In one chapter, Gladwell described how the US security expert Gregory Treverton distinguished between puzzles and mysteries. Puzzles are there when we lack some essential information to a factual answer. If we obtain that information, we get the answer. For example, Osama bin Laden’s whereabouts are a puzzle. If you hunt down high ranking people in Al Qaeda who knows his hiding place, you find the answer.
In contrast, mysteries require judgments and the assessments of uncertainty. For example, what would happen to Iraq after overthrowing Saddam Hussein was a mystery. You cannot get the answer even if his officials and sons honestly reply to your every question. The major difference between puzzles and mysteries is that in the latter condition, you are not having insufficient information. You just cannot make use of the information at hand.
Of course, not every one would agree to the definitions. However, when you are trying to solve a problem, it is useful to think why you have not got the answer yet and how the answer can be obtained. Without the insight, wrong moves will get you nowhere.
Many medical students spend countless hours reading textbooks and lecture notes without realizing that their future job demands mostly the ability to solve mysteries. If I ask you the tests for diagnosing pulmonary embolism, it is a simple puzzle one can solve by reading a textbook. The trouble is patients never ask you what the diagnostic tests are. They just tell you a symptom and show abnormalities here and there. If you cannot make the diagnosis, it is unlikely because you have not heard of pulmonary embolism before. Instead, you are probably overwhelmed by the information you cannot fully interpret and organize. Simply said, the answer is not in a textbook.