ertainty and similar states of “knowing what we know” arise out of primary brain mechanisms that, like love or anger, function independently of rationality or reason. Feeling correct or certain isn’t a deliberate conclusion or conscious choice. It is a mental sensation that happens to us. The importance of being aware that certainty has involuntary neurological roots cannot be overstated. If science can shame us into questioning the nature of conviction, we might develop some degree of tolerance and an increased willingness to consider alternative ideas — from opposing religious or scientific views to contrary opinions at the dinner table.