One of the eXCltmg challenges of medicine has been the reaching of decisions based on less than complete evidence. As undergraduates in teaching hospitals future physicians are taught to think in clear and absolute black and white terms. Diagnoses in teaching hospitals all are based on supportive positive findings of in- vestigations. Treatment follows logically on precise diagnosis. When patients die the causes of death are confirmed at autopsy. How very different is real life in clinical practice, and particularly in family medicine. By the very nature of the common conditions that present...