Controversy about psychiatric disease categories is ubiquitous. Do fidgety young boys have a disease that goes by the name "Attention Deficit Hyperactivity Disorder"? Should a person who grieves the death of a spouse be excluded from a diagnosis of depression? Are psychiatric disease categories coextensive with specific abnormalities of brain physiology? This book—a collection of fifteen chapters written by prominent figures in psychiatry and philosophy of psychiatry—addresses such questions of psychiatric nosology: the logic of psychiatric diseases.