Adopting Murdoch’s pragmatist reading of Bohr’s theory of meaning with regard to Bohr’s notion of complementarity, in this paper I try to see Bohr’s post-Como and, in particular, post-EPR philosophy of quantum mechanics in the light of Peircean pragmatism with the hope that such a construal can shed more light to Bohr’s philosophy. I supplement Murdoch’s position on Bohr’s pragmatism by showing that in addition to his complementarity, Bohr’s correspondence principle, instrumentalism and realism can be read on the (...) basis of Peirce’s pragmatic maxim and his notion of indeterminism has commonalities with Peirce’s tychism. Also, Bohr’s practice of applying the correspondence principle can be interpreted in the light of Peirce’s fallibilism. However, when it comes to Bohr’s understanding of the symbolic character of quantum mechanics, Bohr’s philosophy deviates from Peircean pragmatism. Bohr’s philosophy distinguishes between the symbolic language of quantum formalism, which counts as a tool practically useful for prediction, and observation sentences which are visualizable in space and time and refer to the so-called individual phenomena. Such an epistemologically significant distinction is not recognized by Peircean pragmatism. (shrink)

Steen Brock paints a cross-disciplinary picture of the philosophical and scientific background for the rise of the quantum theory. He accounts for the unity of Kantian metaphysics of Nature, the Helmholtzian principles, and the Hamiltonian methods of modern pre-quantum physics. Brock shows how Planck's vision of a generalization of classical physics implies that the original quantum mechanics of Heisenberg can be regarded as a successful attempt to maintain this modern unity of physics.However, for Niels Bohr, the unity of science and (...) metaphysics did not end in the world of physics. The development of quantum physics had general implications both for other sciences and for various philosophical issues. Brock discusses these matters with respect to recent topics within the philosophy of science and major interpretations of Bohr's ideas. The author invites the reader to follow a long andwinding route of thought which, in the end, culminates in Bohr's ideas of complementarity, culture and Spirit. (shrink)

Murdoch describes the historical background of the physics from which Bohr's ideas grew; he traces the origins of his idea of complementarity and discusses its meaning and significance. Special emphasis is placed on the contrasting views of Einstein, and the great debate between Bohr and Einstein is thoroughly examined. Bohr's philosophy is revealed as being much more subtle, and more interesting than is generally acknowledged.

A review of *Niels Bohr’s Philosophy of Quantum Physics in the Light of the Helmholtzian Tradition of Theoretical Physics *.

Ever since the beginning of development of Quantum Mechanics there was a metaphysical division between the “macro” world as described in “everyday language” and the “micro” world described by quantum formalism. A discussion is offered of the need to reunite these arbitrarily divided worlds through an overview of the main interpretations of the formalism. Bohr’s Copenhagen interpretation, as well as the problems it faces due to EPR thought experiment, is presented in greater detail. It is claimed that Bohr’s answers to (...) the said experiment demand more than a restriction of everyday descriptive metaphysics, when describing phenomena at the micro-level. Thus, the special place Bohr’s interpretation takes among other interpretations of the formalism is forfeited. It is also shown that MacKinnon’s more detailed schema aiming to connect the theoretical and everyday language cannot be applied to EPR conclusions and Bohr’s reply to those. MacKinnon’s own modifications of the “everyday language” induced by the mathematical conclusions of Quantum Mechanics are considered too radical and too coarse to take the vacated special place among formalism interpretations. (shrink)

In an interview with Thomas Kuhn the day before he died, Niels Bohr claimed "I think that it would be reasonable to say that no man who is called a philosopher really understands what is meant by the complementary descriptions." Since the "principle of complementarity," which Bohr initially formulated in 1927 and continued to refine throughout his life, lies at the heart of his influential "Copenhagen interpretation of quantum mechanics," this was a regrettable acknowledgment. Now, however, we are exceedingly fortunate (...) in having two recent publications presenting such comprehensive and penetrating analyses of Bohr's philosophy of physics, that were he alive today, I am certain he would retract the above statement. (shrink)

The article deals with the approach to understanding science and technology as well as natural and cultural practices developed by the American philosopher Karen Barad in the concept of agential realism. The peculiarity of her approach consists in referring as a starting point to quantum mechanics in its interpretation, which was proposed by Niels Bohr. Barad proposes a reinterpretation of Bohr's propositions through revealing their ontological content. In this regard, the article addresses the epistemological and ontological problems that quantum (...) physics has faced, such as the conditions for the possibility of an objective description of the world, the nature of measurement, and the relationship between language and the material world. Discussed is the shift that Barad argues is asserted in Bohr's philosophy-physics, which consists of quantum mechanics moving from the linguistic concepts in which the world of classical science was represented to what Barad calls material-discursive practices through which the world is articulated and explained. The possibilities of a different interpretation of Niels Bohr's philosophy-physics are considered. (shrink)

— Niels Bohr, 19231 “There must be quite definite and clear grounds, why you repeatedly declare that one must interpret observations classically, which lie absolute ly in thei r essenc e. . . . It must belong to your deepest conviction—and I cannot understand on what you base it.”.

Although Bohr's reply to the EPR argument is supposed to be a watershed moment in the development of his philosophy of quantum theory, it is difficult to find a clear statement of the reply's philosophical point. Moreover, some have claimed that the point is simply that Bohr is a radical positivist. In this paper, we show that such claims are unfounded. In particular, we give a mathematically rigorous reconstruction of Bohr's reply to the _original_ EPR argument that (...) clarifies its logical structure, and which shows that it does not rest on questionable philosophical assumptions. Rather, Bohr's reply is dictated by his commitment to provide "classical" and "objective" descriptions of experimental phenomena. (shrink)

Niels Bohr’s complementarity principle is a tenuous synthesis of seemingly discrepant theoretical approaches based on a comprehensive analysis of relevant experimental results. Yet the role of complementarity, and the experimentalist-minded approach behind it, were not confined to a provisional best-available synthesis of well-established experimental results alone. They were also pivotal in discovering and explaining the phenomenon of quantum tunneling in its various forms. The core principles of Bohr’s method and the ensuing complementarity account of quantum phenomena remain highly relevant guidelines (...) in the current controversial debate and in experimental work on quantum tunneling times. (shrink)

The paper argues that Bohr understood his correspondence principle, or at least an aspect of it expressed by the notion of rational generalization, as grounded in Hankel's principle of permanence.

The Heisenberg microscope and its analysis by Weizsäcker are used by Grete Hermann in her 1935 essay on the foundations of quantum mechanics to argue her claims about causality in quantum mechanics. In this chapter, I wish to draw a comparison between Hermann’s use of the Heisenberg microscope and another famous use of a very similar thought experiment : Bohr’s analysis of the suspended single slit in his reply to EPR. I shall argue that Hermann’s use of different aspects of (...) the classical pictures in the treatment of the Heisenberg microscope makes her treatment closer to Bohr’s discussion of the suspended slit than to Heisenberg’s own treatment of the microscope. This suggests that Hermann, who equally gave an extensive analysis of complementarity in her 1935 essay, may be an especially acute interpreter of Bohr’s views. I conclude by looking at Hermann’s approach in the context of more general examples of measurement and at possible limitations of the approach. (shrink)

In conventional quantum mechanics, complementarity appears as a remarkable but somewhat useless consequence of the formalism. On the contrary, in Bohr’s view, his notion of complementarity – what I call Bohr’s complementarity – apart from offering a consistent interpretation of QM, was setting the requirement for a ‘thorough revision’ of our common attitude towards ‘physical reality’ and was teaching an ‘epistemological lesson’ transcending the domain of physical sciences. In the present paper, the discussion on the internal rationale of Bohr’s thought (...) from a contemporary philosophical viewpoint permits me to argue that BC stems from a realistic standpoint which starts by accepting an ontology compatible with the non-separable structure of quantum formalism and comes to recognize the necessity of largely revising the epistemological ideas of traditional scientific realism. In this respect, I propose an elaborated form of BC which recognizes the participation of the human perspective in the content of knowledge and, on this basis, attempts to ground scientific objectivity on the notions of ‘perspectival contextuality’ and ‘perspectival plurality’ which integrate reductionistic and holistic epistemological demands in a realistic worldview. The epistemology delineated here creates, I claim, a promising epistemological bridge between physical sciences and humanities. (shrink)

We go through Bohr's talk about complementary features of quantum theory at the Volta Conference in September 1927, by collating a manuscript that Bohr wrote in Como with the unpublished stenographic report of his talk. We conclude – also with the help of some unpublished letters – that Bohr gave a very concise speech in September. The formulation of his ideas became fully developed only between the fifth Solvay Conference, in Brussels in October, and early 1928. The unpublished stenographic (...) reports of the Solvay Conference suggest that we reconsider the role that discussions with his colleagues possibly had on Bohr's final presentation of the complementary sides of atomic physics in his 1928 papers. (shrink)

This paper analyses Bohr’s complementarity framework and applies it to biosemiotic studies by illustrating its application to three existing models of living systems: mechanistic biology, Barbieri’s version of biosemiotics in terms of his code biology and Markoš’s phenomenological version of hermeneutic biosemiotics. The contribution summarizes both Bohr’s philosophy of science crowned by his idea of complementarity and his conception of the phenomenon of the living. Bohr’s approach to the biological questions evolved – among other things – from the consequences (...) of an epistemological lesson of quantum theory and in light of complementarity of observer as a priori living creature and ex post scientific explanation of the living. In a manifestation of the phenomenon of the living, each model of living system and its description makes accessible – from its own presuppositions, contexts and concepts – some features which are not accessible from the others. Nevertheless, for a general understanding of that phenomenon, incompatible sophisticated approaches are equally necessary. Bohr’s epistemology of complementarity turns out to be a heuristic and methodical framework for testing the extent to which biosemiotics can become one of the special sciences or its potential as a cross-disciplinary branch of study. (shrink)

Seit ihrer Verurteilung vor allem im Deutschen Idealismus hatte die Popularphilosophie, in der zweiten Halfte des 18. Jahrhunderts eine der einflussreichsten Stromungen, einen faden Beigeschmack. Dabei verstand sich die Diskussion uber eine Philosophie, die mehr Nahe zum Leben der Menschen suchte, als Teil der umfassenden Selbstverstandnisdebatte von Aufklarung insgesamt. Vor allem die Auseinandersetzung mit der kritischen Philosophie Kants zwang dazu, Anspruch, Grenzen und Moglichkeiten popularer Philosophie zu uberdenken. So wurde Popularitat zu Programm und Problem von Philosophie, damals wie heute. - (...) Der vorliegende Band zeichnet die Geschichte der Popularphilosophie nach: ihre Vorgeschichte, die Diskussion im 18. und ihre Nachklange im 19. und fruhen 20. Jahrhundert bis hin zur gegenwartigen Auseinandersetzung. Since its condemnation, above all by German idealism, popular philosophy, which had been one of the most influential movements of the 18th century, had a negative connotation. The discussion about a philosophy which tried to get closer to peoples lives did however see itself as a part of the widespread debate on self-understanding of Enlightenment as a whole. It was mainly the study of Kant's critical philosophy which forced people to rethink the demands, limitations and possibilties of popular philosophy. Thus popularity became the agenda and the problem of philosophy, then as now. This volume traces the history of popular philosophy: its previous history, the discussion in the 18th century and its reverberations in the 19th and early 20th centuries up to the present time. (shrink)

Soviet attitude towards Bohr reflects changes in the ideological approach to science. During the last period before Stalin's death ?danov proclaimed the campaign against Western influence in Soviet philosophy and science. Nevertheless the physicist M. A. Markov tried to introduce complementarity as a materialistic interpretation of quantum?mechanics in 1948. He was officially condemned. This was followed by a period (1948?54) during which heavy attacks were made against the Copenhagen school. In 1958, after a personal exchange of thoughts with Bohr, (...) academician Fock declared complementarity and probability to be irreversible steps towards a new insight into physical reality, at the same time correcting some of Bohr's epistemological conceptions. (shrink)

Niels Bohr’s model of the hydrogen atom is widely cited as an example of an inconsistent scientific theory because of its reliance on classical electrodynamics together with assumptions about interactions between matter and electromagnetic radiation that could not be reconciled with CED. This view of Bohr’s model is controversial, but we believe a recently proposed approach to reasoning with inconsistent commitments offers a promising formal reading of how Bohr’s model worked. In this paper we present this new way of reasoning (...) with inconsistent commitments and compare it with other approaches before applying it to Bohr’s model and offering some suggestions for how it might be extended to account for subsequent developments in old quantum theory. (shrink)

The Copenhagen interpretation, which informs the textbook presentation of quantum mechanics, depends fundamentally on the notion of ontological wave-particle duality and a viewpoint called “complementarity.” In this paper, Bohr's own interpretation is traced in detail and is shown to be fundamentally different from and even opposed to the Copenhagen interpretation in virtually all its particulars. In particular, Bohr's interpretation avoids the ad hoc postulate of wave function ‘collapse' that is central to the Copenhagen interpretation. The strengths and weakness (...) of both interpretations are summarized. ‡I thank Edward Mackinnon, Henry Folse, and Greg Anderson for valuable comments on the penultimate draft. The final responsibility for the paper rests with the author. †To contact the author, please write to: Bhaktivedanta Institute, 2334 Stuart Street, Berkeley, CA; e-mail: [email protected]. I have been unable to achieve a sharp formulation of Bohr's principle of complementarity despite much effort I have expended on it. (Einstein 1949, 674) While imagining that I understand the position of Einstein, as regards the EPR correlations, I have very little understanding of his principal opponent, Bohr. (Bell 1987, 155) Niels Bohr brain-washed a generation of physicists into believing that the problem had been solved fifty years ago. (Gell-Mann 1979, 29) Every sentence I say must be understood not as an affirmation, but as a question. (Niels Bohr, quoted in Jammer 1966, 175) Bohr's interpretation has never been fully clarified. It needs an interpretation itself, and only that will be its defense. (Weizsäcker 1971, 25). (shrink)

Soviet attitude towards Bohr reflects changes in the ideological approach to science. During the last period before Stalin's death danov proclaimed the campaign against Western influence in Soviet philosophy and science. Nevertheless the physicist M. A. Markov tried to introduce complementarity as a materialistic interpretation of quantum-mechanics in 1948. He was officially condemned. This was followed by a period (1948-54) during which heavy attacks were made against the Copenhagen school. In 1958, after a personal exchange of thoughts with Bohr, (...) academician Fock declared complementarity and probability to be irreversible steps towards a new insight into physical reality, at the same time correcting some of Bohr's epistemological conceptions. (shrink)

This essay shows the difficulties inherent in the very term of ›culture‹ itself, spe- cifically in political and philosophical contexts between 1910 and 1933. Despite the eagerness and the striking idealism of its founders, Logos never offered an under- standing of culture that was able to resist the totalitarian tendencies of its own time. The term ›culture‹ thus continues to contaminate every attempt to formulate the legacy of the Logos project. From today’s perspective, that means recognizing the need to come (...) to terms with the connotations and the implications of such a project as Logos rather than rushing into a naive and simplistic affirmation. Al- though not the first, Klaus Christian Köhnke and Rüdiger Kramme were the most insistent researchers who brought up this painful subject of the modern history of philosophy. (shrink)

Although Wittgenstein’s influence on logic and foundations of mathematics is well recognized, nonetheless, his legacy concerning other sciences is much less elucidated, and in this article we aim at shedding new light on physics, artificial intelligence, and cognitive science from a Wittgensteinian perspective. We focus upon three issues amongst other things: the Chosmky versus Norvig debate on the nature of language; a Neo-Kantian parallelism between Bohr’s philosophy of physics and Hilbert’s philosophy of mathematics; the relationships between cognitive contextuality (...) and physical contextuality as shown by recent Bell-type results. The Chosmky versus Norvig debate may be seen as a battle between Wittgenstein’s earlier and later conceptions of meaning, i.e., picture theory and use theory. From a Wittgensteinian point of view, quantum physics may be seen as a physical version of the Linguistic Turn. The parallelism between Bohr’s philosophy of classical concepts and Hilbert’s philosophy of finitism builds upon transcendental philosophy in the Kantian tradition, both Bohr and Hilbert having been influenced by Neo-Kantian thinkers, such as Hertz, whose sign theory is actually a common root of Wittgenstein’s picture theory and Hilbert’s axiomatics. Wittgenstein is considered a root of contextualism in contemporary philosophy. Contextuality has different manifestations in physics and cognitive science, and contextuality studies across the sciences are rapidly developing in cutting-edge research. We elucidate both analogies and disanalogies between contextuality of reality and contextuality of reason in terms of the nature of probabilities involved. In passing, we also give a reformulation of Penrose’s quantum mind thesis. (shrink)

I reinterpret Bohr's attitude towards quantum mechanical formalism and its empirical content, based on his understanding of the correspondence principle and its approximate applicability. I suggest that Bohr understood complementarity as a limitation imposed by the commutation relations upon the applicability of the idealizations which had grounded the use of the correspondence principle. By discussing this interpretation against the contemporary background of discussions regarding “naïve realism” about operators (as observables), I suggest that a Bohrian view on the empirical content (...) of quantum mechanical operators may provide a middle ground between complete contextualism and an untenable realism about quantum properties. (shrink)

I argue that instead of a rather narrow focus on N. Bohr's account of complementarity as a particular and perhaps obscure metaphysical or epistemological concept (or as being motivated by such a concept), we should consider it to result from pursuing a particular method of studying physical phenomena. More precisely, I identify a strong undercurrent of Baconian method of induction in Bohr's work that likely emerged during his experimental training and practice. When its development is analyzed in light (...) of Baconian induction, complementarity emerges as a levelheaded rather than a controversial account, carefully elicited from a comprehensive grasp of the available experimental basis, shunning hasty metaphysically motivated generalizations based on partial experimental evidence. In fact, Bohr's insistence on the “classical” nature of observations in experiments, as well as the counterintuitive synthesis of wave and particle concepts that have puzzled scholars, seem a natural outcome (an updated instance) of the inductive method. Such analysis clarifies the intricacies of early Schrödinger's critique of the account as well as Bohr's response, which have been misinterpreted in the literature. If adequate, the analysis may lend considerable support to the view that Bacon explicated the general terms of an experimentally minded strand of the scientific method, developed and refined by scientists in the following three centuries. (shrink)

Since the Niels Bohr centenary of 1985 there has been an astonishing international surge of scholarly analyses of Bohr's philosophy. Now for the first time in Niels Bohr and Contemporary Philosophy Jan Faye and Henry Folse have brought together sixteen of today's leading authors who have helped mould this new round of discussions on Bohr's philosophy. In fifteen entirely new, previously unpublished essays we discover a surprising variety of the different facets of Bohr as the (...) natural philosopher whose `framework of complementarity' shaped the final phase of the quantum revolution and influenced two generations of the century's leading physicists. There is much on which the authors included here agree; but there are also polar disagreements, which assure us that the philosophical questions revolving around Bohr's `new viewpoint' will continue to be a subject of scholarly interest and discussion for years to come. This collection will interest all serious students of history and philosophy of science, and foundations of physics. (shrink)

This article explains why Bohr does not need to discuss the projection postulate or the "problem of measurement". Beginning with a thumbnail sketch of Bohr 's general views, it is argued that Bohr interprets the state function as giving a statistical summary of experimental outcomes. Against the objection that Bohr was too much a microrealist to endorse such an instrumentalist statistical interpretation it is suggested that he rejected the issue of microrealism as not well formed. It is shown that on (...) his statistical interpretation Bohr does not need the projection postulate or face the usual problem of measurement. (shrink)