Feynman warns about the dangers of absolute certainty, particularly when people become convinced that their beliefs cannot be questioned. In the wider passage, he links dogmatism with attempts to force others to accept the same views and with behaviour that may contradict the principles being defended.

The quotation reflects Feynman’s broader preference for doubt, openness and the willingness to revise beliefs. His point is not that strong convictions are inherently harmful, but that certainty becomes dangerous when it removes the possibility of criticism or correction. When ideas are treated as beyond question, disagreement can be interpreted as disloyalty rather than as an opportunity for examination. The remark therefore connects intellectual humility with political and social restraint, suggesting that societies are better protected when beliefs remain open to evidence, argument and reconsideration.

Full quotation

“Looking back at the worst times, it always seems that they were times in which there were people who believed with absolute faith and absolute dogmatism in something. And they were so serious in this matter that they insisted that the rest of the world agree with them. And then they would do things that were directly inconsistent with their own beliefs in order to maintain that what they said was true.”