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HERMANN LOTZE — SCIENCE, BELIEF AND THE LATE NINETEENTH CENTURY completely separated from philosophy, and was even in contradiction with the latter." In the field of medicine Friedrich Wilhelm Schelling (1775-1854) took a prominent place in Germany with his philosophy of nature, an anti-mechanical worldview. His speculative approach gave rise to romantic medical thinking and neglected empirical research. He studied the parallelism between the microand macrocosmos. He spoke of the ens mori, affections that entered the body. He belonged to the last surge of speculative medicine. Even in 1827 Alexander von Humboldt (1769-1859) had attacked speculative Naturphilosophie (philosophy of nature).’ Lotze would criticise the romantic vitalistic speculations in medicine and defend a mechanistic view, as prepared by Descartes with his man as machine (homme-machine). Descartes too was interested in physiology. His research in optics and neurophysiology was remarkable.® It is also notable that Lotze’s doctoral dissertation on philosophy had, among others, Descartes as its theme. Not only physics but also psychology underwent a transition and became a science. The widespread opinion that the activities and contents of the mind could never be measured, and would remain subjective, was contradicted in the early the nineteenth century by Ernst H. Weber (1795-1878) and Gustav Fechner (1801-1887), two teachers of Lotze. They related physical stimuli to mental experiences. Among other things Weber studied the two-point threshold, a case of measuring the smallest distance noticeable to touch at various parts of the body. He ascertained that the smallest threshold (1 mm) was situated on the tongue, the largest (60 mm) on the back. Gustav Fechner, a colleague of Wilhelm Wundt’s (1832-1920), studied medicine at Leipzig, where Weber was teaching. He perfected Weber’s Law, by stating that the perceived difference of weight is not absolute, but depends in fact on the height of the weights compared. The recognizable difference is expressed as a fraction (1/40), regardless ofthe weights concerned. Fechner changed the law in a logarithmic formula. Lotze too was to make a contribution towards psychology, namely by establishing his theory of Local Signs, which describes the formation of spatial awareness, by means of the sensations of eye muscle movement in combination with spatial movement of the body. The “local signs” are marks which accompany the sensations produced through stimulation of the sensory nerves of the organ. Science was in tutelage to the natural sciences and to mathematics. The pantometric thinking was omnipresent and corresponded with Descartes’ res 6 Rapport van de Gulbenkian Commissie, 1996, 13. 7 Cf. SLuaa, Hans, Gottlob Frege, London — Boston — Henby, Routledge & Kegan Paul, 1980, 14. 8 Sacy, Samuel S de, Descartes par lui-méme, Paris, Seuil, 1956, 69-83. * 233 ¢
