Copyright by Harry Russell Kahl 1951 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. THE PHILOSOPHICAL WORK OF HERMANN VON HELMHOLTZ The Philosophy and Epistemology oi the German Scientist by H. Russell Kahl Submitted in partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in the Faculty of Philosophy Columbia University Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. i PREFACE ■While Helmholtz's writings on philosophy have been the sub­ ject of a number of monographs in German, nothing in the way of a systematic study of his work has appeared in English* The same, almost, may be said of his achievements in the field of science* Frequent reference may be found to his monumental works in phy­ siological optics and physiological acoustics* It is also pos­ sible to find occasional references to his historic papers on the conservation of force, to his contributions to the early history of non-Euclidean geometry, and to his influence on Hertz* Little, however, has been done in English on his general position in the history of nineteenth century science and philosophy, on the at­ titude which underlies his scientific work, on the interconnections which he saw among the various fields in which he worked, and on his general philosophical thought* It is the purpose of the following essay to attempt to show Helmholtz's interpretation of the function of philosophy and to formulate his conclusions in epistemology and in the philosophies of science and mathematics* This in turn will lead us to consider a number of topics not usually understood to be part of philosophy, and will necessitate frequent reference to Helmholtz’s scientific work* This, as will be seen later, is due to the fact that Helm­ holtz's conclusions in the field of epistemology are inseparably connected with his scientific studies, particularly with his epoch making contributions to physiological optics* In addition to the field of physiological optics, however, Helmholtz's work covered many other fields, ranging from his early Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ii experimental -work in physiology to the theoretical physics of his later years, and he was recognized as a master in all of the sciences to which he made contributions# And not only did he mix epistemological considerations with each of his scientific studies (as did a number of his contemporaries in German science), but his fundamental philosophical and methodological position entered into each science, and each in turn made its contributions to this posi­ tion and attitude* Thus, an investigation of Helmholtz’s epistem­ ology will lead us from the physiology of the senses, and in particu­ lar, the physiology of the sense of sight, to the philosophical re­ flections which stemmed from his work in theoretical physics# And it will lead in addition to a consideration of his essays on the axioms of geometry, essays which were one of the results of his studies in physiological optics, and which led in turn to his work on arithmetic, counting, and measurement, and to his discussions of general problems in the philosophy of science# Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Table of Contents Chapter I* Helmholtz’s Life, His Scientific Work, and His Conception of Philosophy p» 1 Chapter II© Sensation 28 Chapter III© Perception 55 Chapter 17. Perception (cont.) 8o Chapter 7. Perception (cont.) 90 Chapter 71. Geometry 113 Chapter 711. Counting and Measurement 158 Chapter Till. The Principles of Science 186 Chapter IX* Conclusion 2l2f Bibliography 2$h Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CHAPTER I Helmholtz’s Life, His Scientific Work, And His Conception of Philosophy Any discussion and evaluation of Helmholtz’s work in epistem- ology and in the philosophies of science and mathematics will be facilitated by some consideration of his life and of his scien­ tific achievements» This is true for several reasons* A short mention of his life is important because, while his conclusions concerning epistemological problems are closely and inseparably connected with his later and more scientific studies, his in­ terest in some of the general problems of philosophy and particu­ larly his interest in and his inclination towards epistemology antedates all of bis scientific worko This interest started be­ fore he began his student life in Berlin through the influence of his father and a number of his father’s colleagues, all of whom were followers of the philosophies of Kant, Fichte, or Hegel,^ and it continued after he had first begun his formal studies of medicine* It was at this early age, too, that he began to arrive at his conception of the function of philosophy, a conception which he retained unaltered throughout his life* Thus it may be said that, as far as epistemology is concerned, Helmholtz applied, at a later time, scientific conclusions to problems and questions 1 Hermann von Helmholtz, "An Autobiographical Sketch," Popular Lectures on Scientific Subjects, Volume II, p* 285* "The interest ?or questions in the" ‘theory of cognition had been im­ planted in me in my youth, when I often heard my father, who had retained a strong impression from Fichte’s idealism, dispute with his colleagues who believed in Kant or Hegel*" Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 2 •which had been with him from his earlier years* In addition, a short introductory account of his life and work will indicate more clearly the intellectual fields in which Helmholtz's greatest interest lay and may, perhaps, give some in­ dication of the temperament and attitude which lies behind the more philosophical considerations to be treated in later chapters* There are still further reasons for considering both Helm­ holtz's scientific as well as his philosophical work* His fame rests almost entirely upon his achievements in science* Helm­ holtz was an important investigator in almost all fields of nine­ teenth century science, his career starting in medicine and ending, fifty years later, in theoretical physics, and his leadership, or at least his tremendous influence, was felt in every science in which he worked* It is justly that Maxwell called him a "uni­ versal genius♦" His interests were catholic and his contributions equally so. At the age of 26 he wrote his famous paper on the conservation of force, a key contribution in the history of this principle which was to become so fundamental in the physics of the latter half of the nineteenth century* Among other works he con­ tributed basic studies in physiological optics and physiological acoustics* It was Helmholtz who led Hertz to the experimental - verification of Maxwell's equations, and it was Helmholtz who began scientific ophthalmology with the invention of the ophthal­ moscope* He was tremendously influential in uncovering the scientific problems, in establishing the experimental procedures, and in furthering the scientific attitude which was so important in science during the last half of the nineteenth century* Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3 A much more important reason, however, for considering briefly •in this essay Helmholtz’s scientific work is the fact that Helm­ holtz ’s conclusions in philosophy are almost always built upon the foundation of his purely scientific work or were at least sug­ gested by it, and a knowledge of this is important in order to understand his epistemology* His theory or sensation, his theory of perception, h XS "*»0 rk on non-Euclidean geometry, his studies of measurement and on the foundations of science in general and of physics in particular, in short, almost all of his work in epistemology and in the philosophies of mathematics and science, is directly connected to and arises from some previous work in experimental or mathematical science* Even his antagonism to­ wards metaphysics, or, more specifically, his reaction to the idealism of Schelling and Hegel and to the materialism of Vogt and Moleschott, is based in large part on his scientific work and attitude» Helmholtz rs long life spans much of the nineteenth century, beginning at the time when the experimental sciences characteris­ tic of the period were just getting well started and ending just before the turn of the century when the classical theoretical physics which was his first love was about to be shocked by the discovery of radioactivity and by the first of Planck’s papers on quantum theory* The period of his life encompasses the begin­ nings of physiological psychology and of scientific medicine* He saw the great generalization of the conservation of energy grad­ ually become a ruling law in physics and he witnessed the growth of non-Euclidean geometry to importance and popularity* And, to Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4 his satisfaction, he witnessed the decline of Schelling and Hegel's "Philosophy of Nature" in Germany, and the rise to respect of the experimental and mathematical methods of procedure of which he was such a confirmed advocate. Hermann von Helmholtz was born in 1321, the son of an in­ structor in philology and philosophy in the Potsdam gymnasium. He early showed an interest in mathematics and physics, teaching himself geometry and optics while still a student in the gym­ nasium.- His earliest intellectual inclination seems to have been towards physics but at the age of sixteen he was forced, due to the limited financial resources of his family, to turn to medi­ cine. At the time the Prussian government was offering scholar­ ships at the Royal Frederick Wilhelm Institute of Medicine and Surgery in Berlin to exceptional students who were willing to serve for a period of four years as a surgeon in the Prussian Army after the completion of their training. It was on such a scholar­ ship that Helmholtz went to Berlin. In 1842, at the age of twenty-one, he completed his studies at the Institute with the dissertation, "The Structure of the Nervous System in Inverte­ brates" (De Fabrica Systematis Nervosi Fvertebratorum), in which he showed, basing his conclusions on microscopic studies, that the nerve cells of ganglia, discovered by von Ehrenberg in 1833j are individually connected with the separate nerve fibres which O lead from them. VJhile at the Institute Helmholtz studied under Gustav Magnus, 2 See E. G. Boring, History of Experimental Psychology, p. 290. Boring here cites this Investigation and discovery by Helm­ holtz as foreshadowing the neuron theory. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 5 the physicist whom he was later to succeed as professor of physics at Berlin, and under Johannes Muller, the physiologist, whose law of the specific energy of nerves was to become the central scientific foundation of his later psychological and philosophi­ cal work on sensation and perception® It was at the Institute, too, that he began his first serious reading of some of the classics of philosophy and science® Ihile working part time as librarian he read the works of Euler, Daniel Bernoulli, d'Alem­ bert, and Lagrange, in addition to undertaking the study of Kant’s epistemology® With the completion of his dissertation began a series of contributions to many sciences, extending over the next fifty years® In 181|? Helmholtz wrote his famous paper n0n the Con­ servation of Force,” which, along with the work of Joule, Meyer, Colding, and others, helped to establish this principle as one of the fundamental laws of physics, a law which was to become of central importance in the subsequent development of nineteenth century science® During his career as a student the question as to the existence of a vital force had been under discussion, opinion ranging from complete acceptance to complete denial of such a force. Even Johannes MBller, Helmholtz’s most influential teacher, while making significant advances in physiology, still struggled between the older view of acceptance (which Helmholtz characteristically calls metaphysical) and the newer, more nat­ uralistic, one of denial* Most physiologists had at the time adopted Stahl’s view that, while there are important physical and chemical forces acting in the organs and substances of the living Reproduced with permission of the copyright owner. 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