Psychiatry is the branch of medicine that deals with mental disease. Almost universally, a language (descriptive psychopathology) (DP) is now used to record the symptoms of mental disease, and it consists of a vocabulary, a syntax, assumptions about the nature of behaviour, and some application rules. This language was composed in Europe during the first half of the nineteenth century, and has proved to be surprisingly stable. It is likely that both neurobiological and psychological and social factors are responsible for this stability which, at least in theory, depends on: a) the durability of the cognitive or social aims of the ‘community of users’ or ‘thought collective’, b) the permanency of the object of inquiry itself, namely the neurobiological signal, and c) the dynamic matching between object and the language of description. Descriptive psychopathology is thus a conceptual network meshing observer, patient and symptoms together.

Mental symptoms are (mostly) intermittent and quantitative variations in speech and human action. The latter, in turn, are complex, theory-bound states. It follows that attempts at producing ‘atheoretical’ or ‘phenomenological’ descriptions of mental signs and symptoms are misconceived. Successful description in psychiatry consists in little more than the obtention of reliable morsels of behaviour which, hopefully, still contain enough of the biological signal which caused them in the first place and which provides the information for diagnosis, treatment, and research. Infelicitous descriptions, or descriptions ‘manqué’ are likely to be a common occurrence in the daily affairs of psychiatric practice.