examine Dodge's abdomen, which had been poked and prodded many times by many physicians, and to reassure her that irritable bowel syndrome, while uncomfortable and annoying, should be treated as the internist had recommended, with an appropriate diet and tranquilizers.

But that is exactly what Falchuk did not do. Instead, he began to question, and listen, and observe, and then to think differently about Dodge's case. And by doing so, he saved her life, because for 15 years a key aspect of her illness had been missed.

Complex Matter
What goes on in a doctor's mind as he or she treats a patient is a complex matter. Older physicians often complain that each new generation of young doctors is not as insightful or competent as its forebears. Such criticism is couched like this: "When I was in training 30 years ago, there was real rigor and we had to know our stuff. Nowadays, well . . ." These wistful, aging doctors speak as if some magic that transformed them into consummate clinicians has disappeared. Until recently, I confess, I shared that nostalgic sensibility.

But there also were major flaws in my own medical training. My generation was never explicitly taught how to think clinically. We learned medicine catch-as-catch-can. Trainees observed senior physicians the way apprentices observed master craftsmen in a medieval guild. Somehow, the novices were supposed to assimilate their elders' approach to diagnosis and treatment. Rarely did an attending physician actually explain the mental steps that led to a decision.

Over the past few years, there has been a sharp reaction against this catch-as-catch-can approach. Medical students and residents are now taught to follow preset algorithms and practice guidelines in the form of decision trees. For

To restore her system, her internist had told Dodge to consume 3,000 calories a day, mostly in easily digestible carbohydrates like cereals and pasta. But the more Dodge ate, the worse she felt. Her doctor said she had developed irritable bowel syndrome, in addition to anorexia and bulimia.

example, a common symptom like "sore throat" would begin the algorithm, followed by a series of branches with "yes" or "no" questions about associated symptoms. Is there a fever? Are the lymph nodes swollen? Have other family members suffered a sore throat? A laboratory test like a throat culture for bacteria would appear farther down the tree, with "yes" or "no" branches based on the results of the culture. Ultimately, following the branches to the end should lead to the correct diagnosis and therapy.

Clinical algorithms can be useful for run-of-the-mill diagnosis and treatment—distinguishing strep throat from viral pharyngitis, for example. But they quickly fall apart when symptoms are vague or multiple and confusing, or when test results are inexact. In such cases—the kinds of cases where we most need a

discerning doctor—algorithms discourage physicians from thinking independently and creatively. Instead of expanding a doctor's thinking, they can constrain it.

Similarly, a movement is afoot to base all treatment decisions strictly on statistically proven data. This so-called evidence-based medicine is rapidly becoming the canon in many hospitals. Treatments outside the statistically proven are considered taboo until a sufficient body of data can be generated from clinical trials. Of course, every doctor should consider research studies in choosing a therapy. But rigid reliance on evidence-based medicine risks having the doctor choose care passively, solely by the numbers. Statistics embody averages, not individuals.

In recent years, I have watched the students and residents on my service eye their algorithms and then invoke statistics from recent studies. I concluded that the next generation of doctors was being conditioned to function like a well-programmed computer, within a strict binary framework. My growing unease about trainees' reliance on algorithms and evidence-based therapies alone, and my equally unsettling sense that I didn't know how to broaden their perspective, led me to ask a simple question: How should a doctor think?

This question, not surprisingly, spawned others: Do different doctors think differently? Are different forms of thinking more or less prevalent among the different specialties? In other words, do surgeons think differently from internists? Is there one "best" way to think, or are there multiple, alternative styles that can reach a correct diagnosis and choose the most effective treatment? How does a doctor think when forced to improvise, when confronted with a problem for which there is little or no precedent? (Here algorithms are essentially irrelevant and statistical evidence is absent.) How does a doctor's thinking differ during routine