Jared Lee Loughner's motives are obscure, but it's hard to disentangle the shooting of a congresswoman, the killing of a federal judge, a 9-year-old girl, and four other people from the political culture that it occurred in, an environment of exaggerated divisions, the demonization of opponents as socialists or traitors, and a lot of gun rhetoric, gun imagery, and... guns. Almost certainly, history will tie the two together no matter what we learn about Loughner in the coming weeks. Political madness is a recurring strain in American history in which, on some level, we all take part: "I shouted out/Who killed the Kennedys?/When after all/It was you and me."
So, this is a collective problem. Pinning blame won't really work, because we end up back in the workings of Loughner's mind, which we don't understand right now, and may never. We're probably not going to find some triggering phrase in all the millions of nasty political words spoken in the past couple of years, either. See Ken Silber's reasoned take on rhetoric. Clearly, for instance, Sarah Palin was not inciting violence with her "rifle sights" (or "surveyor's symbol"), graphic, crass and obnoxious as it was. Sharron Angle, with her "Second Amendment remedies" quote, came right up to that line, however. But it's doubtful Loughner was paying much attention to a Nevada Senate race.
But we can identify some trends that created an atmosphere of exaggerated rhetoric and imagery that portrays political opponents as at best illegitimate and at worst enemies of America, that suggests tyranny and/or subversion are sources of our current political predicament, demanding some kind of armed response. In a culture where some have viewed spraying gunfire at innocent people as a ticket to immortality, it's not a healthy trend.
As Paul Krugman points out, the outre rhetoric is at the moment overwhelmingly a feature of the right. (That doesn't mean it always was, or always will be. But right now, the notion of left-right symmetry in this area doesn't hold up.) One source of this is the right's highly effective media-political complex, in which pro-Republican, anti-Democrat messages are tested, amplified and circulated with efficiency and alacrity. Cable talking heads and radio hosts compete to be outrageous, and are rewarded with attention and piles of cash the more outrageous they are.
Over the past two years, the short-term advantages of stoking the Republican base have created perverse incentives for politicians to go all-in with the outrage derby. Political leaders who are supposed to know better have mostly remained silent because all of this was working. The political media, which worships the appearance of mastery and aggression, mostly went along. It was politics, it was metaphorical, anything goes. In the process, they defined deviancy down.
As with the dysfunctional workings of Congress, this reflects an erosion not just of bipartisan comity and civility, but of basic, shared standards that American politics have operated on for decades. It's a symptom of a deeper breakdown that we're now grappling with, none too effectively. One way to start to fix it would be to take a deep breath and start thinking before speaking. Maybe this is that opportunity.