The Dunning–Kruger effect is a cognitive bias in which the unskilled suffer from illusory superiority, mistakenly rating their ability much higher than average. This bias is attributed to a metacognitive inability of the unskilled to recognize their mistakes.
Actual competence may weaken self-confidence, as competent individuals may falsely assume that others have an equivalent understanding. As Kruger and Dunning conclude, “the miscalibration of the incompetent stems from an error about the self, whereas the miscalibration of the highly competent stems from an error about others” (p. 1127).
Although the Dunning–Kruger effect was put forward in 1999, David Dunning and Justin Kruger have quoted Charles Darwin (“Ignorance more frequently begets confidence than does knowledge”) and Bertrand Russell (“One of the painful things about our time is that those who feel certainty are stupid, and those with any imagination and understanding are filled with doubt and indecision”) as authors who have recognised the phenomenon.
Erol Morris has a fascinating interview with Dunning called The Anosognic’s Dilemma.
David Dunning, in his book “Self-Insight,” calls the Dunning-Kruger Effect “the anosognosia of everyday life.” When I first heard the word “anosognosia,” I had to look it up. Here’s one definition:.
Anosognosia is a condition in which a person who suffers from a disability seems unaware of or denies the existence of his or her disability. 
Dunning‘s juxtaposition of anosognosia with everyday life is a surprising and suggestive turn of phrase. After all, anosognosia comes originally from the world of neurology and is the name of a specific neurological disorder.
DAVID DUNNING: An anosognosic patient who is paralyzed simply does not know that he is paralyzed. If you put a pencil in front of them and ask them to pick up the pencil in front of their left hand they won’t do it. And you ask them why, and they’ll say, “Well, I’m tired,” or “I don’t need a pencil.” They literally aren’t alerted to their own paralysis.
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