Abstract

Categorising mental disorders for purposes of diagnosis, research and practice has historically been justified on philosophical terms as a pragmatic activity; categories which have been subject to wide-ranging philosophical critique have been defended on the grounds that they serve as heuristic devices providing loose representations of shared experiences, not labels for real structures. In acknowledgement of this, there has been increasing recognition that subclassifying multiple discrete forms of persistent depression moves too far away from the notion of a heuristic and that attempts to create more precise categories become less clinically useful. Hence the most recent Diagnostic and Statistical Manual of Mental Disorders (V.5) and International Classification of Diseases (V.11) both group persistent forms of depression together. However, the UK National Institute for Health and Care Excellence has delineated certain subclassifications of persistent depression in its new guideline, which grossly distorts the phenomenology of depression. This approach commits a fundamental philosophical error in conflating absence of knowledge with knowledge of absence. In this sense, the new guideline appears to be engaging in an activity akin to the digital game Minecraft, in which the craft of building structures from units of construction is largely divorced from the laws of physics. The risk of ignoring these philosophical errors and making false claims about scientific plausibility is that the guideline recommendations inevitably represent a highly distorted phenomenology of depression and will be of very little value to patients or practitioners looking for guidance on best possible treatment options.