In a cogent Washington Times column, Tod Lindberg suggests that social conservatives are losing the debate over gay marriage because, having recognized that "a moral argument against homosexuality as such doesn't travel well anymore," they're relying on unpersuasive consequentialist arguments. "In the public square these days," he writes, "we find very few moralists and a great many sociologists, the latter articulating their opposition to gay marriage (even if it is ultimately moral opposition) in terms of its supposedly deleterious social effects. The weakness of this argument is becoming obvious."
An editorial in the latest issue of National Review illustrates the disarray this issue has caused on the right. Although it takes conservatives such as George Will, David Horowitz, and NR's own Jonah Goldberg to task for opposing a Federal Marriage Amendment, its best argument is that failing to support the amendment will alienate evangelical Christians, thereby destroying "the conservative coalition."
As for the moral case against homosexuality, NR agrees with Lindberg that sociological arguments–e.g., about the stability of gay unions or the happiness of children raised by homosexuals–are beside the point, or at least inadequate. It offers this in response to David Brooks' (moral and consequentialist) argument that "we should insist on gay marriage":
People have souls, but our lives are also bounded by our flesh and by our gender. Marriage is not only a union of souls; it is two persons becoming "one flesh" (and, in the procreative act, not merely metaphorically). If biology is so easily transcended, by the way, shouldn't homosexuals just turn heterosexual?
It's not surprising that such arguments don't "travel well." But even if they did, it's not clear why they would be relevant to the question of whether same-sex couples should be able to enjoy the same legal rights and privileges as heterosexuals. Conservatives who say they should not have to do more than argue that homosexuality is immoral. Unless they believe the government should prohibit every sin, they have to explain how same-sex unions threaten the rest of us. That's why they've been emphasizing the lame arguments about "supposedly deleterious social effects" that Lindberg and NR see as a weak substitute for a straightforward condemnation of homosexuality.