Defining Disease: Much Ado about Nothing?

Abstract

Medical science, of course, tries hard to characterise more definitely and fully the symptoms and causes of particular conditions generally referred to as diseases. Equally obviously, clinicians are called upon all the time to make diagnoses — to decide, against the background provided for them by the present state of medical science, and on the basis of their perceptions of the signs and symptoms, whether or not someone under their care has a particular condition: lung cancer, diabetes mellitus, congestive heart failure, or whatever. There is often a good deal of uncertainty about such judgments. Doctors strive hard to become more skilled at making them, and some philosophers — employing techniques from decision theory and artificial intelligence — have tried to help them. The topic of this paper, however, is not judgments of this sort, but rather of a second sort that medics are also sometimes called upon to make. These are second-level or meta-level judgments of the following kind: having identified some definite set of signs and symptoms, and being, let’s suppose, confident that they have diagnosed the correct condition, clinicians may then be called upon to decide whether or not that condition amounts to a genuine disease or illness. They often feel very uncomfortable about such judgments. Perhaps philosophers, with their expertise in conceptual matters, can provide significant help here by providing a clear-cut and defensible characterisation, not of any particular disease (that seems clearly a purely scientific issue), but of the class of diseases — of what might be called “disease-in-general.”