Something something Burt Ward
Our deeds are teachers, but being that our actions are the produce of our humanity, the teachers are only human, and therefore imperfect. We can teach children, for instance, an idea such as "self-defense", but experience teaches that in a room where five people all agree that "self-defense" is the only justification for violence, we will also find five separate standards of self-defense.
Consider the American experience. We've hated, institutionally, indigenous American tribes, Catholics, women, blacks, Italians and Irish (see Catholics), Jews, Asians, atheists, Muslims, witches, and gays. And that list is incomplete; I didn't find a place in there for Mexicans and other Latin American classifications. One would think that history teaches the detriment of hatred, but for some reason the lesson seems to come down that hating Catholics is wrong, or hating blacks, or hating women.
A simplistic example. Joe loses his temper, kicks his wife. He gets arrested. He loses his temper and kicks his son. He gets arrested, his wife divorces him, and his son never speaks to him again. He loses his temper again and kicks his dog. He doesn't get arrested, but as he buries his best friend in the back yard, he realizes, "When I get another dog, I cannot kick him. Kicking my dog is wrong, no matter how mad I am." A few weeks later, Joe loses his temper yet again and instead of kicking his new girlfriend, her son from an earlier marriage, or the new dog, he kicks a fire hydrant. And breaks his foot. Sitting on the sofa the next Wednesday, playing GTA and drinking cheap beer, Joe realizes: "Kicking a fire hydrant was stupid. I shouldn't kick things that can break my foot."
When will Joe realize that the broader, more universally-applicable and consistent response would to reassess the value of kicking? So far, he is focused on the object: the wife, the son, the dog, the hydrant. Kicking any of these things is bad. Well, kicking anything is a pretty useless expression of immediate frustration. What if next time it's the guy Joe thought was gay but wasn't actually hitting on him? What if, when the guy said, "I owe you a beer," and smiled that way he was simply recalling the stupid bet over a two-rail combo to drop the eight? Admittedly, Joe's error would be to have forgotten the bet; the homophobia is actually a secondary issue only used for simplicity's sake. But if Joe had considered the idea of kicking and violence instead of the target of that manifest frustration, maybe he wouldn't be explaining to a cop how he thought the guy was trying to pick him up, and after the year he's had the last thing he needed was some fudgepacker trying to turn his out-valve into a pincushion.
In the American experience, we're down to gays, for instance. As long as homophobes believe their rhetoric of choice, they feel justified in despising homosexuals because it's disgusting to the homophobe's sense of aesthetics, and it's something people choose to do.
In other words, having gone through public convulsions over blacks, Jews, &c., many people haven't yet grasped the concept of hatred. They're still focused on the object of their psychiatric violence. Much like Joe's physical violence, people--e.g. "the masses", or "the mob mentality"--seem to understand that we can't hate the blacks for being black anymore; we can't hate the Jews for being Jews; we can't hate women simply because they're women. The larger concept, that we cannot treat people wrongly for those things beyond their control, seems to scare the hell out of people. I'm convinced that people are aware of it, since they blast the idea as "liberal elitism" and such, but perhaps such mythical criticisms take root in fertile soil. Do the people appear to resist the idea because they still do not understand it?
Try the idea in reverse: we can send Tom to Alcoholics Anonymous, Adulterers Anonymous, Gamblers Anonymous, Narcotics Anonymous, Domestic Abusers Anonymous ... we could even enroll him with the Promise Keepers. But at the very least we must also address whatever it is that compels Tom to such behavior.
When a leader or even a culture says, "We'll teach the side of evil a lesson because of what they have done to us," the lesson of history most people accept and adopt focuses too sharply on the target of violence.
This focus includes in its results an extended period before the concept of violence is accepted as wrong. The idea of violence is often justified as a response to violence. But a number of blurry, smeared spots mark the map. Foremost is the smearing of violence itself. Even our moral constructs in Western culture tend to ridicule certain classifications of violence as mere excuses. Launching a nuclear missile to destroy an inbound killer asteroid: this is not "violence". But at the same time, it rather quite is. Defending oneself against immediate assault: this is not "violence", except that it is. What about vigilantism, provocateurism? What about hunting down and punishing an offender after the fact? These forms of violence are included in the same word that describes fending off a rapist? Contemporary cynicism regards harshly the splitting of certain hairs, which is part of the reason so many escalatory classifications of violence--e.g. vigilantism, provocateurism, "just" vengeance--are included under the paradigm of justifiable violence.
Do we need separate terms for the violence of immediate need--e.g. killer asteroid, rapist, &c.--and the escalatory violence asserted of justice? And, perhaps a third term representing arbitrary violence, or violence of discredited justice, or whatever that remaining politic would be?
Humans and their social institutions have had much difficulty with violence: unfortunately, the lists are long and the formulae complex, and it appears we'll be about this warring, brutal experiment for a while. The best hope would seem to be the devising of a philosophical expression compelling a new perspective on violence itself. Right now, for instance, it's right to hit Muslims engaged in "terrorism", it's wrong to hit Muslims for being Muslim, and the difference between the two conditions is one massive gray zone. At least, that seems to be the popular American assessment. We're focusing too much on violence, which in its most general consideration has solved little, if anything for humanity.
Maybe violence is simply an aberration. It is a stumbling block, a temporary halt in our collective human development of peace, prosperity, and security.
At some point, people must stop focusing on the object and justification of violence, but rather the fact of violence itself. History teaches quite soberly and clearly, but there's something up with the students. They're just not paying attention. They're making more work for themselves than they need to. And besides, Americans still cringe at the thought of social studies classes.