Scientific American – Science denialism is not just a simple matter of logic or ignorance:  “Americans increasingly exist in highly polarized, informationally insulated ideological communities occupying their own information universes. Within segments of the political blogosphere, global warming is dismissed as either a hoax or so uncertain as to be unworthy of response. Within other geographic or online communities, the science of vaccine safety, fluoridated drinking water and genetically modified foods is distorted or ignored. There is a marked gap in expressed concern over the coronavirus depending on political party affiliation, apparently based in part on partisan disagreements over factual issues like the effectiveness of social distancing or the actual COVID-19 death rate. In theory, resolving factual disputes should be relatively easy: Just present strong evidence, or evidence of a strong expert consensus. This approach succeeds most of the time, when the issue is, say, the atomic weight of hydrogen. But things don’t work that way when scientific advice presents a picture that threatens someone’s perceived interests or ideological worldview. In practice, it turns out that one’s political, religious or ethnic identity quite effectively predicts one’s willingness to accept expertise on any given politicized issue. “Motivated reasoning” is what social scientists call the process of deciding what evidence to accept based on the conclusion one prefers. As I explain in my book, “The Truth About Denial,” this very human tendency applies to all kinds of facts about the physical world, economic history and current events…”