My immediate reaction to the shooting of Congressman Gabrielle Giffords was "Crap, I hope she wasn't a liberal." There are two reasons for that: if she was, then 1) I wouldn't be able to watch or read the news for several weeks without being inundated by stupid commentary about the "irresponsible vitriol" directed at liberals from the political right; and 2) this random, despicable crime, committed by an obvious lunatic, could significantly impede the new Republican House majority's agenda to curb the growth of government control over the economy. It turns out Giffords was/is not particularly liberal, but because she was a Democrat, it looks like many on the left will try to coopt this tragedy for political gain anyway.
It almost goes without saying (at least for the half-dozen people who read this blog from time to time), but I'll say it anyway, that it is idiotic to blame our political discourse for such a tragedy. Besides the fact that political speech is probably more polite and "PC" than at any time in US history, especially when it comes to very emotional and significant political issues, it's unclear that the use of violent imagery and harsh criticism is even positively correlated with political violence, let alone materially so. And any causal relationship is even less clear. Finally, even if colorful political rhetoric could be proven to increase political violence, I think that's just something we have to accept as a society. In a country of 310MM people, the level of political violence is so low that the threat of violence simply doesn't have the intended effect (assuming of course the perpetrator of the threat is not thinking one level deeper and attempting to sabotage the opponents of his target).
I'll end this post by pointing out what a jackass Pima County Sheriff Clarence Dupnik is. Without any evidence (the shooter is not talking), he implied strongly that recent political fights in Arizona, which he equates to prejudice and bigotry, would have a motivating effect on unbalanced people like the shooter to commit violence.
His implication of course is logically inconsistent with the facts concerning the shooting. If the political environment in Arizona is so toxic that unbalanced people could be incited to commit violence, why was there zero security at a campaign event for a sitting congressman? Literally zero -- there wasn't even a security guard on duty at the shopping mall. If the sheriff really believed that political violence was caused by vitriolic rhetoric, and that Arizona was the "capital" and the "Mecca" of such rhetoric, then he was completely negligent in carrying out his duties.
The fact that congressmen generally do not receive security at public events, even liberal congressman who are the targets of Tea Party ire, undermines the credibility of after-the-fact accusations like those of the sheriff's. To be clear, I think it's amazing that important public officials like congressmen do not routinely have security. That's pretty good evidence that the real professionals in the law enforcement establishment do not take political rhetoric seriously.