Mental disorder (earlier entitled “illness” or “disease”) is ascribed to deviations from normal thoughts, reasoning, feelings, attitudes, and actions that are considered socially or personally dysfunctional and apt for treatment. Schizophrenia, depression, and bipolar disorder are core examples. The concept of mental disorder plays a role in many domains, including medicine, social sciences such as psychology and anthropology, and the humanities, including literature and philosophy. Philosophical discussions are the primary focus of the present entry, which differs from the entry on (...) Philosophy of Psychiatry in noting several different approaches—not only those of the philosophy of science and mind, but also those arising from phenomenology and social theory. -/- Mental disorder is a widely contested concept and there are longstanding debates on whether disorders are biological or social in nature. Even uncontroversial disorders, such as those listed above, were not always regarded as disorders in the past (Porter 2002). Moreover, the status of mental disorder has frequently indicated ethical, as much as other deficiency (Irwin 2013). Such reminders direct our attention to contemporary medical psychiatry’s sometimes uncompromisingly neurobiological, and avowedly value-free “medical model”, with its incumbent analogies and assumptions, and to the general question of how the taxa of psychiatric classifications are to be viewed as objects of natural science. This model has received intensive philosophical scrutiny, including arguments that deny these conditions are deficiencies at all. Along with issues arising from cognitive psychology and the neurosciences, such foundational matters make up much of the following entry. Because of their focus on issues central to the philosophy of mind and ethics (e.g., the mind-body problem, moral responsibility, agency and identity), analyses of mental disorder have extensive implications for those fields. As clinical phenomena, they also reflect an inescapable, everyday, social reality, giving theoretical inquiries additionally urgent practical, moral, and legal implications. (shrink)