In papers published in the 25 years following his famous 1964 proof John Bell refined and reformulated his views on locality and causality. Although his formulations of local causality were in terms of probability, he had little to say about that notion. But assumptions about probability are implicit in his arguments and conclusions. Probability does not conform to these assumptions when quantum mechanics is applied to account for the particular correlations Bell argues are locally inexplicable. This account involves no superluminal (...) action and there is even a sense in which it is local, but it is in tension with the requirement that the direct causes and effects of events are nearby. (shrink)

Quantum theory launched a revolution in physics. But we have yet to understand the revolution's significance for philosophy. Richard Healey opens a path to such understanding. The first part of this book offers a self-contained but opinionated introduction to quantum theory. The second part assesses the theory's philosophical significance.

What ontology does realism about the quantum state suggest? The main extant view in contemporary philosophy of physics is wave-function realism . We elaborate the sense in which wave-function realism does provide an ontological picture, and defend it from certain objections that have been raised against it. However, there are good reasons to be dissatisfied with wave-function realism, as we go on to elaborate. This motivates the development of an opposing picture: what we call spacetime state realism , a view (...) which takes the states associated to spacetime regions as fundamental. This approach enjoys a number of beneficial features, although, unlike wave-function realism, it involves non-separability at the level of fundamental ontology. We investigate the pros and cons of this non-separability, arguing that it is a quite acceptable feature, even one which proves fruitful in the context of relativistic covariance. A companion paper discusses the prospects for combining a spacetime-based ontology with separability, along lines suggested by Deutsch and Hayden. (shrink)

It has been the dominant view that probabilistic explanations of particular facts must be inductive in character. I argue here that this view is mistaken, and that the aim of probabilistic explanation is not to demonstrate that the explanandum fact was nomically expectable, but to give an account of the chance mechanism(s) responsible for it. To this end, a deductive-nomological model of probabilistic explanation is developed and defended. Such a model has application only when the probabilities occurring in covering laws (...) can be interpreted as measures of objective chance, expressing the strength of physical propensities. Unlike inductive models of probabilistic explanation, this deductive model stands in no need of troublesome requirements of maximal specificity or epistemic relativization. (shrink)

INTRODUCTION Before Kant almost every philosopher subscribed to the view that truth is some kind of correspondence between ideas and 'what is the case'. ...

I argue that one good reason for Scientific Realists to be interested in correspondence theories is the hope they offer us of being able to state and defend realistic theses in the face of well-known difficulties about modern physics: such theses as, that our theories are approximately true, or that they will tend to approach the truth. I go on to claim that this hope is unlikely to be fulfilled. I suggest that Realism can still survive in the face of (...) these difficulties, as a claim about the kind of theories we want to aim for. I relate this conception of Realism to various contemporary discussions, both by realists and antirealists. (shrink)

An intuitive argument for scientific realism suggests that our successes in predicting and intervening would be inexplicable if the theories that generate them were not approximate y true. This argument faces many objections, some of which are briefly addressed in this paper, and one of which is treated in more detail. The focal criticism alleges that appeals to success cannot deliver conclusions that parts of science are true in the sense of truth-as-correspondence that realists prefer. The paper responds to that (...) criticism, in versions proposed by Michael Williams, Michael Levin, and, especiaIly, Paul Horwich, by arguing that critics typically stop at a shallow level of psychological explanation. If we probe more deeply we discover a genuine explanatory role for correspondence truth. (shrink)

An intuitive argument for scientific realism suggests that our successes in predicting and intervening would be inexplicable if the theories that generate them were not approximately true. This argument faces many objections, some of which are briefly addressed in this paper, and one of which is treated in more detail. The focal criticism alleges that appeals to success cannot deliver conclusions that parts of science are true in the sense of truth‐as‐correspondence that realists prefer. The paper responds to that criticism, (...) in versions proposed by Michael Williams, Michael Levin, and, especially, Paul Horwich, by arguing that critics typically stop at a shallow level of psychological explanation. If we probe more deeply we discover a genuine explanatory role for correspondence truth. (shrink)

The quantum theory of decoherence plays an important role in a pragmatist interpretation of quantum theory. It governs the descriptive content of claims about values of physical magnitudes and offers advice on when to use quantum probabilities as a guide to their truth. The content of a claim is to be understood in terms of its role in inferences. This promises a better treatment of meaning than that offered by Bohr. Quantum theory models physical systems with no mention of measurement: (...) it is decoherence, not measurement, that licenses application of Born’s probability rule. So quantum theory also offers advice on its own application. I show how this works in a simple model of decoherence, and then in applications to both laboratory experiments and natural systems. Applications to quantum field theory and the measurement problem will be discussed elsewhere. (shrink)

The work of Gleason and of Kochen and Specker has been thought to refute a naïve realist approach to quantum mechanics. The argument of this paper substantially bears out this conclusion. The assumptions required by their work are not arbitrary, but have sound theoretical justification. Moreover, if they are false, there seems no reason why their falsity should not be demonstrable in some sufficiently ingenious experiment. Suitably interpreted, the work of Bell and Wigner may be seen to yield independent arguments (...) for the falsity of naïve realistic approach to quantum mechanics. Quantum mechanics is no more like classical statistical mechanics than its creators thought it was. (shrink)

While its applications have made quantum theory arguably the most successful theory in physics, its interpretation continues to be the subject of lively debate within the community of physicists and philosophers concerned with conceptual foundations. This situation poses a problem for a pragmatist for whom meaning derives from use. While disputes about how to use quantum theory have arisen from time to time, they have typically been quickly resolved, and consensus reached, within the relevant scientific sub-community. Yet rival accounts of (...) the meaning of quantum theory continue to proliferate . In this article I offer a diagnosis of this situation and outline a pragmatist solution to the problem it poses, leaving further details for subsequent articles. (shrink)

I offer an account of how the quantum theory we have helps us explain so much. The account depends on a pragmatist interpretation of the theory: this takes a quantum state to serve as a source of sound advice to physically situated agents on the content and appropriate degree of belief about matters concerning which they are currently inevitably ignorant. The general account of how to use quantum states and probabilities to explain otherwise puzzling regularities is then illustrated by showing (...) how we can explain single-particle interference phenomena, the stability of matter, and interference of Bose–Einstein condensates. Finally, I note some open problems and relate this account to alternative approaches to explanation that emphasize the importance of causation, of unification, and of structure. 1 Introduction2 Two Requirements on Explanations in Physics3 What We Can use Quantum Theory to Explain4 The Function of Quantum States and Born Probabilities5 How These Functions Contribute to the Explanatory Task6 Example One: Single-Particle Interference7 Example Two: Explanation of the Stability of Matter8 Example Three: Bose Condensation9 Conclusion. (shrink)

I offer an account of how the quantum theory we have helps us explain the enormous variety of phenomena it is generally taken to explain. The account depends on what I have elsewhere called a pragmatist interpretation of the theory. This rejects views according to which a quantum state describes or represents a physical system, holding instead that it functions as a source of sound advice to physically situated agents like us on the content and appropriate degree of belief about (...) matters concerning which they are currently inevitably ignorant. So while the account given here is incompatible with some views of structural explanation in quantum theory it is nevertheless able to incorporate what I take to be their valuable insights. (shrink)

This is a book review of: Robert B. Brandom, Articulating Reasons: An Introduction to Inferentialism. Cambridge: Harvard University Press, 2000. Pp. 230.

This is a new volume of original essays on the metaphysics of quantum mechanics. The essays address questions such as: What fundamental metaphysics is best motivated by quantum mechanics? What is the ontological status of the wave function? Does quantum mechanics support the existence of any other fundamental entities, e.g. particles? What is the nature of the fundamental space of quantum mechanics? What is the relationship between the fundamental ontology of quantum mechanics and ordinary, macroscopic objects like tables, chairs, and (...) persons? This collection includes a comprehensive introduction with a history of quantum mechanics and the debate over its metaphysical interpretation focusing especially on the main realist alternatives. (shrink)

First published in 1978, this reissue presents a seminal philosophical work by professor Putnam, in which he puts forward a conception of knowledge which makes ethics, practical knowledge and non-mathematic parts of the social sciences just as much parts of 'knowledge' as the sciences themselves. He also rejects the idea that knowledge can be demarcated from non-knowledge by the fact that the former alone adheres to 'the scientific method'. The first part of the book consists of Professor Putnam's John Locke (...) lectures, delivered at the University of Oxford in 1976, offering a detailed examination of a 'physicalist' theory of reference against a background of the works of Tarski, Carnap, Popper, Hempel and Kant. The analysis then extends to notions of truth, the character of linguistic enquiry and social scientific enquiry in general, interconnecting with the great metaphysical problem of realism, the nature of language and reference, and the character of ourselves. (shrink)

This is a new volume of original essays on the metaphysics of quantum mechanics. The essays address questions such as: What fundamental metaphysics is best motivated by quantum mechanics? What is the ontological status of the wave function? What is the nature of the fundamental space (or space-time manifold) of quantum mechanics?

Selection of thirty six articles by Putnam, mostly written after 2000.

Philosophers of quantum mechanics have generally addressed exceedingly simple systems. Laura Ruetsche offers a much-needed study of the interpretation of more complicated systems, and an underexplored family of physical theories, such as quantum field theory and quantum statistical mechanics, showing why they repay philosophical attention. She guides those familiar with the philosophy of ordinary QM into the philosophy of 'QM infinity', by presenting accessible introductions to relevant technical notions and the foundational questions they frame--and then develops and defends answers to (...) some of those questions. Finally, Ruetsche highlights ties between the foundational investigation of QM infinity and philosophy more broadly construed, in particular by using the interpretive problems discussed to motivate new ways to think about the nature of physical possibility and the problem of scientific realism. (shrink)

Winner of the Wolf Prize for his contribution to our understanding of the universe, Penrose takes on the question of whether artificial intelligence will ever ...

Once upon a time, the twentieth-century investigations of the behaviors of sub-atomic particles were thought to have established that there can be no such thing as an objective, observer-independent, scientifically realist, empirically adequate picture of the physical world.

Huw Price has proposed an argument that suggests a time-symmetric ontology for quantum theory must necessarily be retrocausal, i.e. it must involve influences that travel backwards in time. One of Price's assumptions is that the quantum state is a state of reality. However, one of the reasons for exploring retrocausality is that it offers the potential for evading the consequences of no-go theorems, including recent proofs of the reality of the quantum state. Here, we show that this assumption can be (...) replaced by a different assumption, called lambda-mediation, that plausibly holds independently of the status of the quantum state. We also reformulate the other assumptions behind the argument to place them in a more general framework and pin down the notion of time symmetry involved more precisely. We show that our assumptions imply a timelike analogue of Bell's local causality criterion and, in doing so, give a new interpretation of timelike violations of Bell inequalities. Namely, they show the impossibility of a time-symmetric ontology. (shrink)