Giffords Shooting: Why did six people have to die last year at a grocery store near Tucson?

by Tom Zoellner - This was the work of a single disturbed individual, but this is a connected universe and events never happen in a vacuum. Individual human beings -- even the crazy ones -- are pushed and pulled by what surrounds them, and far more than we ever suspect...

Nobody will ever determine beyond a shadow of a doubt exactly why it happened, and this will be argued about for decades.

There will always be excuses to dismiss the mountain of contextual factors that were stacking up in Tucson that winter and consider this a force majeure beyond all human control.

But to ignore the cluster of enabling factors right now is even more risky than it was to dismiss them back in the tense days before the shooting.