During its development, two distinct definitions of “mental disorder” were drafted for the DSM-5. The first was an iteration of the previous DSM definition and took mental disorder to be a value-laden concept, i.e. it claimed that disorders are necessarily harmful. The second definition characterized mental disorder as mental dysfunction, and aimed to offer a value-free account. The working groups said that a decision between these two definitions would be made at a later date. Note that philosophers of medicine generally hold that value-laden and value-free accounts of disorder are competing accounts. To be consistent one has to opt for one or the other.
However, when the DSM-5 was finally published, the definition of ‘disorder’ sought a compromise between the two draft definitions. According to the DSM-5,
"A mental disorder is a syndrome characterized by clinically significant disturbance in an individual’s cognition, emotion regulation, or behaviour that reflects a dysfunction in the psychological, biological, or developmental processes underlying mental functioning. Mental disorders are usually associated with significant distress or disability in social, occupational, or other important activities…" (emphasis added, DSM-5, p. 20)
This definition bears no resemblance to the sorts of definition via necessary and sufficient conditions that philosophers tend to propose; in any particular case it is unclear whether harm is needed prior to diagnosis or not. Philosophers tend to think that clarity is a good thing, and from such a stance the DSM-5 definition of mental disorder looks to be a very bad definition.
However, a different tradition has it that in certain contexts ambiguity may be useful, and rather than being refined away, may be retained, or even created. In The Concept of Law (1961), H.L.A. Hart discusses the “open texture” of language, and how it enables judges to employ sensible discretion in the application of rules. The rule may say “No vehicles in the park” but the ambiguity of “vehicle” means that the judge is left free to make sensible and context-specific decisions about bikes, wheelchairs, skateboards and so on. Specifying in advance exactly what would count as a “vehicle” would not be helpful.
The definition of “mental disorder” included in the DSM-5 can perhaps best be understood as answering such goals. In failing to provide necessary and sufficient criteria for a condition to count as a disorder it places no constraints on what might be added to the classification in the future. And, from a certain point of view this might be considered a useful feature. Those who speak ambiguously now, leave themselves free to claim what they wish later.
This article has been posted on behalf of Rachel Cooper, who is a senior lecturer in philosophy at Lancaster University.
Her new book Diagnosing the Diagnostic and Statistical Manual of Mental Disorders will be published by Karnac later this year.