This dissertation is about ‘mental disorder.’ More specifically, the focus of this work will be a particular approach to understanding ‘mental disorder’ which I label “biological functionalism.” What the defenders of biological functionalism claim is that any successful account of disorder must take seriously the idea of natural dysfunction. Because ‘natural dysfunction’ is thought to be drawn directly from the facts of natural function, the biological functionalist goes on to assert that ‘natural dysfunction’ is free of evaluative content.
The relevance of this approach to ‘mental disorder’ lies in its implications for the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM). The DSM offers a definition of mental disorder which is intended to address certain concerns over the legitimacy of psychiatry. In particular, it is meant to answer anti-psychiatry critics who question the way the psychiatric establishment distinguishes between disorder and psychiatric normality. I argue that the DSM's efforts are not successful because a key component of its definition — ‘dysfunction’ — is left ambiguous.
To address this weakness, biological functionalism offers a naturalistic understanding of ‘dysfunction’ which supposedly honors the DSM's scientific focus. My main contention is that the biological functionalist project fails on two counts. The first flaw is in its execution. I argue that leading biological functionalist accounts do not pay proper respect to the practical commitments of psychiatry. But a second, more critical flaw occurs at the conceptual level. Biological functionalism fails to recognize that ‘dysfunction’ is an inherently evaluative concept. Consequently, the biological functionalist paradigm is left in a dilemma. It either commits the naturalistic fallacy; that is, it attempts to derive an evaluative sense of ‘dysfunction’ from a strictly explanatory sense of ‘natural function.’ Or it cannot account for the evaluative elements entailed by ‘dysfunction.’
In light of biological functionalism's failure, I go on to propose a different approach based on Martha Nussbaum's work on human development. My view seeks to answer psychiatry's critics while accounting for the evaluative nature of ‘dysfunction’ in a non-relativistic manner.