Halvorson and Clifton have given a mathematical reconstruction of Bohr’s reply to Einstein, Podolsky and Rosen, and argued that this reply is dictated by the two requirements of classicality and objectivity for the description of experimental data, by proving consistency between their objectivity requirement and a contextualized version of the EPR reality criterion which had been introduced by Howard in his earlier analysis of Bohr’s reply. In the present paper, we generalize the above consistency theorem, with a rather elementary proof, (...) to a general formulation of EPR states applicable to both non-relativistic quantum mechanics and algebraic quantum field theory; and we clarify the elements of reality in EPR states in terms of Bohr’s requirements of classicality and objectivity, in a general formulation of algebraic quantum theory. (shrink)

As the theory of the atom, quantum mechanics is perhaps the most successful theory in the history of science. It enables physicists, chemists, and technicians to calculate and predict the outcome of a vast number of experiments and to create new and advanced technology based on the insight into the behavior of atomic objects. But it is also a theory that challenges our imagination. It seems to violate some fundamental principles of classical physics, principles that eventually have become a part (...) of western common sense since the rise of the modern worldview in the Renaissance. So the aim of any metaphysical interpretation of quantum mechanics is to account for these violations. (shrink)

Einstein's philosophy of physics (as clarified by Fine, Howard, and Held) was predicated on his Trennungsprinzip, a combination of separability and locality, without which he believed objectification, and thereby "physical thought" and "physical laws", to be impossible. Bohr's philosophy (as elucidated by Hooker, Scheibe, Folse, Howard, Held, and others), on the other hand, was grounded in a seemingly different doctrine about the possibility of objective knowledge, namely the necessity of classical concepts. In fact, it follows from Raggio's Theorem in algebraic (...) quantum theory that - within an appropriate class of physical theories - suitable mathematical translations of the doctrines of Bohr and Einstein are equivalent. Thus - upon our specific formalization - quantum mechanics accommodates Einstein's Trennungsprinzip if and only if it is interpreted a la Bohr through classical physics. Unfortunately, the protagonists themselves failed to discuss their differences in this constructive way, since their debate was dominated by Einstein's ingenious but ultimately flawed attempts to establish the "incompleteness" of quantum mechanics. This aspect of their debate may still be understood and appreciated, however, as reflecting a much deeper and insurmountable disagreement between Bohr and Einstein about the knowability of Nature. Using the theological controversy on the knowability of God as a analogy, we can say that Einstein was a Spinozist, whereas Bohr could be said to be on the side of Maimonides. Thus Einstein's off-the-cuff characterization of Bohr as a 'Talmudic philosopher' was spot-on. (shrink)

: Philosophical naturalism is ambiguous between conjoining philosophy with science or with nature understood scientifically. Reconciliation of this ambiguity is necessary but rarely attempted. Feminist science studies often endorse the former naturalism but criticize the second. Karen Barad's agential realism, however, constructively reconciles both senses. Barad then challenges traditional metaphysical naturalisms as not adequately accountable to science. She also contributes distinctively to feminist reinterpretations of objectivity as agential responsibility, and of agency as embodied, worldly, and intra-active.

Standard quantum mechanics undeniably violates the notion of separability that classical physics accustomed us to consider as valid. By relating the phenomenon of quantum nonseparability to the all-important concept of potentiality, we effectively provide a coherent picture of the puzzling entangled correlations among spatially separated systems. We further argue that the generalized phenomenon of quantum nonseparability implies contextuality for the production of well-defined events in the quantum domain, whereas contextuality entails in turn a structural-relational conception of quantal objects, viewed as (...) carriers of dispositional properties. It is finally suggested that contextuality, if considered as a conditionalization preparation procedure of the object to be measured, naturally leads to a separable concept of reality whose elements are experienced as distinct, well-localized objects having determinate properties. In this connection, we find it necessary to distinguish the meaning of the term reality from the criterion of reality for us. The implications of the latter considerations for the notion of objectivity in quantum mechanics are also discussed. (shrink)

In this paper, I argue that Heisenberg's mature philosophy of quantum mechanics must be understood in the context of his epistemological project to reinterpret and redefine Kant's notion of the a priori. After discussions with Weizsäcker and Hermann in Leipzig in the 1930s, Heisenberg attempted to ground his interpretation of quantum mechanics on what might be termed a 'practical' transformation of Kantian philosophy. Taking as his starting point, Bohr's doctrine of the indispensability of classical concepts, Heisenberg argued that concepts such (...) as space, time and causality can be regarded as 'practically a priori', in so far as they remain the conditions for the possibility of experience and even of 'objective reality', though they are not universal and necessary in a strictly Kantian sense. We cannot avoid using classical concepts in the description of experiments in quantum theory, despite the fact that there are limits to their applicability. Such concepts are, for Heisenberg, historically contingent, yet indispensable in our time, because we have no other language through which we can describe and conceive of the interaction between 'object' and 'measuring device'. (shrink)

We clarify Bohr’s interpretation of quantum mechanics by demonstrating the central role played by his thesis that quantum theory is a rational generalization of classical mechanics. This thesis is essential for an adequate understanding of his insistence on the indispensability of classical concepts, his account of how the quantum formalism gets its meaning, and his belief that hidden variable interpretations are impossible.

This paper investigates some of the philosophical and conceptual issues raised by the search for a quantum theory of gravity. It is critically discussed whether such a theory is necessary in the first place, and how much would be accomplished if it is eventually constructed. I argue that the motivations behind, and expectations to, a theory of quantum gravity are entangled with central themes in the philosophy of science, in particular unification, reductionism, and the interpretation of quantum mechanics. I further (...) argue that there are —contrary to claims made on behalf of string theory— no good reasons to think that a quantum theory of gravity, if constructed, will provide a theory of everything, that is, a fundamental theory from which all physics in principle can be derived. (shrink)

For many years after Bohr's response to the EPR argument, Bohr was considered to have provided an authoritative rebuttal of the ideas of the paper, and more generally of Einstein's stance on quantum theory. More recently, however, there has been great difficulty even in achieving general agreement on Bohr's meaning. Two recent papers, by Dickson, and by Clifton and Halvorson, have sought to establish the structure of Bohr's argument. In the present paper, the papers of EPR and Bohr are re-assessed (...) in the light of these recent papers, and also in light of the development and presentation of quantum information theory. (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)

What becomes of our clearest theories of explanation, when faced with the unpalatable quantum phenomena that seem to undermine the direct conceptual connection between the fundamental material entities and the self-standing material objects of everyday parlance? The general explanatory theory advocates unification of explanatory concepts with everyday discourse, identification of essentially similar characteristics between direct experience and the hypothesised explanatory ontology, and a conceptualisation of phenomena in terms of objects enduring causally regulated change. On the other hand quantum theory feeds (...) antirealist suspicions about the worth of realist explanatory endeavour with examples of phenomena in which the structure of material separation and individuation based on spatial extension is insufficient for construction of deeper explanatory narratives. An example from history of science, that of Newton’s law-constitutive definition of objects in response to D escartes problem of bodies is used to suggest a possible strategy for explanations unifying the quantum and common-sense conceptual domains, provided the anti-realist challenge to such enterprise is read as questioning the epistemological justification of interpretation of experience in both cases.Što se događa s najjasnijim dostupnim teorijama objašnjenja kada se suoče s problematičnim kvantnim pojavama koje naizgled potkopavaju neposrednu konceptualnu poveznicu između fundamentalnih materijalnih entiteta i samoopstojnih materijalnih predmeta iz svakodnevnog govora? Opća teorija objašnjenja preporuča objedinjenje teoretskih eksplanatornih pojmova sa svakodnevnim govorom, određenje esencijalno sličnih karakteristika između neposrednog iskustva i hipotetske eksplanatorne ontologije te konceptualizaciju pojava kroz predmete koji istraju kroz uzročno regulirane promjene. S druge strane, kvantna teorija potkrjepljuje antirealistične sumnje o valjanosti eksplanatornog nastojanja realizma primjerima pojava u kojima je struktura materijalne razdvojenosti i individuacije temeljene na prostornoj protežnosti nedovoljna za izgradnju dubljih eksplanatornih narativa. Primjerom iz povijesti znanosti, Newtonovom definicijom predmeta temeljenom na zakonima kao odgovorom na Descartesov problem materijalnih tijela, daje se moguća strategija izgradnje objašnjenja koja objedinjuju kvantne i “zdravorazumske” konceptualne domene, ukoliko se antirealistična kritika te izgradnje u oba slučaja shvati kao propitivanje epistemološkog opravdanja tumačenja iskustva. (shrink)

Halvorson and Clifton have given a mathematical reconstruction of Bohr’s reply to Einstein, Podolsky and Rosen (EPR), and argued that this reply is dictated by the two requirements of classicality and objectivity for the description of experimental data, by proving consistency between their objectivity requirement and a contextualized version of the EPR reality criterion which had been introduced by Howard in his earlier analysis of Bohr’s reply. In the present paper, we generalize the above consistency theorem, with a rather elementary (...) proof, to a general formulation of EPR states applicable to both non-relativistic quantum mechanics and algebraic quantum field theory; and we clarify the elements of reality in EPR states in terms of Bohr’s requirements of classicality and objectivity, in a general formulation of algebraic quantum theory. (shrink)

Descartes’ derivation of the primary qualities of matter and their role in explaining observed physical phenomena are briefly reviewed. The lesson drawn from Descartes’ methodology of explanation is that we ought to aim to reduce complex phenomena to simple unifying principles and conceptual primitives. Three proposed solutions to the apparent paradoxes in contemporary quantum physics (primarily associated with the notion of entanglement) are briefly compared with lessons taken from Descartes. It is argued that further research in this field should provide (...) criteria for selecting modifications to the standard (largely Cartesian) conceptual scheme, along the lines of either visualisable causality or the physical spatial separability of all material objects. (shrink)

Quantum mechanics is an area of Physics that deals with subatomic phenomena. It can be extracted from a vision of the physical world which contradicts many aspects of our everyday perception, prompting many philosophical debates and admitting different interpretations. Among the wide range of problems within the interpretation of quantum theory, there is the measurement problem. Some philosophical aspects of the problems concerning the notion of “measurement” in quantum mechanics are analyzed in order to identify how the problem arises in (...) discussions about the foundations of the interpretation of quantum theory and how it holds up even in the most recent interpretations, conflicting in various ways (including ontological) with a worldview that can be drawn from classical physics – assuming that it provides a worldview. Although Bohr has, on several occasions, addressed the measurement problem, he did not get to properly formulate a measurement theory. This was done by von Neumann, who presented an axiomatic formulation of a measurement theory along with a critique of the Bohrian model and, at the same time, an alternative grounded in the introduction of a dualistic notion of consciousness (nonphysical) with causal power in quantum measurement. It is precisely the introduction of the dualistic concept of consciousness within the scope of the concept of measurement that inserts into the philosophical discussion as an ontological problem insofar as it comes to the introduction of a new entity in the universe. The first subjetivistic interpretations, proposed by London and Bauer, are analysed, passing through the solipsistic difficulty to this subjectivist interpretations placed through Wigner’s work, up to the interpretations inspired by the late work of the physicist Erwin Schrödinger, which proposes a monistic interpretation of the notion of “consciousness”. Some distinct attitudes towards measuring the philosophical problems are outlined very briefly in the form of sampling, to illustrate the plural character of the proposals for interpretation of the term “measurement” in quantum mechanics. Although strictly speaking there is no “best” interpretation of quantum mechanics, it is suggested that the formulation of an ontology that takes into account quantum mechanics could help in understanding certain concepts, such as “measurement” or “consciousness” without that philosophical difficulties – as dualism – or paradoxical situations – such as solipsism – necessarily accompany them. (shrink)

Philosophical naturalism is ambiguous between conjoining philosophy with science or with nature understood scientifically. Reconciliation of this ambiguity is necessary but rarely attempted. Feminist science studies often endorse the former naturalism but criticize the second. Karen Barad's agential realism, however, constructively reconciles both senses. Barad then challenges traditional metaphysical naturalisms as not adequately accountable to science. She also contributes distinctively to feminist reinterpretations of objectivity as agential responsibility, and of agency as embodied, worldly, and intra-active.