The Two Faces of Semi-Physicalism

Some critics believe Quine's semantic indeterminacy (indeterminacy of radical translation at home as well as abroad) thesis is true, but innocent, since it is just scientific underdetermination in linguistics. The Quinean reply is that in scientific underdetermination cases there are facts of the matter making claims true or false (whether knowable or not), whereas in semantic indeterminacy cases there simply are not. The critics' rejoinder that there are such facts, studied in linguistics, is met by the final reply that linguistics either on the whole or in part is riddled with appeals to “meanings” and is, thereby, as suspect as analyticity and radical translation. I recommend “saving”(?) linguistics by holding that it is permanently entangled in epistemology. Finally, the argument the critics should have made concerns paralleling semantic indeterminacy to indeterminacies in current quantum mechanics.

There are now several, realist versions of quantum mechanics on offer. On their most straightforward, ontological interpretation, these theories require the existence of an object, the wavefunction, which inhabits an extremely high‐dimensional space known as configuration space. This raises the question of how the ordinary three‐dimensional space of our acquaintance fits into the ontology of quantum mechanics. Recently, two strategies to address this question have emerged. First, Tim Maudlin, Valia Allori, and her collaborators argue that what I have just called the ‘most straightforward’ interpretation of quantum mechanics is not the correct one. Rather, the correct interpretation of realist quantum mechanics has it describing the world as containing objects that inhabit the ordinary three‐dimensional space of our manifest image. By contrast, David Albert and Barry Loewer maintain the straightforward, wavefunction ontology of quantum mechanics, but attempt to show how ordinary, three‐dimensional space may in a sense be contained within the high‐dimensional configuration space the wavefunction inhabits. This paper critically examines these attempts to locate the ordinary, three‐dimensional space of our manifest image “within” the ontology of quantum mechanics. I argue that we can recover most of our manifest image, even if we cannot recover our familiar three‐dimensional space.

Van Fraassen's modal interpretation of non-relativistic quantum mechanics is articulated to support an anti-realist account of quantum theory. However, given the particular form of van Fraassen's anti-realism (constructive empiricism), two problems arise when we try to make it compatible with the modal interpretation: one difficulty concerns the tension between the need for modal operators in the modal interpretation and van Fraassen's skepticism regarding real modality in nature; another addresses the need for the truth predicate in the modal interpretation and van Fraassen's rejection of truth as the aim of science. After examining these two problems, I suggest a formal framework in which they can be accommodated – using da Costa and French's partial structures approach – and indicate a variant of van Fraassen's modal interpretation that does not face these difficulties. Quanta 2014; 3: 1–15.

Many world interpretations (MWIs) of quantum mechanics avoid the measurement problem by considering every term in the quantum superposition as actual. A seemingly opposed solution is proposed by modal interpretations (MIs) which state that quantum mechanics does not provide an account of what “actually is the case,” but rather deals with what “might be the case,” i.e., with possibilities. In this paper we provide an algebraic framework which allows us to analyze in depth the modal aspects of MWI. Within our general formal scheme we also provide a formal comparison between MWI and MI, in particular, we provide a formal understanding of why—even though both interpretations share the same formal structure—MI fall pray of Kochen–Specker-type contradictions while MWI escape them.

A central problem in the interpretation of non‐relativistic quantum mechanics is to relate the conceptual structure of the theory to the classical idea of the state of a physical system. This paper approaches the problem by presenting an analysis of the notion of an elementary physical proposition. The notion is shown to be realized in standard formulations of the theory and to illuminate the significance of proofs of the impossibility of hidden variable extensions. In the interpretation of quantum mechanics that emerges from this analysis, the philosophically distinctive features of the theory derive from the fact that it seeks to represent a reality of which complete knowledge is essentially unattainable.

In this paper I examine the role of dispositional properties in the most frequently discussed interpretations of non-relativistic quantum mechanics. After offering some motivation for this project, I briefly characterize the distinction between non-dispositional and dispositional properties in the context of quantum mechanics by suggesting a necessary condition for dispositionality namely contextuality and, consequently, a sufficient condition for non-dispositionality, namely non-contextuality. Having made sure that the distinction is conceptually sound, I then analyze the plausibility of the widespread, monistic ontological thesis about the reducibility of dispositional properties to categorical properties in the context of the philosophy of quantum mechanics. I conclude that with the exception of Bohmian mechanics, the other minimally realist views of quantum mechanics require essential dispositions, i.e., dispositions of a non-reducible kind. Interestingly, seen behind the lenses of dispositionalism, Bohr's and Bohm's interpretations of quantum mechanics are much closer than it is usually recognized, a fact that could teach us something about the way the quantum world is.

This article probes the question of what interpretations of quantum mechanics actually accomplish. In other domains, which are briefly considered, interpretations serve to make alien systematizations intelligible to us. This often involves clarifying the status of their implicit ontology. A survey of interpretations of non-relativistic quantum mechanics supports the evaluation that these interpretations make a contribution to philosophy, but not to physics. Interpretations of quantum field theory are polarized by the divergence between the Lagrangian field theory, which leads to the Standard Model of Particle physics and the Algebraic quantum field theory that discounts an ontology of particles. Ruetsche’s interpretation offers a potential for loosening the sharp polarization that presently obtains. A brief evaluation focuses on the functional ontology of quantum field theory considered as an effective theory.

We suggest a contextual realist interpretation of relational quantum mechanics. The principal point is a correct understanding of the concept of reality and taking into account the categorical distinction between the ideal and the real. Within our interpretation, consciousness of the observer does not play any metaphysical role. The proposed approach can also be understood as a return to the Copenhagen interpretation of quantum mechanics, corrected within the framework of contextual realism. The contextual realism allows one to get rid of the metaphysical problems encountered by various interpretations of quantum mechanics, including the relational one.

Contemporary theology has realized the importance of integrating what we know from the “new physics”-quantum mechanics and relativity theory-into the metaphysical and ontological categories used by theology to consider God, the world, and the God-world relationship. The categories of subjectivity and relationality have risen to prominence in these discussions. Both academic and popular presentations can obscure the vital distinction between what physicists agree on concerning quantum mechanics and the contested interpretation of quantum mechanics, or what quantum mechanics reveals about reality. After (1) summarizing the significant distinction between quantum mechanics per se and the interpretations of quantum mechanics and (2) the agreed upon quantum mechanical experimental procedure and its attendant mathematical formalism, as well as a few of the foremost interpretations, this paper (3) attempts a minimalist culling of some rudimentary but clear ontological principles and categories from what is agreed upon in quantum mechanics, without appeals-tacit or explicit-to one of the many controversial interpretations or to contestable philosophical assumptions and deductions, and these are: experience, subjectivity, relationship, and event. The paper closes by (4) commending one speculative scheme that is especially conducive to developing an interpretation of quantum mechanics consonant with the ontological principles and categories so derived, that of Alfred North Whitehead

The last decade has seen an increasing number of references to quantum mechanics in the humanities and social sciences. This development has in particular been driven by Karen Barad’s agential realism: a theoretical framework that, based on Niels Bohr’s interpretation of quantum mechanics, aims to inform social theorizing. In dealing with notions such as agency, power, and embodiment as well as the relation between the material and the discursive level, the influence of agential realism in fields such as feminist science studies and posthumanism has been profound. However, no one has hitherto paused to assess agential realism’s proclaimed quantum mechanical origin including its relation to the writings of Niels Bohr. This is the task taken up here. We find that many of the implications that agential realism allegedly derives from a Bohrian interpretation of quantum mechanics dissent from Bohr’s own views and are in conflict with those of other interpretations of quantum mechanics. Agential realism is at best consistent with quantum mechanics and consequently, it does not capture what quantum mechanics in any strict sense implies for social science or any other domain of inquiry. Agential realism may be interesting and thought provoking from the perspective of social theorizing, but it is neither sanctioned by quantum mechanics nor by Bohr’s authority. This conclusion not only holds for agential realism in particular, it also serves as a general warning against the other attempts to use quantum mechanics in social theorizing.

The present work, which is a sequel to ‘Reichenbach and the Logic of Quantum Mechanics’ (this volume; henceforth referred to as Part I), endeavors to place Reichenbach’s proposed quantum logic RQL within the context of his overall interpretation of quantum mechanics (QM). Although it is argued in Part I that Reichenbach intended RQL to provide an alternative logico-linguistic framework for the formulation of the quantum theory, in the present work we interpret RQL as being entirely on a par with mainstream quantum logic (MQL). In particular, we regard RQL as pertaining, not to the theory formulation language TL(QM), but rather exclusively to the elementary (observation) language RL(QM), which is obtained from the elementary language OL(QM), associated with MQL, by adding a variety of three-valued truth-functional connectives. Also, like Part I, the present work is essentially comparative in nature, the purpose being to analyze Reichenbach’s interpretation of QM in the light of more recently proposed interpretations. We take the chief themes of Reichenbach’s interpretation to include the following: the distinction between phenomena and interphenomena; the distinction between exhaustive and restrictive interpretations of QM; the Principle of equivalent descriptions; the proposal of a non-bivalent semantics for the observation language of QM.

On Rayleigh's Pendulum On Schrodinger's Wave Mechanics On the Invariant form of the Wave Equation and of the Equations of Motion for a Charged Massive Point A Comment on Quantization of the Harmonic Oscillator in a Magnetic Field On the Relation Between the Integrals of the Quantum Mechanical Equations of Motion and the Schrodinger Wave Equation Generalization and Solution of the Dirac Statistical Equation Proof of the Adiabatic Theorem On Improper Functions in Quantum Mechanics On the Notion of Velocity in the Dirac Theory of the Electron On the Dirac Equations in General Relativity Dirac Wave Equation and Riemann Geometry A Comment on the Virial Relation An Approximate Method for Solving the Quantum Many-body Problem Application of the Generalized Hartree Method to the Sodium Atom New Uncertainty Properties of the Electromagnetic Field The Mechanics of Photons A Comment on the Virial Relation in Classical Mechanics Configuration Space and Second Quantization On Dirac's Quantum Electrodynamics On Quantization of Electro-magnetic waves and Interaction of Charges in Dirac Theory On Quantum Electrodynamics On the Theory of Positrons On Quantum Exchange Energy On the Numerical Solution of Generalized Equations of the Self-Consistent Field An Approximate Representation of the Wave Functions of Penetrating Orbits On Quantum Electrodynamics Hydrogen Atom and Non-Euclidean Geometry Extremal Problems in Quantum Theory The Fundamental Significance of Approximate Methods in Theoretical Physics The Method of Functionals in Quantum Electrodynamics Proper Time in Classical and Quantum Mechanics Incomplete Separation of Variables for Divalent Atoms On the Wave Functions of Many-Electron Systems On the Representation of an Arbitrary Function by an Integral Involving Legendre's Function with a Complex Index On the Uncertainty Relation Between Time and Energy Application of Two-electron Functions in the Theory of Chemical Bonds On the Interpretation of Quantum Mechanics On the Canonical Transformation in Classical and Quantum Mechanics.

Harrigan and Spekkens (2010) provided a categorization of quantum ontological models classifying them as $\psi$-ontic or $\psi$-epistemic if the quantum state describes respectively either a physical reality or mere observers' knowledge. Moreover, they claimed that Einstein - who was a supporter of the statistical interpretation of quantum mechanics - endorsed an epistemic view of $\psi$. In this essay we critically assess such a classification and some of its consequences by proposing a two-fold argumentation. Firstly, we show that Harrigan and Spekkens' categorization implicitly assumes that a complete description of a quantum system (its ontic state, $\lambda$) only concerns single, individual systems instantiating absolute, intrinsic properties. Secondly, we argue that such assumptions conflict with some current interpretations of quantum mechanics, which employ different ontic states as a complete description of quantum systems. In particular, we will show that, since in the statistical interpretation ontic states describe ensembles rather than individuals, such a view cannot be considered psi-epistemic. As a consequence, the authors misinterpreted Einstein's view concerning the nature of the quantum state. Next, we will focus on Relationalist Quantum Mechanics and Perspectival Quantum Mechanics, which in virtue of their relational and perspectival metaphysics employ ontic states lambda dealing with relational properties. We conclude that Harrigan and Spekkens' categorization is too narrow and entails an inadequate classification of the mentioned interpretations of quantum theory. Hence, any satisfactory classification of quantum ontological models ought to take into account the variations of $\lambda$ across different interpretations of quantum mechanics.

The no-hidden-variable proofs of von Neumann, Jauch and Piron and Kochen and Specker have left many workers in the foundations of quantum mechanics unconvinced. Nonetheless, it is probably fair to say that most are convinced by the Bell-Wigner argument that local hidden variables are impossible. A notable exception is Arthur Fine, who insists that the Bell-Wigner result has nothing to do with locality, and who defends a point of view which, while not described as a hidden variable theory, claims that quantum mechanics can be understood as "... an essentially statistical account of a well-defined and localized domain."1 By "well-defined", Fine means that every magnitude has a definite value and that classical logic is preserved. In this paper, I attempt to throw cold water on Fine's hopes for a classical understanding of quantum theory by focussing on his treat ment of the problem of joint distributions. I will begin with an earlier paper, 'Probability and the Interpretation of Quantum Mechanics'2, which provides important background, and then proceed to 'On the Completeness of Quantum Mechanics' in which the above thesis is defended. The main point of the earlier paper is to argue that no violations of our ordinary concepts of probability and logic are involved in the fact that quantum mechanics does not provide joint distributions for every set of magnitudes. The programme of that paper involves introducing a family L of propositions each of the form

The article takes under consideration three versions of the ensemble (statistical) interpretation of quantum mechanics and discusses the interconnection of these interpretations with the philosophy of science. To emphasize the specifics of the problem of interpretation of quantum mechanics in the USSR, the Marxist ideology is taken into account. The present paper continues the author’s previous analysis of ensemble interpretations which emerged in the USA and USSR in the first half of the 20th century. The author emphasizes that the ensemble approach turned out to be a dead end for the development of the interpretation of quantum mechanics in Russia. The article also argues that in Soviet Russia, the classical Copenhagen (standard) approach to quantum mechanics was used. The Copenhagen approach was developed by Lev Landau in 1919–1931 and became the basis of the Landau-Lifshitz famous course on quantum mechanics, one of the classics of twentieth-century physics literature (the first edition was published in 1947). Although Vladimir A. Fock’s approach to the interpretation of quantum mechanics differs from the standard presentation by Lev Landau and Evgeny Lifshitz, Fock put forward a very important principle that complementarity is a “firmly established law of nature”. The fundamental writings of Lev Landau, Vladimir Fock and Igor Tamm, the authors of the mid-twentieth century, did a lot to defend the standard point of view such as the popular interpretations by Landau and Lifshitz. This approach can be traced back to Landau’s early writings and to Fock’s criticism of the ensemble approach.