ICD-11 and operationalism: response

To the Editor

I thank Dr Saraga for this observation, with which I am in full agreement. Just as the recipe is not the cake, an operational definition of a disorder is not an operational diagnosis of a case. In inexperienced hands, each may turn out badly. The confusion of the two is a category error. I have long taught that the proper place of operational diagnostic criteria is for confirming that the idiographic, narrative-based diagnoses made case-wise by clinicians conform to a minimum nomothetic data set (Carroll, 1984, 2012). Before there could be operational diagnostic criteria there first had to be a construct of what was being diagnosed. Nowadays, however, the tail wags the dog and, like shadows on the wall of Plato’s cave, the summary criteria are taken to instantiate the construct. As Dr Saraga notes, the practice of checklist diagnosis is a shallow substitute for an educated psychopathological assessment. The physicist Percy Bridgman, who introduced operationalism in science, would be aghast: the framers of DSM-III mistook a simple nominalist description for a complex cognitive operation.