I've got my nose in a great book at the moment called Ahead of the Curve: Two Years at Harvard Business School by Philip Broughton, & came across a great excerpt from the book in which Broughton outlines the HBS learning model written in a 1954 essay called "Tough Mindedness and the Case Method" by Malcolm McNair, a former professor at the school. Certainly worth a scan:

William James, a great teacher of psychology and philosophy at Harvard during the early years of this century, made the useful distinction between people who are tough-minded and people who are tender-minded. These terms have nothing to do with levels of ethical conduct; the toughness referred to is toughness of the intellectual apparatus, toughness of the spirit, not toughness of the heart.

Essentially, it is the attitude and the qualities and the training that enable one to seize on facts and make these facts a basis for intelligent, courageous action. The tough-minded have a zest for tackling hard problems. They dare to grapple with the unfamiliar and wrest useful truth from stubborn new facts. They are not dismayed by change for they know that change at an accelerated tempo is the pattern of living, the only pattern on which successful action can by based.

Above all, the tough-minded do not wall themselves in with comfortable illusions. They do not rely on the easy precepts of tradition or on the mere conformity to regulations. They know that the answers are not in the book.