Clinical judgment, expert programs, and cognitive style: a counter-essay in the logic of diagnosis

The question of the extent to which one can rationally reconstruct the process of medical diagnosis and reduce it to an algorithm is explored. The act of diagnostic insight is such that a computational program cannot 'catch on' in the way that a competent diagnostician can. Clinical diagnostic reasoning in a particular case requires as a necessary condition an extraordinarily complex and rich structure of background knowledge as well as an intuitive element, such as is manifest when one 'catches on' to a joke. Computers cannot 'catch on' due to their limitations in the computational mode. As a consequence, there can be no computer simulation of an essential element in diagnostic procedures.