Ludwig Boltzmann, whose influence extended to Einstein and Planck, centered his notion of physics, and more broadly of natural sciences and of observational sciences, around phenomenology. Given his phenomenological leanings, he rejected any extensive role for the a priori in sciences, and rejected much of Kant’s version of physics.
Yet in some ways he seems to explicitly reject phenomenology. There is a tension within Boltzmann's thought: while arguing against phenomenologists, and eschewing the label of phenomenologist, he appears to embrace and even rigorously apply some phenomenological principles.
Both in science and in mathematics, Boltzmann sought a synthetic method which he considered to be simpler. Simplicity as a decision procedure for choosing between competing theories, which otherwise map nicely to the same data sets, is a familiar concept in the philosophy of science. Ernst Mach was roughly contemporary to Boltzmann. Alluding to Mach, Boltzmann wrote in 1892 about an economy of effort, which might be an analogue to simplicity as the concept is used in the philosophy of science concerning competing theories:
In mathematics and geometry the return from purely analytic to constructive methods and illustration by means of models was at first occasioned by a need for economy of effort. Although this seems to be purely practical and obvious, it is just here that we are in an area where a whole new kind of methodological speculations has grown up which were given most precise and ingenious expression by Mach, who states straight out that the aim of all science is only economy of effort.
The ambiguity in Boltzmann's relationship with phenomenology may arise from his use of some form of the principle of verification. Boltzmann's career path touched Ernst Mach's at a number of points, and Mach was a founding member of the Vienna Circle. The Circle was, of course, strongly linked to the verificationist understanding of meaning. Boltzmann was perhaps less interested in meaning and language, and used the verificationist principle more in the context of the philosophy of science. Inasmuch as verificationism is part of a radical empiricist program, and because both empiricism and phenomenology take raw sense-data as their foundation or point of departure, there is an overlap between verificationism and phenomenology, and this overlap gives rise to Boltzmann's ambiguity regarding phenomenology.
The more radical versions of empiricism and phenomenology take sense-data not only as a point of departure, but as the only possible point of departure - not as a foundation, but as the only possible foundation. The overlap between the two is highlighted in their more radical versions. Because much of Boltzmann's work in physics centered around particles invisible to the naked eye, the usual caveats about "indirect" or "in principle" observation apply to empirical verification of scientific theories. Paul Pojman writes that Ernst Mach
became embroiled in a long-standing dispute with Boltzmann, propounder of the kinetic theory of gasses. Boltzmann and Mach ended up agreeing in essence: if atomic theory was fruitful it should be used, but adopted what today might be considered an anti-metaphysical stance toward a theory that was still largely unsubstantiated. It is generally agreed that it was not until 1905 with Einstein's study of Brownian motion that the kinetic theory of molecules found full verification.
Consistently applying the phenomenological method, while seemingly denying that he was a phenomenologist, Boltzmann offered a critique of Friedrich Wilhelm Ostwald. Ostwald had wanted to relegate matter to the status of a construct; for Ostwald, matter was not among the atomic or foundational concepts of the world. As Joachim Schummer wrote,
The more Ostwald became convinced that thermodynamics is the fundamental theory of science — for which he saw evidence in the pioneering works of the American physicist Josiah Willard Gibbs and others — the more he engaged in natural philosophy. Two aspects may roughly characterize his philosophy. First, he asserted the primacy of energy over matter (matter being only a manifestation of energy) in opposition to widespread scientific materialism. Ostwald reformulated older concepts of dynamism dating back to the 17th-century German polymath Gottfried Leibniz with the principles of thermodynamics to form a new metaphysical interpretation of the world that he named “energetics.” Second, he asserted a form of positivism in the sense of rejecting theoretical concepts that are not strictly founded on empirical grounds. Although energetics found few adherents, the latter position found many contemporary proponents, such as the physicist-philosophers Ernst Mach in Austria and Pierre Duhem in France. As a consequence of his beliefs, for some 15 years Ostwald rejected atomism and was heavily involved in philosophical debates with his atomist colleagues, such as the Austrian physicist Ludwig Boltzmann, before he acknowledged the growing experimental evidence for the atomic hypothesis in 1909.
Detecting an inconsistency in Ostwald’s views, Boltzmann noted that it was equally unfounded to take energy as foundational or atomic to the universe. The arguments leveled against matter, or against the reality of matter, can be effectively and equally reformulated and leveled against energy. Boltzmann, again with Mach, sees matter and energy as equally derivative. What is foundational, as far as anything can be foundational in phenomenology, are sense-data. In a consistent phenomenological system, sensations are taken as the given. In 1904, Boltzmann wrote:
Mach pointed out that we are given only the law-like course of our impressions and ideas, whereas all physical magnitudes, atoms, molecules, forces, energies and so on are mere concepts for the economical representation and illustration of these law-like relations of our impressions and ideas. These last are thus the only thing that exists in the first instance, physical concepts being merely mental additions of our own. Ostwald understood only one half of this proposition, namely that atoms did not exist; at once he asked: what then does exist? To this his answer was that it was energy that existed. In my view this answer is quite opposed to Mach’s outlook, for which energy as much as matter must be regarded as a symbolic expression of certain relations between perceptions and of certain equations amongst the given phenomena.
Although Boltzmann was not in the mainstream of phenomenology, he is nonetheless a phenomenologist of some sort. Admittedly, some scholars refuse to classify his as such. Neither is he an idealist, in the sense of George Berkeley, but he veers close to some type of idealism. Manfred Grunwald corroborates Boltzmann’s influence, but disputes his phenomenology and idealism, when he writes:
Der berühmte Physiker und materialistiche Denker hat auf die weltanschaulichen Auffassungen Plancks und Einsteins großen Einfluß ausgeübt.
The question of whether radical empiricism and radical phenomenology are finally identical lies at the core of the question of whether or not Boltzmann is to be counted as some type of phenomenologist. His rejection of anything which he saw as metaphysical nudges him in the direction of empiricism. If it nudges him far enough into empiricism, and if empiricism at some point becomes one with phenomenological approaches, then we might be correct to label Boltzmann a phenomenologist, despite his own objections to that label, and despite a large body of respectable secondary literature which also declines to call him a phenomenologist.
Framed more broadly, the question emerges as this: is every empiricist a phenomenologist? is every empiricism a phenomenology? If we answer 'no' then we must articulate the distinction between phenomenology and empiricism. Alternatively, we can see phenomenology as a methodology within empiricism.
A surprising connection between Boltzmann's anti-Kantian view of physics and his social and ethical views arises from his interest in Darwin. Boltzmann's affection for Darwinism, however, gives rise to some methodological questions. Does Darwinism require Boltzmann to abandon the rigor with which he usually follows his phenomenological method? Can the arguments which Boltzmann directs against Kant and against Kantianism also be directed against Darwin and Darwinism? Manfred Grunwald continues:
Von Interesse ist Boltzmanns Stellungnahme zum Apriorismus. Er kritisierte den Apriorismus vor allem von dem einem Standpunkt, der sich aus der Entwicklungstheorie Darwins ergibt. Die sogenannte Denkgesetze hätten sich nach dem biologischen Gesetzen der Evolution gebildet und allmälich die Festigkeit aprioristischer Sätze angenommen. Die Einseitigkeit des nur durch die biologische Evolutionstheorie geprägten Herangehens und die Gefahren sozialdarwinistischer Deutungen werden in den Stellungnahmen Boltzmanns zu ethischen Fragen deutlich. Handlungen sind für ihn richtig und gut, soweit sie der Fortentwicklung der lebenden Materie dienen. Das Grundproblem der Ethik sah Boltzmann in der Beziehung zwischen der Behauptung oder Unterordnung des Willens eines Individuums und der zu fördernden Existenz eines Ganzen (Familie, Stamm, Menschheit). Einerseits behauptete er, daß sich aus den primitiven Formen der Materie, in Pflazen und Tieren, anzutreffenden Fähigkeiten (Vererbung, Zuchtwahl, Wahrnehmung, Willen, Lust, Schmerz) und ihrer quantitativen Steigerung das Denken und Wollen, das künstlerische Schaffen, die wissenschaftliche Forschung und das moralische Verhaltung der Menschen hinreichend erklären ließen. Andererseits erklärte er, daß er nur die »;naturwissenschaftliche begreifliche Seite« betrachte. Boltzmann lehnte die Verbindung naturwissenschaftlicher und religiöser Begriffe ab, weil beide aus gänzlich verschiedenen Bereichen stamman. Es zeigt sich die bei bürgerlichen Naturwissenschaftlern verbreitete Tendenz, der Religion das Gebiet der Moral zuzuweisen.
To the nature of Boltzmann's phenomenology - for phenomenology it was, if an unorthodox phenomenology - the following passage is in a longer text written by Byong-Chul Park:
As one of the founders of statistical thermodynamics, Boltzmann could not fully endorse the phenomenological method in physics. It is nevertheless an undeniable fact that Boltzmann uses the term 'phenomenology' in such a way that phenomenology in his sense is only concerned with our experience without any hypothesis in dealing with phenomena.
However one might characterize Boltzmann's phenomenology, and however it may compare and contrast to the phenomenological systems of other philosophers, Darwinism would entail a number of hypotheses which Boltzmann's understanding of phenomenology would not admit. In 1886, Boltzmann wrote:
Nowhere less than in natural science does the proposition that the straight path is the shortest turn out to be true. If a general intends to conquer a hostile city, he will not consult his map for the shortest road leading there; rather he will be forced to make the most various detours, every hamlet, even if quite off the path, will become a valuable point of leverage for him, if only he can take it; impregnable places he will isolate. Likewise, the scientist asks not what are the currently most important questions, but “which are at present solvable?” or sometimes merely “in which can we make some small but genuine advance?”
It would seem, then, from Boltzmann's philosophy of science, that the formulation of a grand system explaining the origin of life from lifeless matter, and this billions of years prior to any possible observation, would have no place in sober science. Boltzmann's phenomenological sense of science rejects the grand speculative systematic drive, present already in Kant and manifested grossly in Hegel. But does consistency demand that this sense of science likewise reject Darwinism with its hypotheses about processes which may have happened billions of year prior to any possible observation, with its hypotheses about life arising spontaneously from lifeless matter, and with speculations about matter and time emerging ex nihilo? Has Boltzmann violated his own methodological principles in embracing Darwin?
Boltzmann may have had some sense of the tension between his phenomenological and his non-phenomenological leanings. Note the contrast between the words 'internal' and 'external' in this passage, which he wrote in 1890:
I am of the opinion that the task of theory consists in constructing a picture of the external world that exists purely internally and must be our guiding star in all thought and experiment; that is in completing, as it were, the thinking process and carrying out globally what on a small scale occurs within us whenever we form an idea.
In Boltzmann's philosophy of science, then, theory is a speculative generalization - a projection - a writing large of our thoughts onto the universe. By thus defining 'theory' Boltzmann perhaps wished to avoid the methodological tensions between his attempt to apply a rigorous if idiosyncratic phenomenology and his affection for Darwinism. While not a phenomenologist in any usual sense of the word, he was certainly influenced by phenomenological methodologies. Albert Moyer writes:
Boltzmann did not agree that generalized, phenomenological theories were better equipped to reestablish order than were specialized, atomomechanical hypotheses. Though appreciative of phenomenological theories, he denied that such theories were free from hypotheses or idealizations and hence irrefutable. "Without some departure, however slight, from direct observation," he maintained, "a theory or even an intelligibly connected practical description for predicting the facts of nature cannot exist." Moreover, Boltzmann felt that the usefulness of phenomenological theories was limited merely to summarizing or developing "knowledge previously acquired." On the other hand, specialized and admittedly tentative hypotheses "give the imagination room for play and by boldly going beyond the material at hand afford continual inspiration for new experiments, and are thus pathfinders for the most unexpected discoveries." Consequently, he rejected the accusation that the "development of mathematical methods for the computation of the hypothetical molecular motions has been useless and even harmful." He also felt that the recent web of experiments involving cathode rays and radioactivity added credence to the atomistic viewpoint. Boltzmann was particularly optimistic about statistical mechanics.
Despite his dissimilarity to other phenomenologists, and despite what seems to be his explicit rejection of phenomenology, Boltzmann's sense of methodology retains features of phenomenology. Perhaps aware of this internal tension, some of his statements reflect perhaps an attempt to resolve such possible inconsistencies.
