The concepts of complementarity and entanglement are considered with respect to their significance in and beyond physics. A formally generalized, weak version of quantum theory, more general than ordinary quantum theory of physical systems, is outlined and tentatively applied to two examples.

In this study Arun Bala examines the implications that Niels Bohr's principle of complementarity holds for fields beyond physics. Bohr, one of the founding figures of modern quantum physics, argued that the principle of complementarity he proposed for understanding atomic processes has parallels in psychology, biology, and social science, as well as in Buddhist and Taoist thought. But Bohr failed to offer any explanation for why complementarity might extend beyond physics, and his claims have (...) been widely rejected by scientists as empty speculation. Scientific scepticism has only been reinforced by the naïve enthusiasm of postmodern relativists and New Age intuitionists, who seize upon Bohr's ideas to justify anti-realist and mystical positions. Arun Bala offers a detailed defence of Bohr's claim that complementarity has far-reaching implications for the biological and social sciences, as well as for comparative philosophies of science, by explaining Bohr's parallels as responses to the omnipresence of grown properties in nature. (shrink)

Of all the developments in twentieth century physics, none has given rise to more heated debates than the changes in our understanding of science precipitated by the quantum revolution''. In this revolution, Niels Bohr's dramatically non-classical theory of the atom proved to be the springboard from which the new atomic physics drew it's momentum. Furthermore, Bohr's contribution was crucial not only because his interpretation of quantum mechanics became the most widely accepted view but also because in his role (...) as educator and spokesman for atomic physics Bohr was very much the patron spirit of the entire quantum revolution. The conceptual framework which he proposed to provide a new viewpoint for understanding the quantum theoretical description of atomic systems became for most of this century the dominant outlook of countless productive experimental and theoretical physicists. He called this new framework complementarity''. (shrink)

Bohr’s interpretation of quantum mechanics has been criticized as incoherent and opportunistic, and based on doubtful philosophical premises. If so Bohr’s influence, in the pre-war period of 1927–1939, is the harder to explain, and the acceptance of his approach to quantum mechanics over de Broglie’s had no reasonable foundation. But Bohr’s interpretation changed little from the time of its first appearance, and stood independent of any philosophical presuppositions. The principle of complementarity is itself best read as a conjecture of (...) unusually wide scope, on the nature and future course of explanations in the sciences (and not only the physical sciences). If it must be judged a failure today, it is not because of any internal inconsistency. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Buddhist-Christian Studies 22 (2002) 149-162 [Access article in PDF] Buddhist-Christian Complementarity in the Perspective of Quantum Physics Lai Pan-chiu Chinese University of Hong Kong Introduction The idea of Buddhist-Christian complementarity is by no means new. 1 But what is meant by "complementarity"? In quantum physics, the concept of "complementarity" has been extensively discussed due to the principle of complementarity introduced by Niels (...) Bohr (1885-1962). This principle is also one of the hotly debated issues in the areas of religion and natural science. Many scholars attempt to show that there are cases in Christian theology comparable to the complementarity in quantum physics. The most discussed case is perhaps the Christological doctrine of two natures in Jesus Christ. 2 Some scholars even attempt to interpret the relationship between theology and science in terms of complementarity. 3 This kind of discussion is not merely fanciful imagination originated by Christian theologians, since even Niels Bohr himself did advise Christian theologians to apply the complementary way of thinking in theology. 4 An interesting question may then be whether the principle of complementarity in quantum physics may cast light on the problem concerning Buddhist-Christian complementarity. This is the issue this essay attempts to address. Complementarity in Quantum Physics Modern physics, especially the theory of relativity and quantum physics, as Werner Heisenberg pointed out, brings forth to us an important philosophical issue—the relationship between language and reality. Some modern physicists find that they have to make use of ordinary language to establish a visual understanding or presentation of some events, which can hitherto only be expressed by a bundle of mathematical formulae. However, the ordinary language, together with its derived concepts, used in classical physics cannot adequately interpret some of the discoveries of modern physics. For example, conventional concepts of time and space can no longer apply directly in the general theory of relativity. The inadequacy of the classical concepts of "wave" and "particle" in quantum physics is another illustrative case. According to Bohr's theory, physicists can make use of these classical concepts in a [End Page 149] loose way, even though these concepts may seem to contradict each other when applied together. 5The principle of complementarity proposed by Niels Bohr refers specifically to the use of the two seemingly contradictory concepts in classical physics—"particle" and "wave"—to explain the behavior of a particular entity, light. Wave and particle are mutually exclusive concepts in classical physics. According to the classical understanding, wave possesses some characteristics that particle does not have, such as reflection, refraction, diffusion and interference. In reverse, particle also possesses some characteristics that wave does not have, such as occupying certain space. However, quantum physicists have discovered that in some experiments, light "behaves" as wave, whereas in others it behaves as particle. The results of experiments seem to suggest that neither "wave" nor "particle" can adequately explain the quantum phenomena. For this reason, some physicists, including Albert Einstein, suggest abandoning the use of the concepts of wave and particle in the subatomic realm. Contrary to this view, Bohr insists that the concepts of "wave" and "particle" remain usable and useful in quantum physics because "however far the phenomena transcend the scope of classical physical explanation, the account of all evidence must be expressed in classical terms." 6 As Bohr puts it, "the fundamental postulate of the indivisibility of the quantum of action is itself, from the classical point of view, an irrational element which inevitably requires us to forego a causal mode of description and which, because of the coupling between phenomena and their observation, forces us to adopt a new mode of description designated as complementary in the sense that any given application of classical concepts precludes the simultaneous use of other classical concepts which in a different connection are equally necessary for the elucidation of the phenomena." 7The principle of complementarity can thus be understood as a method or "mode of description" using two or more mutually exclusive concepts of a specific realm (classical physics) to explain a phenomenon of another realm (quantum physics) that... (shrink)

Quantum complementarity is interpreted in terms of duality and opposition. Any two conjugates are considered both as dual and opposite. Thus quantum mechanics introduces a mathematical model of them in an exact and experimental science. It is based on the complex Hilbert space, which coincides with the dual one. The two dual Hilbert spaces model both duality and opposition to resolve unifying the quantum and smooth motions. The model involves necessarily infinity even in any finitely dimensional subspace of the (...) complex Hilbert space being due to the complex basis. Furthermore, infinity is what unifies duality and opposition, universality and openness, completeness and incompleteness in it. The deduced core of quantum complementarity in terms of infinity, duality and opposition allows of resolving a series of various problems in different branches of philosophy: the common structure of incompleteness in Gödel’s (1931) theorems and Enstein, Podolsky, and Rosen’s argument (1935); infinity as both complete and incomplete; grounding and self-grounding, metaphor and representation between language and reality, choice and information, the totality and an observer, the basic idea of philosophical phenomenology. The main conclusion is: Quantum complementarity unifies duality and opposition in a consistent way underlying the physical world. (shrink)

Many commentators have remarked in passing on the resonance between deconstructionist theory and certain ideas of quantum physics. In this book, Arkady Plotnitsky rigorously elaborates the similarities and differences between the two by focusing on the work of Niels Bohr and Jacques Derrida. In detailed considerations of Bohr's notion of complementarity and his debates with Einstein, and in analysis of Derrida's work via Georges Bataille's concept of general economy, Plotnitsky demonstrates the value of exploring these theories in relation (...) to each other. Bohr's term complementarity describes a situation, unavoidable in quantum physics, in which two theories thought to be mutually exclusive are required to explain a single phenomenon. Light, for example, can only be explained as both wave and particle, but no synthesis of the two is possible. This theoretical transformation is then examined in relation to the ways that Derrida sets his work against or outside of Hegel, also resisting a similar kind of synthesis and enacting a transformation of its own. Though concerned primarily with Bohr and Derrida, Plotnitsky also considers a wide range of anti-epistemological endeavors including the work of Nietzsche, Bataille, and the mathematician Kurt Gödel. Under the rubric of complementarity he develops a theoretical framework that raises new possiblilities for students and scholars of literary theory, philosophy, and philosophy of science. (shrink)

The idea of complementarity already appears in William James’ (1890a, p. 206) Principles of Psychology in the chapter on “the relations of minds to other things”. Later, in 1927, Niels Bohr introduced complementarity as a fundamental concept in quantum mechanics. It refers to properties (observables) that a system cannot have simultaneously, and which cannot be simultaneously measured with arbitrarily high accuracy. Yet, in the context of classical physics they would both be needed for an exhaustive description of (...) the system. (shrink)

Besides the application of the notion of complementarity to psychological and physical descriptions of the individual, this paper explores the possibility of defining complementary observables in the same phenomenal domain. Complementary emotional observables are defined from experimental data on experienced emotions reported by subjects who have been prepared in a state of induced emotion. Complementary physiological observables are defined in correspondence with conjugate, physiological quantities that can be measured. -/- Keywords: Complementarity, Psychophysics, Emotional observables, Induced emotion, Physiological observables, (...) Conjugate physiological quantities. (shrink)

Complementarity can be considered as the weirdest idea associated with quantum mechanics. For Bohr, Complementarity is important in order to be able to convey successfully the non-classical features of quantum mechanics. This paper discusses the epistemic and ontological implications of different new experiments that attempt to detect complementarity. Complementarity has surely survived the attempts to overcome it, yet some of these experiments have led to a more general form of complementarity. Others claim to be able (...) to differentiate among the different interpretations of quantum physics. Nonetheless, such claims have revealed contradictory representations of the ontological picture of the universe. Hence, Bohr’s position is still valid. (shrink)

The concept of complementarity, originally defined for non-commuting observables of quantum systems with states of non-vanishing dispersion, is extended to classical dynamical systems with a partitioned phase space. Interpreting partitions in terms of ensembles of epistemic states (symbols) with corresponding classical observables, it is shown that such observables are complementary to each other with respect to particular partitions unless those partitions are generating. This explains why symbolic descriptions based on an ad hoc partition of an underlying phase space description (...) should generally be expected to be incompatible. Related approaches with different background and different objectives are discussed. (shrink)

A coherent account of the connections and contrasts between the principles of complementarity and uncertainty is developed starting from a survey of the various formalizations of these principles. The conceptual analysis is illustrated by means of a set of experimental schemes based on Mach-Zehnder interferometry. In particular, path detection via entanglement with a probe system and (quantitative) quantum erasure are exhibited to constitute instances of joint unsharp measurements of complementary pairs of physical quantities, path and interference observables. The analysis (...) uses the representation of observables as positive-operator-valued measures (POVMs). The reconciliation of complementary experimental options in the sense of simultaneous unsharp preparations and measurements is expressed in terms of uncertainty relations of different kinds. The feature of complementarity, manifest in the present examples in the mutual exclusivity of path detection and interference observation, is recovered as a limit case from the appropriate uncertainty relation. It is noted that the complementarity and uncertainty principles are neither completely logically independent nor logical consequences of one another. Since entanglement is an instance of the uncertainty of quantum properties (of compound systems), it is moot to play out uncertainty and entanglement against each other as possible mechanisms enforcing complementarity. (shrink)

The term complementarity plays a central role in quantum physics, not least in various approaches to defining entanglement and the conditions for its occurrence. It has, however, been used in a variety of ways by different authors, denoting different concepts and relationships. Here we describe and clarify some of them and analyze the role they play with respect to the phenomenon of entanglement. Based on these considerations we discuss the recently proposed system-theoretical generalization of the concepts entanglement and (...) complementarity (Atmanspacher et al. in Found Phys 32(3):379–406, 2002; von Lucadou et al. in J Conscious Stud 14(4):50–74, 2007; Filk and Römer in Axiomathes 21(2):211–220, 2011; Walach and Von Stillfried in Axiomathes 21(2): 185–209, 2011). We hope that a clarification regarding the specific meaning of these terms can be useful to the growing engagement with this interesting hypothesis and its critical investigation. (shrink)

The discovery of a letter in the Niels Bohr archives written by Bohr to a Danish schoolteacher in which he reveals his early knowledge of the Daodejing led the present author on a search to unveil the influence of the philosophy of Yin-Yang on Bohr's famed complementarity principle in Western physics. This paper recounts interviews with his son, Hans, who recalls Bohr reading a translated copy of Laozi, as well as Hanna Rosental, close friend and associate who also (...) confirms the influence of ancient Chinese philosophy on this major figure in Western physics. As with Bohr’s dual perspective approach to the wave-particle, in which describing matter as either wave or particle is not considered inherently contradictory, this article likewise argues that Eastern and Western perspectives about philosophy, reality and life in general need not antagonize one another as is the case in Hegelian dialecticism. Through developing a globally accessible, harmonized system of Eastern and Western thought, this article suggests that individuals can more easily overcome limitations arising from cultural singularity in conventional philosophical approaches and, in turn, achieve a greater degree of social harmony and depth of philosophical understanding, all in the same stroke. (shrink)

In part-1, I shall outline the principle details of Bohr’s interpretation. Bohr’s basic interpretive insight is ‘ quantum inseparability’ . Complementarity of phenomena and a “revision to our attitude towards physical explanation” then follow. Together , these can be said to constitute Bohr’s general viewpoint of ‘complementarity’. Bohr does not quite clearly spell out the content of these three ideas; I do.

We relate notions of complementarity in three layers of quantum mechanics: (i) von Neumann algebras, (ii) Hilbert spaces, and (iii) orthomodular lattices. Taking a more general categorical perspective of which the above are instances, we consider dagger monoidal kernel categories for (ii), so that (i) become (sub)endohomsets and (iii) become subobject lattices. By developing a ‘point-free’ definition of copyability we link (i) commutative von Neumann subalgebras, (ii) classical structures, and (iii) Boolean subalgebras.

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.

Piercing incisively and deeply into the nature of the overlapping of the material andmental realms. Aage Petersen uncovers the reciprocal relations between quantum physics and theconcepts of metaphysics and epistemology, assessing the extent to which each has influenced theother. The author is eminently qualified to undertake this important work, which grew out of hisclose contact with Neils Bohr and his Copenhagen school during the years 1952-1962.Although themathematical formalism of quantum physics has long since been established, the question of (...) itsphysical interpretation is not yet closed, and the question of its philosophical interpretationremains in a formative state. The most widely accepted physical interpretation of the quantalformalism emerged from discussions between Bohr and Heisenberg in the winter of 1926-1927. ThisCopenhagen Interpretation centers around the relations of indeterminacy around the relations ofindeterminacy and the concept of complementarity, and was refined but not radically altered in theyears following, especially during the famous debate with Einstein on the completeness possible inthe description of events. The philosophical interpretation has proceeded along two principal lines:Bohr's emphasis on complementarity as a unifying concept, and Heisenberg's exploration of therelationship of quantum physics to the traditional categories of philosophy.To Bohr's mind, thecentral feature of human knowledge is the distinction between subject and object. The indeterminacyof the placing of the partition between instrument and system, which played so large a part inquantal description was, Bohr believed, an expression of the general relation between the knower andthe knowable. He thus sought to find relationships of complementarity in areas beyond quantumphysics.Quantum physics and traditional philosophy certainly relate enough to interact--even thoughthe effects of interaction may produce uncertain results. Heisenberg's view also emphasizes thatscience describes, not nature itself, but the interplay between nature and man, nature as affectedby man's method of questioning, thus denying the school of philosophical thought that began withDescartes' sharp separation of the World and the I.The author's investigation leads him as well tobelieve that complementarity is deeply linked to the basis of philosophy, but that the details ofthe relationship are so obscure that some other feature of quantum physics that makes amore directconnection with philosophy should be sought. He is led to choose the idea of correspondence as suchfeature. This idea played a key role in the development of the matrix version of the formalism andof the Copenhagen interpretation.Mathematically, the idea of correspondence was seen to imply thatquantal formalisms should emerge as generalizations of classical entities, that matrix mechanics wasa generalization of classical Hamiltonian mechanics. It is in this possibility of treating thetraditional categories of philosophy as limits of a more general scheme, or as analogies of a deeperorder, that the fruitfulness of the correspondence idea lies. (shrink)

We show that Bohr's principle of complementarity between position and momentum descriptions can be formulated rigorously as a claim about the existence of representations of the canonical commutation relations. In particular, in any representation where the position operator has eigenstates, there is no momentum operator, and vice versa. Equivalently, if there are nonzero projections corresponding to sharp position values, all spectral projections of the momentum operator map onto the zero element.

Building on Peres’ idea of “Delayed-choice for entanglement swapping” we show that even the degree to which quantum systems were entangled can be defined after they have been registered and may even not exist any more. This does not arise as a paradox if the quantum state is viewed as just a representative of information. Moreover such a view gives a natural quantification of the complementarity between the measure of information about the input state for teleportation and the amount (...) of entanglement of the resulting swapped entangled state. (shrink)

The term complementarity plays a central role in quantum physics, not least in various approaches to defining entanglement and the conditions for its occurrence. It has, however, been used in a variety of ways by different authors, denoting different concepts and relationships. Here we describe and clarify some of them and analyze the role they play with respect to the phenomenon of entanglement. Based on these considerations we discuss the recently proposed system-theoretical generalization of the concepts entanglement and (...) complementarity (Atmanspacher et al. in Found Phys 32(3):379–406, 2002; von Lucadou et al. in J Conscious Stud 14(4):50–74, 2007; Filk and Römer in Axiomathes 21(2):211–220, 2011; Walach and Von Stillfried in Axiomathes 21(2): 185–209, 2011). We hope that a clarification regarding the specific meaning of these terms can be useful to the growing engagement with this interesting hypothesis and its critical investigation. (shrink)

It is argued that Niels Bohr ultimately arrived at positivistic and antirealist-flavored statements because of weaknesses in his initial objective of accounting for measurement in physical terms. Bohr’s investigative approach faced a dilemma, the choices being conceptual inconsistency or taking the classical realm as primitive. In either case, Bohr’s ‘Complementarity’ does not adequately explain or account for the emergence of a macroscopic, classical domain from a microscopic domain described by quantum mechanics. A diagnosis of the basic problem is offered, (...) and an alternative way forward is indicated. (shrink)

Quantum-mechanical event descriptions are context-dependent descriptions. The role of quantum (nondistributive) logic is in the partial ordering of contexts rather than in the ordering of quantum-mechanical events. Moreover, the kind of quantum logic displayed by quantum mechanics can be easily inferred from the general notion of contextuality used in ordinary language. The formalizable core of Bohr's notion of complementarity is the type of context dependence discussed in this paper.

Process philosophy endeavors to replace the classical ontology of substances by a process ontology centered on the notions of change and transition. We argue that the substantial and processual approach are mutually complementary in the sense of a generalized quantum theory which is not limited to physical phenomena. From this point of view, restricting oneself to either substance ontology or process ontology would be as ill-advised as exclusively relying on position or momentum representations in physics. A new view on (...) Zeno's paradox lends itself. The meaning of a 'mental energy' observable, complementary to 'internal time', and its relationship to acategorial states of the human mind will be tentatively discussed. (shrink)

A growing number of commentators have, in recent years, noted the important affinities in the views of Immanuel Kant and Niels Bohr. While these commentators are correct, the picture they present of the connections between Bohr and Kant is painted in broad strokes; it is open to the criticism that these affinities are merely superficial. In this essay, I provide a closer, structural, analysis of both Bohr's and Kant's views that makes these connections more explicit. In particular, I demonstrate the (...) similarities between Bohr's argument, on the one hand, that neither the wave nor the particle description of atomic phenomena pick out an object in the ordinary sense of the word, and Kant's requirement, on the other hand, that both ‘mathematical’ (having to do with magnitude) and ‘dynamical’ (having to do with an object's interaction with other objects) principles must be applicable to appearances in order for us to determine them as objects of experience. I argue that Bohr's ‘complementarity interpretation’ of quantum mechanics, which views atomic objects as idealizations, and which licenses the repeal of the principle of causality for the domain of atomic physics, is perfectly compatible with, and indeed follows naturally from a broadly Kantian epistemological framework. (shrink)

The interpretation of quantum mechanics presented in this paper is inspired by two ideas that are fundamental in Bohr’s writings: indivisibility and complementarity. Further basic assumptions of the proposed interpretation are completeness, universality and conceptual economy. In the interpretation, decoherence plays a fundamental role for the understanding of measurement. A general and precise conception of complementarity is proposed. It is fundamental in this interpretation to make a distinction between ontological reality, constituted by everything that does not depend at (...) all on the collectivity of human beings, nor on their decisions or limitations, nor on their existence, and empirical reality constituted by everything that not being ontological is, however, intersubjective. According to the proposed interpretation, neither the dynamical properties, nor the constitutive properties of microsystems like mass, charge and spin, are ontological. The properties of macroscopic systems and space-time are also considered to belong to empirical reality. The acceptance of the above mentioned conclusion does not imply a total rejection of the notion of ontological reality. In the paper, utilizing the Aristotelian ideas of general cause and potentiality, a relation between ontological reality and empirical reality is proposed. Some glimpses of ontological reality, in the form of what can be said about it, are finally presented. (shrink)

This chapter contains sections titled: Cognitive Equivalence The Complementarity Argument Evolutionary Arguments Conclusion: The Importance of the Mark of the Cognitive.

The principle of complementarity in physics can be generalized and extended to information studies. It helps explain the dilemma faced by information studies today. The prevailing endeavor that going beyond the limitation of formal theories and to develop a unified theory of information falls in the dilemma which is structurally homologous to the dilemmas in quantum physics. The dilemma is caused by an epistemological paradox called assignment paradox. The paradox can be removed through generalized complementarity. It (...) means that the concept of information embodying in different theoretical contexts are different phenomenon. They are complementary to each other. The analysis brings bad news to methodologically reductionism and fundamentalism but good news to transdisciplinary approach. (shrink)

Afshar et al. claim that their experiment shows a violation of the complementarity inequality. In this work, we study their claim using a modified Mach-Zehnder setup that represents a simpler version of the Afshar experiment. We find that our results are consistent with Afshar et al. experimental findings. However, we show that within standard quantum mechanics the results of the Afshar experiment do not lead to a violation of the complementarity inequality. We show that their claim originates from (...) a particular technique they use to analyze their results. In their analysis, they assume a classical concept, that particles have a definite trajectory before detection, thus, they obtain which-way information by particle detection plus path extrapolation by applying momentum conservation. This analysis technique is standard in experimental particle physics. Important discoveries such as the detection of vector bosons have been made through the application of this technique. We note that particle detection plus path extrapolation is a suitable technique within de Broglie-Bohm theory of quantum mechanics. (shrink)

The noetic model is the first theory of any kind to explain qualia in physical terms. The formal delineation of the life principle or élan vital explains not only the origin of self-organisation in living systems, providing the basis for the first comprehensive dualist theory, but also is what makes the model empirically testable allowing this volume to make history. The floodgates are about to open to almost unimaginable advances in the field of consciousness studies. This book introduces a comprehensive (...) empirically testable model of dualism-interactionism to legitimise the interactionist model at a level tantamount to any other avenue of epistemological investigation. (shrink)

Philosophers have discussed the relationship of cause and effect from ancient times through our own.Prior to the work of Niels Bohr, these discussions presupposed that successful causal attribution implies explanation.The success of quantum theory challenged this presupposition.Bohr introduced a principle of complementarity that provides a new way of looking at causality and explanation. In this succinct review of the history of these discussions, John Losee presents the philosophical background of debates over the cause-effect relation.He reviews the positions of Aristotle, (...) Rene Descartes, Isaac Newton, David Hume, Immanuel Kant, and John Stuart Mill.He shows how nineteenth-century theories in physics and chemistry were informed by a dominant theory of causality and how specific developments in physics provided the background for the emergence of quantum theory. Problems created for the "causality implies explanation" thesis by the emergence of quantum theory are reviewed in detail.Losee evaluates Bohr's proposals to apply a principle of complementarity within physics, biology, and psychology.He also discusses the feasibility of using complementarity as a principle of interpretation within Christian theology.This volume, which includes an in-depth index, is an essential addition to the libraries of advanced undergraduate and graduate students, philosophers, and those interested in causality and explanation. (shrink)

Although Niels Bohr's notion of complementarity is usually referred to in the context of quantum mechanics, it is not of physical origin. Bohr derived it from the philosophical idea of a holistic entanglement of knowledge and action. Bohr's complementarity primarily refers to a key element of the pragmatist tradition, the reflective relation between the immediate experience of an object and the awareness of its objectification. Similar relations have been observed by Kurt Goldstein in his studies of brain-injured patients. (...) From a pragmatic point of view, Goldstein's idea of adequacy in biological knowledge might lead to novel approaches to current ethical questions in medicine as well as biotechnology. (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)

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)

Rom Harré thinks that the Emergence–Reduction debate, conceived as a vertical problem, is partly ill posed. Even if he doesn’t wholly reject the traditional definition of an emergent property as a property of a collection but not of its components, his point is that this definition doesn’t exhaust all the dimensions of emergence. According to Harré there is another kind (or dimension) of emergence, which we may call—somewhat paradoxically—“horizontal emergence”: two properties of a substance are horizontally emergent relative to each (...) other if they cannot be displayed in the same conditions. Contrary to vertical emergence, horizontal emergence is a symmetrical relation. Harré endorses horizontal emergentism. I argue that this position faces a principled difficulty: it makes it impossible to bind different horizontally emergent discourses in an interesting way. Physics and biology for example become “island” discourses, each speaking of a distinct kind of entities. The only way to ensure that two different discourses can relate to the same entity is to reintroduce verticality into the picture. (shrink)

This reply to five continuing commentaries on my 1991 target article on “Is human information processing conscious” focuses on six related issues: 1) whether focal attentive processing replaces consciousness as a causal agent in third-person viewable human information processing, 2)whether consciousness can be dissociated from human information processing, 3) continuing disputes about definitions of "consciousness" and about what constitutes a “conscious process” , 4) how observer-relativity in psychology relates (and does not relate) to relativity in physics, 5) whether the (...) first-person viewable causal efficacy of consciousness counts as ‘real’ causal efficacy and 6) a clarification of the sense in which first- and third-person causal accounts of mental processing are complementary and mutually irreducible. (shrink)

Complementarity is not only a feature of quantum mechanical systems but occurs also in the context of finite automata.

To what extent does the black hole information paradox lead to violations of quantum mechanics? I explain how black hole complementarity provides a framework to articulate how quantum characterizations of black holes can remain consistent despite the information paradox. I point out that there are two ways to cash out the notion of consistency in play here: an operational notion and a descriptive notion. These two ways of thinking about consistency lead to (at least) two principles of black hole (...) complementarity: an operational principle and a descriptive principle. Our background philosophy of science regarding realism/instrumentalism might initially lead us to prefer one principle over the other. However, the recent physics literature, which applies tools from quantum information theory and quantum computational complexity theory to various thought experiments involving quantum systems in or around black holes, implies that the operational principle is successful where the descriptive principle is not. This then lets us see that for operationalists the black hole information paradox might no longer be pressing. (shrink)

Gallagher [2019] defends a form of naturalised phenomenology based on a non-classical view of science. A central component of this argument involves an analogy between phenomenology and quantum-mechanics: Gallagher suggests that both require us to give up key components of a classical view of the natural world. Here, I try to clarify this analogy and consider two associated problems. The first problem concerns the concept of subjectivity and its different roles in physics and phenomenology, and the second concerns the (...) concept of complementarity in quantum mechanics. I argue that complementarity is poorly suited to the integrative view of science that Gallagher ultimately wishes to defend. Instead, a better model of integration can be found in examples of multiscale modelling, which is widespread in science, including classical physics. Gallagher is right to reject an overly narrow view of naturalism, but we do not need to consider the peculiarities of quantum mechanics to find inspiration for a broader view. (shrink)

Nobel Laureate in physics Wolfgang Pauli studied philosophy and the history of ideas intensively, especially in his later years, to form an accurate ontology vis-à-vis quantum theory. Pauli's close contacts with the Swiss psychiatrist C.G. Jung gave him special qualifications for also understanding the basic problems of empirical knowledge. After Pauli's sudden death in 1958, this work was maintained mainly in his posthumously published correspondence, which so far extends only to 1939. Because Pauli's view differs essentially from the direction (...) physics research took after the deaths of the founding fathers of quantum theory, this article attempts to describe the main features in Pauli's revolutionary thought, which is based on nature's “epistemological lesson” as revealed by Pauli's atomic research. Pauli's conclusions have important implications for various issues in Western culture, not least with the limits of science and the relation of science to religion. (shrink)

We presented a contextual statistical model of the probabilistic description of physical reality. Here contexts (complexes of physical conditions) are considered as basic elements of reality. There is discussed the relation with QM. We propose a realistic analogue of Bohr’s principle of complementarity. In the opposite to the Bohr’s principle, our principle has no direct relation with mutual exclusivity for observables. To distinguish our principle from the Bohr’s principle and to give better characterization, we change the terminology and speak (...) about supplementarity, instead of complementarity. Supplementarity is based on the interference of probabilities. It has quantitative expression trough a coefficient which can be easily calculated from experimental statistical data. We need not appeal to the Hilbert space formalism and noncommutativity of operators representing observables. Moreover, in our model there exists pairs of supplementary observables which cannot be represented in the complex Hilbert space. There are discussed applications of the principle of supplementarity outside quantum physics. (shrink)

On several occasions I have pointed out that the lesson taught us by recent developments in physics regarding the necessity of a constant extension of the frame of concepts appropriate for the classification of new experiences leads us to a general epistemological attitude which might help us to avoid apparent conceptual difficulties in other fields of science as well. Since, however, the opinion has been expressed from various sides that this attitude would appear to involve a mysticism incompatible with (...) the true spirit of science, I am very glad to use the present opportunity of addressing this assembly of scientists working in quite different fields but united in their striving to find a common ground for our knowledge, to come back to this question, and above all to try to clear up the misunderstandings which have arisen. (shrink)