Blurred boundaries between the normal and the pathological are a recurrent theme in almost every publication concerned with the classification of mental disorders. However, systematic approaches that take into account the philosophical discussions about vagueness are rare.

This is the first volume to systematically draw various lines of philosophical and psychiatric inquiry together, including the debates about categorical versus dimensional approaches in current psychiatric classification systems, the principles of psychiatric classification, the problem of prodromal phases and sub-threshold disorders, and the problem of over-diagnosis in psychiatry, and to explore the connections of these debates to philosophical discussions about vagueness.

The book consists of three parts. The first part encompasses historical and recent philosophical positions regarding the nature of demarcation problems in nosology. Here, the authors discuss the pros and cons of gradualist approaches to health and disease, and the relevance of philosophical discussions of vagueness for these debates. The second part of the book narrows the focus to psychiatric nosology. The authors approach the vagueness of psychiatric classification by drawing on contentious medical categories, such as PTSD or schizophrenia, and on the dilemmas of day-to-day diagnostic and therapeutic practice. Against this background, the chapters critically evaluate how current revisions of the ICD and DSM manuals conceptualise mental disorders and how they are applied in various contexts. The third part is concerned with social, moral, and legal implications that arise when being mentally ill is a matter of degree. Not surprisingly, the law is ill-equipped to deal with these
challenges due to its binary logic. Still, the authors show that there are more and less reasonable ways of dealing with blurred boundaries and of arriving at warranted decisions in hard cases.

About the Author:
Geert Keil, Professor of Philosophy, Department of Philosophy, Humboldt University, Berlin, Lara Keuck, Research Fellow, Humboldt University Berlin, Department of History, Rico Hauswald, Research Fellow, Dresden University of Technology, Department of Philosophy

Geert Keil is Professor of Philosophy at Humboldt-Universitat Berlin. He studied philosophy, linguistics and German literature at the Universities of Bochum and Hamburg. In 1991, he received his PhD with a book on philosophical naturalism. In 1999 he received his Habilitation (second dissertation) with a book on causation and agency. Awarded with a Feodor Lynen scholarship of the Humboldt Foundation and a Heisenberg scholarship of the German Research Foundation (DFG), he was a visiting scholar at the Universities of Trondheim, Stanford and Basel. From 2005 to 2010 he held a chair in theoretical philosophy at RWTH Aachen University. He co-directed the research project "Dealing Reasonably with Blurred Boundaries" (2009-2013). His main areas of research are the philosophy of mind and action, philosophy of language, epistemology and metaphysics.

Lara Keuck is a Research Scholar at the Department of History at Humboldt University Berlin and a 'Society in Science - Branco Weiss Fellow' of ETH Zurich. Her research interests lie in the history and philosophy of the biomedical sciences, broadly construed. She has published on epistemological issues surrounding the classification and modelling of mental disorders in History and Philosophy of the Life Sciences, Medicine Studies, Journal of Medical Ethics, and Studies in History and Philosophy of Biological and Biomedical Sciences. In 2012, she was awarded the Prize for Philosophy in Psychiatry of the German Association of Psychiatry, Psychotherapy and Psychosomatics (DGPPN).

Rico Hauswald studied philosophy and sociology in Dresden, Germany, and Fribourg, Switzerland. In 2013, he did his PhD at Humboldt University of Berlin with a thesis about the classification of people in the social and medical sciences. He is currently a research fellow at Dresden University of Technology. His areas of specialization include the philosophy of medicine, general philosophy of science, social epistemology, and social ontology. His recent publications include "The Ontology of Interactive Kinds" (forthcoming in the Journal of Social Ontology), the monograph Soziale Pluralitaten (Munster: Mentis 2014), and the volume Warum ist uberhaupt etwas und nicht vielmehr nichts? (Hamburg: Meiner 2013, co-edited with D. Schubbe and J. Lemanski).