CAN we cure our ailing health care system by sending in more doctors? That is the treatment prescribed by the Association of American Medical Colleges, which has recommended increasing the number of doctors they train by 30 percent, in large part to keep up with the growing number of elderly patients. But the most serious problems facing our health care system — accelerating costs, poor quality of care and the rising ranks of the uninsured — cannot be solved by more doctors. In fact, that approach, like prescribing more drugs for an already overmedicated patient, may only make things worse....