Many people tend to resist data that explicitly contradicts what they believe, and in an attempt to overcome uncomfortable cognitive dissonance, even doctors will occasionally try to explain away or justify new data. When strong beliefs, sometimes century-long beliefs, are disputed, people tend to double down. This is true for many people–from cult members, to respected researchers. And Dr. Marty Makary suggests that it’s notably present in medicine, and in the way we tend to groupthink.