"Risks and Riddles"

The Soviet Union was a puzzle. Al Qaeda is a mystery. Why we need to know the difference By Gregory F. Treverton

There's a reason millions of people try to solve crossword puzzles each day. Amid the well-ordered combat between a puzzler's mind and the blank boxes waiting to be filled, there is satisfaction along with frustration. Even when you can't find the right answer, you know it exists. Puzzles can be solved; they have answers.

But a mystery offers no such comfort. It poses a question that has no definitive answer because the answer is contingent; it depends on a future interaction of many factors, known and unknown. A mystery cannot be answered; it can only be framed, by identifying the critical factors and applying some sense of how they have interacted in the past and might interact in the future. A mystery is an attempt to define ambiguities."

While few doctors would put it this way, they act upon something that might be called Bayesian mystery framing. Bayes' theorem is a statistical technique for adjusting subjective probabilities in light of new, but inconclusive, evidence. Doctors base an initial assessment of a patient's health on propensity, as revealed by his or her medical history, and on diagnosis, determined through an examination. If the doctor's initial assessment is of a high probability of disease, he or she orders more tests, which in turn refine that probability. For chronic concerns, such as high blood pressure leading to heart disease, the initial assessment leads to a decision about whether and how to treat, followed by subsequent tests to see if the original probability of problems can be revised downward.