Lately there has been a rash of news stories and columns decrying the stupidity of Americans, mostly based on a finding by the Pew Research Center that 18 percent of Americans think that Barack Obama is a Muslim. Predictably, the New York Times joined the pile-on with this column by Timothy Egan: "Building a Nation of Know-Nothings." Egan focuses, however, not on Americans in general, but on Republicans: That ill-informed woman -- her head stuffed with fabrications that could be disproved by a pre-schooler -- now makes up a representative third or more of the Republican party. It's not just...