"An ignorant mind is precisely not a spotless, empty vessel, but one that’s filled with the clutter of irrelevant or misleading life experiences, theories, facts, intuitions, strategies, algorithms, heuristics, metaphors, and hunches that regrettably have the look and feel of useful and accurate knowledge.
"This clutter is an unfortunate by-product of one of our greatest strengths as a species. We are unbridled pattern recognizers and profligate theorizers. Often, our theories are good enough to get us through the day, or at least to an age when we can procreate. But our genius for creative storytelling, combined with our inability to detect our own ignorance, can sometimes lead to situations that are embarrassing, unfortunate, or downright dangerous—especially in a technologically advanced, complex democratic society that occasionally invests mistaken popular beliefs with immense destructive power...
"As the humorist Josh Billings once put it, 'It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so.' (Ironically, one thing many people 'know' about this quote is that it was first uttered by Mark Twain or Will Rogers—which just ain’t so.)"
- David Dunning, "We Are All Confident Idiots," 2014
Related: Dunning-Kruger Effect