The distinction between mental disorders and brain disorders is a distinction that allows for many borderline cases. There are hundreds of mental disorders that a psychiatrist might diagnose. Although the diversity of their forms and origins might tempt one to give up on the idea of mental disorders, it would be too quick to reject that idea solely on the grounds. Although the theoretical challenges that originate in the diversity of mental disorders may be shared across the life sciences, there are other challenges that are more peculiarly psychiatric, and that are not shared by other branches of medicine. It has long been known that the brain plays a central role in the creation of the mind, but rather little is known about the way in which that role is to be explained. There are open questions about how it is that mental processes are grounded in the brain’s physical properties, whether those mental processes are disorderly or not.