We do not say: “He really knows about what he is talking about.”
We say “He really knows what he is talking about.” And when we say this, we are making a tacit distinction between knowing and knowing about.
*
If a person has been in a situation, wrestled with the concrete realities of that situation, particularly those that have resisted conceptualization and explicit language, and then subsequently reflected upon these realities and found ways to conceptualize this experience, this person knows what he is talking about.
And even if such a person is unable to conceptualize or articulate fully what he has experienced, he will be able to identify people who do or do not know what they’re talking about.
*
Until a student of some topic has been in a situation and wrestled with the concrete realities of that situation and attempted to apply his acquired knowledge to act within the situation, he does not know to what degree he knows what he is talking about.
My own experience has shown me again and again that preparatory study of any area I am preparing to research in the field is merely preparatory, and that this knowledge will inevitably undergo deep and unpredictable developments. Only when I return from the field do I really know what I am talking about. This has happened to me again and again — I know what I am talking about.
*
Were it not for the interpretive gap – that deep gulf between theory and practice that dogs the inexperienced – we would have no need to say “He knows what he is talking about.” The ability to talk about some topic would establish the fact that what needs knowing is known.
Maybe some people who say “he knows what he is talking about” are making a different distinction: that this person is relating facts that he really has learned by studying credible sources, as opposed to “making up what he is talking about.” But then we should ask: what makes a source credible? And we should also ask whether we would still say this masterful student knows what he is talking about if he is unable to apply this knowledge practically. He would be promptly re-classified as merely “book smart” or “academic”.
*
There’s a huge difference between studying a subject prior to having experienced the realities it attempts to conceptualize and studying it after one has experienced them.
Reading is far more rewarding when you know you are reading an author who really knows what he’s talking about. It is not a matter of trusting the author and feeling confident that the author is both honest and well-informed. It is a matter of experiencing the truth of what is being said. This is true of all subjects, especially philosophy.
*
People who know what they are talking about in one subject gain a certain kind of meta-knowledge about experience and expertise. Or, to put it more succinctly, they acquire bullshit detectors.