Medicine, Health Care and Philosophy 4: 37–46, 2001. © 2001 Kluwer Academic Publishers. Printed in the Netherlands. On the difficulty of defining disease: A Darwinian perspective

Abstract. Most attempts to craft a definition of disease seem to have tackled two tasks simultaneously: 1) trying to create a series of inclusion and exclusion criteria that correspond to medical usage of the word disease and 2) using this definition to understand the essence of what disease is. The first task has been somewhat accomplished, but cannot reach closure because the concept of “disease ” is based on a prototype, not a logical category. The second task cannot be accomplished by deduction, but only by understanding how the body works and what each component is for, in evolutionary detail. An evolutionary view of the origins of the body and its vulnerabilities that result in disease provides an objective foundation for recognizing pathology. Our social definition of disease will remain contentious, however, because values vary, and because the label “disease ” changes judgments about the moral status of people with various conditions, and their rights to medical and social resources. Key words: Darwinian perspective, defence mechanisms, disease concept, evolution, genetic traits The problem of defining disease has occupied so many good minds for so long with so much continuing contention, that it seems foolhardy for a nonspecialist to even venture thoughts on the issue. However, the very lack of consensus suggests that the question ma