LordOmar has the best possible explanation for the recent increases in school shootings -- it's a self-perpetuating cycle fueled by the media...but how did the cycle start to begin with? Blaming the problem on guns is ridiculous, it's a superficial attack on a very deep and insidious problem. Yes, to have guns lying around within reach of a child is stupid, but most of these shootings have involved teenagers, who obviously did not act rationally...at some point they had to know that what they were doing was wrong and disastrous to their future.
When someone decides to shoot up their school, they effectively end their own lives in a vengeful display of aggression and retaliation. They have already decided that revenge is more valuable than their lives, so the problem is: why do people find so much glory in killing eachother? The Columbine killers got exactly what they wanted. They became immensely famous, and they deliberately planned on dying and becoming martyrs. Their entire goal was to wreak bloody havoc on their classmates, and then to be plastered all over the media as an example of what happens when you push the wrong kids around.
I would go as far as to say that almost every kid who experiences true bullying has violent fantasies. A huge percentage of these kids (probably 99.99999% or so, who knows) are truly rational and know that there is no point in acting on these fantasies. One of the best consolations one can find is "they're idiots, someday I will be successful and they will be worthless to society." Living well is the best revenge, but some people, for whatever reason, choose to use deadly force instead. But some people lose the ability to judge their own thoughts; to say "That's a crazy, fucked up thought, and there's no way I'm acting on it." Obsessive-compulsive people (such as myself) often live with the most insane and violent thoughts possible, but they constantly judge them as such, and ignore them. I've heard of mothers obsessing about stabbing their babies to death, mothers who are otherwise perfectly suited to raising a child -- mothers who DO successfully raise their children without acting on the relentless "bad thoughts" that consume them.
When I was in Middle School I was subjected to bullying; I never got into any fights or had any true physical threats of violence, but I was harassed on a pretty regular basis. I often fantasized about killing my enemies, but also fantasized about being twenty years older and successful and happy, all of this being a mere memory. This latest California shooter was probably harassed moreso than I; his bookbag had been dumped in a toilet on one occasion, and he was constantly antagonized for his "fish out of water" appearance.
Just about every adolescent is a little bit crazy, if crazy means "irrational." In criminal cases we define "insane" as "unable to know the difference between right and wrong," but I think more cases of insanity involve people who DO know the difference, but choose to act in defiance or indifference to morality. Teenagers are constantly being told that they are immature and irresponsible, yet they are burdened with new responsibilities and stresses on a regular basis. They often feel persecuted and misunderstood, and have a tendency to feel alienated. Some are much smarter or more reasonable than others, but strangely enough these shootings often involve rather intelligent kids, sometimes suffering from what society has deemed "mental disorders." These kids aren't stupid. It's not that they don't know that killing is wrong. They want to do wrong because of all the wrong that has been done to them.
Some people are truly crazy, but most of the insane function within society for the majority of their lives. Eric Harris lived for nearly two decades before self-destruction. Insanity is a combination of inner perception and outer reality; one can be driven deeper and deeper into a self-perpetuating state of paranoia and hatred, where every little thing that happens reinforces one's dislike of the world and the humans that inhabit it. Crazy people often function until something pushes them over the edge. No one really deserves to die for pushing someone around in high school, but to that student who is constantly the recipient of everybody's aggressions, the entire planet is guilty. This is why these school shooters never seem to kill the people that really piss them off. Instead, they take to hating the human race as a whole, and fire off with reckless abandon, often killing people who have nothing at all to do with their persecution.
True misanthropy is bred by bad experiences and preconceptions. The more a person is antagonized by individual people, the more they begin to dislike humanity as a whole. That's what drives these people to commit violence. I'm sure I have shared many of their thoughts and fantasies, and I even wrote a story or two about school vengeance "in my day." But I never acted on this urges; some people choose otherwise. Why does it take so long for this to happen? School is every American's first intense social experience away from the protective world of childhood. Children can be cruel and mean and often unreasonable -- and when they focus all of their negative energy onto one person, they can instigate a level of hatred that they could never individually imagine.
So what's the moral of the story? Don't harass people, don't push people around, don't drive like an asshole. Remember Road Rage? It's the same situation; every time you drive you are exposing yourself to hundreds of people. Any one of them could be completely insane, so how do you protect yourself? By not driving like a complete ass, that's how.
Every time a school shooting occurs, hundreds of kids collectively fantasize a little more about pulling one off themselves. Every time it happens, it gives somebody else the courage to try it also. How do we stop the cycle? We could start by teaching kids not to persecute eachother for their differences. And parents can make more of an effort to address their children's possible insanity. If your kid has a tendency to brood and seems to lack motivation, talk to them, but don't accuse them or spy on them behind their backs. Sometimes people just need to be aware of the fact that their existence means something to someone else. Being distant with your children is the worst possible thing you can do. And don't assume that the answer is in a pill. Prozac might make things better, but there is a growing body of evidence pointing to the fact that some people have a completely whacked-out reaction and become highly suicidal. This is rare, but it happens. Anti-depressant drugs may alleviate the symptoms of the problem, but it's not going to correct the true cause -- a lack of self worth. People who kill other people feel inherently worthless. I doubt any murderer over the age of 10 hasn't been clearly aware of the fact that they are effectively dead to society once they've committed the act.