This is a very, very dangerous heuristic. Competence does not imply the ability to articulate said competence. Many (most? all?) competences are in the doing, n

This is a very, very dangerous heuristic. Competence does not imply the ability to articulate said competence. Many (most? all?) competences are in the doing, not the saying. Articulation is its own competence, and there's a bridge from one to the other, but only a bridge. It is so dangerous because you are more likely to write someone off (yourself or others) if the articulation requirement isn't met. When it's others that you write off, you compound whatever latent Dunning-Kruger effect you may be experiencing. When it's yourself, you then open yourself to distortion caused by the Dunning-Kruger effect in others. eg, "he seems to know what he's talking about" etc.