Michael Heidelberger

From Helmholtz’s Philosophy of Science to Hertz’s Picture-Theory

Until far into the second half of the last century, many efforts were made to follow the Newtonian paradigm in taking account of electrodynamic phenomena. One wanted to reduce them to attractive and repulsive central forces of electric particles which were supposed to act directly at a distance, in analogy to gravitational force. In later years, this view was superseded by a theory of contiguous action, i.e., electromagnetic field theory as developed by Michael Faraday (1791–1867) and elaborated by James Clerk Maxwell (1831–1879). According to this new view, the main role is not played by the carrier of the charges but by the medium which continuously transports the action from place to place. This transition to field theory is one of the major turning points in the history of physics. In the German speaking world, this change was brought under way and promoted mainly by Hermann von Helmholtz (1821–1894), although in the end he could not free himself from the idea of action at a distance after all. The ultimate establishment of the new theory and the defeat of the action at a distance view is due to his student, Heinrich Hertz (1857–1894).

Applying Models in Fluid Dynamics

The following article treats the ‘applicational turn’ of modern fluid dynamics as it set in at the beginning of the 20th century with Ludwig Prandtl’s concept of the boundary layer. It seeks to show that there is much more to applying a theory in a highly mathematical field like fluid dynamics than deriving a special case from a general explanatory theory under particular antecedent conditions. In Prandtl’s case, the decisive move was to introduce a model that provided a physical/causal conception of viscous flow at high Reynolds numbers. It facilitated an approximate solution to the Navier–Stokes equations, which in turn gave rise to many special applications. After a detailed account of Prandtl’s achievement, the article discusses the role of the physical model and its experimental and mathematical significance. It is shown that the mathematical simplification provided by the physical model greatly expanded the explanatory capacity of the theory which the Navier–Stokes equations alone could not provide.

Origins of the logical theory of probability: Von Kries, Wittgenstein, Waismann

The physiologist and neo-Kantian philosopher Johannes von Kries (1853-1928) wrote one of the most philosophically important works on the foundation of probability after P.S. Laplace and before the First World War, his Principien der Wohrscheinlich-keitsrechnung (1886, repr. 1927). In this book, von Kries developed a highly original interpretation of probability, which maintains it to be both logical and objectively physical. After presenting his approach I shall pursue the influence it had on Ludwig Wittgenstein and Friedrich Waismann. It seems that von Kriess approach had more potential than recognized in his time and that putting Waismanns and Wittgensteins early work in a von Kries perspective is able to shed light on the notion of an elementary proposition.

From Neo-Kantianism to Critical Realism: Space and the Mind-Body Problem in Riehl and Schlick

This article deals with Moritz Schlicks critical realism and its sources that dominated his philosophy until about 1925. It is shown that his celebrated analysis of Einsteins relativity theory is the result of an earlier philosophical discussion about space perception and its role for the theory of space. In particular, Schlicks method of coincidences did not owe anything to entirely new principles based on the work of Einstein, Poincar or Hilbert, as claimed by Michael Friedman, but was already in place before these principles were developed. The first part of the article is devoted to Alois Riehls critical realism—a neo-Kantian variant which rejects the dominant interpretation of the thing-in-itself as a mere limiting concept and takes empirical theories of space perception into consideration. The second part deals with the central role of Psychological Parallelism for Riehl and its integration with Kants epistemology. In the third part it is shown that Schlicks theory of knowledge is based on Riehls intricate reworking of Kantian epistemology, physiological psychology, theory of sense perception and philosophy of mathematics. The conclusion stresses the position of the unity of consciousness in Riehls philosophy which Schlick admittedly cannot cope with.

Gustav Theodor Fechner

Physicist, psychologist and philosopher, Fechner is noted for the introduction of quantitative methods into psychology. He also developed a “theory of collectives” which is built on the frequency interpretation of probability.

Functional relations and causality in Fechner and Mach

In the foundations of Fechners psychophysics, the concept of “functional relation” plays a highly relevant role in three different respects: (1) in respect to the principles of measurement, (2) in respect to the mind-body problem, and (3) in respect to the concept of a law of nature. In all three cases, it is important to explain the difference between a functional dependency of a variable upon another and a causal relationship between two (or more) variables. In all three respects, Ernst Mach developed Fechners ideas further and tried to extend the lessons he had learned from using the concept of a functional relation in psychophysics to the whole of science. For all three cases, I explain why they are still relevant for psychophysics and philosophy today.

From Mill via von Kries to Max Weber: Causality, Explanation, and Understanding

In the second part of his “Critical studies in the logic of the cultural sciences” published in 1906, which carries the title “Objective possibility and adequate causation in historical explanation” (Weber 1906, 164-188/266-290)1 Max Weber (1864-1920) wrote that he feels “almost embarrassed in view of the extent to which here again, as in so much of the preceding argument, I am ‘plundering’ von Kries’ ideas” (Weber 1906, 186/288).2 Weber thus admits a very strong influence on his approach by the physiologist, philosopher, and theoretician of probability, von Kries (1853-1928), who was for sometime his colleague in Freiburg in southwest Germany. Von Kries had suggested a legal criterion for attributing a deed to an agent that exerted a strong influence on German civil law and was also taken up by the legal system of other countries. This earned him the title of an honorary doctor of the law faculty of the University of Erlangen in 1897.

Concepts of Self-Organization in the 19th Century

Several contemporary schools of thought are participating in the current debate on self-organization. These schools, it seems to me, have not yet reached complete agreement on the question of what self-organization exactly means and what the most central and most basic intuitions of this concept are. In such a situation, it should be fruitful to have a closer look into the history of the most prominent ideas in this debate.

Some Patterns of Change in the Baconian Sciences of the Early 19th Century Germany

Gillispie once made the remark that the Encyclopedists boasted of having liberated science from metaphysics and that the generation succeeding them after the French revolution completed this emancipation by taking away from science even ontology - and not only that; any claim to grasp reality beyond controlled observation, experience and experiment became utterly impossible.1 For the generation of the philosophes science still was the source of gaining knowledge of the objective reality and, in turn, this knowledge was taken as the source for the enlightened perfection of man. In the postrevolutionary phase no effort was spared to make the sciences the dynamic motor of human history and social development. The claims that science gains knowledge in the old sense of the word are becoming to be forgotten, sometimes they are redefined’ and often even negated. The ideal of an enlightenment through knowledge and cognition undergoes a profound change and it turns into the vision of progress by prediction and control. This redefinition of the task of science is a direct result of the French revolution.

Über eine Methode der Bestimmung theoretischer Terme

Angenommen, eine Theorie T bestehe aus einem zweisortigen Bereich D 1 ,D 2 und aus drei Funktionen s,υ 1 ,υ 2 , die jedem Paar aus den zwei Bereichen eine reelle Zahl zuordnen; also