What Is Mental Disorder? An Essay in Philosophy, Science, and Values

Imagine you are a member of the admissions committee for DSM-V. Your set of applications include night-eating syndrome, hoarding, racism, and Internet addiction. It is your job to decide if these are “real” psychiatric disorders worthy of inclusion in DSM-V. By what criteria would you decide if these applications represent a true mental disorder versus a non-disordered “problem of living” or social deviance?

In this thought-provoking book, clinical psychologist and philosopher Derek Bolton asks whether it is possible to develop a single clear definition of mental disorder to which such a committee could refer. Perhaps surprisingly, he reaches a negative conclusion, writing, “there is no natural, principled boundary between normal and abnormal conditions of suffering” (p. 194).

Much of Bolton’s book critiques the naturalist approach to mental illness. This idea—probably a comfortable one to many readers of this journal—is that there exists in the real world a clear distinction between mental health and disorder. All we have to do is be smart enough to find it and define it clearly. He evaluates several approaches to naturalist definitions of psychiatric disorders. However, he spends the most time on the influential work of Jerry Wakefield, which emphasizes an objective dysfunction of an evolved mental process, the consequences of which cause harm to the individual. At the risk of oversimplification, Bolton suggests that in principle it is just too hard to know what represents a dysfunction of an evolved mental system. Since Homo sapiens evolved in a social milieu, and many of our mental functions develop in an intertwined manner from both genetic and environmental factors, trying to distinguish social from evolutionary dysfunction may be inherently impossible. Problems could also arise when an evolved system is not really dysfunctional, but the environment has changed so dramatically that its impact has become harmful (perhaps an underlying explanation for the obesity epidemic). He argues that Wakefield, rather than trying to make the difficult determination of what functions have evolved for what purpose, actually uses a rough “understandability” measure when, for example, he argues that conduct disorder should not be applied to children growing up in some inner-city neighborhoods where gang membership might be adaptive or that depression should not be diagnosed when it occurs after a major loss. Bolton also examines and rejects the concept that mental disorders represent the breakdown of meaningful connections. With regard to the important issue of the abuse of psychiatry, as occurred in the former Soviet Union, he concludes that is more a task for governments and judicial systems than for psychiatric diagnostic manuals.

Ultimately, Bolton opts for a harm-based approach to defining what should go into our diagnostic manuals. That is the point of greatest consensus for all stakeholders in the business of mental health. He dislikes the term “disorder,” because in many of these syndromes, mental life remains ordered and meaningful.

I suspect most readers, like myself, will find this book a bit disturbing. We would much prefer a comfortable and neat and tidy solution to this boundary problem. Given the current ascendancy of the biological psychiatric paradigm, many of us want to ground ourselves in our physician identity and see ourselves as treating “real” biological disorders that can be cleanly and decisively separated from problems of living and social deviance. Bolton tries hard to puncture this comfortable belief system.

Bolton writes well, with only a modest amount of “philosophy-speak.” My main gripe is the book is not concise. Many of his well-developed arguments are repeated several times in different forms. I also think he underestimates the striking differences across disorders in seeking generic solutions to definitional questions about mental disorders.

I began this book with only a modest knowledge of the relevant literature and a rather naive sense that with a bit of “hard thinking,” we could come up with a clear, defensible definition of mental disorders. Upon completion, I no longer believed as such and have a much deeper appreciation of the subtlety and complexity of this definitional question. Did Bolton convince me the problem is intractable? Not quite, but my naiveté has surely been laid to rest.

Who should read this book? This book will be of most value to those who, because of their clinical or research work (or because they are contributing to current revisions of DSM and ICD manuals), are really interested in the problem of defining the boundaries of psychiatric illness. While it is not the easiest of reads, such individuals will be amply rewarded for their efforts. This book might be of interest to a wider group of individuals, from the fields of both mental health and philosophy, who want to see a good example of analytic philosophy being applied with skill and scholarship to a difficult real-world problem that really matters.