 Some might argue that ordinary usage is ideological, shaped by false failure to be conscious of the insights of social and interactionist models. But defining “disability” in rough conformity to ordinary usage hardly implies that its referents are selected by biomedical criteria, let alone that the traits selected cause the disadvantages faced by their bearers or dictate the appropriate social response to those disadvantages. Rather, this view on what “disability” and “people with disabilities” refer to is compatible with a wide variety of positions on how those referents are picked out: e.g., by biomedical criteria; by the rules of a civil-rights movement; by the assumptions of the dominant ideology about bodily dysfunction; or by the demands of justice. The extent to which what counts as a disability, or a person with a disability, varies with context will depend on the account adopted; on biomedical accounts, the extension of “disability” will be as stable as human biology; on other accounts, it will change with changing social norms, economic needs, or political developments. Further, on some accounts, the referents will have common features, identifiable by inspection; on others, what they have in common can only be understood in terms of an ideology or a theory of justice.