The breakdown of the black family is a sensitive topic, though it's not new and it's not in dispute. President Barack Obama, who grew up with an absent father, often urges black men to be responsible parents.

Nor is there any doubt that African-American children would be better off living with their married parents. Kids who grow up in households headed by a single mother are far more likely than others to be poor, quit school, get pregnant as teens and end up in jail.

But these facts were once inflammatory. Fifty years ago next month, a Labor Department official named Daniel Patrick Moynihan published a paper titled, "The Negro Family: The Case for National Action," which argued that "a tangle of pathology" afflicting black communities had emerged because "the Negro family in the urban ghettos is crumbling." His key fact: Nearly one-fourth of black babies were born to unwed mothers.

He was accused of blaming the victim, but he was onto something important. Today, Moynihan, later a liberal Democratic senator, is invoked by conservatives to explain why African-Americans' progress has been so slow.

Jason Riley, a senior fellow at the Manhattan Institute, claims that "family structure offers a much more plausible explanation of these outcomes than does residual white racism." Fox News host Bill O'Reilly is more blunt. "The reason there is so much violence and chaos in the black precincts is the disintegration of the African-American family," he said last year. "White people don't force black people to have babies out of wedlock."

They're right, up to a point. It's far from optimal for 72 percent of black children to be born out of wedlock. Social ills would diminish if there were more stable, two-parent black households.

The problem with this line of thinking is that it's incomplete. Worse, it's often used to gloss over intractable realities that continue to hinder black progress.

It's true that whites don't force blacks to have children out of wedlock. But it's wrong to suggest that whites bear no responsibility. Poverty is often the result of lack of access to good jobs or any jobs, and discrimination by employers didn't stop in 1965—and hasn't stopped yet.

The impact of drug laws, and the harsher treatment black men get from the criminal justice system, means that many have records that scare employers away. But research indicates that white applicants with criminal records are more likely to get interviews than blacks without criminal records.

A lot of the well-paid blue-collar jobs once abundant in cities have vanished. Moynihan lamented that unemployment had long been much higher for black men than for whites, and the gap is bigger today.

Without decent jobs, these men are not likely to be able to find wives or support families. They are not likely to get married or stay married. If family breakdown causes poverty, poverty also causes family breakdown.

African-Americans often find it hard to leave blighted neighborhoods. They can find themselves steered away from white communities by real estate agents or rejected by landlords. The Urban Institute reports a fact that ought to shock: "The average high-income black person lives in a neighborhood with a higher poverty rate than the average low-income white person" (my emphasis).

The concentration of poverty in inner cities means many black children are exposed daily to crime and violence. Their turbulent environment makes it harder for them to acquire habits of discipline and self-restraint.

It's tempting to blame African-American social ills on the modern welfare state, which allegedly breeds idleness. But most poor black households are poor despite having at least one adult who works. The welfare reform of the 1990s, which induced many recipients to take jobs, didn't reverse the decline of marriage.

Poor black neighborhoods are not the unassisted creation of poor black people, but largely the malignant result of factors beyond their control. These places generate a vicious cycle of poverty and dysfunction that mires children in desperate conditions. Then we wonder why many of these kids end up unemployed, addicted to drugs, behind bars or murdered.

Moynihan's report contained a passage that conservatives rarely quote: "Three centuries of injustice have brought about deep-seated structural distortions in the life of the Negro American. … The cycle can be broken only if these distortions are set right." He would be sorry to learn that we have yet to set them right, and that his insights are used to rationalize our failure.