There's much that can be said about how so many words turn out, in fact, to be very poorly understood especially if when using common sense as basis for definit

There's much that can be said about how so many words turn out, in fact, to be very poorly understood especially if when using common sense as basis for definition---but the point is, the article is talking about learning from a scientific standpoint, so the colloquial sense of "knowledge" is irrelevant.