Like a slow-mo fender-bender on ice, I could see the bad-dad moment coming.

My son had stomach pains, and the pediatrician was querying him: “What did you have for breakfast?”

A sausage patty, my offspring said, indicting me for second-degree cholesterol. “I’ve had one every day this week,” he volunteered. It was no good explaining about how oatmeal has been on the outs lately and how at least we’d found a breakfast he’d eat.

It could be worse, seriously, grimly worse. My boy eats. I manage to feed him. Neither of us face anything sterner than pediatric shaming and the remote fear that, someday, this could turn up on someone’s permanent record. Food seems picayune when other children suffer real neglect.

That’s why I’m mainly heartened by talk in Chicago of a boarding school, a public one, aimed at children who come from truly dysfunctional homes. “There are certain children where home isn’t working,” the Chicago schools chief executive officer, Arne Duncan, said, and he’s right.

The whispering qualms that the idea sets off are, I suppose, a sign that Mr. Duncan’s talking about powerful things.

His Chicago Public Schools will call for proposals next month for a public boarding school aimed at children who are homeless or whose family life is chaotic. One charter school hoping to put in a bid, North Lawndale College Prep, says 6% to 8% of its students are homeless at any time, either because their parents are in prison or have vanished.

“Some children should not go home at night; some of them we need 24-7,” Mr. Duncan told a newspaper. This revives an idea first floated in Chicago in the 1990s but dropped because of cost, now guesstimated in the $20,000s or $30,000s per pupil. Given the economic toll alone levied by those for whom schooling fails, that might not be too steep.

The idea has some charms — at least treating a key symptom if not touching upon its cause. It acknowledges that school failure, a gateway to adult membership in the underclass, stems from family breakdown. Senator Moynihan was right, and the elite’s long flirtation with blaming capitalism or suburbs or racist Amerikkka when children disengage from school could be ending. Boarding schools are a step toward agreeing that when Daddy’s vanished or Mama’s a crack whore, that’s a crisis. But the real issue is that the boarding school idea won’t bring mommy and daddy back into the picture — the most wholesome remedy of all. This proposal is at best a substitute. Still, it’s something.

Then why worry? Because of mission creep.

If Mama is a crack whore, then boarding school seems indisputable. If Mama, instead, is sometimes drunk but Grandma’s 56, spry, and capable, then boarding school is only a maybe.

What if Mama’s a Bible-thumper with unfashionable views about child discipline? This is not exactly theoretical. In February, an appeals judge outlawed home schooling in California, saying that even parents armed with the best of curricula don’t qualify as teachers.

The case began as an investigation into child abuse, and afterward, “child advocates” and other fretters maintained that a problem with home schooling is that such children can’t be easily monitored by an adult — other than their parents, that is. Lawmakers should worry a bit, said one law professor, about “the potential for bad child-abuse cases” in home schooling.

No one wants child abuse. Laws are fairly clear on what child abuse is. Until they’re not: In some jurisdictions, it’s abuse to smoke in a car if a child is along. I know people who would regard my son’s sausage-patty breakfasts as abuse. Not to mention what Richard Dawkins would think of the traditionalist Catholic school I send him to.

Mind you, I’m not worried, yet, that anyone’s coming to take my kids. For one thing, existing boarding schools are usually voluntary.

They’re often not even in public schools. New York, for instance, has two such programs aimed at removing children from troubled environs — both at Brooklyn Catholic high schools, Catherine McAuley in Flatbush and Bishop Loughlin in Fort Greene. Demand outstrips capacity.

Chicago’s brainstorming is said to be driven by the success of Washington’s SEED Public Charter School. “We really want to be working with families, not removing kids from families,” one of its founders, Eric Adler, told a reporter. In Chicago, a former SEED principal hired to explore the idea says children would board only if their parents chose it.

This is reassuring — even if it’s unexplained how missing parents can do such choosing. The answer is that most parents aren’t permanently missing. You notice this among the voucher-accepting private schools in my hometown, Milwaukee: Even students with unbelievably deprived home lives manage to find an adult to fill out the school-choice registration papers.

This also suggests a natural safeguard against the temptations of social engineering implicit in an education that separates a child from his home. The safeguard is for such schools to be, even if publicly funded, voluntary, by charter or voucher, and not directly government-run. It would fit. Enthusiasm for unorthodox schooling is the hallmark of the charter school movement, as is drawing students by choice, not mandate. I wish Chicago luck. Even as I’m depressed by its straits — what have we come to, that public authorities must provide substitute parenting? — it’s possible to see this in another way.

If such schooling is truly voluntary, it affirms that even parents incapable of providing a stable home can be trusted to choose one for their children if they’re given the means. Even bad dads can know there’s something better.

Mr. McIlheran is a columnist for the Milwaukee Journal Sentinel.