James Fallows has an insight on the Fort Hood shootings that I feel is wise: "The shootings never mean anything. Forty years later, what did the Charles Whitman massacre 'mean'? A decade later, do we 'know' anything about Columbine? There is chaos and evil in life. Some people go crazy."
I would add that the felt need to learn a lesson from individual madness often leads to institutionalized madness--as with the "zero tolerance" rules that sprouted up in schools after Columbine and result in suspensions of girls found with Midol, or a first grader with his Cub Scout camping utensil. Indeed, if there's a lesson from these events, it's that we need to be free to act on our judgment about people whom we think are unbalanced--a version of "if you see something, say something." Sometimes the crazy person is allowed to remain notwithstanding numerous warnings because of the sense of disempowerment wrought by the rights revolution. Seung-Hui Cho, the student who murdered 32 people at Virginia Tech in 2007, had of long history of pathological conduct. But psychologists and others who had seen the dangers didn't send warnings to the family or university officials because of his "right to privacy."