 At the bottom of the naturalist conception of disease (most influentially stated by Boorse (1975) and defended in Boorse (1997, 2014) is that the human body comprises organ systems that have natural functions from which they can depart in many ways. Some of these departures from normal functioning are harmless or beneficial, but others are not. The latter are ‘diseases’. So to call something a disease involves both a claim about the abnormal functioning of some bodily system and a judgment that the resulting abnormality is a bad one. Boorse uses‘illness’ to describe the concept of a disease that causes one’s life to deteriorate. This language is not universal, but the distinction between bodily malfunction and normative judgement is widely used. Naturalists contend that the determination of bodily malfunction is an objective matter to be determined by science. They may also argue (Boorse 1997) that determining whether a malfunction is detrimental to human well-being is also an objective matter, but often they concede that normative considerations are the basis for that judgment. So the naturalist position is that a disease is a bodily malfunction that causes one’s well-being to lessen. This malfunction could take many forms: it is not a necessary part of the naturalist case that diseases constitute a natural kind.