"A generation ago, an American child could reasonably expect to grow up with his or her father. Today, an American child can reasonably expect not to. . . . Never before in this country have so many children been voluntarily abandoned by their fathers. Never before have so many children grown up without knowing what it means to have a father."

Those words from the introduction to his new book, "Fatherless America," pretty much describe the culture change that David Blankenhorn believes is America's "most urgent social problem."

Blankenhorn believes (as I do) that the trend toward fatherlessness -- the diminution in the public mind of the importance of fathers -- is driving any number of America's social crises. The economic consequences are clear; fatherless households are statistically the poorest households in America. But I think the trend is also implicated in matters like crime and violence -- both because boys who grow up without fathers are less likely to get the discipline that can keep them straight and because the decline in the importance of marriage makes boys (and men) less valuable to their families and communities than they might otherwise be. This marginalization, I am convinced, feeds antisocial behavior.

Blankenhorn believes it too -- believes, moreover, that there is a growing recognition that the trend toward fatherlessness has been overwhelmingly negative for children and for the society in general. His frustration is his -- and the society's -- inability to come up with a solution to the problem.

"People now recognize that there's an elephant in the room," he said in an interview from the Institute for American Values (which he founded) in New York City. "They know it's an elephant, not a mouse, and they know it's not okay to leave him there. They just don't know how to get him out."

The problem, he says, is that the trend toward fatherlessness has become rooted in the culture. "The conventional wisdom is that it was brought on by economic changes -- industrialization, the loss of blue-collar jobs, that sort of thing," he says, "but I suspect it's deeper than that. It may involve the shift toward expressive individualism, the idea that your basic responsibility is to yourself, which means that your obligation to others becomes weaker. The mother-child bond remains the closest thing we have to an unbreakable bond, but the belief is growing that the father is not a necessary component of the family unit, that you don't really have to have a marriage. I don't think it really enhances the happiness of the adults, but it's been an unquestioned disaster for children."

And emphatically not just for black children. "This phenomenon never was confined to any race or class," he says, "but now it has really burst out. It's us!"

There are a couple of things Blankenhorn isn't saying. First, he's not proposing that single mothers could improve their children's prospects by rushing out and marrying the first male they see. Second, he's not saying that existing marriages must be maintained at all cost. As to the first, he makes only the common-sense point that it's generally much better for children if their parents are committed to them and to one another -- that is, married. As to the second: To say that children generally fare better if they live in homes is not to say that we shouldn't get them out if the house is on fire. Some marriages are on fire.

Still, Blankenhorn entertains no doubt that the trend toward what he calls the "superfluous father" has been a disaster for our society. His quandary, to repeat, is what to do about it.

He makes a number of recommendations in his book (including changing textbooks to be more supportive of the marriage idea), and he is using his book tour to try to get 10,000 men to take the pledge to try to become better fathers.

But he is frank to say that if all his ideas are implemented, it still may not be enough.

"We don't have much experience in knowing how to reverse cultural trends," he told me. "This isn't something that an institution can do or the government can do. We are talking about how to get a huge number of individuals to change their minds, at some cost to their own autonomy. It's very hard to figure out."

And yet, he insists, we have to try. "The people who say we can't do anything about the trend may be right. Nobody knows. I do know that we'll never change the culture if we just sit around and say we can't."