 There is little reason to expect scientific and common sense concepts to agree in general, so if medicine and everyday thought disagree about disease, we may ask which concept should be adopted. If we wish to distil a concept that can play a role in medical inquiry, we may side with the scientists. But such proposals, which argue for a sharp separation between scientific and folk uses, are not neutral pieces of observation about the language. They are proposals for purging science from commonsense constraints that hinder its development. A revisionist view of this sort, in this case, says that our concepts of health and disease might be a necessary starting point but should not constrain where the inquiry ends up. Other forms of revisionism are possible. A revisionist naturalist argues that we should follow the science where it takes us and come up with concepts that further scientific inquiry, for example, even if that means that we eventually use the language in ways that look bizarre from the standpoint of current common sense. But a revisionist constructivist could argue that our thought, whether medical or lay, should be reformed in the service of other goals, such as emancipation for hitherto oppressed groups. Such revisionist thought was important in overturning the psychiatric view, dominant until the 1970s, that homosexuality is a mental illness. Activists argued that homosexuality was diagnosed for offensive moral reasons and not for medical ones and the classification of homosexuality as a disease was changed as a result of lobbying on moral grounds rather than on the basis of any new discovery. Naturalists will respond that this was not an example of using constructivism for emancipatory ends, but of bringing psychiatrists to understand that they were not obeying their own naturalist principles about mental disorder, and showing them that there was no good reason to retain the diagnosis. Much debate between naturalists and constructivists involves competing histories in just this way. Constructivists strive to uncover the role that moral and social values have always played in medical diagnosis and argue that our disease categories are hence not properly naturalistic. Naturalists, though they must concede that many diagnoses have been based on moral values that we would now renounce, still insist that the concept of disease, when correctly applied, as it often is, is thoroughly naturalistic and not impugned by past failures by the medical profession to live up to its own scientific ambitions.