  Proponents of the strong interpretation, then, can agree with Guze that there are distinct mental illnesses with characteristic symptoms and natural histories. But they go further. If psychiatry is really a branch of medicine, they suspect, we should see the specific causal hypotheses emerge about mechanisms that cause the symptoms of mental illness. Both Andreasen and Guze assume that to find the specific causes of disease we need a background theory of normal function. Psychopathology is to be identified as the departure of a psychological system from its proper state. (We should note what counts as a malfunction is often contested in psychology and neuroscience. Furthermore, the presence of a malfunction does not suffice for mental illness. Most scholars agree that our thoughts about the nature of disease are sensitive to biological abnormalities but are also guided by judgments that such abnormalities impede human flourishing (See Cooper 2007, Murphy 2006, Sadler 2004, Wakefield 1992). The medical model also sees abnormalities or dysfunctions as necessary but not sufficient for mental illness. The broader issues involved will be put aside here. Our question is: how far can psychiatry adopt medical reasoning about pathogenic neurobiological processes? )