Many American liberals live in political bubbles. Some people in overwhelmingly blue parts of the country, for example, were shocked to find that Trump got so many votes in 2016. (“I live in a rather special world. I only know one person who voted for [Richard] Nixon,” the film critic Pauline Kael famously said of the former president, acknowledging her own political bubble just weeks after Nixon smashed George McGovern in 1972.) Some of those same blue-area Democrats were just as confident that Senator Elizabeth Warren would be the party nominee. But Republicans also live in bubbles.

Human beings aren’t particularly comfortable hearing information that challenges our closely held beliefs, and the urge to reject evidence that goes against our political opinions is especially strong. Reading only certain websites or watching particular TV channels shields Americans from facts and opinions they don’t like, and geographic sorting protects partisans from unpleasant interactions with people who hold different beliefs. Political segregation in America has increased dramatically in the past decade. “For about one in five Republicans, and two in five Democrats, less than a quarter of their neighbors belong to the opposite political party,” according to a recent study published in Nature. In other words, Trump voters might find it hard to believe that Biden won the election because their neighbors and friends mostly voted for Trump too.