In trying to explain why our political paralysis seems to have gotten so much worse over the past year, analysts have rounded up a plausible collection of reasons including: President Obama's tactical missteps, the obstinacy of congressional Republicans, rising partisanship in Washington, the blustering idiocracy of the cable-news stations, and the Senate filibuster, which has devolved into a super-majority threshold for any important legislation. These are all large factors, to be sure, but that list neglects what may be the biggest culprit in our current predicament: the childishness, ignorance, and growing incoherence of the public at large.

Anybody who says you can't have it both ways clearly hasn't been spending much time reading opinion polls lately. One year ago, 59...