Michael Heidelberger

In the 19th century, "Psychophysical Parallelism" was the most popular solution of the mind-body problem among physiologists, psychologists and philosophers. (This is not to be mixed up with Leibnizian and other cases of "Cartesian" parallelism.) The fate of this non-Cartesian view, as founded by Gustav Theodor Fechner, is reviewed. It is shown that Feigl's "identity theory" eventually goes back to Alois Riehl who promoted a hybrid version of psychophysical parallelism and Kantian mind-body theory which was taken up by Feigl's teacher Moritz Schlick.

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.

In the foundations of Fechner's 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 Fechner's 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

In philosophischen wie nichtphilosophischen Darstellungen wird heutzutage der Ursprung des Leib-Seele-Problems überwiegend mit dem kartesischen Dualismus in Verbindung gebracht. Es wird die Meinung vertreten, daß erst durch Descartes’ Aufteilung des Menschen (und damit der Welt) in die beiden einander ausschließenden Substanzen der res extensa und der res cogitans das philosophische Grundübel in die Leib-Seele-Philosophie gekommen sei.1 Folgerichtig ist man fest davon überzeugt, daß sich das Problem nur lösen läßt, wenn man es an der Wurzel packt und konsequent Descartes’ ontologischen Dualismus verwirft. Ein Herumdoktern an den Symptomen nach Art des Okkasionalismus oder der Leibnizschen Lehre von der prästabilierten Harmonie wird demgegenüber als metaphysisch suspekt und aussichtslos angesehen. Zwar ist inzwischen die Hoffnung, durch bloßen Anti-Cartesianismus ans Ziel zu kommen, etwas geschwunden, nachdem man feststellen mußte, daß die anfänglich so vielversprechende Kritik des Behaviourismus an Descartes nicht zum Ziel führte. Und auch mit der nächsten, von der Identitätstheorie hervorgerufenen großen Welle der Descartes-Kritik sind die Lösungen bis heute nicht so befriedigend ausgefallen, wie man sie gerne hätte. Die Überzeugung ist aber weiterhin stark, daß eine Lösung für das Leib-Seele-Problem zuallererst die Verwerfung des kartesischen Dualismus erfordert.

Ludwig Büchner wrote one of the most popular and polemical books of the strong materialist movement in the later nineteenth-century Germany, his Kraft und Stoff (Force and Matter) (1855). He tried to develop a comprehensive worldview, which was based solely on the findings of empirical science and did not take refuge in religion or any other transcendent categories in explaining nature and its development, including human beings. When Büchner tried to expose the backwardness of traditional philosophical and religious views in scientific matters, his arguments had some force, but the positive part of his programme was not free of superficiality and naivety. Büchner’s writings helped to strengthen progressive and rational traditions inside and outside philosophy, but they can also serve as the prime example of the uncritical nineteenth- century belief in science’s capacity to redeem humankind from all evil.

Since the late 1950s one of the most important and influential views of post-positivist philosophy of science has been the theory-ladenness of observation. It comes in at least two forms: either as a psychological law pertaining to human perception (whether scientific or not) or as conceptual insight concerning the nature and functioning of scientific language and its meaning. According to its psychological form, perceptions of scientists, as perceptions of humans generally, are guided by prior beliefs and expectations, and perception has a peculiar holist character. In its conceptual form it maintains that scientists’ observations rest on the theories they accept and that the meaning of the observational terms involved depends upon the theoretical context in which they occur. Frequently, these two versions are combined with each other and give rise to a constructivist view of scientific knowledge (I shall use the term “constructivism” roughly in the same way as Golinski [1998, chap. 1]). According to this outlook, our experience is categorized and preconditioned by prior belief since the process of gaining knowledge through science always involves the use of concepts from some theory or other. This view can easily be strengthened to serve as the cornerstone of a constructivist and anti-empiricist account of science: The categories in terms of which we carve up our experience are not read off from the external world but follow from prior theoretical commitments.

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.