This paper considers the prospects for a quantum perspectivism that seeks to reconcile competing approaches to quantum theory as distinct scientific perspectives on quantum reality. In other areas of the philosophy of science, perspectivism holds the promise of a way to embrace pluralism without contradiction—what appear to be competing theories can be accepted because they each provide a distinct “window on the same reality.” The contemporary situation in quantum foundations is arguably a case of underdetermination. If this is so, this brand of perspectivism may offer a resolution.

The question of whether Everettian quantum mechanics (EQM) justifies the existence of metaphysical indeterminacy has recently come to the fore. Metaphysical indeterminacy has been argued to emerge from three sources: coherent superpositions, the indefinite number of branches in the quantum multiverse and the nature of these branches. This paper reviews the evidence and concludes that those arguments don’t rely on EQM alone and rest on metaphysical auxiliary assumptions that transcend the physics of EQM. We show how EQM can be ontologically interpreted without positing metaphysical indeterminacy by adopting a deflationary attitude towards branches. Two ways of developing the deflationary view are then proposed: one where branches are eliminated, and another where they are reduced to the universal quantum state.

The principle of least action (PLA) has often been cited as a counterexample to the dominant mode of causal explanation in physics. In particular, PLA seems to involve an appeal to final causes or some other teleological ideology. However, Ben-Menahem (Causation in science, Princeton University Press, Princeton, 2018) argues that such implications no longer apply given that PLA can be recovered as limiting case from quantum theory. In this paper, I argue that the metaphysical implications of PLA-based explanations are not undermined by its status as derivative. However, I contend that PLA functions as a diachronic constraint that licenses explanations by constraint (Lange, Because without cause: non-casual explanations in science and mathematics. Oxford University Press, Oxford, 2016). PLA-based explanations, on this account, are non-causal but also differ from familiar cases of teleological explanations in several respects.

Metaphysical indeterminacy in the context of quantum mechanics is often motivated by the eigenstate-eigenvalue link. However, the sparse view of Glick (Thought J Philos 6(3):204–213, 2017) illustrates why it has no such implications. Other links connecting quantum states and property ascriptions—such as those associated with the GRW theory—may introduce indeterminacy, but such indeterminacy may be viewed as merely representational and is susceptible to familiar treatments of vagueness. Thus, I contend that such links fail to provide a compelling motivation for quantum metaphysical indeterminacy.

Quantum mechanics (QM) has long been thought to challenge scientific realism.The Copenhagen school maintained that QM was unable to provide the realist's sought after description of microscopic reality.Today, many believe such a description can be found, but new challenges have arisen.The impressive collection of essays Scientific Realism and the Quantum, edited by Steven French & Juha Saatsi, seeks to explore several such challenges.The fourteen contributed chapters are organized into five parts: Rethinking scientific realism; underdetermination and interpretation; pragmatism about quantum theory; wavefunction and quantum state realism; and scientific realism and quantum field theory.In this review, I'll touch on three main themes that run throughout the volume.First, the underdetermination brought about by the presence of multiple interpretations of QM.Second, the role of explanation in motivating realist approaches to QM.And third, the implications for scientific realism of the recognition that QM (and quantum field theory) is not a fundamental theory.Despite the best efforts of some of the contributors, I contend that each of these issues remains unresolved.Nevertheless, their consideration is essential for the development of a scientific realism appropriate for QM.

Ontic structural realism (OSR) claims that all there is to the world is structure. But how can this slogan be turned into a worked-out metaphysics? Here I consider one potential answer: a metaphysical framework known as 'generalism' (Dasgupta [2009], [2016]). According to the generalist, the most fundamental description of the world is not given in terms of individuals bearing properties, but rather, general facts about which states of affairs obtain. However, I contend that despite several apparent similarities between the positions, generalism is unable to capture the two main motivations for OSR. I suggest instead that OSR should be construed as a meta-metaphysical position.

Quantum mechanics (QM) has long been thought to challenge scientific realism. The Copenhagen school maintained that QM was unable to provide the realist’s sought after description of microscopic reality. Today, many believe such a description can be found, but new challenges have arisen. This impressive collection of essays seeks to explore several such challenges. The contributions cover a range of different issues and viewpoints bearing on the broad topic of realism and QM. In this review, I’ll touch on three main themes.

Experiments involving delayed-choice entanglement swapping seem to suggest that particles can become entangled after they've already been detected. This astonishing result is taken by some to undermine realism about entanglement. In this paper, I argue that one can offer a fully realist explanation of delayed-choice entanglement swapping by countenancing timelike entanglement relations. I argue that such an explanation—radical though it may be—isn't incoherent and doesn't invite paradox. I compare this approach to the antirealist alternative and a more deflationary realist strategy defended by Egg (2013), each of which face certain challenges. The upshot is that we should take seriously the possibility of timelike entanglement and seek to develop a framework for quantum theory which allows for it.

Next Home Previous The Quantum Revolution in Philosophy Richard Healey Reviewed by David Glick The Quantum Revolution in Philosophy Richard Healey Oxford: Oxford University Press, 2017, £35.00 ISBN 9780198714057 What is it that's revolutionary about quantum theory (QT)? Traditionally, it has been thought that the answer consists in novel and surprising aspects of the world it describes:

A growing literature is premised on the claim that quantum mechanics provides evidence for metaphysical indeterminacy. But does it? None of the currently fashionable realist interpretations involve fundamental indeterminacy and the ‘standard interpretation’, to the extent that it can be made out, doesn’t require indeterminacy either.

In this paper I elicit a prediction from structural realism and compare it, not to a historical case, but to a contemporary scientific theory. If structural realism is correct, then we should expect physics to develop theories that fail to provide an ontology of the sort sought by traditional realists. If structure alone is responsible for instrumental success, we should expect surplus ontology to be eliminated. Quantum field theory (QFT) provides the framework for some of the best confirmed theories in science, but debates over its ontology are vexed. Rather than taking a stand on these matters, the structural realist can embrace QFT as an example of just the kind of theory SR should lead us to expect. Yet, it is not clear that QFT meets the structuralist's positive expectation by providing a structure for the world. In particular, the problem of unitarily inequivalent representations threatens to undermine the possibility of QFT providing a unique structure for the world. In response to this problem, I suggest that the structuralist should endorse pluralism about structure.