Rod Dreher at the American Conservative:

"... I know I promised y’all a post on why I don’t think the analogy between interracial marriage and same-sex marriage succeeds. I’m going to have to point you to my friend Frank Beckwith, who analyzes the issue from a legal point of view.

Excerpt:

It is clear then that the miscegenation/same-sex analogy does not work. For if the purpose of anti-miscegenation laws was racial purity, such a purpose only makes sense if people of different races have the ability by nature to marry each other. And given the fact that such marriages were a common law liberty, the anti-miscegenation laws presuppose this truth. But opponents of same-sex marriage ground their viewpoint in precisely the opposite belief: people of the same gender do not have the ability by nature to marry each other since gender complementarity is a necessary condition for marriage. Supporters of anti-miscegenation laws believed in their cause precisely because they understood that when male and female are joined in matrimony they may beget racially-mixed progeny, and these children, along with their parents, will participate in civil society and influence its cultural trajectory.

In other words, the fact that a man and a woman from different races were biologically and metaphysically capable of marrying each other, building families, and living among the general population is precisely why the race purists wanted to forbid such unions by the force of law. And because this view of marriage and its gender-complementary nature was firmly in place and the only understanding found in common law, the Supreme Court in Loving knew that racial identity was not relevant to what marriage requires of its two opposite-gender members. By injecting race into the equation, anti-miscegenation supporters were very much like contemporary same-sex marriage proponents, for in both cases they introduced a criterion other than male-female complementarity in order to promote the goals of a utopian social movement: race purity or sexual egalitarianism.

In other words, it all turns on the question: “What do you say marriage is?”