Cognitive Dissonance
The unpleasant mental state that arises when our thoughts about the world conflict with reality or with one another. Leon Festinger named the phenomenon in 1957 after studying a UFO doomsday cult whose predictions failed: rather than abandon their beliefs, members doubled down. The brain seeks internal harmony, so when faced with new evidence that conflicts with existing beliefs, it often makes an unconscious decision to ignore the evidence in order to protect the belief — even when the belief is demonstrably false.