Table Of ContentTHE REALITY OF THE UNOBSERVABLE
BOSTON STUDIES IN THE PHILOSOPHY OF SCIENCE
Editors
ROBERT S. COHEN, Boston University
JÜRGEN RENN, Max-Planck-Institute for the History of Science
KOSTAS GAVROGLU, University of Athens
Editorial Advisory Board
THOMAS F. GUCK, Boston University
ADOLF GRÜNBAUM, University of Pittsburgh
SYLVAN S. SCHWEBER, Brandeis University
JOHN J. STACHEL, Boston University
MARX W. WARTOFSKYt, (Editor 1960-1997)
VOLUME 215
THEREALITY
OF
THE UNOBSERVABLE
Observability, Unobservability
and Their Impact on the Issue
of Scientific Realism
Edited by
EVANDRO AGAZZI
Department of Philosophy,
Universify of Genoa, Italy
and
MASSIMO PAURI
Department of Physics (Theoretical Division),
University of Parma, Italy
Springer- Science+B usiness Media, B. V.
A c.I.P. Catalogue record for this book is available from the Library of Congress.
ISBN 978-90-481-5458-6 ISBN 978-94-015-9391-5 (eBook)
DOI 10.1007/978-94-015-9391-5
Printed on acid-free paper
All Rights Reserved
© Springer Science+Business Media Dordrecht 2000
Originally published by Kluwer Academic Publishers in 2000.
Softcover reprint of the hardcover 1s t edition 2000
No part of the material protected by this copyright notice may be reproduced or
utilized in any form or by any means, electronic or mechanical,
including photocopying, recording or by any information storage and
retrieval system, without written permission from the copyright owner.
TABLE OF CONTENTS
INTRODUCTION
EVANDRO AGAZZI and MASSIMO PAURI:
Observabilityand Scientific Realism 1
Section Summaries 8
HISTORY
ERHARD SCHEIBE: ..
The Origin of Scientific Realism:
Boltzman, Planck, Einstein 31
GENERAL PHILOSOPHY, SCIENTIRC REALISM
EVANDRO AGAZZI:
Observabilityand Referentiality 45
PAUL M. CHURCHLAND:
A new Approach to Human Cognition and its
Significance for the Philosophy of Science 59
JEAN P. DESCLES:
Abduction and Non-Observability -Some Examples
from Language Science and the Cognitive Science
ROBERTO TORRETTI:
'Scientific Realism' and Scientific Practice 113
PETER GALISON:
Random Philosophy 123
MARIO CASARTELLI:
Formal Representation and the Subjective Side
of Scientific Realism 129
GERHARD HEINZMANN:
Convention and Observability -Poincare once again 137
v
vi TABLE OF CONTENTS
RAMÖN QUERALTö:
Scientific Realism, Objectivity,
and 'Technological Realism' 145
PHILOSOPHY OF OBSERVATION
DUDLEY SHAPERE:
Testability and Empiricism 153
JANFAYE:
Observing the Unobservable 165
GIOVANNI BONIOLO:
What does it Mean to Observe Physical Reality? 177
ALBERTO CORDERO:
Realism, and the Case of Rival Theories
without Observable Differences 191
MAURO DORATO:
Measurability, ComputabiJity and the Existence
of Theoretical Entities 207
JESOS MOSTERlN:
Observation, Construction
and Speculation in Cosmology 219
MARK WILSON:
Where did the Notion that Forces are Unobservable
come from? 231
PHILOSOPHY OF QUANTUM THEORY
NANCY CARTWRIGHT:
Quantum Mechanies without the Observables 241
BERNARD D' ESPAGNAT:
Observation, Contextuality and ReaJism 251
MASSIMO PAURI:
Leibniz, Kant and the Quantum -A Provocative
Point of View about Observation, Space-Time, and
the Mind-Body Issue 257
TABLE OF CONTENTS vii
OLIVIER COSTA DE BEAUREGARD:
Efficient and Final Causes as CPT Reciprocals 283
SPECIFIC ISSUES OF OBSERVABILITY IN QUANTUM THEORY
CHARLES P. ENZ:
Observability and Realism in Modem Experiments
with Correlated Quantum Systems 293
BERNULF KANITSCHEIDER:
Quantum Mechanics, Realism
and the Ultimate Observer 311
PETER MITTELSTAEDT:
Individualistic and Statistical Interpretation
of Quantum Mechanics 317
BRIGITTE FALKENBURG:
How to Observe Quarks 329
GlOVANNI M. PROSPERl:
Common Experience and Quantum Theory -Observables
and Beables 343
ENRICO G. BELTRAMETTI and SLAWOMIR BUGAJSKI:
On the Relationships between Classical
and Quantum Mechanics 353
EVANDRO AGAZZI AND MASSIMO PAURI
INTRODUCTION
Observability and Scientific Realism
It is commonly thought that the birth of modern natural science was made possible by
an intellectual shift from a mainly abstract and specuJative conception of the world to
a carefully elaborated image based on observations. There is some grain of truth in
this claim, but this grain depends very much on what one takes observation to be. In
the philosophy of science of our century, observation has been practically equated
with sense perception. This is understandable if we think of the attitude of radical
empiricism that inspired Ernst Mach and the philosophers of the Vienna Circle, who
powerfully influenced our century's philosophy of science. However, this was not the
atti tude of the fo unders of modern science: Galileo, fo r example, expressed in a f amous
passage of the Assayer the conviction that perceptual features of the world are merely
subjective, and are produced in the 'anima!' by the motion and impacts of unobservable
particles that are endowed uniquely with mathematically expressible properties, and
which are therefore the real features of the world. Moreover, on other occasions, when
defending the Copernican theory, he explicitly remarked that in admitting that the Sun
is static and the Earth turns on its own axis, 'reason must do violence to the sense' , and
that it is thanks to this violence that one can know the tme constitution of the universe.
From these remarks, it follows that ancient natural science was mainly based on
observation, understood as a careful report of sense data, while modern science was
based, to use again a famous expression of Galileo, on 'sensible experiences and
mathematical demonstrations'. The 'sensate esperienze' of Galileo are not so much
observations, but rather 'experimental investigations', such that one is entitled to
translate this expression as 'sensible experiences' (rather than 'sense experiences'),
something that is by no means alien to the I talian meaning of' sensate' even at the time
of Galileo, and has become very common subsequently. In this light, one can see that
perceptual experience must be guided, interpreted, integrated in a theoretical framework,
in order to be scientifically significant. All this amounts to saying that modern science
is different from ancient science in that it is experimental, and this is even
terminologically clear, for example, in Newton, who speaks of 'experimental
philosophy' when he wants to denote the new natural science.
What these people wanted to exclude from science was the admission, by means of
pure speculation, of alleged 'intimate essences' or' hidden qualities' of things: but
these expressions (of Galileo and Newton respectively) did not have the meaning of
'unobservable' features or entities. The correct understanding of these expressions would
show that they are related to other epistemological and ontological issues (such as the
distinction between essence and accidents, and the power of inteJlectual intuition, for
example), but we shall not dweil on this issue here.
1
E. Agazzi and M. Pauri (eds.), The Reality 0/ the Unobservable, 1-30.
© 2000 Kluwer Academic Publishers,
2 EVANDRO AGAZZI AND MASSIMO PAURI
In addition, if we consider the rapid and impressing growth of modern science in the domain
Df mechanics, and then in other domains, we must admit that only a limited amount of new
observations stimulated this growth, while its advancements chiefly consisted in the introduction
and development of many powerful idealizations of an intellectual kind: progress of science
was not the result of looking hard, but of thinking hard.
The foregoing reflections by no means aim at minimizing the role of observation in science,
but rather at making clear what this role precisely is, and to this end one must stress that
observation certainly includes sense perception, but is not reduced to it. This becomes particularly
clear if one considers that the observations on which the advancements of all empirical sciences
have been based are of an instrumental kind. Such a fact is often interpreted according to two
correct and obvious characteristics: (a) instruments allow for a much greater accuracy than
simple unaided sense perception; (b) instrumental observation is standardized, and therefore
practically free of those subjective features that inevitably accompany any sense perception.
These are certainly significant advantages, but they can only be correctly admitted when
instrumental observation and unaided sense perception are abaut the same things, and this
occurs only seldom in science. In most cases instrumental observations that amounted to real
breakthroughs in scientific knowledge were those that permitted the 'observation' of something
that was not' perceivable' by pure sensation. Of course, one must 'see' something in or through
the instrument (this is why perception is included in observation) but the not unreasonable
question is whether this something 'really' exists, or is rather a simple image produced by the
instrument.
Certain scholars (such as Cremonini) who refused to acknowledge Galileo's astronomical
discoveries obtained through the telescope, precisely relied on such a legitimate doubt. The
classical methodological maxim nonfit scientia per visum solum (science is not based on sight
alone) was based on the awareness of common sense illusions, or of artificially created optical
illusions (like those of disfiguring mirrors), and required that for a sense perception to be
accepted as true, it had to be in keeping with an al ready existing, accepted and sound theoretical
framework. In the case of the opponents of Galileo's observational astronomical discoveries,
such an accepted theoretical framework was a metaphysical cosmology in which the number
of celestial bodies, their trajectories, their intrinsic motion, etc. were allegedly determined in a
cogent way, and exactly corresponded to the evidence provided by the unaided sense perception.
Since the new sense perceptions provided by the instrument were in contrast with such a
framework, they had to be rejected as illusions, like several well-known optical illusions. The
most obvious way of rejecting such objections is that of convincingly demonstrating the
reliability of the instrument, but it would be very naive to imagine that such ademonstration be
provided by a simple comparison of perceptions in certain favorable cases. What is needed is
a theoretical justification of this reliability. In our example this could only partially be provided
by a correct optical theory of the telescope: sooner or later, the general theoretical framework
that made the new observations unacceptable would have to be replaced. This meant that a new
cosmology had to be constructed (and this was what historically actually occurred).
Such a complex but propitious solution, however, may not always be available. Historians
of science had noted that in several ancient books on microscopic anatomy there appeared
carefully drawn figures of structures that we do not actually observe today. The mystery was
explained when certain scholars decided to repeat the observations by using the same methods
INTRODUCTION 3
of preparation of the tissues and the same microscopes that were used by the ancient scientists:
the mysterious figures appeared again, and it was not difficult to discover that this was due to
the fact that such old microscopes were not acromatic, and therefore produced 'aberrations'
that could not be detected as being such at that time. In this case, it was a technological
advancement that allowed for an improvement of the reliability of the instrument (and, at the
same time, permitted to explain-away the initial observations which were 'untenable').
Something similar occurred at the beginning of our century when histological methods were
introduced in the study of the brain and started providing 'observational evidence' in favor of
the neuronal theory. Such evidence was possible thanks to very special procedures (having
mainly to do with the particular kind of 'impregnation' adopted for the tissues), but for a while
there remained questions as to whether the observed structures were simply 'brought to light'
by the method in question, or rather 'produced' by it.
The discussions and examples provided lead us to formulate a few fundamental questions.
Some contemporary philosophers of science equate observation and perception, and maintain
that we cannot, for example, observe electrons because we cannot perceive them. We can only
perceive the traces they allegedly produce in a cloud chamber or on a photopiate. Therefore,
these scholars conclude: admitting the existence of electrons is simply a consequence of
accepting a given physical theory, and of giving to this theory a particular ontological purport.
It is clear that this position is not characterized by something that could appear as a mere
nominalistic 'simplification' (that is, the equation of observation and perception), but by
attributing, to perception alone, the privilege of having an ontological purport, since it is
(all egedl y) f ree of theoretical commi tments. What perception ostends exists, w hil e w hat a theory
claims might not exist. This position can be challenged for several reasons. First, because it
apparently accepts a moderate or minimal level of realism, to the extent that features attested
by direct observation are considered to be real. In the second place, however, observation is
reduced to perception, thus annihilating almost all the advantages science has obtained from
instrumental observation, since such an observation is devoid of ontological purport. In the
third place, the reason why perception alone is ontologically committed is because it does not
imply theory. Each of these points raises serious questions.
The minimal level of realism accepted in this position relies upon a simple (or simple
minded) analysis of the notion of existence: we unproblematically say that chairs, tables,
mountains, etc. exist, because we observe (perceive) them. We do not want to deny that science
can speak of existing things, but demand that the meaning of existence remain the same.
Therefore, we can attribute existence, at least in principle, to those entities spoken ofby science
which might possibly be brought within the range of accessibility of our observation (perception),
like the features of a very distant planet that we can see only with a telescape, but that would
actually be perceived if we could look at them directly from aspaceship one day. A theory
cannot produce the same result, since it may at best give a sufficient logical explanation of
certain observational (perceptual) states of affairs, but never a necessary (that is cogent and
univocal) one.
Some questionable aspects of this perspective can be reduced to the following. There is the
reasonable intention of preserving common sense realism, but this could possibly degenerate
into some form of the Berkeleyan idealism: esse est percipi (real things are reduced to bundles
of perceptions). However, serious scrutiny of the actual ways in which existence is predicated,
