Michael Heidelberger

It is widely held that the current debate on the mind-body problem in analytic philosophy began during the 1950s at two distinct sources: one in America, de- riving from Herbert Feigl's writings, and the other in Australia, related to writings by U. T. Place and J. J. C. Smart (Feigl [1958] 1967). Jaegwon Kim recently wrote that "it was the papers by Smart and Feigl that introduced the mind-body problem as a mainstream metaphysical Problematik of analytical philosophy, and launched the debate that has continued to this day" (Kim 1998, 1). Nonetheless, it is not at all obvious why these particular articles sparked a debate, nor why Feigl's work in particular came to play such a prominent part in it, nor how and to what extent Feigl's approach rests on the logical empiricism he endorsed

In 1874, the French philosopher Émile Boutroux wrote a dissertationon the contingency of the laws of nature that highly influenced academic philosophy during the French Third Republic and led to a more hypothetical view of the natural sciences and mathematics. Boutroux took over the concept of contingency from the neo-Kantian philosopher Eduard Zeller who had insisted against Hegel on the role of contingency in history, and carried it over to nature. From this he tried to show that the sciences are hierarchically structured such that each layer is irreducible to its more basic predecessor. He also distinguished between two kinds of natural laws in a way very similar to Nancy Cartwright in the1980s. It is finally shown that Boutroux’s view on the nature of mathematics as a hypothetical science had a strong impact on Poincaré.

Alan Richardson, one of the editors of the present volume, dryly remarks in a footnote to the introduction: “Logical empiricism remains alive in philosophical memory chiefly by the significance of its death.” I think that this pertinent paradox can be enlarged to generally characterise the relation of present-day philosophy of science to logical empiricism : the more philosophy of science has struggled in the past to distance itself from central tenets of the movement of LE, the more it had to realise how close and how indebted it remains to LE and how much “post-positivism” itself willy-nilly keeps its spirit alive. Thus, there is the growing feeling that the identity of today’s philosophy of science is much more closely tied to LE, many manifestations to the contrary notwithstanding. The renewed interest in LE that has resulted from this insight must necessarily have lead to repercussions also on the appraisal of LE as a philosophical position. The once almost unanimous and rash condemnation of LE in the sixties and seventies is today followed by a prudent and broad-minded second look that tries to do fuller justice to the historical background and development. One can understand that for some of those who take the foregoing considerations seriously the news of LE’s death seems to be a little premature

Um die Mitte des 19. Jahrhunderts tritt die Sinnesphysiologie in eine neue Phase ein. Sie löst sich allmählich von der akademischen Philosophie und bildet sich zu einer professionellen experimentellen Disziplin aus. Trotzdem ist die Philosophie aber nicht völlig aus dem Spiel; es kommt vielmehr zu einem Wettstreit physiologischer Schulen innerhalb der Physiologie selbst um ihre impliziten philosophischen Anschauungen. Außerdem liefern sich die längst etablierte Disziplinen der Physik, Physiologie und Psychologie so etwas wie einen Machtkampf um das Anrecht, die Sinnesphysiologie als Teil ihres Gebiets ansehen zu können. Die einzelnen Wahrnehmungstheorien unterscheiden sich also sowohl durch die Rolle, die sie den einzelnen Wissenschaften bei der Erklärung der Wahrnehmung zuweisen, als auch durch die ihnen zugrundeliegenden philosophischen Anschauungen. (Vgl. Heidelberger 1993, 1997).

Aus dem vielfältigen Werk von Hermann von Helmholtz versammelt diese Ausgabe die im engeren Sinne philosophischen Abhandlungen, vor allem zur Wissenschaftsphilosophie und Erkenntnistheorie, sowie Vorträge und Reden, bei denen der Autor seine Ausnahmestellung im Wissenschaftsbetrieb nutzte, um die Wissenschaften und ihre Institutionen in der bestehenden Form zu repräsentieren und zu begründen. Ein Philosoph wollte Helmholtz nicht sein, aber er legte der philosophischen Reflexion wissenschaftlicher Erkenntnis und wissenschaftlichen Handelns große Bedeutung bei. Vor allem bezog er, in der Regel ausgehend von seinen fachwissenschaftlichen Forschungen, in den verschiedensten Kontexten zu erkenntnistheoretischen und methodologischen Problemen der Wissenschaften Stellung. Bereits »Ueber die Erhaltung der Kraft« (1847) lässt erkennen, wie verwoben naturwissenschaftliche Grundlagenforschung und philosophische Grundlagenreflexion in seinem Werk sind. Die aus den frühen sinnesphysiologischen Forschungen hervorgegangene empiristische Wahrnehmungslehre trug ihm den Ruf ein, ein maßgeblicher Vertreter des Neukantianismus zu sein. Spätere Arbeiten v.a. zur Geometrie und Arithmetik – das zeigt die vorliegende Ausgabe – stellen jedoch eine radikale Absage an den konstitutiven Kern des Kantianismus (nämlich die Existenz synthetischer Urteile a priori) dar. Helmholtz’ philosophische Beiträge sind bisher in ihrer Vollständigkeit nicht annähernd so gut zugänglich wie sein naturwissenschaftliches Werk. Die Ausgabe enthält außerdem bibliographische Vorberichte zur Einordnung, detaillierte Namens- und Sachregister sowie mit 575 Einträgen für den Zeitraum zwischen 1842 und 2012 die erste umfassende Bibliographie von Helmholtz verfasster Werke überhaupt. »Ich glaube, dass der Philosophie nur wieder aufzuhelfen ist, wenn sie sich mit Ernst und Eifer der Untersuchung der Erkenntnissprocesse und der wissenschaftlichen Methode zuwendet. Da hat sie eine wirkliche und berechtigte Aufgabe.« Helmholtz in einem Brief um 1875

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.

In this paper, I would like to show that considering technological models as they arise in engineering disciplines can greatly enrich the philosophical perspective on models. In fluid mechanics, (at least) three types of models are distinguished: mathematical, computer and physical models. Very often, the choice of a particular mathematical, computer or physical model highly affects the type of solutions and the computational time needed for it. Technological models not only aim at a correct description of the physical phenomena, but also for an efficient and accurate simulation. The problem arises how heterogeneous models of an engineering problem can be brought together and be compared to each other as regards their function and technological efficiency. There are two developments in the history of fluid mechanics that have greatly influenced the use of models in the field: The introduction of the concept of the boundary layer by Ludwig Prandtl in 1904 made it possible to apply ideal analytical solutions, which at the time were almost entirely based on Euler’s equations for inviscid fluids, to interesting real cases and to approximate the theoretical Navier-Stokes equations to practical engineering problems, i.e. to cases at high Reynolds numbers. This made it possible to link the empirical tradition of hydraulics with the theoretical tradition of analytical mechanics and therefore lead to a kind of equilibrium in the use of mathematical and physical models. In the 1970s the introduction of the computer has greatly pushed back the importance of both physical and mathematical (analytic) models alike without making them superfluous. There remain, however, three different ways to conceive of physical models in fluid mechanics, and thus of the experimental ingredient, depending on whether they are devised from an analytical, computational or measurement theoretical point of view. Yet even inside the tradition of computer simulation, different practices have formed according to the programming methods used. The choice of method either depends on considerations of efficiency in terms of costs and time, or on historically contingent factors, like availability of instruments and programming packages or the arbitrary choice of a forerunner. Seen from a technological point of view the factors that make models “autonomous agents” and thus (relatively) independent from theory depend on efficiency constraints. Models are means to solve problems in a certain practical perspective by the most efficient means available. To develop a model is a “fast and frugal way” to get to grips with a certain region of reality, whereas the theoretical approach stresses the importance of universal features.

Wenn hier Fechners Philosophie als „wissenschaftlich-philosophische Weltauffassung“ bezeichnet wird, dann soll damit gesagt werden, dass Fechner mit seiner Philosophie einen wissenschaftlichen Anspruch verfolgt hat und dass sie tatsächlich auf einem weltanschauungsfreien Fundament ruht. Ich möchte sogar so weit gehen zu behaupten, dass Fechner damit zur Tradition der „wissenschaftlichen Philosophie“ des 19. Jahrhunderts zu rechnen ist, deren folgenreichstes späteres Produkt im 20. Jahrhundert der logische Empirismus darstellt. Der „Wiener Kreis“ als die bekannteste Schule dieser Tradition bediente sich (in seinem Manifest von 1929) des Ausdrucks „Wissenschaftliche Weltauffassung“, um sich von allen spekulativen Weltanschauungen abzugrenzen.

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 Kries's approach had more potential than recognized in his time and that putting Waismann's and Wittgenstein's early work in a von Kries perspective is able to shed light on the notion of an elementary proposition.