Capturing the will: Imposture, delusion, and exposure in Alfred Russel Wallace’s defence of spirit photography

•The Slade trial showed the impasse facing spiritualism in questions of imposture.•Wallace and Carpenter showed the impasses of spiritualism in questions of delusion.•Wallace thought Myers’ idea of the subliminal self threatened belief in objectivity.•Wallace argued spirit photography provided the best evidence for spiritualism.•Wallace’s defence of spirit photography rested on a form of mechanical objectivity.

The co-discoverer of natural selection, Alfred Russel Wallace, found himself deeply embroiled in a range of controversies surrounding the relationship between science and spiritualism. At the heart of these controversies lay a crisis of evidence in cases of delusion or imposture. He had the chance to observe the many epistemic impasses brought about by this crisis while participating in the trial of the American medium Henry Slade, and through his exchanges with the physiologist William Benjamin Carpenter and the psychical researcher Frederic Myers. These contexts help to explain the increasing value that Wallace placed on the evidence of spirit photography. He hoped that it could simultaneously break these impasses, while answering once and for all the interconnected questions of the unity of the psyche and the reliability of human observation.