So how can you tell when voters are acting out of prejudice? Again, Smith says, employment discrimination law provides a useful analogy. In discrimination cases, courts look for pretexts. If someone gives a reason for a hiring decision that is obviously false or makes little sense in context, the court has good reason to believe that prejudice or bias may have influenced the hiring decision.

Trump’s unprecedented, compulsive, easily documented lying during the 2016 campaign made him an irrational choice. It’s reasonable to conclude that voters were willing to swallow the falsehoods because they liked what they heard: overt racist appeals and incessant lies about rising crime rates. Research has since suggested that plenty of Trump voters were indeed strongly motivated by racist resentment and anti-immigrant animus.