<p>A simple view of psychiatry sees mental and physical disorders in the same realm and that the definition and categorization of mental disorder should follow the same lines as physical disorder. This position is associated with the work of Kendell and Kass. In such a view, all disorders are free of value judgments. Boorse attempted to expand on this idea by defining an organism as &#147;healthy&#148; if it is not diseased, which he defined as interference with normative species function. For Boorse, a disease became an illness if it was undesirable, entitled a patient to treatment, and provided a valid excuse for otherwise abnormal behavior on the part of the sufferer, such as in the adoption of the &#147;sick role.&#148; Such views seem to provide an impoverished account of psychiatric disorder and mental illness, prompting Wakefield to attempt a definition of mental disorders as &#147;harmful dysfunctions&#148; involving the failure to perform a “natural function” for which a particular physiological mechanism had evolved. Wakefield added a value judgment to this definition in stipulating that such dysfunction is undesirable. Such a definition is problematic in that &#147;undesirability&#148; involves a form of relativism. In trying to define dysfunction in a more universal, naturalistic sense, much of the discussion of defining &#147;species normative functions&#148; for humans has followed the Aristotelian notion of capacity for rational thought as being the species normative function for humans. As such, a comprehensive account of psychiatric disorder necessitates it being, in essence, a physiological failure creating an undesirable failure of the capacity for rational thought. In contrast, the anti-psychiatrists, such as Szasz, saw mental disorder as a social construct created to marginalize those experiencing &#147;problems in living,&#148; making psychiatry a form of social agency.</p> <h4>ABOUT THE AUTHORS</h4> <p>Michael Robertson, MB, BS, FRANZCP, is Clinical Senior Lecturer, Discipline of Psychological Medicine, Central Clinical School — University of Sydney, Australia. Garry Walter, MB, BS, PhD, FRANZCP, is Professor of Child and Adolescent Psychiatry, University of Sydney, and Area Clinical Director, Child and Adolescent Mental Health Services, Northern Sydney Central Coast Health, NSW, Australia.</p> <p>Address correspondence to: Michael Robertson, MB, BS, FRANZCP: e-mail <a href="mailto:mrobertson@med.usyd.edu.au">mrobertson@med.usyd.edu.au</a>.</p> <p>Dr. Robertson and Dr. Walter have disclosed no relevant financial relationships.</p> <h4>EDUCATIONAL OBJECTIVES</h4> <ol> <li>Assess the philosophical underpinnings of psychiatric diagnosis.</li> <li>Describe the ethical implications of psychiatric diagnosis.</li> <li>Review the misuse of psychiatric diagnosis in recent history.</li> </ol>