Logic structure of clinical judgment and its relation to medical and psychiatric semiology.

BACKGROUND The logical nature of clinical judgment has been conceptualized in different ways, but a clear connection between the features of clinical judgment and those of semiology is still lacking. METHODS The characteristics of clinical judgment, medical semiology, and psychiatric semiology are described. Connections between them are drawn. RESULTS Clinical judgment is described as an abductive inference. Abductive inferences are especially useful to balance universal and singular information. In psychiatric semiology, due to some specific features, a careful balance between the information present in descriptive definitions and the information absent from the definition but present in singular symptoms is needed. The main types of out-of-definition information are reviewed. CONCLUSIONS The implications of the results for diagnosis and research are drawn.