  Doing that involves not just the empirical study of mental disorder, but a strong interpretation of the medical model, with its commitment to a view of disease as not just a syndrome but a destructive process. It is certainly possible to collect data using the DSM concept of depression, especially information about epidemiology and natural history. In that sense normal medical reasoning can indeed be employed, but much medical reasoning is directed at trying to understand causes. It is here that we come to the strong interpretation, with its commitment to the idea that a mental disorder, like any other disease, is not just a construct to guide inquiry, but a genuine part of the causal structure of the biological world—a destructive entity with a distinctive pathophysiology which explains the observable phenomena that the minimal model is content with.