Let's examine, for a minute, how "birtherism" -- widespread questioning of Obama's birthplace -- works in our political culture.

Birtherism relies heavily on misinformation and uncertainty. It reminds us that public views are probably less fact driven than we'd like to think. They're more like mass impressions, with feeling, logic, and "truth" leading individuals to answer polls, express views to other people, and vote (or not vote) in ways that connect them to morally and emotionally significant universes, as much as to agreed upon "facts."

It also persists out of reasonable agnosticism and empirical skepticism. If a rational person hasn't investigated Obama's birthplace, or read news stories written by those who have, he/she logically would say "I don't know" when asked if Obama was born here.

Many Republican politicians have given that same response. The assumed subtext has been that these politicians are playing to conspiracy theories, but their uncertainty is sometimes legitimate. This represents a failure by the media to ask better questions, such as: Should we be investigating whether the president is constitutionally eligible for the office he holds?

I, myself, held the same uncertainty for a while. I didn't think Obama's birthplace was a particularly important question, so, for a while, I never looked into it. I read headlines and skimmed the first sentences of news stories. I wasn't too concerned. When people asked whether I thought Obama was born in Hawaii, I'd say, "How should I know? I wasn't there." As I read about it, that changed.

Agnosticism, by the way, is GOP hopeful Herman Cain's stance on birtherism. While Cain's base might include birthers, he tells reporters he hasn't looked into it and doesn't have an opinion, at all. This has been taken by some liberal media outlets as full-on birtherism, but it's not.

Hazy questions, hazy answers, and misinformation have kept birtherism alive. When Roy Blunt, the Republican congressman who had served as GOP whip until January 2009, was asked later that year about Obama's birthplace, he called it a "legitimate question." Which it is, since presidents are required by the Constitution to have been born here. But Blunt didn't seem to know that the president's campaign had produced a certificate of live birth, and a spokesman soon told reporters that Blunt did think Obama was born here. Adding to the mishmash, unedited footage also showed Blunt acknowledging that he didn't "have any reason not to believe" that Obama was born here.

This type of all-around confusion has allowed birtherism to prosper.

People hear such things and receive chain birther emails, and they don't investigate. They don't have the time or inclination, or they don't know where to look for a good answer. Birtherism remained an uncertainty for 10 percent of the recent Fox News poll. Of the 24 percent who held it as an opinion, some probably weren't sure but chose to believe because it reinforced some view they already had about Obama. (Just a guess.)