A police officer has been murdered, gunned down in the line of duty, leaving behind a grieving wife and three fatherless children.

The last thing most Philadelphians want to hear is a discussion of the social conditions that create men like the baby-faced suspect alleged to have shot Officer Chuck Cassidy during a doughnut shop robbery.

But if this city is going to prevent the murders of more officers (four others have been wounded by gunfire since Oct. 28); if this city is ever going to become safer for anyone who wants to buy a doughnut, or walk to school, or simply watch the world through a window of her home - then it has to have this discussion.

First, there must be an acknowledgment that violent crimes are a reflection of the violence we see in too many other aspects of our daily lives.

It's the new normal. Just check out TV, radio and film. There's even a commercial in which "moms" want to "whack" the Burger King king. Yeah, that's funny. Don't like the king? Go Tony Soprano on him.

Philadelphia is about to get a new mayor and police commissioner who promise to be aggressive in ferreting out and arresting criminals. But that's the easy part. Much tougher is preventing crime from occurring in the first place. Retiring Police Commissioner Sylvester Johnson has said that again and again.

To reduce crime, especially violent crime, you must address the factors that produce it, including unemployment, poverty and bad schools. There's plenty of each in any big city in America. But in all of the Democratic and Republican presidential debates, have you heard anyone detail a cohesive national urban policy aimed at these issues?

Studies have shown that teenagers who have received high-quality education, beginning in preschool, are less likely to be arrested for violent crimes. Yet urban schools continue to be underfunded - in Philadelphia and elsewhere.

The result is high dropout rates that produce the jobless young men who end up committing crimes and serving time in prison. And prison is the worst place for many of them. They're not rehabilitated; they're turned into hardened felons who are even more likely to commit violent crimes when they get out.

And they do get out, almost all of them, eventually. Uneducated, and likely to have a drug habit, they become predators who rob doughnut shops and shoot police officers who get in the way.

When is America going to learn that warehousing prisoners only delays crime, it doesn't stop it? When is it going to make adequate funding of schools a top priority? What good is waging a worldwide war against terrorism when the terror outside our doors is scarier? The violence won't stop until we take a good look at ourselves.