Hanna Rosin, a senior editor at The Atlantic and at Slate, is the author of "The End of Men: And the Rise of Women."

I’m not sure whether a child needs a father. Sophisticated studies on single motherhood show that the circumstances surrounding such families – poverty, instability – can be rough on children, but not that single motherhood itself is an issue. And from my own decade or so of mother experience and intuition, the answer to what children need seems fairly obvious: at least one loving adult who is a stable, reliable presence; a few more loving adults hopefully thrown into the mix; and enough resources not to be constantly struggling. Beyond that, I leave the question of what comprises a family up to the ever-evolving American imagination.

I’m not sure whether a child needs a father. But fathers deeply need to be good parents, and those who can't are left further and further behind.

But what I’m pretty sure about is that men need fatherhood. The great tragedy of the last 30 years is how a certain segment of men have fallen off the map. A series of recessions made it hard for working-class men to find work, and they haven’t quite adjusted to the new "college degree required" work force. The result shows up in the new statistics about female breadwinners. Women head their households because they think the men won’t be all that helpful. The phrase I’ve heard most often from single mothers describing the fathers of their children? “Just another mouth to feed.” And the tragedy has its own momentum. Men don’t work, so they can’t support their children, so they have nothing to work for.

The sociologists Kathryn Edin and Timothy Nelson have a new book out called "Doing the Best I Can," following fathers in the inner city. Edin and Nelson are trying to counter the portrait of the cocky deadbeat content to sow his wild oats and walk out. But the reality they uncover is even more heartbreaking. The men they profile desperately want to be fathers. They talk about quality time and tender moments and yearn so much to do it right that you realize the yearning is just as essential in them as in any mother. But they can’t.

So what do we need men for in modern families? To save the men.