The quality of being fatuous; habitual foolishness combined with an absence of awareness of one's own stupidity.
From 'fatuous' (adjective) plus the noun-forming suffix '-ness', creating an abstract noun for the characteristic of being fatuous.
The fatuousness of confident wrongness appears throughout history—people who were absolutely certain about false facts often shaped world events, showing how dangerous foolishness can be when paired with certainty.
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