Table Of Contents
© 1993 Henk de Regt, Amsterdam
Omslag : Anne-Marie van Sprang
Opni a a k : Pe f er v an Dorp
Druk: ; Ponsen & Looijen, Wageningen
VRIJE UNIVERSITEIT
A A TMT^Ifc /yn j^t-r T "FITI f~\T7T!Cy friTTTT1
llol_.rl ! JKwtil ov^tiKLi I
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van de faculteit der wijsbegeerte
op maandag 18 oktober 1993 te 13.30 uur
uw van de universiteit, De Boelelaan 1105
Urlvnsr/vXr
TJ tTxTt
prof.dr P.P. Kirschenmann
dr J.A. Radder
prof.dr D.G.B.J. Dieks
Bij de voorbereiding en de vervaardiging van dit proefschrift heb ik
het voorrecht gehad dat een aantal mensen mij op deskundige en
enthousiaste wijze heeft geholpen. Van hen wil ik allereerst Hans
Radder en Peter Kirschenmann noemen. Het is voor een belangrijk
deel aan hun begeleiding en betrokkenheid te danken geweest dat
het onderzoek voorspoedig verliep. Zij hadden steeds tijd voor mij,
waardoor onze gezamenlijke besprekingen soms marathonzittingen
werden. Hoewel het project aanvankelijk hun geesteskind was, kon
ik het door de vrijheid die ze me gaven, al gauw tot het mijne maken.
Hun kritisch commentaar op mijn geschriften, de vele suggesties en
verbeteringen, had ik echter niet kunnen missen.
Ook de overige leden van de VF-groep "Normativiteit en Kennis"
hebben een bijdrage geleverd in de discussies die naar aanleiding
van mijn stukken gevoerd zijn.
Dennis Dieks wil ik bedanken voor zijn bereidheid om als refe-
rent op te treden, maar ook voor zijn altijd scherpzinnige en relevante
commentaar op eerdere versies van enkele hoofdstukken.
In de totstandkoming van het proefschrift in zijn uiteindelijke
vorm hebben verscheidene mensen een rol gespeeld. Tina en Bas
Jongeling namen de taak op zich mijn Engels te verbeteren. Deson-
danks kunnen er nog taalkundige ongerechtigheden voorkomen, om-
dat ik tot het laatste moment wijzigingen heb aangebracht. Peter van
Dorp verzorgde de lay-out. Anne-Marie van Sprang zette haar artis-
tieke gaven in om de omslag vorm te geven. Vincent van Dijk, Barend
van Engelenburg, Arnoud Heerings en Paul van Acker lazen en cor-
rigeerden ieder een gedeelte van de voorlaatste versie.
Martien verdient ten slotte een bijzondere vermelding. Zij heeft
me in de afgelopen tijd op vele manieren geholpen en geïnspireerd.
9
16
f science 17
ence' 29
2.3.1 Delineating philosophy and science 31
2.3.2 A taxonomy of philosophical ideas 33
2.4 Basic assumptions of the historical case studies 39
lies 45
CHAPTER 3
Maxwell, Boltzmann. and the kinetic theory of gases 47
3.1 Introduction 47
3.2 The philosophical ideas of Maxwell and Boltzmann 49
3.2.1 The philosophy of James Clerk Maxwell 50
3.2.2 The philosophy of Ludwig Boltzmann 58
3.3 Maxwell, Boltzmann, and the specific heat anomaly 65
3.4 Evaluating the analyses of Clark and Nyhof 80
1
4.2 The philosophical roots of Niels Bohr's physics
4.2.1 Bohr's early philosophical ideas and their sources
4.2.2 Bohr's atomic theory
4.2.3 Bohr's philosophical development,
4. berg,
theory in the 1920s
4.3.1
4.3.2 Quantum theory i;
4.4 The electron spin hypothesis
4.
mechanics
4.5.1
5.2 Four theories of science
5.2.1 Kuhn's theory of scientific development
203
212
SUMMARY IN DUTCH
The history of science abounds with examples of scientists who claim
that their work is based on particular philosophical principles. For a
long time, philosophers of science tended to ignore such examples.
They had set themselves the task of answering the question of how
scientific knowledge could be justified, which they considered an is-
sue that had to be tackled by means of a priori reasoning. The idea
that a study of the actual history of science could illuminate this
problem was regarded as misguided, and accordingly, philosophers
were not really interested in the philosophical views of scientists
themselves. This traditional conception of the task and method of the
philosophy of science was codified in the well-known distinction be-
tween 'context of discovery' and 'context of justification', which was
championed by the logical empiricists and Karl Popper. The context
distinction separates the empirical study of science, as practised by
historians, sociologists and psychologists, from the philosophical study
of science. Empirical study of science, it was argued, concerns the
context of discovery and cannot contribute to the resolution of prob-
lems regarding the epistemological status of scientific knowledge. The
latter issues belong to the context of justification, which is the domain
of the philosophy of science.
The context distinction thus serves to define the domains of dis-
tinct disciplines, which address different types of questions. It has
been taken to imply, moreover, a demarcation between different kind
of processes, studied by these distinct disciplines; the process of the
production or discovery of scientific knowledge has to be separated
from the process of the justification- of this knowledge. Proponents of
INTRODUCTION 9
the distinction argue that the latter process is governed by the laws
and criteria of logic and epistemology alone, which they suppose to be
of a non-empirical, immutable nature. By contrast, the process of dis-
covery is an empirically given process, and, though perhaps interest-
ing by itself, it is allegedly irrelevant to the problems with which
philosophers of science are occupied. If practising scientists endorse
particular philosophical principles and claim that their scientific re-
sults are in accordance with these principles, then these are facts
pertaining to the process of discovery. The traditional philosopher of
science considers only the scientific results in question, while the
philosophical principles of the scientist who discovered them are rele-
gated to the context of discovery. The latter are regarded, at least
from the philosophical point of view, as irrelevant idiosyncrasies.
The last three decades, however, have witnessed a radical trans-
formation of the methods and aims of the philosophy of science. This
change was initiated by Thomas Kuhn, whose work has made philoso-
phers of science more sensitive to the history of science, In his cele-
brated book The Structure of Scientific Revolutions, Kuhn argued that
the eternal criteria governing the justification of scientific knowledge,
which the logical empiricists and Popper sought to uncover, do not ex-
ist. What does exist are only the actual standards of scientific com-
mumtiGs« Kuhn s*to.t6cii in other words, that there is no point in distin-
guishing between ideal justification and real acceptance of knowl-
edge. Scientific knowledge which is accepted as such by the scientific
community simply is justified knowledge. In Kuhn's view, an exami-
nation of the history of science, particularly of the criteria for accept-
ance of scientific communities, may illuminate issues which were
previously considered to be the exclusive domain of the philosophers
of science, namely questions as to what is meant when knowledge is
tween context of justification and context of discovery as domains of
different disciplines. A consequence of this changed conception of the
task and methods of the philosophy of science is that the philosophical
views of practising scientists cannot be ignored anymore. Standards of
scientific communities are standards of real people, and the philo-
sophical commitments of these people may be expected to influence
their standards.
It was only natural that, as a consequence of the breakdown of
the context distinction, the process of discovery as such caught the at-
tention of an increasing number of philosophers of SCI612C8 « Since
1980, when two important collections of essays on scientific discovery
appeared, the study of discovery has been a distinct and weighty topic
on their agenda.1 The proponents of philosophical analysis of discov-
1 Nickles (1980a) and Nickles (1980b)
INTRODUCTION 11
ery processes claim that the ways in which scientists arrive at hypo-
theses, theories, and other results, may have epistemic import. To be
sure, it was not for the first time that scientific discovery was viewed
philosophers believed that it was possible to construct algorithmic
'logics of discovery', which could provide ' generative epistemic sup™
ception of discovery is no lonejox* considered ten9.1)1 e » Sciei-i.ti.fic dis—
covery is presently viewed as a process which is neither determined
by rules nor completely arbitrary. Instead, in the process of discovery,
scientists employ heuristics. Heuristics consists in strategies which
guide the scientist in the construction of hypotheses, theories, and so
precisely they work, and what is their philosophical import. The pro-
ponents of discovery analysis set themselves the task of answering
these questions.
Now, it may be expected that the philosophical views of scientists
themselves play a role in the heuristics they employ. Indeed, this gen-
eral idea was accepted even by traditional philosophers of science,
such as Popper, but they did not regard it as a philosophically interest-
ing topic. Since heuristics is currently viewed as being of philosophi-
cal importance, however, a systematic analysis of the heuristic role of
philosophical conceptions m the development of science öLppeöxs to be
of special philosophical interest. Such an . analysis has not yet been
provided, and the present study is an attempt to fill this gap.
The general aim of this study is to examine and display the
heuristic function of philosophical conceptions in the development of
science. In other words, its subject is the role of philosophy in scien-
tific discovery. The approach which will be taken in pursuing this aim
starting point of its philosophical analysis. Accordingly, I will carry out
two case studies in the history of modern physics in which I investi-
r
gate the philosophical views of individual physicists and the way in
which these have influenced their scientific work. The first case study
deals with the history of the kinetic theory of gases in the second half
of the nineteenth century. The second one has the development of the
case studies, which are presente d in Chapters 3 and 4, take up the
greatest part of this dissertation. The reason for this is that, in ray
view, a philosophical understanding of science is unattainable without
a serious study of the history of science. 1 believe that it does not suf-
fice merely to present a philosophical view of science and to clothe it
with scattered examples from history, as has often been done. Instead,
one should immerse oneself into the details of actual history, and by
