Well, this is something.

David Blankenhorn, a traditional-marriage advocate and star witness in the Proposition 8 trial in California in 2010, shocked his allies with an Op-Ed article in The New York Times last June announcing that he was quitting the fight against same-sex marriage. “Instead of fighting gay marriage,” Mr. Blankenhorn wrote, “I’d like to help build new coalitions bringing together gays who want to strengthen marriage with straight people who want to do the same.”

He is about to find out how much support such a coalition can get.

On Thursday, Mr. Blankenhorn’s research group, the Institute for American Values in New York, plans to issue “A Call for a New Conversation on Marriage,” a tract renouncing the culture war that he was once part of, in favor of a different pro-marriage agenda. The proposed conversation will try to bring together gay men and lesbians who want to strengthen marriage with heterosexuals who want to do the same.

The document is signed by 74 well-known activists, writers and scholars, on the left and the right, including the conservative John Podhoretz, editor of Commentary magazine; John Corvino, a gay philosopher; Robert N. Bellah, a sociologist; Caitlin Flanagan, a social critic; and Glenn C. Loury, an economist — once conservative, now less so.

“While the nation’s attention is riveted by a debate about whether a small proportion of our fellow citizens (gays and lesbians) should be allowed to marry,” the statement reads, “marriage is rapidly dividing along class lines, splitting the country that it used to unite.”

It’s something, but I don’t think it’s going to amount to much. There are writers and thinkers on that list of signatories whom I respect, and in some cases who are personal friends. I wish them well. Anybody who is trying to strengthen marriage in this culture is doing good work.

But I think it’s not going to amount to much for much the same reason various government attempts to raise the birth rate — as Singapore, Russia, and various European countries have done — never succeed. If marriage and family are considered institutions that we can manipulate to suit our own wants, as opposed to institutions to which we must be conformed, then they lose their power to bind and to direct. Nobody gets married, or has more than two children, because it is good for them, or good for society. They do so because they believe marriage and/or children are a positive good. If you have to make a “case” for marriage, or for having children, the battle is largely lost.

I’ll state again that I don’t believe gay marriage is responsible for the rolling collapse of marriage culture in the US, but rather a symptom of something that started long before anybody had the slightest idea that same-sex marriage might be desirable. Aside from concerns having to do with religious liberty, the reason people like me are against SSM has to do with SSM being the thing that ratifies and institutionalizes an approach to marriage I believe will be, in time, impossible to sustain. That is to say, SSM is a Rubicon in terms of culture and social psychology. To that end, I think Blankenhorn has made his goal more difficult to achieve with his conversion, but then again, I think it was a pretty hard goal to reach anyway. Again, good luck to him and to the people of goodwill involved in this project, but I think it’s stillborn.