Mara Beller - Using extensive archival research, Beller shows how Bohr and others marketed their views, misrepresenting and dismissing their opponents as "unreasonable" and championing their own not always coherent or well-supported position as "inevitable"

Mara Beller, Quantum Dialogue. University of Chicago Press, 1999.


"Science is rooted in conversations," wrote Werner Heisenberg, one of the twentieth century's great physicists. In Quantum Dialogue, Mara Beller shows that science is rooted not just in conversation but in disagreement, doubt, and uncertainty. She argues that it is precisely this culture of dialogue and controversy within the scientific community that fuels creativity.
Beller draws her argument from her radical new reading of the history of the quantum revolution, especially the development of the Copenhagen interpretation. One of several competing approaches, this version succeeded largely due to the rhetorical skills of Niels Bohr and his colleagues. Using extensive archival research, Beller shows how Bohr and others marketed their views, misrepresenting and dismissing their opponents as "unreasonable" and championing their own not always coherent or well-supported position as "inevitable."
Quantum Dialogue, winner of the 1999 Morris D. Forkosch Prize of the Journal of the History of Ideas, will fascinate everyone interested in how stories of "scientific revolutions" are constructed and "scientific consensus" achieved.


"This a very impressive book: a ‘must-read’ for readers of this journal interested in thehistory of quantum physics. (...) To sum up: this is an excellent, though controversial, book. Future work on the early history of quantum theory, and especially on the history of the Copenhagen interpretation, starts here." - Jeremy Butterfield

"The book is a bold attempt to analyse carefully the complex process by which the insights and predilections of individuals contributed to the emergence of a consensus. Of course, one may not agree with all the conclusions. Nevertheless, Quantum Dialogue is an intellectually stimulating piece of work, energised by a distinct point of view that should appeal to physicists and philosophers alike." - Dipankar Home

"Hers is a complex story, written for experts, yet full of observations that will enlighten the determined reader. (...) (I)t demands courage from the uninstructed, but promises rewards in proportion to the effort." - Brian Pippard


Creativity is inherently elusive. In science, its definition is beset by an intriguing interplay between the individual and the group. This challenge is taken up in Mara Beller's book with regard to the early development of quantum mechanics (QM), and in particular the evolution of QM's so-called "Copenhagen interpretation" by Niels Bohr and his colleagues.
The book is a bold attempt to analyse carefully the complex process by which the insights and predilections of individuals contributed to the emergence of a consensus. Of course, one may not agree with all the conclusions. Nevertheless, Quantum Dialogue is an intellectually stimulating piece of work, energised by a distinct point of view that should appeal to physicists and philosophers alike.
The central theme is what Beller calls "dialogical flux": a dialectical process of "creative" conversations seeking to resolve tension between conflicting approaches by synthesis. That the evolution of the Copenhagen interpretation was agitated by such a flux of dialogues is brought out emphatically. The account results from a painstaking, comprehensive study of primary sources: correspondence, notebooks and, of course, original scientific papers.
The first seven chapters roughly cover the period 1925-35, during which both matrix and wave-mechanical versions of QM, though conceived independently, turned out to be equivalent representations giving rise to Heisenberg's uncertainty relation and Bohr's complementarity. Beller argues that the uncertainty relation and complementarity appeared not so much because of a prior commitment either to indeterminism or positivism, but rather as a response to Schrodinger's wave mechanics and to ensure consistency with some crucial experiments. Complementarity then sparked off the Bohr-Einstein debates, which culminated in the Einstein-Podolsky-Rosen (EPR) paper of 1935 challenging the completeness of QM.
The high point of the analysis is the way Beller shows how the Copenhagen school shifted its focus from arguing for consistency to arguing for inevitability. This transformation was prompted by Einstein changing his position from finding a contradiction with the uncertainty relation to showing that the QM description of the state of a system was incomplete. Beller illustrates the shift by pointing out differences between Bohr's reply to the 1935 EPR paper and his 1928 Como lecture. His response to EPR was particularly apocalyptic, with its strong statements such as that there was "no question of any unambiguous interpretation of the symbols of quantum mechanics other than that embodied in the well-known rules".
Prior to EPR, concepts such as uncertainty and complementarity were attributed essentially to the uncontrollable and inevitable "disturbance" caused by a measurement. This notion of "disturbance" was crucial to the way in which EPR defined both "elements of reality" and the "locality condition". As Beller correctly points out, Bohr cleverly avoided questioning the locality condition. Instead he introduced the "wholeness" of the composite system, comprising the spatially separated parts together with the measuring set-up. This led to what Bohr criticised as an "ambiguity" in the EPR argument that hinged on inferring a value "without disturbing the system in question". However, the way a measurement on one sub-system specifies the experimental context of the other remained ambiguous in Bohr's reply. This was reflected in his introduction by fiat of the "unanalysability" of measurement interactions, a strange notion that restricts the universality of QM.
Beller quite clearly brings out the above weakness in Bohr's response to EPR. The book stresses that in the post-EPR period Bohr's mode of argumentation increasingly followed Louis Pasteur's maxim for a persuasive strategy: "Make it look inevitable." Bohr asserted as a "simple logical demand" the "indispensability" of the classical description of an apparatus, while leaving the boundary between quantum and classical behaviour unspecified. Interestingly, soon after his seminal 1925 paper, Heisenberg had become aware of the problem of reconciling quantum mechanics with the everyday macroscopic world. Ironically, this classical-limit problem remains one of the unresolved issues in QM.
As an example of the usefulness of "dialogical analysis", Beller undertakes a comparative study of Heisenberg's "seemingly confident" published paper suggesting the uncertainty relation and a draft he sent in a letter to Pauli. This brings out hidden ambiguities in the published paper. Another application of the method is Beller's decipherment of apparently obscure texts like Bohr's Como lecture. Beller seeks to demystify it by viewing it as a juxtaposition of several arguments directed towards different issues raised by Bohr's colleagues. Internal divergences within the Copenhagen school were skilfully smoothed over and an apparently monolithic structure with a sense of "finality" presented to the physics community as a whole. Beller discusses in depth, within this framework of "dialogical flux", how these rhetorical strategies adopted by Bohr and his colleagues worked to achieve triumph for the Copenhagen interpretation.
However, the entire story of alternative later approaches to interpreting QM, such as David Bohm's scheme and dynamical models of collapse, is omitted by Beller, because of the book's focus on the 1920s and 1930s. Seventy-five years on, foundational issues of QM are presently undergoing an extensive reappraisal. The role of "dialogical flux" in the current scenario needs its own critical study.
The 19th-century linguist Max Muller once observed: "I believe we both care far more for what is right than who is right ... Facts and correct deductions from facts are all we ought to care for." How hard the maintaining of this ethos is when personal prejudices and individual egos influence the making of a theory is the most important lesson conveyed by Quantum Dialogue . - Dipankar Home

Mara Beller's book centers around the quantum revolution, using it to describe first the "anatomy of scientific discovery" and then the "strategies of consolidation" of a particular theory (in this case, the orthodox Copenhagen interpretation). Her emphasis is on the notion of dialogue, specifically as a process used by scientists to reach their conclusions -- and a means for the historian and philosopher of science to retrace those steps and understand "how revolutionary stories in history of science are constructed."
       Beller goes on to detail a "dialogical" approach to the understanding of scientific discovery and of the dominance of specific theories over others ("a tentative program for a dialogical historiography of science"). The Copenhagen interpretation provides a convincing example of her methodology. Retelling the story of the quantum revolution, she is able to sharply differentiate it from the simplified historical accounts (often fostered by the main actors) that concentrate on the results and not how they were obtained (and, in fact, blur and omit many of the steps in seeking the appearance of inevitability about the results).
       Scientific dialogue is a fruitful area of study, because so much of science does arise out of dialogue. Science is rarely done in isolation. Indeed, science is famous for the constant exchange of ideas, the constant communication between those involved. In conversation, at conferences, in the many professional journals, in letters, and, evermore, via the Internet there is a constant flow of ideas and debate that lead to further scientific advancement.
       The quantum revolution is fairly well documented in the letters, lectures, papers, and reminiscences of the scientists involved in it. Beller makes the most of this material in re-examining the process of discovery using her dialogic approach. Her book is remarkable for this undertaking alone, a valuable chapter in the history of science. Whether in pointing out significant contributions from scientists who have since been relegated to the sidelines in historical accounts, or in showing how much retroactive re-defining of problems and approaches the quantum revolution has been subject to, Beller shines an illuminating light on much that has long been hidden in shadowy darkness.
       Much of the record is clear, yet still subject to misinterpretation. A notable example is the unfortunate consequences of the misguided hero worship around Niels Bohr. As Beller points out, "part of the Bohrian myth is that he thought very clearly and only expressed himself obscurely," and she dares suggest that, in a number of instances, his thinking too was muddled. Bohr's ambiguous presentation allows for a multitude of interpretations, satisfying different concerns of different audiences -- a situation Beller rightly sees as troublesome. Bohr's complementarity, in particular, is vulnerable to criticism because it is never clearly and consistently defined or delineated, but it generally remains above reproach. Beller shows that such uncritical acceptance can help to lead to the unwarranted hegemony of an idea (as occurred with Bohr and the Copenhagen interpretation).
       Beller speaks of the "rhetoric of inevitability" surrounding the Copenhagen interpretation, pointing out that both the rhetoric and the interpretation itself rest on "two central pillars -- positivism and the doctrine of the necessity of classical concepts." As Beller shows, these are vulnerable pillars. Nevertheless, historically the rhetoric of the inevitability of the Copenhagen interpretation prevailed. It is a fascinating process that led to the adoption and success of the theory, with personality conflicts, hero worship, and a fair amount of ambiguity all playing a role -- all carefully documented and detailed by Beller.
       An excellent example is also the misconstruction of the Einstein-Podolsky-Rosen argument. Beller dismisses Bohr's response, and suggests why he nevertheless emerged as a victor in the argument:
A few ingenious rhetorical moves characterize Bohr's response and create the illusion of victory. By giving a short, nonmathematical summary of the dense and complex EPR paper, Bohr ensured that few would read the EPR paper itself.
       The overwhelming majority of presentations of the Bohr-Einstein debate use Bohr's nonmathematical summary of EPR. Yet this summary is misleading and introduces weaknesses not present in the original EPR paper. Those who lightly dismiss the EPR challenge dismiss in fact Bohr's version of it.
       This is one of the more contentious sections of Beller's book, source of what we are certain will be much lively debate. (We leave it to the professionals, though we acknowledge that Beller makes an impressive case for her point of view.)
       The evidence Beller presents regarding the quantum revolution clearly supports one of her conclusions:
The Copenhagen interpretation was erected, not as a consistent philosophical framework, but as a collection of local responses to changing challenges from the opposition.
       The hegemony of the Copenhagen interpretation has been surprisingly enduring, still keeping much criticism at bay. Beller addresses the fate of alternate theories, particularly David Bohm's. Again, her dialogic approach is fruitful in explaining the dominance of one interpretation -- and in suggesting where weaknesses can be found that will eventually lead to scientists moving beyond it.
       Overall Beller makes a very convincing case with her well-constructed argument. Neatly summing up her points, she presents an argument -- and a dialogic approach -- that seem an immensely useful addition to the field.
        Quantum Dialogue is a quite stunning achievement, offering a wealth of material specifically about the quantum revolution but also suggesting broader applications of Beller's approach. Clearly written, well presented, and exceptionally well researched it is an impressive example of scientific, philosophical, and historical analysis. The implications of the work are far-reaching, and it is highly recommended to any and all interested in the philosophy and history of science.
       Quantum Dialogue is a specialist book, clearly written for an academic audience. It is not highly technical, though some scientific literacy is necessary to make one's way through it and familiarity with the basics of quantum mechanics are necessary for a full understanding of a number of the points discussed. There is little demanding maths (an eigenfunction or two, relegated to the footnotes, mention of Hamiltonians and the like) and we suspect the book will be at least fundamentally comprehensible to anyone whose eyes do not blur over at the mere sight of terms such as "matrix theory" and "wave-particle duality". However, philosophical and scientific backgrounds certainly help facilitate understanding (and enjoyment) of the text. - The Complete Review

Mara Beller, a professor of history and philosophy of science at the Hebrew University of Jerusalem, has devoted several works to various aspects of the history of quantum mechanics; this book synthesises her findings. Two main threads are apparent in this book, each addressing a rather different audience, although the two threads emerge from the same case studies: A) a revisionist history of quantum mechanics, which would be of the greatest interest to any physicist who ever felt baffled by quantum mechanics; B) a new approach to the history of ideas, or to philosophy of science or epistemology, which would be more of interest to philosophers or historians of science. A) Revisionist history of quantum mechanics. In the author's analysis, the historical account of the development of three concepts of quantum mechanics is in need of major revision: the emergence of matrix mechanics; the notion of quantum uncertainty; and Bohr's principle of complementarity. In a similar vein, the author argues that the received wisdom about the development and acceptance of the Copenhagen interpretation of quantum mechanics is flawed. According to Beller's analysis, Heisenberg's opposition to Schrodinger's wave mechanics was not primarily physical, but sociological: Heisenberg did draw some insights from Schrodinger's works, and was originally sympathetic, but became virulently critical of wave mechanics when it threatened to overshadow his own matrix mechanics (Chapter 2 to Chapter 5). Heisenberg's desire to achieve preeminence recurs throughout the book (e.g., pp. 70-71, 195). Bohr's principle of complementarity is scrutinised thoroughly (Chapters 6 and 11). The author's conclusion is that the principle was never clearly stated by Bohr, was used inconsistently, and was applied in areas (like psychology) where it was unlikely to represent more than a clumsy metaphor. While the book is not intended to be a critical biography of Niels Bohr, it could certainly fulfill the role. Nearly four pages of the bibliography are filled with references to Bohr publications, and Bohr's scientific work is discussed in no less than 8 chapters (from Chapter 6 to Chapter 13). Mara Beller does not shy from pointing out Bohr's conceptual about-faces, rhetorical strategies, and scientific shallowness. In contrast to most scholars and nearly all physicists, she refuses to ascribe to her intellectual limitations her difficulty in grasping Bohr's thought. In her opinion, if Bohr's physical and philosophal views appear contradictory, it is not because of their subtlety, but because they are poorly conceived (Chapter 12). In particular, in the Einstein-Bohr exchange on the Einstein-Podolsky-Rosen paradox, the author is very critical of Bohr's argumentation, which is described as deceitful (Chapter 7). Mara Beller asserts that the 'triumph of the Copenhagen interpretation' has less to do with its explanatory power than with the success of the Copenhagen school in enforcing orthodoxy among the vast majority of physicists. Furthermore, the traditionally accepted history of quantum mechanics is presented as an instance of 'Whiggish history' (history written by the winner). These points are developed in particular in Chapters 9 and 10. B) New approach to the history of ideas. As a historian and philosopher of science, Mara Beller is trying to discover how scientific progress takes place. Several prominent scholars have proposed approaches on this topic, most notably Karl Popper, Thomas Kuhn, Paul Feyerabend, and more recently the social constructivists. Dissatisfied with these, and particularly with Kuhn's approach (Chapter 14), she proposes instead the dialogical approach, discussed in Chapters 1 and 15. Although the discussion is lucid, the present reviewer was left with the impression that, in the end, adoption of a scientific model in the dialogical approach is a matter of taste. (This potential weakness may well disappear once the approach has had a chance to mature.) The central chapters of this book are certainly worth reading for any physicist with an interest in quantum mechanics. In particular, students struggling with the Copenhagen interpretation might find Chapters 9 to 13 (or any subset of these) to be quite an eye opener. - Claude Plante

In Quantum Dialog, Mara Beller presents a revisionist history of the
development of quantum theory and its philosophy. The author, a professor of
the history and philosophy of science at the Hebrew University of Jerusalem,
focuses on the controversies of the late 1920s. Her approach, which she calls
"dialogical," consists of a comprehensive analysis of the participants'
conversations, letters, lectures, and other writings to produce a complete
context within which to contemplate the sources of their ideas, their progress,
and their motivations. The technique leaves much room for the contributions of
minor players and the arguments of dissenters. As the author is intensely
aware, these can be buried in the rewriting of history that invariably takes
place as a successful theory comes first to be accepted, then presented as an
irresistible standard, and finally is made to seem inevitable. Beller makes a
good case for how the steamroller of orthodoxy came to take over the
development of quantum theory. But while she makes her point in many ways, she
unfortunately also demonstrates the serious weaknesses in the technique,
wherein one's own convictions can lead one to make much too much out of very
little evidence. Ultimately the argument bogs down in her thoroughly
unconvincing attacks on the intellectual integrity of figures such as Bohr and
Heisenberg.
The first half of the book shows how Heisenberg, Bohr, Born, and their
collaborators slowly developed the Copenhagen interpretation of quantum theory,
partly in response to challenges from Schrödinger, Einstein, and others. This
was primarily a process of trying to splice together a consistent
explanation--using various thought experiments, with the gradual inclusion of
the uncertainty principle, complementarity, and Bohr's insistence of the
importance of classical measuring devices--while refuting the objections that
were constantly being raised against the theory. Beller sees as the end product
of this process an inconsistent melange of ideas, where others see a totally
consistent theory.
In the second half of the book, the author makes a case for a gradual shift in
the rhetoric of defending and explaining the theory. The arguments that showed
the consistency of the standard interpretation were, through a process of grand
overreaching, slowly replaced by an account that claimed to show the
inevitability of this interpretation. Beller believes that its acceptance was
no simple success story, but was due primarily to intimidation and abuse of
authority by Bohr and his collaborators.
Now there are many accounts in the literature that show that Bohr's charisma
and single-minded determination could, at times, prove rather daunting, and so
her arguments to this effect seem to make sense up to a point. But she goes way
overboard and implies a conscious attempt by Bohr and Heisenberg to browbeat
the opposition into accepting an interpretation that they knew could not be
defended. She uses words, like "deceptive," that imply a deliberate
intellectual dishonesty on their part. It is hard to deny the strength of her
conviction in quotes like "There was neither belief nor commitment on
Heisenberg's part--only a selective and opportunistic use of Bohrian doctrine
in those circumstances where Heisenberg's aim was to argue against the
opposition...This is a characteristic example of a powerful social strategy of
legitimation disguised as an abstract theoretical argument." But the evidence
just doesn't support such a negative spin on the situation.
Beller attributes the acceptance of the Copenhagen interpretation by most
physicists, in no small part, to hero worship. She believes that "One cannot
overestimate the impact of the authority figure in the evaluation and
acceptance of ideas. Bohr's unprecedented authority not only promoted the
widespread, uncritical acceptance of the Copenhagen philosophy but obtained a
favorable reception for his dubious and poorly developed ideas outside of his
area of competence." She gives many quotes to indicate his acceptance as a
"father figure," both professional and personal, to the younger physicists
about him. She claims "it became almost obligatory, when writing about Bohr, to
refer to the 'subtlety' of his thinking." She then points out that he was
exceptionally hard to understand and essentially accuses everyone who praised
the depth of his thought of having been intimidated into accepting obscurity as
profundity. When she quotes "Pais graciously remarks that 'Bohr's strength lay
in his formidable intuition and insight rather than in erudition'" (my
italics), she cannot believe that he really means it.
Although even Bohr's intellectual opponents (Bohm and Hiley) call him subtle,
she remarks that they too felt the pressure of intimidation. She seems to feel
that everyone but her has been cowed by this--even Einstein and Schrödinger.
The tremendous displays of warmth and affection for Bohr shown by the students
at his institute, and even their parodying of him, Beller takes as further
evidence of "hero worship and the associated suppression of criticism." She
quotes an anecdote by Feynman to the effect that when the young Feynman met
Bohr at Los Alamos and (not knowing who he was) criticized him, Bohr suggested
that the next time they discussed ideas they should do so privately, so as to
avoid all the big shots who always said "yes, yes Dr. Bohr." She offers this to
show how intimidated physicists were by Bohr but seems unaware that the
anecdote also has a contrary interpretation--one suggesting both Bohr's great
sensitivity and how the enormous affection everyone had for him might have been
earned.
By the way, the issue here is not whether physicists are hero worshipers. My
own experience convinces me that they certainly are. The real issue is whether
Bohr would deliberately and dishonestly use his authority to intimidate others
into accepting a position that he did not believe to be true.
Beller takes great pains to show that Bohr was not at home with difficult
mathematics, and she uses this to imply that he was actually, deep down, sort
of a bumbler. She even calls him "a tragic figure," who should not have been
taken so seriously by so many great physicists. But truly great insights in
physics rarely come primarily from mathematical sophistication, and I find her
arguments somewhat irrelevant to the issue of how much respect Bohr is due.
Einstein, who never accepted Bohr's interpretation of quantum theory, called
Bohr's insights "the highest form of musicality in the sphere of thought."
(This quote is not from Beller's book, but it is hard for me to see
intimidation at work here.)
As a parallel case, I remember when I found out that Irving Berlin could not
read a note of music. Rather than convince me that his songs were no longer
worth listening to, this made me appreciate all the more what a phenomenal
natural genius he must have been. My reaction to Bohr's mathematical
deficiencies is similar.
Also, many of Beller's other arguments against Bohr depend on accepting her
reading of very weak evidence. There is just no smoking gun here. When one
reads everything someone has written over several decades, it is easy to find
shifting opinions, contradictions, and confusing remarks. This does not
necessarily make a case for intellectual dishonesty. Nor does trying to use
different strategies of argument, geared to different types of audiences, prove
that one is disingenuous. I think Beller is guilty of trying to force the worst
possible conclusions out of very slight and ambiguous evidence. The problem is
that she has not approached her subject with a very open mind. One can begin to
see her bias in comments such as "One interesting attempt to find some
stability, objectivity, and cohesion, despite the impressive impact of social
studies of science that deny those characteristics to science, is..." This
jaundiced look at science in general leads to such opinions as "finality is an
ideological, not a conceptual, position, and this is perhaps the reason
scientific controversy often looks more like a political campaign, with one
side discrediting and caricaturing the other, than an open-minded dialogue
about fundamentals."
So what is one to make of Quantum Dialog? The author makes a good case for the
contention that arguments about the consistency of the Copenhagen
interpretation came to support the incorrect conclusion that it was the only
possible interpretation. How could this happen? I think this is a fascinating
question, well worth a book. But I also think that it is a serious mistake to
look for villains. That makes the process much simpler and less significant
than it was. The problem becomes much more interesting and important when one
sees the process unfolding and asks how could so many people, all looking for
the truth, have convinced themselves that one viable interpretation was
actually unique and unassailable.
It is easy to construct a much more conventional and, to my mind, plausible
scenario as to how this occurred, one without conspiracy theories. Furthermore,
scientists like to believe that the scientific enterprise is a self-correcting
one. And although there is nothing inevitable in the process, in the case of
quantum theory, one can see the corrections slowly taking place. The original
Copenhagen interpretation had a tremendous formal mathematical beauty, and Von
Neumann had "proven" that a hidden variable interpretation was not viable. So
it is easy to see how most physicists accepted this and considered the matter
closed.
Only in the 1950s did Bohm invent his alternate model, which led John Bell to
disprove Von Neumann's result. (Beller mentions a previous argument against Von
Neumann's proof by a student of Heisenberg, but because she doesn't give any
details, one cannot evaluate its merit.) Bell then also proved his own famous
theorem, which showed that one can experimentally test certain types of
realistic interpretations. This not only led to a series of still-ongoing
experiments to test aspects of various interpretations, but it also increased
interest in the possibility of other interpretations. Since then, Bohm's
interpretation and several others as well have slowly been winning converts.
Many philosophers have become interested in the new models. In general, the
situation is now much more favorable for the acceptance of new models than it
was in the past, although none have yet caught on among working physicists,
mostly because there are no new experimental situations that have needed to be
explained by them. But in this history, one can see the gradual development of
an open-mindedness in the field.
Scientists unfortunately do jump on bandwagons and make flawed judgments, and
this does slow the process of choosing between theories. But in this case the
process does seem to be slowly correcting itself. There is no necessity for
seeing dark forces at work here or for impugning the character of the
scientists. Making Heisenberg and Bohr into villains doesn't ring true and
doesn't solve the interesting problems involved. (Of course, Beller is fully
aware of everything I have said above, but she would certainly not agree with
me. To the extent that one denies objectivity to science, "self-correcting"
becomes a meaningless concept, and one is forced to find more sinister
explanations based on the foibles of individuals.) - Daniel Greenberger


An interesting essay by Beller regarding the so-called Sokal-hoax
Copenhagen - Another Round by Beller 
Comments of the Fictional Character ‘Michael Frayn’ on Mara Beller’s Another Round