Imperceptible Signs: Remnants of Magnétisme in Scientific Discourses on Hypnotism in Late Nineteenth-Century France

In 1880s France, hypnotism enjoyed unique medico-scientific legitimacy. This was in striking contrast to preceding decades when its precursor, 'magnétisme animal', was rejected by the medical/academic establishment as a disreputable, supernaturally tinged practice. Did the legitimation of hypnotism result from researchers repudiating any reference to the wondrous? Or did strands of magnetic thinking persist? This article interrogates the relations among hypnotism, 'magnétisme', and the domain of the wondrous through close analysis of scientific texts on hypnotism. In question is the notion that somnambulist subjects possessed hyperacute senses, enabling them to perceive usually imperceptible signs, and thus inadvertently to denature researchers' experiments (a phenomenon known as unconscious suggestion). The article explores researchers' uncritical and unanimous acceptance of these ideas, arguing that they originate in a holdover from 'magnétisme'. This complicates our understanding of the continuities and discontinuities between science and a precursor "pseudo-science" and, more narrowly, of the notorious Salpêtrière-Nancy "battle" over hypnotism.