There’s a difference between how we see ourselves and how we really are. To be blunt; “If you’re incompetent, you can’t know you’re incompetent.”
Dunning wrote that “The skills you need to produce a right answer are exactly the skills you need to recognize what a right answer is.”
To make it even simpler, you don’t know what you don’t know. If you knew what something was, then you would know how much/little you know about it. If you don’t know what it is, then you can make no assessment and proceed in darkness.
Dunning and Kruger decided to run some experiments at Cornell University. They asked undergrads various questions. Then they asked each to estimate their overall score and compare it to the scores of the other participants.
The lowest-ranking students consistently and substantially overestimated their own ability.
Students in the bottom 25% thought that they out-performed two-thirds of the other students on average; they thought they were in the top 33%.
As most of us have learned in life; it is the stupidest person in the room who thinks he is the brightest.