Supervenience and psychiatry: Are mental disorders brain disorders?

Prominent psychiatrists have moved to rebrand psychiatry as clinical neuroscience and rechristen mental disorders as brain disorders. Recent shifts in research and funding priorities have followed suit, privileging neuroscience over psychological and behavioral research. With the possible exception of identifying general paresis with advanced syphilitic brain infection, however, no theorized identities between mental and brain disorders have been empirically corroborated. Consequently, we regard the thesis that mental disorders are brain disorders as an ontological hypothesis. Any robust formulation of the hypothesis that mental disorders are brain disorders logically requires the minimal thesis that mental disorders supervene upon brain disorders. A mental disorder supervenes upon a brain disorder if there could be no change in the mental disorder without a change in the brain disorder. In this paper we analyze contemporary diagnostic criteria used to individuate certain mental disorders to argue that at least some mental disorders fail to supervene upon brain disorders. Hence, we conclude that at least some mental disorders are not and cannot be (merely) brain disorders. This conclusion highlights a basic heterogeneity in psychiatry’s subject matter: some mental disorders constitutively involve psychological experiences or sociocultural relationships to the external environment that cannot be identified with or reduced to brain states or functioning. We propose that establishing cases of supervenience failure represents a method for discriminating between more robustly mental (as opposed to brain) disorders.