There is confusion among scholars of Bohr as to whether he should be categorized as an instrumentalist (see Faye 1991) or a realist (see Folse 1985). I argue that Bohr is a realist, and that the confusion is due to the fact that he holds a very special view of realism, which did not coincide with the philosophers’ views. His approach was sometimes labelled instrumentalist and other times realist, because he was an instrumentalist on the theoretical level, but a realist (...) on the level of models. Such a realist position is what I call phenomenological realism. In this paper, and by taking Bohr’s debate with Einstein as a paradigm, I try to prove that Bohr was such a realist. (shrink)

The aim of this paper is to combine the intellectual and the psychosocial aspects. blurring the distinction between the conceptual and the anecdotal history of quantum mechanics. The full realization of the importance of such “anecdotal” factors leads to the revision of our understanding of the conceptual development itself. The paper concludes with the suggestion that a major part of numerous inconsistencies in the Copenhagen interpretation of quantum physics are of a psychosocial origin.

The received view on the contributions of the physics community to the birth of molecular biology tends to present the physics community as sharing a basic level consensus on how physics should be brought to bear on biology. I argue, however, that a close examination of the views of three leading physicists involved in the birth of molecular biology, Bohr, Delbrück, and Schrödinger, suggests that there existed fundamental disagreements on how physics should be employed to solve problems in biology even (...) within the physics community. In particular, I focus on how these three figures differed sharply in their assessment of the relevance of complementarity, the potential of chemical methods, and the relative importance of classical physics. In addition, I assess and develop Roll-Hansen’s attempt to conceptualize this history in terms of models of scientific change advanced by Kuhn and Lakatos. Though neither model is fully successful in explaining the divergence of views among these three physicists, I argue that the extent and quality of difference in their views help elucidate and extend some themes that are left opaque in Kuhn’s model. (shrink)

The ArgumentDavid Bloor often wrote that Karl Mannheim had “stopped short” in his sociology of knowledge, lacking the nerve to consider the natural sciences sociologically. While this assessment runs counter to Mannheim's own work, which responded in quite specific ways both to an encroaching “modernity” and a looming fascism, Bloor's depiction becomes clearer when considered in the light of his principal introduction to Mannheim's work — a series of essays by Robert Merton. Bloor's reading and appropriation of Mannheim emerged from (...) his background in experimental psychology and his attempts to supercede Merton's own structural-functionalist program for the sociology of knowledge. By retracing this extended trail of readings and re-readings, we may begin to understand the roots of Bloor's curious interpretation of Mannheim's sociology of knowledge, and inquire in a reflexive way about the present and future directions of science studies. (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)

Hilbert arithmetic in a wide sense, including Hilbert arithmetic in a narrow sense consisting by two dual and anti-isometric Peano arithmetics, on the one hand, and the qubit Hilbert space (originating for the standard separable complex Hilbert space of quantum mechanics), on the other hand, allows for an arithmetic version of Gentzen’s cut elimination and quantum measurement to be described uniformy as two processes occurring accordingly in those two branches. A philosophical reflection also justifying that unity by quantum neo-Pythagoreanism links (...) it to the opposition of propositional logic, to which Gentzen’s cut rule refers immediately, on the one hand, and the linguistic and mathematical theory of metaphor therefore sharing the same structure borrowed from Hilbert arithmetic in a wide sense. An example by hermeneutical circle modeled as a dual pair of a syllogism (accomplishable also by a Turing machine) and a relevant metaphor (being a formal and logical mistake and thus fundamentally inaccessible to any Turing machine) visualizes human understanding corresponding also to Gentzen’s cut elimination and the Gödel dichotomy about the relation of arithmetic to set theory: either incompleteness or contradiction. The metaphor as the complementing “half” of any understanding of hermeneutical circle is what allows for that Gödel-like incompleteness to be overcome in human thought. (shrink)

This paper is the sequel of a previous one where we have introduced a paraconsistent logic termed paraclassical logic to deal with 'complementary propositions'. Here, we enlarge upon the discussion by considering certain 'meaning principles', which sanction either some restrictions of 'classical' procedures or the utilization of certain 'classical' incompatible schemes in the domain of the physical theories. Here, the term 'classical' refers to classical physics. Some general comments on the logical basis of a scientific theory are also put in (...) between the text, motivated by the discussion of complementarity. (shrink)

This paper re-evaluates the formative year of quantum mechanics—from Heisenberg’s first paper on matrix mechanics to Schrödinger’s equivalence proof—by focusing on the role of radiation in the emerging theory. We argue that the radiation problem played a key role in early quantum mechanics, a role that has not been taken into account in the standard histories. Radiation was perceived by the main protagonists of matrix and wave mechanics as a central lacuna in these emerging theories and continued to contribute to (...) the theoretical development and conceptual clarification of quantum mechanics. Studying the interplay between quantum mechanics and radiation, the paper provides an account of (a) how quantum mechanics was able to connect to its empirical basis in spectroscopy and (b) how Schrödinger’s equivalence proof emerged from his explorative calculations on the emission of radiation. (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)

The ArgumentIn this paper I argue that Kuhn's and Hanson's notion of incommensurable paradigms is rooted in the rhetoric of finality of the Copenhagen dogma — the orthodox philosophical interpretation of quantum physics. I also argue that arguments for holism of a paradigm, on which the notion of the impossibility of its gradual modification is based, misinterpret the Duhem-Quine thesis. The history of science (Copernican, Chemical, and Quantum Revolutions) demonstrates fruitful selective appropriation of ideas from seemingly “incommensurable” paradigms (rather than (...) the impossibility of communication between their representatives). I argue in conclusion that such openness underlies scientific creativity, and that dialogue between different alternatives is indispensable for the growth of knowledge. (shrink)

The ArgumentThe aim of this paper is to provide a critical perspective for Einstein's opposition to the Copenhagen interpretation of quantum physics, by analyzing the ingenious rhetoric of Bohr's principle of complementarity. I argue that what Bohr presents as arguments of “inevitability” are in fact merely arguments for the consistency of the quantum-mechanical scheme. Einstein's resistance to being persuaded by this potent technique of argumentation, and his rejection of Bohr's interpretation of quantum physics, appear consequently as an eminently reasonable position (...) and not as a conservative stand, as it is often presented by the adherents of the Copenhagen orthodoxy. (shrink)