Abstract
The management of low-grade fever in adults has not been codified. This gap is related not only to the numerous possible aetiologies but also to the difficulty of escaping the monocausal model of diseases. This article explores the complex issue of positive signs in 'psychogenic fever' through Reimann's 1930s series. The discussion emphasises Canguilhem's positions regarding vital signs and proposes (1) a semantic clarification of 'habitual hyperthermia' and (2) an amendment of the Belgian diagnostic criteria based on the concept of functional disorder. This paper also suggests following Peirce's pragmatism in the face of an uncommon clinical picture.