Helmholtz, Du Bois-Reymond, and the Transcendent Diculty of Explaining the Relation Between Sensations and the Physical World

According to Hermann von Helmholtz, sensations are signs (symbols) that external causes impress on our sense organs; those signs are then used by themind to acquire knowledge of the reality. Helmholtz’s work points out the di›culty of dening a notion of causality suitable for explaining the relation between sensations on the one hand and the physical world on the other. In fact, he states that: 1) Physical stimuli, understood as the causal origins of sensations, are unknowable in themselves; 2) ere is no empirical evidence for the kind of causality fromwhich sensations originate; 3) A transcendental causality is nothing but the urge of the intellect to know everything. It is necessary to keep in mind that Helmholtz is a committed empiricist: therefore, he believes that all knowledge originates from sensations. He tries avoiding commitments with any kind of pre-established harmony between the two sides of the causal relation. at is to say, sensible perceptions give us information about the peculiarities of the external world, but the relation between sensations and the reality should be explained and should not be taken for granted. In this paper, I study Helmholtz’s struggles with providing a suitable explanation of that relation; in doing so, I also make use of Emile Du Bois-Reymond’s work concerning the limits of human understanding, and in particular the transcendent di›culty of grasping the origins of sensations.