JAMES TARANTO: The Moralistic Fallacy: How value judgments cloud social thought.

Hymowitz’s hypothesis that family breakdown causes “boy troubles” is an entirely plausible one. But there’s still a problem with it: That framing makes the argument circular. Recall that she posed the question as (among other things) why “poor and working-class boys” fail to become “reliable husbands and fathers.” She ends up concluding that the cause of fatherlessness is . . . fatherlessness.

Which isn’t as absurd as we just made it sound, for circular causation is distinct from circular reasoning. Life would be impossible without circular causation–after all, babies come from parents, who started off as babies, who came from parents, and so on into the mists of the distant past. But identifying a causal cycle begs the question if the question is about the ultimate cause. If your child is sophisticated enough to ask how human beings came into existence, he won’t be satisfied if you answer by explaining where babies come from.

It may be true that fatherlessness begets fatherlessness, but widespread illegitimacy is a recent phenomenon whose ultimate causes demand inquiry. In his landmark 1965 report, “The Negro Family: A Case for National Action,” Daniel Patrick Moynihan observed that “both white and Negro illegitimacy rates have been increasing, although from dramatically different bases. The white rate was 2 percent in 1940; it was 3.07 percent in 1963. In that period, the Negro rate went from 16.8 percent to 23.6 percent.”

The 2011 figures (which exclude Hispanics) were 29.1% for whites and 72.3% for blacks–a more than eightfold increase for whites and more than threefold for blacks. A cycle of fatherlessness operating over two to three generations cannot be sufficient to explain such an enormous rise.

So what does? In our view, a dramatic change in incentives owing to two major social changes that were just getting under way when Moynihan wrote.

Yeah, you could write a book on that.