Thanks to Eugene and also to Dale Carpenter whose work I admire a great deal.

Recently I had a front row seat at the great Andrew Sullivan v. David Blankenhorn debate on gay marriage at the Institute for American Value's annual symposium.. It was like watching two majestic battleships, armed and deadly with torpedoes ready, pass each other harmlessly by. The testoterone level was high but they were punching air.

David, who has spent the last two years researching a book on marriage as a cross-cultural universal human phenomenon, and that last twenty years building the nation's most influential think tank on marriage and fatherhood, said something like this (I'm quoting from memory here):

David: "Marriage is a trans-legal social institution whose main mission is creating sexual unions between men and women so they create families where children have fathers as well as mothers."

Andrew Sullivan: "That's a fantasy." (Andrew cited the usual argument: lots of married couples don't have children and lots of children aren't born to married couples.)

Two very bright people, face to face, mano a mano, looked each other in the eye and saw--a blank wall.

A lot of this debate is like that.

I've learned from much experience that when two intelligent people cannot even understand how the other person's can possibly believe their own argument—that's when something really interesting is going on.

I have no illusions I'm going to spend this week persuading people to change their minds on gay marriage. So I'd like to try to do something else big and important: to "achieve disagreement". To figure out for myself, and maybe for you too, what has changed that makes the original, cross-cultural, historic understanding of marriage literally unintelligible to so many of this country's best and brightest. In the process, maybe some advocates of gay marriage will understand why, quite apart from any disagreement about sexual orientation, so many Americans are deeply disturbed by the idea of gay marriage.