The crucial problem in the philosophy of psychiatry is to determine under which conditions certain behaviors, mental states, and personality traits should be regarded as symptoms of mental illnesses. Participants in the debate can be placed on a continuum of positions. On the one side of the continuum, there are naturalists who maintain that the concept of mental illness can be explained by relying on the conceptual apparatus of the natural sciences, such as biology and neuroscience. On the other side (...) of the continuum, there are normativists who maintain that the appropriate characterization of the concept of mental illness cannot avoid reference to epistemic, moral and other social values. Although, this article is primarily an introduction to the debate, we stress the importance of the normativist positions. (shrink)