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Causality, realism and the two strands of Boltzmann's legacy (1896 - 1936)

Michael Stöltzner

Published Jan 1, 2003• 6 citations
OpenAlex

Abstract

My thesis investigates a debate between Vienna and Berlin about the view that the basic laws of nature are genuinely indeterministic that started long before the advent of quantum mechanics. It involved two different readings of Ludwig Boltzmann's legacy statistical mechanics and two different answers to how causality and ontology ought to be combined. Having adopted Ernst Mach's weak notion of causality, the local Viennese tradition could more easily contemplate ontologies for irreducibly statistical laws that were different from classical physics, while the Berlin tradition departed from Planck's reading of the Kantian tradition, according to which strictly deterministic laws represented an indispensable basis even for probabilistic theories.\nVienna Indeterminism, as I shall call the first reading, became characteristic for a series of physicist-philosophers connected to the Institute of Physics at the University of Vienna, among them Franz Serafin Exner, Erwin Schrödinger, Philipp Frank and Richard von Mises. It involved the acceptance of the highly improbable events admitted by the second law of thermodynamics, an assent to Mach's definition of causality in terms of functional dependencies, an empiricist shift of the burden of proof on the determinist's shoulders, and the adoption of the relative frequency interpretation of probability. Planck and his student Moritz Schlick initially rejected all of these creeds.\nWhile the Viennese reading of Boltzmann's legacy made it possible to accept probabilistic laws as genuine laws years before the advent of quantum mechanics, Schlick had to take a strictly verificationist tack to reconcile his views on probability with the failure of a Kant-inspired notion of causality enforced by the changes in physics. Until his death however, Schlick remained committed to the Spielraum interpretation of Johannes von Kries, compensating his qualified acceptance of indeterminism with an emphasis on the limits of language that were enforced by Heisenberg's uncertainty relations.\nIn view of claims that scientists' abandonment of determinism and causality was triggered, or at least enhanced, by external factors, among them the anti-scientific Weimar milieu and Bohr's power politics, the reconstruction of the philosophical debates between Vienna and Berlin requires historical contextualization. To this end, I initially recapitulate the Forman thesis and the discussions ensuing from it. Most important among them are the recent books of Cushing and Beller that, rejecting Forman's strong claims, nevertheless deny any constructive influence of the scientific aspirations of German physicists on the philosophical debates about causality and indeterminism in the 1920s.\nAgainst this picture, I argue that the philosophical aspirations of physicist-philosophers were rather genuine and followed influential role models, among them Helmholtz and Mach. They represent a characteristic trait of the German-speaking scientific world and were expressed in academic addresses and in the publication of popular writings. After 1913, this philosophical discourse was conducted, to an increasing extent, on the pages of Die Naturwissenschaften. In a separate chapter, I study the role of philosophical and cultural matters in this journal, which can hardly be separated from the personality of its founding editor Arnold Berliner. At about 1930, this discourse among physicist-philosophers partly merged into scientific philosophy, as conducted by Logical Empiricists, and the newly founded Erkenntnis.\nOne of the characteristic features of the discourse among physicist-philosophers was that they were not strictly indebted to philosophical schools but rather willing to form strategic alliances. Such alliances emphasized one philosophical aspect that was considered pivotal at the time which other features, often expressing severe disagreements of content, were played down. This process can be witnessed at the end of the discussion between the Viennese and the Berliners in the 1930s, at a time when Schlick had already become the center of the Vienna Circle. Being confronted with a plethora of "metaphysical" misinterpretations and having taken the linguistic turn, Frank and Schlick formed a strategic alliance on the 1936 Copenhagen Congress for the Unity of Science. It brought them into opposition with Schrödinger's quest for a modification of quantum mechanics, although Schrödinger continued to be a staunch advocate of indeterminism. This year thus signifies the end of the coherence of Vienna Indeterminism, a tradition that reaches back to the publication of Boltzmann's Lectures of Gas Theory.

Related papers

Vienna Indeterminism II: From Exner's Synthesis to Frank and von Mises

Michael Stöltzner

This paper continues an earlier investigation into the philosophical tradition of Vienna Indeterminism until the formation of the Vienna Circle in 1929. It focuses in particular on how Philipp Frank and Richard von Mises were able to contemplate genuine indeterminism in physics before the advent of quantum mechanics. On this account, all apparently deterministic laws could well be the macroscopic limit of indeterministic basic laws valid for the single mirco-events. Philosophically Vienna Indeterminism was launched by Mach's redefinition of causality in terms of functional dependencies. This severed the rigid bond between causality and empirical realism characteristic of the Kantian conception and made possible to adjust the ontology according to the needs of a single theory. The debates between Max Planck and Franz Serafin Exner teach that the indeterminism issue was also a struggle about Boltzmann's philosophical legacy between Vienna and Berlin. Quite in line with Mach's firm empiricism, Vienna Indeterminists rejected any final decision between determinism and indeterminism on the metaphysical level. Once the frequency interpretation had won favor, the empiricist stance, moreover, permitted them to consider mass phenomena as generic observational facts coordinated to statistical collectives and to treat them on a par with moving point particles. The only condition imposed on this ontology was the uniqueness of this coordination, a condition that could be viewed as a late heir of Mach's principle of unique determination which had complemented his relational ontology.

•Mar 1, 2002•1 citation

Parallel convergences: Cassirer and Vienna indeterminism

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Abstract Stöltzner coined the expression ‘Vienna indeterminism’ to describe a philosophical tradition centered on the Viennese physicist Exner, serving as the ‘historical link’ between Mach and Boltzmann, on the one hand, and von Mises and Frank, on the other. During the early 1930s debate on quantum mechanics, there was a ‘rapprochement’ between Vienna indeterminism and Schlick’s work on causality. However, it was Cassirer’s 1936 monograph Determinismus und Indeterminismus that showed a full ‘convergence’ with major tenets of Vienna indeterminism: the fundamentality of statistical laws, the frequency interpretation of probability, and the statistical interpretation of the uncertainty relations. Yet, Cassirer used these conceptual tools to pursue ‘in parallel’ different philosophical goals. While for the Viennese quantum mechanics represented a fatal blow to the already discredited notion of ‘causality,’ for Cassirer it challenged the classical notion of ‘substantiality,’ the ideas of ‘particles’ as individual substances endowed with properties. The paper concludes that this ‘parallel convergence’ is the most striking and overlooked aspect of Determinismus und Indeterminismus, serving as the keystone of its argumentative structure.

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In this article I will focus on the debate on the causality principle that originated in the light of quantum mechanics concerning Moritz Schlick and Karl Popper. The discovery of quantum mechanics led to a broad debate on the interpretation of the principle of causality. Schlick proposed that it should be understood as an empirically verifiable postulate, and therefore with limits regarding causal indeterminacy in quantum physics. This approach had an influence on some scientists, especially Werner Heisenberg. However, Popper would develop a different way of understanding science because of the role played by unverifiable elements in theories that can nevertheless be falsified. It is precisely the discussion around the principle of causality that opens up different ways of understanding science. I will first try to analyse Schlick’s argument in the context of the debate that was taking place in the late 1920s in the light of the new quantum mechanics; secondly, I will look at the reception that Schlick’s idea of causality had in Heisenberg and the Copenhagen Interpretation; thirdly, I will analyse Popper’s argument against Schlick’s interpretation; finally, I will try to see the resonances of this debate in Heisenberg and other physicists.

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In previous chapters we presented and discussed the standard, generally accepted Copenhagen interpretation of quantum mechanics according to which there exists in nature at the most fundamental level an irreducible and ineliminable indeterminism. Although we saw that what historically constituted the Copenhagen interpretation of quantum mechanics is difficult to specify with precision, three central commitments do characterize it. (1) In general, no particle trajectories can exist in a space–time background. (2) No deterministic description of fundamental physical phenomena is possible. (3) There exists in the laws of the fundamental physical phenomena of nature an essential and ineliminable indeterminism or probability (unlike the probability of classical physics, that there reflects our ignorance of the finer details of complex physical phenomena). A flavor of these features of the Copenhagen interpretation of quantum mechanics can be gotten from the quotations at the beginning of Part VIII ( Some philosophical lessons from quantum mechanics ). On this view, it is in principle impossible to predict, say, the exact future behavior of an electron (that is, to give its position and velocity as functions of the time). According to the Copenhagen school, there can be no causal description of microphenomena in terms of a continuous space–time background (as there is in classical physics). It is generally believed that a causal interpretation of quantum mechanics is impossible, although no proof of this exists.

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In the 19th century, determinism was often seen as a presupposition of scientific thinking, although its validity was not universally accepted among scientists and philosophers. There were different conceptions of causality, and the concept of cause was often linked to that of force or energy; but toward the end of the 19th century, the causal conception of forces was increasingly criticised and some argued that the concept of cause should be abandoned altogether. After the development of the modern theory of quantum mechanics in 1925, many physicists and philosophers claimed that this theory implied an overthrow of the classical conception of causality; however, only few authors abandoned causality altogether. The debate of the implications of quantum mechanics for causality soon became muddled because of the many different meanings attached to the term “causality”.

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The political attitude and the ideology of a very small elite of physicists (Niels Bohr, Werner Heisenberg, Max Born and view other) played a major role in the construction of the Copenhagen Interpretation of quantum mechanics in the 1920s.Lastly, the hegemonic standard acausal Copenhagen Interpretation of quantum mechanics abandoned the principle of causality in quantum mechanics and opened a very wide door to mysticism, logical fallacies and wishful thinking in physics and in science as such.Historically, the Second International Congress for the Unity of Science (Copenhagen, June 21-26, 1936) tried to solve the problem of causality within physics but without a success.Thus far, 80 years after the Second International Congress for the Unity of Science this publication will expel Bohr's and Heisenberg's dogma of non-causality out of quantum mechanics and re-establish the unrestricted validity of the principle of causality at quantum level and under conditions of relativity theory by mathematizing the relationship between cause and effect in the form of the mathematical formula of the causal relationship k.In contrast to Bohr, Heisenberg and other representatives of the Copenhagen interpretation quantum mechanics, a realistic interpretation of quantum theory grounded on the unrestricted validity of the principle of causality will expel any kind of mysticism from physics and enable a quantization of the gravitational field too.

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My thesis investigates a debate between Vienna and Berlin about the view that the basic laws of nature are genuinely indeterministic that started long before the advent of quantum mechanics. It involved two different readings of Ludwig Boltzmann's legacy statistical mechanics and two different answers to how causality and ontology ought to be combined. Having adopted Ernst Mach's weak notion of causality, the local Viennese tradition could more easily contemplate ontologies for irreducibly statistical laws that were different from classical physics, while the Berlin tradition departed from Planck's reading of the Kantian tradition, according to which strictly deterministic laws represented an indispensable basis even for probabilistic theories.\nVienna Indeterminism, as I shall call the first reading, became characteristic for a series of physicist-philosophers connected to the Institute of Physics at the University of Vienna, among them Franz Serafin Exner, Erwin Schrödinger, Philipp Frank and Richard von Mises. It involved the acceptance of the highly improbable events admitted by the second law of thermodynamics, an assent to Mach's definition of causality in terms of functional dependencies, an empiricist shift of the burden of proof on the determinist's shoulders, and the adoption of the relative frequency interpretation of probability. Planck and his student Moritz Schlick initially rejected all of these creeds.\nWhile the Viennese reading of Boltzmann's legacy made it possible to accept probabilistic laws as genuine laws years before the advent of quantum mechanics, Schlick had to take a strictly verificationist tack to reconcile his views on probability with the failure of a Kant-inspired notion of causality enforced by the changes in physics. Until his death however, Schlick remained committed to the Spielraum interpretation of Johannes von Kries, compensating his qualified acceptance of indeterminism with an emphasis on the limits of language that were enforced by Heisenberg's uncertainty relations.\nIn view of claims that scientists' abandonment of determinism and causality was triggered, or at least enhanced, by external factors, among them the anti-scientific Weimar milieu and Bohr's power politics, the reconstruction of the philosophical debates between Vienna and Berlin requires historical contextualization. To this end, I initially recapitulate the Forman thesis and the discussions ensuing from it. Most important among them are the recent books of Cushing and Beller that, rejecting Forman's strong claims, nevertheless deny any constructive influence of the scientific aspirations of German physicists on the philosophical debates about causality and indeterminism in the 1920s.\nAgainst this picture, I argue that the philosophical aspirations of physicist-philosophers were rather genuine and followed influential role models, among them Helmholtz and Mach. They represent a characteristic trait of the German-speaking scientific world and were expressed in academic addresses and in the publication of popular writings. After 1913, this philosophical discourse was conducted, to an increasing extent, on the pages of Die Naturwissenschaften. In a separate chapter, I study the role of philosophical and cultural matters in this journal, which can hardly be separated from the personality of its founding editor Arnold Berliner. At about 1930, this discourse among physicist-philosophers partly merged into scientific philosophy, as conducted by Logical Empiricists, and the newly founded Erkenntnis.\nOne of the characteristic features of the discourse among physicist-philosophers was that they were not strictly indebted to philosophical schools but rather willing to form strategic alliances. Such alliances emphasized one philosophical aspect that was considered pivotal at the time which other features, often expressing severe disagreements of content, were played down. This process can be witnessed at the end of the discussion between the Viennese and the Berliners in the 1930s, at a time when Schlick had already become the center of the Vienna Circle. Being confronted with a plethora of "metaphysical" misinterpretations and having taken the linguistic turn, Frank and Schlick formed a strategic alliance on the 1936 Copenhagen Congress for the Unity of Science. It brought them into opposition with Schrödinger's quest for a modification of quantum mechanics, although Schrödinger continued to be a staunch advocate of indeterminism. This year thus signifies the end of the coherence of Vienna Indeterminism, a tradition that reaches back to the publication of Boltzmann's Lectures of Gas Theory.
This paper continues an earlier investigation into the philosophical tradition of Vienna Indeterminism until the formation of the Vienna Circle in 1929. It focuses in particular on how Philipp Frank and Richard von Mises were able to contemplate genuine indeterminism in physics before the advent of quantum mechanics. On this account, all apparently deterministic laws could well be the macroscopic limit of indeterministic basic laws valid for the single mirco-events. Philosophically Vienna Indeterminism was launched by Mach's redefinition of causality in terms of functional dependencies. This severed the rigid bond between causality and empirical realism characteristic of the Kantian conception and made possible to adjust the ontology according to the needs of a single theory. The debates between Max Planck and Franz Serafin Exner teach that the indeterminism issue was also a struggle about Boltzmann's philosophical legacy between Vienna and Berlin. Quite in line with Mach's firm empiricism, Vienna Indeterminists rejected any final decision between determinism and indeterminism on the metaphysical level. Once the frequency interpretation had won favor, the empiricist stance, moreover, permitted them to consider mass phenomena as generic observational facts coordinated to statistical collectives and to treat them on a par with moving point particles. The only condition imposed on this ontology was the uniqueness of this coordination, a condition that could be viewed as a late heir of Mach's principle of unique determination which had complemented his relational ontology.
Abstract Stöltzner coined the expression ‘Vienna indeterminism’ to describe a philosophical tradition centered on the Viennese physicist Exner, serving as the ‘historical link’ between Mach and Boltzmann, on the one hand, and von Mises and Frank, on the other. During the early 1930s debate on quantum mechanics, there was a ‘rapprochement’ between Vienna indeterminism and Schlick’s work on causality. However, it was Cassirer’s 1936 monograph Determinismus und Indeterminismus that showed a full ‘convergence’ with major tenets of Vienna indeterminism: the fundamentality of statistical laws, the frequency interpretation of probability, and the statistical interpretation of the uncertainty relations. Yet, Cassirer used these conceptual tools to pursue ‘in parallel’ different philosophical goals. While for the Viennese quantum mechanics represented a fatal blow to the already discredited notion of ‘causality,’ for Cassirer it challenged the classical notion of ‘substantiality,’ the ideas of ‘particles’ as individual substances endowed with properties. The paper concludes that this ‘parallel convergence’ is the most striking and overlooked aspect of Determinismus und Indeterminismus, serving as the keystone of its argumentative structure.
In this article I will focus on the debate on the causality principle that originated in the light of quantum mechanics concerning Moritz Schlick and Karl Popper. The discovery of quantum mechanics led to a broad debate on the interpretation of the principle of causality. Schlick proposed that it should be understood as an empirically verifiable postulate, and therefore with limits regarding causal indeterminacy in quantum physics. This approach had an influence on some scientists, especially Werner Heisenberg. However, Popper would develop a different way of understanding science because of the role played by unverifiable elements in theories that can nevertheless be falsified. It is precisely the discussion around the principle of causality that opens up different ways of understanding science. I will first try to analyse Schlick’s argument in the context of the debate that was taking place in the late 1920s in the light of the new quantum mechanics; secondly, I will look at the reception that Schlick’s idea of causality had in Heisenberg and the Copenhagen Interpretation; thirdly, I will analyse Popper’s argument against Schlick’s interpretation; finally, I will try to see the resonances of this debate in Heisenberg and other physicists.
In previous chapters we presented and discussed the standard, generally accepted Copenhagen interpretation of quantum mechanics according to which there exists in nature at the most fundamental level an irreducible and ineliminable indeterminism. Although we saw that what historically constituted the Copenhagen interpretation of quantum mechanics is difficult to specify with precision, three central commitments do characterize it. (1) In general, no particle trajectories can exist in a space–time background. (2) No deterministic description of fundamental physical phenomena is possible. (3) There exists in the laws of the fundamental physical phenomena of nature an essential and ineliminable indeterminism or probability (unlike the probability of classical physics, that there reflects our ignorance of the finer details of complex physical phenomena). A flavor of these features of the Copenhagen interpretation of quantum mechanics can be gotten from the quotations at the beginning of Part VIII ( Some philosophical lessons from quantum mechanics ). On this view, it is in principle impossible to predict, say, the exact future behavior of an electron (that is, to give its position and velocity as functions of the time). According to the Copenhagen school, there can be no causal description of microphenomena in terms of a continuous space–time background (as there is in classical physics). It is generally believed that a causal interpretation of quantum mechanics is impossible, although no proof of this exists.
In the 19th century, determinism was often seen as a presupposition of scientific thinking, although its validity was not universally accepted among scientists and philosophers. There were different conceptions of causality, and the concept of cause was often linked to that of force or energy; but toward the end of the 19th century, the causal conception of forces was increasingly criticised and some argued that the concept of cause should be abandoned altogether. After the development of the modern theory of quantum mechanics in 1925, many physicists and philosophers claimed that this theory implied an overthrow of the classical conception of causality; however, only few authors abandoned causality altogether. The debate of the implications of quantum mechanics for causality soon became muddled because of the many different meanings attached to the term “causality”.
The political attitude and the ideology of a very small elite of physicists (Niels Bohr, Werner Heisenberg, Max Born and view other) played a major role in the construction of the Copenhagen Interpretation of quantum mechanics in the 1920s.Lastly, the hegemonic standard acausal Copenhagen Interpretation of quantum mechanics abandoned the principle of causality in quantum mechanics and opened a very wide door to mysticism, logical fallacies and wishful thinking in physics and in science as such.Historically, the Second International Congress for the Unity of Science (Copenhagen, June 21-26, 1936) tried to solve the problem of causality within physics but without a success.Thus far, 80 years after the Second International Congress for the Unity of Science this publication will expel Bohr's and Heisenberg's dogma of non-causality out of quantum mechanics and re-establish the unrestricted validity of the principle of causality at quantum level and under conditions of relativity theory by mathematizing the relationship between cause and effect in the form of the mathematical formula of the causal relationship k.In contrast to Bohr, Heisenberg and other representatives of the Copenhagen interpretation quantum mechanics, a realistic interpretation of quantum theory grounded on the unrestricted validity of the principle of causality will expel any kind of mysticism from physics and enable a quantization of the gravitational field too.