ONE OF the crueler ironies in the aftermath of the Los Angeles riots has been the suggestion, particularly on the part of conservatives, that the real cause of the violence was not racism or poverty but crumbling inner-city families.

The inner-city family has fallen apart, the argument goes, and thus an entire generation of young people has come of age without proper "values." It's all the fault of the liberal social welfare policies of the 1960s, President Bush said recently.

That's a neat formula for evading the responsibility three successive GOP administrations bear for the neglect of America's cities.

The irony, of course, is that conservatives were the ones who insisted on making family breakups a condition for welfare. Remember the "man in the house" rule? That was the one that said families couldn't get assistance if there was an able-bodied man in the house. It was enacted because opponents of welfare, particularly Southern conservatives, simply couldn't abide the idea of government "handouts" to male heads-of-household.

So if a man lost his job, he literally had to leave home if he wanted his children to be eligible for government surplus cheese, beans and peanut butter. Somehow conservatives persuaded themselves that this encouraged "family values."

With the advantage of 20-20 hindsight it's easy to see how the policy had exactly the opposite effect. It accelerated the fragmentation of poor families at just the time low-skilled factory jobs were disappearing. The expansion of the welfare state in the 1960s coincided with the decline of the factory economy in the worst possible way because the no-man-in-the-house rule actually encouraged the breakup of stable, two-parent families.

Conservatives like to talk about the "law of unintended consequences" -- by which they mean the difficulty of predicting the long-term effects of government social policies. Welfare hasn't worked, they argue, because it only produces more dependency.

Yet dependency clearly is a function of the great increase in single-parent, female-headed households over the last 20 years. And that, in turn, was at least in part an unintended consequence of punitive welfare rules that forced poor men to chose between abandoning their children or watching them starve. We are still paying for that mean-spirited policy in Los Angeles and other cities across America.

Doubtless other factors played a role in the break-up of two-parent families over the last generation -- higher divorce rates, teen pregnancy, the corrosive commercial values purveyed by popular music, movies and television. But the no "man in the house" rule was a classic example of how a government social policy aimed at assisting poor families actually undermined them.

If you doubt that, consider this: What would the result have been if the rule had required just the opposite of what it in fact demanded of poor families -- that is, in order to receive assistance, both parents had to live at home with their children?

Glenn McNatt is an editorial writer for The Sun and Evening Sun.