David Blankenhorn, Maggie Gallagher’s longtime collaborator in the defense of traditional marriage, announces today that he has changed sides. Excerpts:

Marriage is how society recognizes and protects this right. Marriage is the planet’s only institution whose core purpose is to unite the biological, social and legal components of parenthood into one lasting bond. Marriage says to a child: The man and the woman whose sexual union made you will also be there to love and raise you. In this sense, marriage is a gift that society bestows on its children.

At the level of first principles, gay marriage effaces that gift. No same-sex couple, married or not, can ever under any circumstances combine biological, social and legal parenthood into one bond. For this and other reasons, gay marriage has become a significant contributor to marriage’s continuing deinstitutionalization, by which I mean marriage’s steady transformation in both law and custom from a structured institution with clear public purposes to the state’s licensing of private relationships that are privately defined.

I have written these things in my book and said them in my testimony, and I believe them today. I am not recanting any of it.

But there are more good things under heaven than these beliefs. For me, the most important is the equal dignity of homosexual love. I don’t believe that opposite-sex and same-sex relationships are the same, but I do believe, with growing numbers of Americans, that the time for denigrating or stigmatizing same-sex relationships is over. Whatever one’s definition of marriage, legally recognizing gay and lesbian couples and their children is a victory for basic fairness.

This is not a retreat, it’s a surrender. He surrendered for strategic reasons, but this is a surrender. Waiting to see what Maggie’s reaction is…