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.