Add to ORKGSeveral philosophical accounts of disease are constructed around the idea that disease is a failure of physiological parts or processes to perform their biological function. Determining whether a phenotype—such as obesity—is a disease or determining the level of functioning at which some aspect of physiology—such as response to insulin—becomes pathological throws considerable weight on the concept of biological function. However, there are a number of philosophical theories of biological function, each of which defines function differently. It is not clear which theory, or combination of theories, we should use to explicate the medical conception of function. We have no systematic way to determine how biologists and medical practitioners co...