Chiara Russo Krauss - Wundt, Avenarius, and Scientific Psychology: A Debate at the Turn of the Twentieth Century

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This research is part of the project Scientific Philosophy: Avenarius, Petzoldt and the Berlin Group, founded by SIR program (MIURItaly), and conducted at the University of Naples Federico II. For the archival documents consulted during the research, the author thanks the following: Staatsbibliothek zu Berlin - Preuischer Kulturbesitz. Handschriftsabteilung (Richard Avenarius Nachlass); Universittsarchiv - Leipzig (Wilhelm Wundts letters); and Universittsbibliothek der Karl-Marx-Universitt Leipzig, Abteilung fr Handschriften und Inkunabeln. This book is a revised and translated version of Chiara Russo Krauss, Con Wundt, oltre Wundt. Richard Avenarius e il dibattito sulla psicologia scientifica tra Otto e Novecento , Soveria Mannelli: Rubbettino, 2016. The author thanks Rubbettino for the permission to publish the translation, and Palgrave Macmillan for making this book available to an international audience.

At the beginning of the nineteenth century, psychology was still regarded as the branch of philosophy studying the soul. However, the situation changed rapidly as the development of experimental physiology resulted more and more in the adoption of scientific methods for the study of phenomena that seemed only classifiable as psychical.

Over the course of a century, Europeand Germany in particularexperienced breathtaking advances in the knowledge of living organisms. Johannes Mller (18011858) trained a whole generation of experimental physiologists. Mathias Schleiden (18041881), Theodor Schwann (18101882), and Rudolf Virchow (18211902) put to good use the recent improvement of microscope optic and developed the first cellular theories. Justus von Liebig (18031873) made a great contribution to the development of organic chemistry. But the list goes on.

This scientific renewal led to the unfolding of a grand research program, aiming at questioning the assumptions of the so-called Naturphilosophie, i.e., the speculative biology that was based on the assumption of a teleological living force animating organic matter. In its place, this new trend affirmed the possibility and necessity of a mechanistic explanation of living beings.

As soon as the perceptual apparatus and the nervous system became the objects of research, the advances in the field of physiology impacted significantly on psychology too. The focus was increasingly on the organisms reaction to stimuli. Ernst Weber (17951878) and Gustav Theodor Fechner (18011887) formulated the law that mathematically described the relationship between the change in a physical stimulus and the change in perception. Charles Bell (17741842), Franois Magendie (17831855), Marshall Hall (17901857), and Hermann von Helmholtz (18211894) outlined the phenomenon of reflex arc, according to which peripherical signals travel toward the central nervous system through sensory nerves, from where a response departs, that proceeds centrifugally down the motor nerves.

As a result, from the field of pure physiology, a new science originated, named psychophysics by Fechner . He defined it as the exact science of the functional or dependency relations between body and mind. An ancient task, indeed. Nonetheless, what was new was how this discipline intended to tackle such a task: by building on experience and mathematical connections of empirical facts (Fechner , V).