The Dunning–Kruger effect is a cognitive bias in which an unskilled person makes poor decisions and arrives at erroneous conclusions, but their incompetence denies them the metacognitive ability to realize their mistakes. The unskilled therefore suffer from illusory superiority, rating their own ability as above average, much higher than it actually is, while the highly skilled underrate their abilities, suffering from illusory inferiority. This leads to the perverse situation in which less competent people rate their own ability higher than more competent people. It also explains why actual competence may weaken self-confidence: because competent individuals falsely assume that others have an equivalent understanding. “Thus, 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.”
The Dunning–Kruger effect was put forward by Justin Kruger and David Dunning. Similar notions have been expressed–albeit less scientifically–for some time. Dunning and Kruger themselves quote 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.”). The Dunning-Kruger effect is not, however, concerned narrowly with high-order cognitive skills (much less their application in the political realm during a particular era, which is what Russell was talking about.) Nor is it specifically limited to the observation that ignorance of a topic is conducive to overconfident assertions about it, which is what Darwin was saying. Indeed, Dunning et al. cite a study saying that 94% of college professors rank their work as “above average” (relative to their peers), to underscore that the highly intelligent and informed are hardly exempt. Rather, the effect is about paradoxical defects in perception of skill, in oneself and others, regardless of the particular skill and its intellectual demands, whether it is chess, playing golf or driving a car.