Schizophrenia and Major depressive episodes should certainly be included in the category of mental disorders. There is no need to suppose that mental disorders must always be, or always not be, the result of chemical imbalances, or of physical perturbations. While still recognizing that hopelessness or pessimism can sometimes qualify as being the symptoms of a mental disorder, even in cases where a bout of flu exacerbates them. Other disorders of the body can also manifest themselves in the contours of their sufferer’s mental life. Although hyperthyroidism is a bodily disorder, and not a mental one, it does typically manifest itself mentally, in a nervous and edgy mood. The problem is about mental causation quite generally, and not only about a sort of causation that is involved in cases of free will. It arises because it is hard to see how mental events can ever cause things, whether or not an exercise of free will occurs when they do so.