It was just after 10:30 at night in a Milwaukee neighborhood so dangerous that residents called it "Little Beirut." Charlie Young Jr., a 36-year-old ex-con, was teasing a 10-year-old boy who was playing with his girlfriend. (Yes, it was late for a 10-year-old to be out, especially in such a hazardous place; and, yes, he seems a little young to have a girlfriend.)

The boy got mad at Mr. Young and later pelted him with an egg. Mr. Young gave chase, pushed the boy down, and struck him in the face, knocking out a tooth. The 10-year-old kept fighting, and soon friends joined him, hitting Mr. Young with tree limbs and baseball bats. As the word went out through the neighborhood, more children got on their bikes and rode to the scene.

By this time a mob of children was swarming around Mr. Young, and he ran. Finally, he took refuge in a friend's house. The children broke the living room window and crawled in. Some had shovels. Some had two-by-fours. The blood spattered on the walls, and Mr. Young lost consciousness.

"Drag him out!" the kids outside yelled. They pulled Mr. Young outside, onto the front porch. Some 20 children, most between the ages of 10 and 14 with a few older teenagers joining the fun, bashed him with folding chairs, broom handles, fence posts, and whatever they could find.

One little boy, a pro-wrestling fan, put Mr. Young in a hold that he had seen on TV, holding up his head so the other kids could whack it easier. Others tried to hit him at a distance, so they would not get blood on their sneakers. By the time the police arrived, Mr. Young was brain-dead.

The next day, police rounded up 16 children. Doctors took Mr. Young off life support and he died. At the hearing, many of the kids' parents did not even bother to show up. Few, if any, had parents who were married to each other. One 14-year-old killer was himself a parent.

At the arraignment, though, where the 10-year-old was transferred to children's court and the others were indicted as adults for murder, at least one parent for each child did show up. They typically said how good their children had always been, and how they shouldn't be held responsible for what happened. One father said, "Kids will be kids." Some of the adolescents were surly, talking back to the police and still trying to act cool, even as they faced 40 years in prison. Others, finally acting like the children they were, cried.

For over a century, the assumption that children are intrinsically innocent has dominated academia and the culture, manifesting itself in parenting manuals and contemporary educational theory.

But parents who take their vocation seriously know that children need to be civilized. They have to be taught to control themselves, from the impulse to go to the bathroom to the impulse to pound their little brothers. Selfishness is natural to a child, but he has to be taught to share. Parents have to put up with their child's emotional tantrums, egotistical demands, and a self-centeredness astonishing in one so small. They have to teach their child to control his passions and to consider the needs of other people, to develop a conscience.

That is to say, children need moral formation. Because children are, in fact, fallen, their nature is to be sinful, rather than innocent. They need spiritual formation. This is why many churches baptize them and why all churches stress Christian education.

When children are left to their own devices, though, when they do what many educators recommend, expressing their inmost selves free of parental or societal constraints, they are capable of the most horrible evil.

William Golding made this point in his novel The Lord of the Flies, a piece of fiction about shipwrecked children that crossed over into reality in Milwaukee. True anarchy comes not so much from the absence of government but from the breakdown of the family.

Actual mobs of children killing adults does not happen very often, of course. And yet, the mentality of brutal, violent moral nihilism is not confined to heartbreakingly disadvantaged inner-city children. This is the worldview that is expressed in much of the music enjoyed not just in the inner city but among middle-class, white, affluent adolescents.

New studies of children's social relationships-especially in parent-free zones such as schools-show how little girls tend to align themselves in vicious hierarchies of popularity, in which "Alpha girls" rule over their "Beta girl" followers-using clothes and other fashions as symbols of belonging. As for the "Gamma girls" who do not conform, Alpha girls and their cliques torment them by gossip, slurs, and humiliations.