Mental disorders have been suggested to differ from somatic diseases because they lack an organic correlate. We show that this argument is both empirically wrong and theoretically irrelevant, because diseases are defined by functional impairments and not biological variation. Due to human diversity, a multitude of functions can be defined, and any selection of medically relevant functional impairments is necessarily value-based. We suggest that such values include individual survival and living in a shared world with others, and that their definition (...) requires public debate and a critical reflection by Philosophical Anthropology. However, the presence of functional impairments that are generally relevant for human life and survival only fulfils the so-called disease criterion, which is necessary but not sufficient to diagnose a clinically relevant malady. This would only be justified if such functional impairments cause individual harm, either because they are accompanied by suffering (the illness criterion) or because they interfere with basic activities of daily living such as personal hygiene and food intake (the sickness criterion of a clinically relevant malady). We apply this theory to mental disorders, conclude that only a fraction of such “disorders” currently listed in international classifications of diseases are clinically relevant mental maladies, suggest focusing on the needs of persons with such maladies and recommend avoiding “pathologization” of human diversity. (shrink)