People have been having a hard time holding two ideas in their head at the same time:
1. What Paul Krugman calls "eliminationist rhetoric" is bad.
2. Contrary to his suggestion, there is no evidence that such rhetoric caused Saturday's events. Even if such evidence is later found, it would not justify the evidence-free claims that have been made in the last 48 hours.
For an example of the murky guilt-by-association tactics that have been employed by people on the left since the minutes after the shooting, consider this quote from the National Jewish Democratic Council (via John Sides):
It is fair to say -- in today's political climate, and given today's political rhetoric -- that many have contributed to the building levels of vitriol in our political discourse that have surely contributed to the atmosphere in which this event transpired.
The bolded passage is a chain of associations that would make Oliver Stone blush. NJDC "surely" doesn't know the circumstances in which this event transpired, nor was there any evidence to support the constant invocations of the Sarah Palin bullseye map over the weekend. Nonetheless, Daily Kos founder Markos Moulitsas tweeted "Mission accomplished, Sarah Palin" after the shootings and Brad DeLong wrote "Remember where the incitement comes from" and posted the Palin map, adding "It comes from Gabrielle Giffords's voting for the Affordable Care Act."
With only the barest outline of events available, pundits and reporters seemed to agree that the massacre had to be the fault of the tea party movement in general, and of Sarah Palin in particular. Why? Because they had created, in New York Times columnist Paul Krugman's words, a "climate of hate."
The critics were a bit short on particulars as to what that meant. Mrs. Palin has used some martial metaphors—"lock and load"—and talked about "targeting" opponents. But as media writer Howard Kurtz noted in The Daily Beast, such metaphors are common in politics... When Democrats use language like this—or even harsher language like Mr. Obama's famous remark, in Philadelphia during the 2008 campaign, "If they bring a knife to the fight, we bring a gun"—it's just evidence of high spirits, apparently. But if Republicans do it, it somehow creates a climate of hate.
Some of the most troubling statements suggesting the use of violence in recent months have come from the right, but Republicans certainly don't have a monopoly on extremist rhetoric. And in any case, there's no indication that the alleged shooter was inspired by those statements. Attacking the entire conservative movement within hours of the shootings betrays the ideological nature of the project. Rather than reducing polarization, Krugman and others like him are creating more.
Update 1/10 12:41 PM -- See also Jon Chait:
Since the closing stages of the 2008 election, conservatives have regularly described President Obama as an alien figure and his policies a fundamental threat to American liberty. It has become normal for conservatives to hint that they will take up arms if they don't get their way politically -- a violation of the cultural norm of respecting democratic outcomes that forms the basis for the stability of our political system. Sharron Angle, not just a fringe activist but the GOP's candidate in a major Senate race, rhetorically flirted with outright sedition, and Republicans paid no attention to this, because they wanted to beat Harry Reid.
This is, I think, a serious problem. But it's also a problem that has nothing, or almost nothing, to do with the tragedy in Arizona. This was not a right-wing militia member taking apocalyptic right-wing rhetoric about watering the tree of liberty too seriously. It was a random act.
I can see why those concerned about the rise of right-wing hysteria would want to use Loughner as a cautionary tale -- even if he wasn't a product of right-wing rage, they may be thinking, he is an example of what right-wing rage could lead to. Yet they fail to understand that this will appear to conservatives as an attempt to use the emotion of the moment to stigmatize them. The mania of Sarah Palin and the Tea Party must be dealt with on their own terms.