The red-blue split on mammograms is particularly striking. In a recent poll, the Pew Research Center asked 1,002 American adults about [the task force's] conclusion that most women can safely begin mammograms at age 50, not 40, and have one every two years, not annually. (Large studies have found that earlier mammograms save almost no lives; since the radiation can cause cancer, it therefore makes sense to minimize them.) Among Republicans, 15 percent agreed with that. Among Democrats? Twice as many.

One reason, of course, is that the mammogram wars have become entangled in health-care reform, with accusations that the advice is part of a dastardly plot to ration care…. But something else is going on, something that speaks to how traits of personality affect political leanings. Since people do not pore over oncology studies and reach their own conclusion on the credibility of the science, they have to trust experts — or not. And thus the partisan divide: Republicans tend to distrust “elites,” especially now that the GOP is more Palin than George H.W. Bush or other scion of the white-shoe establishment. In the mammogram debate, that distrust encompasses pointy-headed scientists and makes those who disdain “the reality-based community,” as an aide to George W. Bush called scientists, go with the “common sense” view that mammograms save lives.

Conservatives, part of whose ideology is to respect and protect the status quo, tend to engage in … “systems justification” more than liberals, tending to view corporations, markets, government, and other institutions as legitimate and benign. Acknowledging climate change means recognizing “shortcomings of the current system” and “admitting that the status quo must change.