Seite 235 [235]
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 micro¬
and 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 (phi¬
losophy 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 Fech¬
ner (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 ¢