For and against physiological interaction of mind and brain: Animists and Vitalists against Leibnitz and psycho-physical parallelism

Hansruedi ISLER
Zürich, Switzerland


G.W. Leibnitz, the polymath who invented binary arithmetic, differential calculus, and German philosophy, rejected the interaction of body and soul. G.E. Stahl's animist school of medicine attributed all functions of the body to the soul. Stahl's book "Skiamachia", 'shadow-fight' of 1720 is a dialogue of Stahl and Leibnitz on these differing views. The controversy survived up to now, sometimes known as the body-mind-problem. Leibnitz' division of the soul from the body was adopted by Boerhaave, and by his student, Haller, who taught Europe experimental physiology. Haller rejected de Sauvages' early electrical theory of nerve conduction, and similarly, Unzer's findings of cerebral tracts and his theory of reflex action as the principle of brain function, which Unzer had learned from Willis. Unzer belonged to the Animist school which was replaced by the Vitalist school in the late 18th century, positing a specific "life force" as the principle of all living matter. The head of that school, Reil, traced tracts in brains preserved in alcohol, coined the term 'psychiatry', and founded the first psychiatric hospitals in early 19th century. Prochaska, a Vitalist in Vienna, matched Unzer's brain research. Unzer and Prochaska were rediscovered by Laycock who translated their works in English. Laycock was the first and most influential teacher of Hughlings Jackson who, however, preferred to return to the doctrine of Leibnitz (known via Laycock), adopting psycho-physical parallelism in his doctrine of concomitance. Meanwhile, the Vitalist Johannes Mueller in Berlin launched his pupils Du Bois Reymond, Helmhotz, Bruecke and a score of others on paradigm-changing careers in the life sciences, especially the neurosciences. Those three became sworn enemies of Vitalism in favour of strict Mechanism, again isolating the body from the psyche. This may have been the origin of the still existing bias of historians against Vitalism and Animism. In the late 19th century, brain localization and motor neurophysiology demonstrated the causal interaction of body and mind, reviving the need for psycho-physiological links. Vitalism was resurrected to help out, in the form of R. Semon's Mnemism: living organisms were distinguished by their ability to record sensory stimuli as engrams, and to reproduce them (ecphore), both in individual and in genetic memory (Mneme). And Wundt, a student of Mueller and Helmhotz, attempted to reintegrate the sciences, from physics through experimental psychology to the psychology of peoples. - Conclusion: Leibnitz' psycho-physical parallelism protected the mainstream of the neurosciences from psychology, and psychology from physiology, while Animists and Vitalists used their psychophysiological perspectives to develop new patterns of discovery.


Session I -- Mind, Brain and Consciousness
Sunday, 2 June 2002, 8:45 am

Seventh Annual Meeting of the International Society for the History of the Neurosciences (ISHN)

Los Angeles, California, USA