I try not to take Twitter seriously, because I find its format frustratingly hostile to clear thinking, but once in a while something provokes me enough that I have to write.
People who think the Connecticut school shooting is "terrorism" are merely living evidence that our discourse has completely degraded the meaning of the term.
Terrorism is not a synonym for "violence you don't like". Terrorism is violence against civilians calculated to elicit an emotional and policy reaction. Properly understood, terrorism is a tactic of asymmetric warfare, no more and no less. It is not terrorism when a lunatic kills people because they are conveniently available targets, and then commits suicide for no particular reason. (Terrorist bombers often commit suicide, but only because it is necessary to deliver the bomb successfully without being captured and interrogated; if they could deliver the same bomb to the same target without risk of capture or death, they generally would.)
Incidentally, for the same reason, the United States' drone strikes are not terrorism either. The US does not perform drone strikes to provoke the Pakistani population into a policy response. It performs drone strikes mostly for the simple utilitarian reason that it wants certain people dead, and (international law be damned) those people shall therefore be killed.
But this is a language game, and I am playing the role of the futile prescriptivist holding the line against a huge tide of people who would prefer that "terrorism" simply be a synonym for "doubleplus-ungood". A perfectly accurate phrase like "heinous criminal violence" is simply not enough for these people: they demand that the T-word be deployed. And in the end, descriptivism is the correct school of linguistics, and thus in the long run I will inevitably be wrong. Eventually, terrorism will be a synonym for "doubleplus-ungood" and a useful tool of thought will have been blunted into uselessness, like a scalpel bashed repeatedly against a brick wall.
This reminds me of how we now call everything "war" — war on drugs, war on poverty, war on women, war on Christmas — except when we pay our armed forces to shoot at another nation's people, in which case we call it "kinetic military action" or whatever.
Does this matter? I can't say for certain, but it seems to me that our national policy response to terrorism is muddled in part because our thinking about terrorism is muddled. I claim you can draw a connection between people who throw around "terrorism" with such carelessness, and the ridiculous anti-terrorism policy of the Bush years, when we reacted to terrorism by invading a country that had not committed terrorist acts against us, sacrificed our liberties to defend our "freedom", and spent untold blood and treasure to prevent terrorists from achieving their goal of provoking America into losing blood and treasure.