This is the third of four appendices to _Psychologism:_A_Case _Study_in_the_Sociology_of_Philosophical_Knowledge_ by Martin Kusch. These appendices will not appear in the printed version. The contents list and the first chapter of the book are also available on the Internet. All copyright: Martin Kusch The printed version of the entire book is available from Routledge: Title: Psychologism Subtitle: A Case Study in the Sociology of Philosophical Knowledge Author: Martin Kusch Series: Philosophical Issues in Science Publisher: Routledge HB: 0415 125545 PB: 0415 125553 For more information contact: philosophy@routledge.com ------------------------------------------------------- APPENDIX III: THE DOCTRINAL BACKGROUND OF THE NEW PSYCHOLOGY Philosophical Background Much of the German philosophical doctrinal background has been succinctly analysed by David Leary (1978, 1980), and I shall here follow his account. Leary shows convincingly that Kant's philosophy of science as well as Kant's sceptical perception of both rational and empirical psychology provided the starting point for subsequent philosophers like Fries, Herbart and Beneke. These philosophers rejected Kant's scepticism with regard to empirical psychology, and thus paved the way for the new experimental psychology. Kant held that rational psychology was impossible, and that empirical psychology could not be raised to the level of a genuine natural science. The idea of a rational psychology was ill-conceived because the nature of the human soul could not be known a priori. Empirical psychology, on the other hand, was seen as a valid enterprise by Kant. At the same time, however, he also argued that the character of the subject matter of empirical psychology, i.e. the human soul, put severe limits on what psychology could achieve as a science. To begin with, because the soul had no spatial dimension, psychology could not employ mathematical tools and thus could not formulate "rational principles", that is, necessary, mathematical laws. At best, laws of psychology were vague generalisations, or, as Kant put it, "laws of experience". Moreover, empirical psychology was also impaired by its reliance upon introspection. Introspection was an insufficient source of information since, firstly, mental experiences could not be altered and invoked at will - thus psychological experimentation was impossible; secondly, the observation of a mental event often altered its nature; and, thirdly, the psychologist was confined to a description of his own mental states. Kant allowed for the possibility that psychology could overcome some of these obstacles by using an "anthropological" methodology based upon the external senses. However, even the anthropological method, i.e. the study of world history, biography, plays and novels, enabled psychology to formulate no more than vague "laws of experience". Turning from Kant to his critics, Jakob Friedrich Fries (1773-1843) defended not only introspection as a scientific method, but also the notion that psychology could be based on rational principles. Developing further Kant's method rather than his speculative ideas, Fries held that psychology was the basic science for all other fields of knowledge, including philosophy. Fries claimed that Kant himself had used empirical and introspective material in his analysis of reason. Indeed, Fries suggested that a priori and transcendental forms of knowledge could only be identified by studying empirical material obtained through introspection. Moreover, as Fries saw it, the fact that introspection occasionally proved unreliable was no reason for rejecting it altogether as the central source of data in psychology. After all, no-one demanded that one rejected the information obtained through the external senses just because the latter also turned out to be unreliable from time to time. Finally, Fries was convinced that psychology could be a proper natural science: it could be based on rational principles that were identified through a critical study of mental phenomena. According to Fries, such principles included the principle of the basic activity of the mind, and the principle of the threefold division of mental faculties. Other phenomena of mental experience were to be explained with reference to such principles. The next step in the series of re-evaluations of Kant's scepticism concerning empirical psychology was taken by Johann Friedrich Herbart (1776-1841). Like Fries before him, Herbart too saw his own work as a continuation of Kant's critical philosophy. Of Fries' work, Herbart wrote that "if Kant were still alive and still possessed his former vigorous powers of thinking, no one would be better able to induce him to revise his system than Herr Fries" (quoted from Leary 1978: 117). However, Herbart disagreed with Fries over the position of psychology within philosophy. For Herbart, psychology was not the basis of all philosophy. Instead, Herbart regarded psychology as a branch of applied metaphysics. Moreover, Herbart saw a way of transforming psychology into a truly mathematical science. Here he took his starting point from Kant who had suggested that psychological phenomena could be treated mathematically - if at all - only by attending to their varying degrees of intensity over time. Herbart assigned numerical values to different degrees of intensity, and assumed that the increase in the intensity of one "presentation" (_Vorstellung_) would have to result in the proportional decrease in the intensity of another presentation. Based on these assumptions, Herbart sought to explain the dynamics of psychological processes by means of an equilibrium model which could be described with mathematical equations. Finally, the last cornerstone of Kant's case against empirical psychology, i.e. his claim that experimentation was impossible in psychology, was rejected by Friedrich Eduard Beneke (1798-1854). Beneke agreed with Herbart's general idea that mathematics should be introduced into psychology, but he felt that Herbart's attempt to quantify psychological phenomena was insufficiently empirical. Beneke suggested that more precise observations of psychological processes were needed, and that these could best be obtained in and through psychological experiments. Although he never carried out psychological experiments himself, Beneke demanded that psychologists should develop their theories, and test them, under controlled conditions and with the systematic variation of variables. Thus, by the 1840s, Kant's key assumptions about empirical psychology - that it could not use mathematical methods, that it could not have a rational core of a priori principles, that it could not be experimental, and that its results were inevitably weakened by its reliance upon introspection - had all been rejected by philosophers who saw themselves as working within a Kantian framework. Kant's scepticism regarding empirical psychology also influenced the leading German Idealists, i.e. Fichte, Schelling, and Hegel, as well as their followers (Leary 1980). All three major German Idealists were by and large antipsychological, although their reasons for this attitude differed from Kant's. For these philosophers psychology was an inadequate science of the human being mainly because it was individualistic, and tended to ignore the shaping of the individual in and through processes of socialisation. This came out especially clearly in Hegel in whose system the isolated individual was but the first, and lowest, level in the teleological development towards the absolute spirit. Idealistic psychology was developed mainly by followers of the three major idealists. Central to the Fichtean psychologists like G.E.A. Mehmel and Karl Fortlage were three Fichtean ideas. The first was a concept of "consciousness" according to which consciousness contained both the subject and the object of knowledge. As these authors saw it, philosophy aimed for a systematic description, a "phenomenology", of consciousness. The second key concept was that of an ever active ego which increasingly overcame the opposition between itself and the world. This idea in turn led to the third central notion, "voluntarism". This was the view that the basic manifestation of the ego's activity was the will. Psychologists in the tradition of Schelling (e.g. Gotthilf Heinrich von Schubert and Karl Gustav Carus) followed their master not only in his emphasis on the unconscious, but also in two other respects. On the one hand, they took up the idea that "inner" spirit and outer nature were ultimately identical. This view strongly influenced Fechner's work on psychophysics. On the other hand, they also held that a systematic science must develop knowledge historically. Thus they wrote books entitled _History_of_the_Soul_, or _On_the_Developmental_History_of_the_Soul_, books which traced the gradual development of consciousness from plants through animals to humans. These perspectives led Carus to engage in comparative psychology, physiology and phrenology. Finally, Hegel had insisted that mind is "not inert being but, on the contrary, absolutely restless being, pure activity". He had opposed reifying different moments of the mind's activity into distinct faculties, and had stressed the "living unity" of the mind. Equally central in Hegel's work had been an emphasis on historical development and social psychology. Some Hegelian psychologists, for instance C.L. Michelet, took up this last theme in particular, and discussed different racial and social types. (This work was soon to influence the _Voelkerpsychologie_ of the Herbartians Lazarus and Steinthal.) It was mainly due to Hegel's work that it became a respectable enterprise to explore the 'mind' of different cultures through a study of art, language, myth, and custom. Other Hegelians opposed empirical methods and were more concerned to apply Hegelian dialectics to the speculative study of consciousness. This direction was informed by the Hegelian view that psychology studied mental processes qua mental, i.e. that psychology excluded from its domain both sensations and specific contents of consciousness. This emphasis led Hegelian writers to ignore physiology of the day. In the end, many psychological writings by Hegelians ended up providing little more than commentaries upon Hegel's own psychological writings. In sum, idealistic psychology provided many key concepts which became prominent in later psychology. It also influenced the development of voluntarism and the emergence of a social-psychological perspective, encouraging a genetic approach as well as comparative studies. However, idealistic psychologists opposed experimental work in psychology, and the more empirically oriented work of writers like Beneke. Before leaving the philosophical background of the new psychology, we need to look at one philosopher not mentioned by Leary. This philosopher is Herrmann Lotze (1817-1881). It is not easy to label Lotze or to place him in any one philosophical camp. He was an interesting transition figure between German Idealism and the subsequent realism and naturalism. Most of Lotze's writings were fairly traditional philosophy, but he also published, in 1852, a book entitled _Medicinische_Psychologie,_oder_Physiologie_der _Seele_. It was primarily Lotze's theory of "local signs"as expounded in this book which became influential in psychology. In order to give a genetic rather than a nativistic theory of perception, Lotze suggested that when stimulated each point on the retina or skin gave rise, firstly, to a sensation that could be associated with sensations from other points on the retina or skin and, secondly, served as an indication or sign of 'where' the sensation came from in external space (Murray 1988: 192-3). It is strong evidence for Lotze's life-long interest in, and advocacy of, empirical psychology that he taught a course on empirical psychology throughout most of his academic career (i.e. from 1842 until 1881) (Russell 1966). Both G.E. Mueller and Stumpf must be counted among his students. Indeed, G.E. Mueller was appointed to Lotze's chair in Gttingen when the latter left for the more prestigious chair in Berlin. Mueller obtained the chair on Lotze's expressed recommendation though he was only 31 years old, lacked teaching experience, and had not been the faculty's first choice (Ash 1980a: 259). Physiology Moving on to the physiological background to the new psychology, I shall confine myself here to the work of Johannes Mueller, Herrmann von Helmholtz and Ernst Heinrich Weber. Johannes Mueller (1801-58) was the central figure in the development of physiology. From 1833 onwards, Mueller headed the most important German physiology laboratory at the University of Berlin. From that central location, Mueller peopled German universities with his students, and by 1850 every German university had a professorship in physiology. It has been suggested that in this respect Mueller achieved for physiology what Wundt was soon to do for the new psychology (Murray 1988: 170). Mueller's biological-empirical, i.e. qualitative and comparative, physiology dominated German physiology until the 1850s, when it was pushed aside by an experimental form of physiology, based on physics and chemistry. The new experimental physiology was developed and advocated by Carl Ludwig, as well as by Mueller's own students like Herrmann von Helmholtz, and Emil Du Bois- Raymond (Verwey 1985: 53). Mueller's most influential contribution to physiology was his "theory of the specific energies of the senses", first formulated in 1826. This theory claimed that "any given nerve has specific effects independent of the nature of its stimulation ... [and conversely] ... the same objective stimulus gives rise to altogether different sensations as it stimulates different sense-nerves" (Meyering 1989: 136). Helmholtz never tired of emphasising the importance of this theory and wrote that what other scholars had only vaguely anticipated, "left Mueller's hands in the form of classical perfection, a scientific achievement whose value I am inclined to consider equivalent to the discovery of the law of gravity" (quoted from Verwey 1985: 59). Helmholtz's (1821-1894) prominence in the pre-history and history of experimental psychology is hard to exaggerate. His main contributions to psychology were his studies on vision and audition, i.e. his _Handbuch_der_physiologischen _Optik_ (1856-66) and his _Lehre_von_den_Tonempfin- dungen_ (1863). In the latter work, Helmholtz's main advance over earlier contributions was his combining of acoustic theory with anatomy, in his explanations of how the ear could transform air vibrations into sensations, and in his account of how the ear was able to detect individual sounds within a complex of sounds (Murray 1988: 186). Of Helmholtz's classical, three-volume _Optik_, two doctrines were especially influential. In volume II, Helmholtz formulated a physiological theory of colour mixture that is now referred to as the Helmholtz-Young theory of vision. In order to explain colour mixing, one needed to assume only that the eye was equipped with three kinds of fibre, one that responded to red light, one that responded to green light, and one that responded to blue-violet light (Murray 1988: 189). In volume III, Helmholtz introduced the notion of "unconscious inference": he claimed that perception typically contained many experiential data that could not be immediately found in the stimulus. These, usually unconscious, additions to the stimulus came from past experience, i.e. from memory. Helmholtz called these unconsciously determined phenomena "unconscious inferences" because they had the character of an inductive or analogical inference (Boring 1950: 308). For Helmholtz the theory of unconscious inferences was a tool for defending empiricism. On his view, humans built up their internal model of external space by means of unconscious inferences (Boring 1950: 309-11; Murray 1988: 193). Deviating from chronology, I mention Ernst Heinrich Weber (1795-1878) last, as his work leads naturally into Fechner's psychophysics. Weber's most famous research started from the question of whether sensitivity to touch varies over the different parts and regions of the body. In order to answer this question, Weber devised an experiment in which different parts of the body were touched with the legs of a pair of compasses. As the two legs were brought closer together, the subject found it increasingly difficult to distinguish between two touches and one touch. The closer together the two points were which continued to elicit sensations of two touches, the more sensitive the skin had to be to separate two touches in that part of the body. By means of this method, Weber constructed charts of the sensitivity of the whole body. He found, for instance, that there is a big difference in sensitivity between the tip of the tongue and the back of the body. Weber also noted that we can estimate the weight of an object better when we lift it than when the object rests passively on our body. He gave different subjects two weights and asked them to report when one was "just noticeably different". Again he found differences between different subjects. Moreover, Weber compared different senses (tactile sense, vision, temperature sense). In this context, he came to formulate what Fechner would later call "Weber's law": DI = kI (where k is a fraction): "The intensity of an increment DI that needs to be added to a stimulus of intensity I to make I just noticeably different is a constant fraction of I." (Murray 1988: 177). Thus e.g., when a subject can tell the different between a stimulus of intensity 100 and one of 101, then she or he will also be able to tell the difference between a stimulus of intensity 1000 and a stimulus of intensity 1010. Psychophysics The "psychophysics" of Gustav Theodor Fechner (1801-1887) is often regarded as the first major experimental-psychological research program. Fechner took a degree in medicine in 1822, but on the basis of an important paper on the quantitative measurements of direct currents he was appointed to a chair in physics at the University of Leipzig in 1834. He resigned this chair only five years later for reasons of health. Fechner was strongly influenced by the idea, central to the Romantic movement, that mind and matter represent but two sides of nature, and that the essential nature of everything is spiritual. He defended this view in a number of philosophical books, of which _Nanna_oder_ das_Seelenleben_der_Pflanzen_ (Nanna or the Mental Life of Plants, 1848), and _Zend-Avesta, _oder_ber_die _Dinge_des_Himmels_und_des_Jenseits_ (Zend-Avesta, or the Things of Heaven and the Beyond, 1851) are the best known. The research that Fechner was eventually to call "psychophysics" was but a by-product of his philosophy, i.e. an attempt to establish his spiritualism with the help of strict experimental methods. And indeed, according to Boring (1950: 293), it was primarily Fechner's rigorous use of experimental methods for answering a psychological question, that is, his introduction of new methods of measurement, that made his work important in the development of the new psychology. In his _Elemente_der_Psychophysik_ (1860), Fechner tried to show experimentally that an increase in physical stimulus is paralleled by an increase in mental experience. More precisely, Fechner argued that an arithmetical increase in sensation magnitude must be the result of a geometric increase in stimulus magnitude. Another, more famous, formulation, is ... S = c log R where S is the sensation strength, c is a constant to be determined, and R the stimulus strength (Murray 1988: 183- 185). LITERATURE Ash, M. (1980), "Academic Politics in the History of Science: Experimental Psychology in Germany, 1879-1941", Central European History XIII: 255-86. Leary, D.E. (1978), "Philosophical Development of the Conception of Psychology in Germany, 1780-1850", Journal of the History of Behavioral Sciences 14: 113-21. Leary, D.E. (1980), "German Idealism and the Development of Psychology in the 19th Century", Journal of the History of Philosophy 18: 299-317. Meyering, T.C. (1989), Historical Roots of Cognitive Science, Kluwer, Dordrecht. Murray, D.J. (1988), A History of Western Psychology, 2nd ed., Prentice Hall, Englewood Cliffs, N.J. Russell, A. (1966), "A Note on Lotze's Teaching of Psychology, 1842-1881", Journal of the History of the Behavioral Sciences 2: 74-75. Verwey, G. (1985), Psychiatry in an Anthropological and Biomedical Context, Reidel, Dordrecht.