"There are known knowns. There are things that we know that we know. There are known unknowns, that is to say, there are things that we now know we don't know. But there are also unknown unknowns. There are things we do not know we don't know, and each year we discover a few more of those unknown unknowns."
I think this notion of known knowns, known unknowns, and unknown unknowns can be applied to people in a variety of ways. For example, some folks carry themselves with a deserved confidence. They are bright, hardworking, and motivated. They enter into situations prepared. When they speak, their words carry weight and they are taken seriously. I would label these individuals as the known knowns.
There are also people who are somewhat dim-witted or who, for whatever reason, don't do their homework. Yet these folks have enough presence and self-awareness to make it clear to others that there are questions whose answers they don't know or topics where their opinions are vacuous or ill-informed. These folks are the known unknowns.
However, the class of people who I would label as unknown unknowns seem to typically have a very high opinion of themselves, think themselves quite clever, and act as if they are experts, when, in fact, they are completely detached from reality. When they speak it is clear even to a casual observer that they are incompetent and utter gibberish. They often are either wholly naive because they have been insulated and isolated, such that they think that their small world encompasses the full measure of reality, or they are windbags or buffoons. Often those that fall into this latter category have built up such an impenetrable wall around themselves that they are lost causes. They will fall prey to no amount of persuasion or argument. However, those unknown unknowns in the category of naive, sure can crumble when they finally get a glimpse of how little they understand or comprehend about topics or areas where they once thought so highly of themselves.
