutional rights, for equal protection under the law, are being violated by any ban on same-sex marriage. But more than the civil rights of a deviant minority may be at stake: not only the matter of gay marriage, but the larger matter of marriage itself,...