Thoughts on VT
There have already been some inevitable reactions. People are calling for gun control, people are blaming videogames, and people are blaming the current US culture. I want to say a bit about these points.
First, gun control may have prevented this. We need to remember that while gun control is remarkably good at keeping guns away from people who obey the law, it's not particularly good at keeping them out of the hands of criminals. I'm not entirely sure where I stand on the issue, but I ask those who hear this to remember that we can't be certain about how things would be different with gun control. As one commentator said, "Don't fear guns, fear cars." We hear about shootings but not fatal crashes, 42,884 Americans die in car crashes a year, which is almost 5 per hour. Just something to keep in mind.
Second, videogames almost certainly had nothing to do with it. A recent study found that videogames don't influence people with "stable" personalities, and that those who are influenced can be made calmer or angrier, and that it's a passing effect. However, the study was done with fairly small samples (22 in the "influenced and angrier" group), so it might not be right. Even so, the evidence indicates that videogames do not cause violent behavior.
Lastly, is our culture to blame? Perhaps we do ingest too much violence for our good, perhaps the murder just snapped under the weight of his failure to meet society's standards. It's entirely possible, and I'm not going to say that I love the US's culture right now; it is despicable in many ways. But I'm hesitant to blame society for this one. While we don't know who this young man was or why he did it, it's best to assume nothing about him. I think the most likely scenario is that several bad things happened to him in a row and he just snapped.
I know that people don't like to believe that extraordinarily bad events can be explained by mundane reasons, they like big events to have big causes. They also like to find blame, whether it be lack of gun control, videogames, or a bad culture. I hope we can move the blame to the back of our minds and instead grieve for the dead, and save reactions until a time when the facts are known and can be weighed with calm minds.