 One key question is whether the biomedical model is the most appropriate approach to psychological or mental conditions and their treatment. Some theorists have argued in favor of naturalistic accounts of disease, notably Thomas Szasz (1961, 1973, 1987). As a result, he famously claimed that “mental diseases” are a myth and do not exist because they do not result from tissue damage; in his view, all diseases must be correlated with this sort of physical damage. He thus argues that the concept of mental illness is a prescriptive concept used as though it were a merely descriptive one, and also a justificatory concept masquerading as an explanatory one. These conclusions lead him to a highly critical analysis of psychiatric practices, and to reclassifying such forms of suffering as “problems in living” rather than diseases. However it is not always clear in his account what his evidence for these claims is, and in particular whether he is making an in principle objection or one that is grounded in the history of the mistreatment of people with mental illnesses, and the disservice done to them in part because of the adoption of the medical model. In addition, some have noted that some psychiatric conditions do in fact correlate with physiologically detectable and other types of biological abnormalities. For instance twin studies have demonstrated that genetics is a major factor in the etiology of schizophrenia among other conditions typically considered to be psychiatric, although clearly not all conditions that are diagnosable according to contemporary psychiatric standards fit this model.