1. The ancient Greeks enjoined us to "know thyself".
And in the last line of Magnum Force (1973), Inspector Harry Callahan (Clint Eastwood) memorably said: "A man's GOT to know his limitations."
To know one's limitation is part of knowing oneself; but it was not from the Greek, but from the Reformed apologist Cornelius Van Til (1895-1987), that I learned the importance of this concept.
Van Til called the concept "epistemological self-consciousness".
Epistemology is just a fancy word for theory of knowledge.
Thus, one is epistemologically self-conscious if:
(a) one knows what one is thinking,
(b) one knows why one is thinking what one is thinking, and
(c) one knows how one is thinking what one is thinking.
2. To know "what" one is thinking and "why" one is thinking what one is thinking require first-order and second-order reflections.
But the "how" of thinking is a different animal of the epistemological zoo.
There is a branch of study called "methodology" that is devoted to the "how" of knowledge.
And learning theory is that part of methodology that study how we acquire new knowledge.
Among the methods that we use to acquire new knowledge, two are particularly important:
(a) The dialectic method; and
(b) The scientific method.
3. In the quotation below, Bertrand Russell (1872-1970) succinctly defined and explained the dialectic method, indicated its limitation and contrasted it with the scientific method.
What I find particular valuable is Russell's discussion of the limitations of the dialectic method.
Many discuss the dialectic method without indicating its limitations.
So paraphrasing Inspector Callahan, as a man got to know his limitations so a man got to know the limitations of his tools, be those tools intellectual tools.
4. (Russell  1982, 109-111):
Dialectic, that is to say, the method of seeking knowledge by question and answer, was not invented by Socrates. It seems to have been first practised systematically by Zeno, the disciple of Parmenides; in Plato's dialogue Parmenides, Zeno subjects Socrates to the same kind of treatment to which, elsewhere in Plato, Socrates subjects others. But there is every reason to suppose that Socrates practised and developed the method. As we saw, when Socrates is condemned to death he reflects happily that in the next world he can go on asking questions for ever, and cannot be put to death, as he will be immortal. Certainly, if he practised dialectic in the way described in the Apology, the hostility to him is easily explained: all the hambugs in Athens would combine against him.
The dialectic method is suitable for some questions, and unsuitable for others. Perhaps this helped to determine the character of Plato's inquires, which were, for the most part, such as could be dealt with in this way. And through Plato's influence, most subsequent philosophy has been bounded by the limitations resulting from his method.
Some matters are obviously unsuitable for treatment in this way -- empirical science, for example. It is true that Galileo used dialogues to advocate his theories, but that was only to overcome prejudice -- the positive grounds for his discoveries could not be inserted in a dialogue without great artificiality. Socrates, in Plato's works, always pretends that he is only eliciting knowledge already possessed by the man he is questioning; on this ground, he compares himself to a midwife. When, in the Phaedo and the Meno, he applies his method to geometrical problems, he has to ask leading questions which any judge would disallow. The method is in harmony with the doctrine of reminiscence, according to which we learn by remembering that we knew in a former existence. As against this view, consider any discovery that has been made by means of the microscope, say the spread of diseases by bacteria; it can hardly be maintained that such knowledge can be elicited from a previously ignorant person by the method of question and answer.
The matters that are suitable for treatment by the Socratic method are those as to which we have already enough knowledge to come to the right conclusion, but have failed, through confusion of thought or lack of analysis, to make the best logical use of what we know. A question such as 'what is justice?' is eminently suited for discussion in a Platonic dialogue. We all freely use the words 'just' and 'unjust', and, by examining the ways in which we use them, we can arrive inductively at the definition that will best suit with usage. All that is needed is knowledge of how the words in question are used. But when our inquiry is concluded, we have made only a linguistic discovery, not a discovery in ethics.
We can, however, apply the method profitably to a somewhat larger class of cases. Wherever what is debated is logical rather than factual, discussion is a good method of eliciting truth. Suppose someone maintains, for example, that democracy is good, but persons holding certain opinions should not be allowed to vote, we may convict him of inconsistency, and prove to him that at least one of his two assertions must be more or less erroneous. Logical errors are, I think, of greater practical importance than many people believe; they enable their perpetrators to hold the comfortable opinion on every subject in turn. Any logically coherent body of doctrine is sure to be in part painful and contrary to current prejudices. The dialectic method -- or, more generally, the habit of unfettered discussion -- tends to promote logical consistency, and is in this way useful. But it is quite unavailing when the object is to discover new facts. Perhaps 'philosophy' might be defined as the sum-total of those inquiries that can be pursued by Plato's methods. But if this definition is appropriate, that is because of Plato's influence upon subsequent philosophers.
Russell, Bertrand.  1982. History of Western Philosophy and its Connection with Political and Social Circumstances from the Earliest Times to the Present Day. 2nd ed. London: Unwin Paperbacks. (Orig. pub. 1946.)