The left's had a lot of fun at the Birthers' expense recently. But it's always worth remembering that this is, in part, an opportunity for learning about how people in general -- not just on the right, or on the left -- succumb to this kind of conspiracist thinking, and why. And that starts with acknowledging that your place on the political spectrum has little to do with it.
Some have already pointed to an old Rasmussen poll about 9/11, which showed that in 2007, 35 percent of Democrats answered yes to the question, "Did Bush know about the 9/11 attacks in advance?" But critics like Media Matters note, correctly, that the wording of that survey might be too ambiguous, as people who know about the infamous briefing President Bush got in August of 2001, for example, might have answered "yes" without actually believing Bush had something to do with it.
As Brendan Nyhan points out at Pollster.com, though, that's not the only Truther poll out there. Another one, conducted in 2006 by Scripps Howard and Ohio University, told respondents, "There are also accusations being made following the 9/11 terrorist attack. One of these is: People in the federal government either assisted in the 9/11 attacks or took no action to stop the attacks because they wanted the United States to go to war in the Middle East." The pollsters then asked how likely respondents considered this scenario.
What Nyhan found, after breaking the Scripps poll down by party, is that the Birther and Truther poll responses are nearly mirror images of each other. 58 percent of Republicans in one poll said they believe President Obama was not born in the U.S., or that they don't know whether he was; 54 percent of Democrats gave a similar response to the 9/11 Truther question.