There is a scene in the novel “Catch-22” in which the central character, Yossarian, a World War II bomber pilot, treats a wound suffered by Snowden, another member of his crew.

Yossarian does everything he’s supposed to do. He stops the bleeding, he cleans the wound, he bandages it. But Snowden still is dying.

Too late, Yossarian discovers that Snowden has another wound, hidden under his uniform. The other wound is much bigger and much, much deeper. That other wound kills Snowden.

I thought of Yossarian treating the wrong wound as I read about the unctuous self-congratulation in the child welfare community over AB 12, the law extending foster care to age 21.

Yes, the law is better than nothing. But AB 12 treats the wrong wound.

The outcomes for young people who stay in foster care until age 21 are not good — they are simply less bad than the outcomes for youths kicked out at 18. A study that found that the current system churns out walking wounded four times out of five also found that if foster care were made perfect, the system still would churn out walking wounded three times out of five.

Yet proponents of AB 12 willfully ignored the bigger, deeper and more dangerous wound: the many children who never should have been put into foster care in the first place. Yes, much of California is doing better on that front — and the progress in Santa Clara County is particularly notable. But the county has had to do it largely on its own, with no special state or federal legislation to help. And the county still takes children at a rate far higher than systems recognized as models for keeping children safe.

The federal Fostering Connections Act, which led to AB 12, contains not one word, and not one penny, to reduce the number of children taken away, often when family poverty is confused with “neglect.” And neither does AB 12.

There is nothing in AB 12 to offer concrete help to alleviate the worst stresses of poverty; there is no new money for drug treatment, or mental health services, or Intensive Family Preservation Services; and no strengthening of due process protections for families. The governor’s $256 million cut in child care subsidies that could have helped low-income working parents avoid losing their children because of “lack of supervision” charges will do far more harm than AB 12 will do good. Too bad so many groups championing AB 12 didn’t work anywhere near as hard to help low-income families.

The only way to really solve the problems of children aging out of foster care is to prevent so many from ever aging in.

But as soon as you talk about keeping families together, you lose that warm, fuzzy feeling the advocacy community and politicians get when they can focus exclusively on innocent children and ignore their “bad parents.” And, of course, all those private agencies that will make more money keeping kids in foster care until age 21 have no interest in keeping children out of the system.

Yes, the bill probably will do some good. After all, to cure any wounded innocent, you have to treat all the wounds. But nothing in AB 12 justifies the current orgy of self-indulgent celebration. Even worse, with the signing of AB 12, a lot of people now are likely to declare victory and get out, leaving the other wound to deepen and fester.

RICHARD WEXLER is executive director of the National Coalition for Child Protection Reform (nccpr.org). He wrote this article for this newspaper.