The question should be "Why does it *not* happen much more often?" In an individualized society with a population of more than 250 million I would expect a Littleton massacre to happen every 4 or 5 months. To try to explain the specific massacre is as absurd as it would be to try to explain why I first began to feel flu symptoms at 10:00a.m. on a Saturday rather than at 10:07:15 or why I'm presently resting my elbows on the arms of the chair I'm sitting in or why some mornings I comb my hair when I get up and other days I don't comb it at all unless I go out someplace.
It is normal behavior, not aberrations, that requires explanation.
This has also distorted the discussion of racism, and is probably behind
the accusation of those who disagree with both Doug and me on the topic that by explaining too much we explain too little or nothing at all. It is true that those two young men were not a lot more racist than the members of this list. So the question is why have none of us shot anyone but instead (most of us) have entered into battle in one way or another to destroy racism. The two young men are trivia.
Carrol