David Blankenhorn was only trying to find a fresh way of talking about the difficulties facing the American family today. But for me, at least, he has provided a way of looking at (and evaluating proposals to ameliorate) social problems of all sorts.

There are, he suggests in a recent issue of "Family Affairs," two categories of explanations for what has gone wrong with the family -- and by (my) extension with much of the society:

1. Reagan closed the bathrooms.

2. Nobody listens to Grandma.

The inspiration for the first is the trend that finds more and more New Yorkers -- "not just the homeless, or even the poor, but all manner of ordinary citizens" -- urinating on the city sidewalks. One explanation for this dismaying trend is the shortage of public toilets and other public amenities occasioned by the Reagan-induced budget cuts.

By that explanation, says Blankenhorn, president of the Institute for American Values, which publishes "Family Affairs," the source of the incivility of which public urination is one example "is not changing standards of personal behavior but instead those larger political and economic forces that, in effect, close the bathrooms."

In other words, the family crisis is not about families but about outside institutions (principally the workforce and the government) that "fail to respond to the new realities of contemporary family life: divorce, single-parent homes, the two-gender work force, teenage parenthood, latch-key children and so on." And the solution lies not in changing family behavior but in changing those larger institutions.

"Schools must help, not stigmatize, unwed teenage parents. Corporations must subsidize child care. Courts must confer equal legal status on alternative lifestyles. Government must provide a wide range of services and subsidies for children and families in need."

The second explanation stems from Blankenhorn's old-fashioned notion that "you will learn more about the American family from 10 randomly chosen grandmothers than you will from 10 randomly chosen family experts."

The experts, loath to make "value judgments," won't tell you that families headed by a father and a mother married to each other are best for children. Mother-only households are just one more alternative to the Ozzie and Harriett model that embraces fewer actual families with each passing year.

"Grandmothers," says Blankenhorn, "tend to be less shy about value judgments. They tend to say things like: 'People today care more about themselves and less about others.' 'They want everything now.' 'They are less willing to make sacrifices.' 'Children today are not taught a sense of right and wrong.' "

For Grandma, the problem is not the system but us: not mean-minded government but our own irresponsible behavior and our unwillingness to make children our top priority.

As with so many of these debates, both sides have valid points. Government policy does affect families in negative ways. Children's allowances, the norm in much of Europe, would help enormously to reduce the poverty of many American families. A full-employment policy or other policies calculated to increase employment opportunities for inner-city youth might greatly reduce the incidence of single-parent households, by rendering it economically sensible for women to marry the fathers of their children. Government aid, including increased funds for Head Start and college loans, would lift more families to middle-class status and, presumably, to middle-class standards of behavior. In other words, Reagan did close the bathrooms.

But a dearth of bathrooms is not the sole explanation for the behavior exemplified by urinating on the streets. A part of it -- perhaps the major part -- is the abandonment of the standards and values Grandma preached. Psychologists would talk about it in terms of "locus of control": whether we see our fate as subject to our own behavior or principally as a matter of outside influences, including luck. Grandma would say it in plainer language: You don't sit on your butt simply because you can't find the job of your dreams. You don't neglect your children simply because their needs conflict with your desire to have a good time. You don't disable the plumbing in your apartment or throw trash on your public-housing courtyard or use or sell drugs simply because life is unfair.

Blankenhorn would reduce the unfairness, even if it means an increase in his taxes. But in the final analysis, he insists, the grandmothers are right.

"Reagan can close public toilets, and I can and do vote against him because of it. But he does not -- he cannot -- cause me to urinate in public. Only I can decide to do that.

"And if what we as a society are doing to the family is the cultural equivalent of urinating in the street, then public policy alone is simply not enough to solve our dilemma."