We have had national conversations about race, national conversations about immigration, and now we’re having a national conversation about health care.

Perhaps it would also be a good idea to hold a national conversation about violence, and the very troubling possibility that America is becoming way too comfortable with it.

Today, the shocking late-October gang rape of a 15-year-old girl that occurred at a Northern California school plays out in the courts. The attack, which occurred outside a homecoming dance, made news around the world for the fact that a crowd of students watched and did nothing to intervene. Reports said as many as 10 people participated in the rape and about 20 others served as spectators — jeering, snapping photographs and text-messaging friends to join in.

Despicable crimes like this have happened before. And we usually express shock, then move on. But the time has come to stop and ask ourselves, as a country, what has happened to basic humanity when bystanders not only don’t call police, not only stand to gawk, but even take part as accessories?

Why does this happen? Experts blame popular music and violent video games, an absence of religious faith, a world where young people are ruled by technology and blur the lines of what’s real and what isn’t.

A television report in the aftermath of the homecoming dance rape continues to haunt. In it, a teenage girl from the school tells a reporter that girls her age are considered nothing more than “meat” by many of the boys. They are not persons, she said in an emotionless, matter-of-fact statement. She also said nobody intervenes or reports crimes even of that extreme nature because they don’t want to be called “snitches.”

This case and others, according to experts, highlight a growing problem in our country of witness apathy. Too many believe it’s always better not to get involved. They become desensitized. They fail to report dangerous activity so as not to be a tattletale.

Law enforcement personnel, of course, are greatly concerned about this see-no-evil mentality. So are other adults, as evidenced from this week’s story out of Ham Lake where concerned parents formed an anti-bullying group for the express purpose of protecting kids from other kids. Fred and Kathy Trosvik, founders of B.U.L.L.Y. (Building Understanding Love and Learning for Youth) recall the death of their son, Tom, who hung himself after merciless teasing on the school bus. Neither the bus driver or fellow passengers did anything to head off the tragedy, they said, and some of the students suggested methods of suicide to him.

If it happened in California and it happened in Ham Lake, it can happen anywhere.

Now is the time to make desensitized violence and witness apathy a much talked-about national issue. It should become a teaching moment here. Let the issues be discussed in classrooms. Let public service messages be printed and broadcast. Let us teach and reinforce the message that, as human beings, we have a civic responsibility to report and intervene whenever possible.

Too many Americans, obviously, believe it’s cool not to intervene. We must make them believe it’s very un-cool not to intervene.