Classifications in psychiatry: a conceptual history

Background: Historical accounts of psychiatric classifications have hithert o been written in terms of a 'received view'. This contains two assumptions , that: (i) the activity of classifying is inherent to the human mind; and (ii) psychiatric 'phenomena' are stable natural objects. Objectives: The aim of this article is to provide an outline of the evoluti on of psychiatric classifications from the perspective of conceptual histor y. This is defined as a theoretical and empirical inquiry into the principl es, sortal techniques and contexts in which alienists carried out their tas k. It assumes that all psychiatric classifications are cultural products, a nd endeavours to answer the question of whether classificatory models impor ted from the natural sciences can be applied to man-made constructs (such a s mental illness) definitionally based on 'personalised semantics'. Methods: Exemplars of classificatory activity are first mapped and contextu alised. Then, it is suggested that in each historical period crafting class ifications has been like playing a game of chess with each move being gover ned by rules. This is illustrated by offering an analysis of the 1860-1861 French debate on classification. Results and Conclusions: (1) Medicine is not a contemplative but a modifica tory activity and hence classifications are only valuable if they can relea se new information about the object classified. (2) It should not be inferr ed from the fact that psychiatric classifications are not working well (i.e . that they only behave as actuarial devices) that they must be given up. C onceptual work needs to continue to identify 'invariants' (i.e. stable elem ents that anchor classifications to 'nature'. (3) Because mental disorders are more than unstable behavioural epiphenomena wrapped around stable molec ular changes, 'neurobiological' invariants may not do. Stability depends up on time frames. Furthermore, it is unlikely that gene-based classifications will ever be considered as classifications of mental disorders. For once, they would have low predictive power because of their lack of information a bout the defining codes of mental illness. 'Social' and 'psychological' inv ariants have problems of their own.