  Liberal eugenics arguments often start by recognizing the value of treatment of disease. Disease, typically defined as a negative departure from species typical functioning (Boorse 1975; Daniels 1994), can interfere with an individual’s participation in society and/or individual flourishing. Buchanan et al. (2000) link disease to a reduction of opportunity, and so argue that provision of medical treatment for disease is a way for the state to promote equality of opportunity. Parents are obliged to ensure that their children get medical treatment for diseases and can be charged with negligence if they fail to do so. This obligation does not obtain in cases of diseases that result in relatively small negative effects on participation (e.g., mild asthma) or where the potential benefits of treatment are still somewhat uncertain or might be outweighed by the possible harms (e.g., some cancer treatments). Parents whose conceptions of the good life do not include medical treatment for serious diseases – as in some religious communities – are not allowed to impose this view on their children because the children deserve the opportunity to choose to adopt those views or not when they are adults. Mandatory life-saving treatment of their childhood diseases helps to ensure that they survive to make such decisions as adults (Feinberg 1980). This requirement has been the subject of some debate (see, e.g., DesAutels, Battin and May 1999).