Kieran Egan asserts: “Nearly everyone who has tried to describe an image of the educated person, from Plato to the present, includes at least two criteria: first, that educated people must be widely knowledgeable and, second, that they must know something in depth. The first criterion is [-p.6] fairly straightforward – pretty well everyone associates being well educated with knowing a fair amount about the world, about its history and geography, about politics in their own and other countries, about what is generally going on in the sciences, about the arts and literature, and so on. That is, a person who really has learned, retained, and somehow made meaningful the curriculum that has been taught in school satisfies the breadth criterion. In addition, we expect that breadth of knowledge not to be some loose assemblage of facts, but also to involve some conceptual schemes that give it order and give the person some general understanding, and we also expect the educated person to have developed habits of critical reflection on what is known, along with a commitment to continuous learning. Such a person is equipped with the knowledge and skills that a modern society requires.
The depth criterion is there because most commentators on education recognize that having a relatively superficial knowledge of many things is somehow not adequate to give an understanding of, to put it a bit vaguely – as it usually is put – the way knowledge works, or the nature of knowledge, or the insecurity of knowledge. By learning something in depth we come to grasp it from the inside, as it were, rather than the way in which we remain always somehow on the outside of that accumulated breadth of knowledge. With regard to the knowledge we learn in breadth, we rely always on the expertise of others; when learning in depth, we develop our own expertise. It is assumed that learning something in depth carries over to a better understanding of all our other, ‘breadth,’ knowledge.
In everyday classrooms, teachers commonly try to achieve both breadth and depth by covering a topic in a general way and exploring some particular themes in more detail, or by allowing students to choose projects they can pursue in more depth within an overall unit of study. The main curriculum provision schools make for achieving the depth criterion is to enable students in high schools to specialize in something or to develop specialized skills as part of vocational preparation. But in terms of satisfying the depth criterion, these faint moves don’t begin to have an [-p.7] impact on the problem. They merely encourage students to learn something a little less superficially.” (pp.5-7)
Egan also notes that: “It is usually assumed, as far as the school system is concerned, that the depth criterion is a bit of a luxury and available mainly to the more academic students or to those in wealthy private schools; the breadth criterion is what we mostly struggle with for the mass of students most of the time – ensuring exposure to and coverage of the general information we consider essential for an effective citizen in today’s world.” (p.7)
Ref: (italics in original; emphases in blue bold mine) Kieran Egan (c2010) Learning in Depth: A Simple Innovation That Can Transform Schooling. University of Chicago Press: Chicago and London