Skills that engender competence in a particular domain are often the very same skills necessary to evaluate competence in that domain one's own or anyone else's - Justin Kruger and David Dunning, in "Unskilled and Unaware of It: How Difficulties in Recognizing One's Own Incompetence Lead to Inflated Self-Assessment," Journal of Personality and Social Psychology, 1999, Vol. 77, No. 6, pp. 1121-1134
When we hear conjectures about a topic, a solution to a problem, that are not based on any principle, but rather on personal anecdote or unsubstantiated opinion, we must consider the speaker a candidate for the Kruger-Dunning Effect
