From http://metamodern.com/2009/05/17/how-to-understand-everything-and-why/

To avoid blunders and absurdities, to recognize cross-disciplinary opportunities, and to make sense of new ideas, requires knowledge of at least the outlines of every field that might be relevant to the topics of interest. By knowing the outlines of a field, I mean knowing the answers, to some reasonable approximation, to questions like these:

What are the physical phenomena? What causes them? What are their magnitudes? When might they be important? How well are they understood? How well can they be modeled? What do they make possible? What do they forbid?

And even more fundamental than these are questions of knowledge about knowledge:

What is known today? What are the gaps in what I know? When would I need to know more to solve a problem? How could I find what I need?