Citations of:
Primitive Ontology and the Structure of Fundamental Physical Theories
In Alyssa Ney & David Z. Albert (eds.), The Wave Function: Essays in the Metaphysics of Quantum Mechanics. Oxford University Press (2013)
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Quantum mechanics seems to portray nature as nonseparable, in the sense that it allows spatiotemporally separated entities to have states that cannot be fully specified without reference to each other. This is often said to implicate some form of “holism.” We aim to clarify what this means, and why this seems plausible. Our core idea is that the best explanation for nonseparability is a “common ground” explanation, which casts nonseparable entities in a holistic light, as scattered reflections of a more (...) 

Realists wanting to capture the facts of quantum entanglement in a metaphysical interpretation find themselves faced with several options: to grant some species of fundamental nonseparability, adopt holism, or to view localized spacetime systems as ultimately reducible to a higherdimensional entity, the quantum state or wave function. Those adopting the latter approach and hoping to view the macroscopic world as grounded in the quantum wave function face the macroobject problem. The challenge is to articulate the metaphysical relation obtaining between threedimensional (...) 

A century after the discovery of quantum mechanics, the meaning of quantum mechanics still remains elusive. This is largely due to the puzzling nature of the wave function, the central object in quantum mechanics. If we are realists about quantum mechanics, how should we understand the wave function? What does it represent? What is its physical meaning? Answering these questions would improve our understanding of what it means to be a realist about quantum mechanics. In this survey article, I review (...) 

This paper reviews the structure of standard quantum mechanics, introducing the basics of the von NeumannDirac axiomatic formulation as well as the wellknown Copenhagen interpretation. We review also the major conceptual difficulties arising from this theory, first and foremost, the wellknown measurement problem. The main aim of this essay is to show the possibility to solve the conundrums affecting quantum mechanics via the methodology provided by the primitive ontology approach. Using Bohmian mechanics as an example, the paper argues for a (...) 

In a quantum universe with a strong arrow of time, it is standard to postulate that the initial wave function started in a particular macrostatethe special lowentropy macrostate selected by the Past Hypothesis. Moreover, there is an additional postulate about statistical mechanical probabilities according to which the initial wave function is a ''typical'' choice in the macrostate. Together, they support a probabilistic version of the Second Law of Thermodynamics: typical initial wave functions will increase in entropy. Hence, there are two (...) 



In a quantum universe with a strong arrow of time, we postulate a lowentropy boundary condition to account for the temporal asymmetry. In this paper, I show that the Past Hypothesis also contains enough information to simplify the quantum ontology and define a unique initial condition in such a world. First, I introduce Density Matrix Realism, the thesis that the quantum universe is described by a fundamental density matrix that represents something objective. This stands in sharp contrast to Wave Function (...) 

I examine the epistemological debate on scientific realism in the context of quantum physics, focusing on the empirical underdetermin ation of different formulations and interpretations of QM. I will argue that much of the interpretational, metaphysical work on QM tran scends the kinds of realist commitments that are wellmotivated in the light of the history of science. I sketch a way of demarcating empirically wellconfirmed aspects of QM from speculative quantum metaphysics in a way that coheres with antirealist evidence from (...) 

`Quantum theory' is not a single physical theory but a framework in which many different concrete theories fit. As such, a solution to the quantum measurement problem ought to provide a recipe to interpret each such concrete theory, in a mutually consistent way. But with the exception of the Everett interpretation, the mainextant solutions either try to make sense of the abstract framework as if it were concrete, or else interpret one particular quantum theory under the fiction that it is (...) 

I provide a fairly systematic analysis of when quantities that are variant under a dynamical symmetry transformation should be regarded as unobservable, or redundant, or unreal; of when models related by a dynamical symmetry transformation represent the same state of affairs; and of when mathematical structure that is variant under a dynamical symmetry transformation should be regarded as surplus. In most of these cases the answer is `it depends': depends, that is, on the details of the symmetry in question. A (...) 

In this paper I review three different positions on the wave function, namely: nomological realism, dispositionalism, and configuration space realism by regarding as essential their capacity to account for the world of our experience. I conclude that the first two positions are committed to regard the wave function as an abstract entity. The third position will be shown to be a merely speculative attempt to derive a primitive ontology from a reified mathematical space. Without entering any discussion about nominalism, I (...) 

What is the quantum state of the universe? Although there have been several interesting suggestions, the question remains open. In this paper, I consider a natural choice for the universal quantum state arising from the Past Hypothesis, a boundary condition that accounts for the timeasymmetry of the universe. The natural choice is given not by a wave function but by a density matrix. I begin by classifying quantum theories into two types: theories with a fundamental wave function and theories with (...) 

The objective of this thesis is to present a naturalised metaphysics of information, or to naturalise information, by way of deploying a scientiﬁc metaphysics according to which contingency is privileged and apriori conceptual analysis is excluded (or at least greatly diminished) in favour of contingent and defeasible metaphysics. The ontology of information is established according to the premises and mandate of the scientiﬁc metaphysics by inference to the best explanation, and in accordance with the idea that the primacy of physics (...) 

*A shortened version of this paper will appear in Current Controversies in Philosophy of Science, Dasgupta and Weslake, eds. Routledge.* This paper describes the case that can be made for a highdimensional ontology in quantum mechanics based on the virtues of avoiding both nonseparability and non locality. 

The main claim of the paper is that one can be ‘realist’ (in some sense) about quantum mechanics without requiring any form of realism about the wave function. We begin by discussing various forms of realism about the wave function, namely Albert’s configurationspace realism, Dürr Zanghi and Goldstein’s nomological realism about Ψ, Esfeld’s dispositional reading of Ψ Pusey Barrett and Rudolph’s realism about the quantum state. By discussing the articulation of these four positions, and their interrelation, we conclude that instrumentalism (...) 

In this paper I investigate, within the framework of realistic interpretations of the wave function in nonrelativistic quantum mechanics, the mathematical and physical nature of the wave function. I argue against the view that mathematically the wave function is a twocomponent scalar field on configuration space. First, I review how this view makes quantum mechanics non Galilei invariant and yields the wrong classical limit. Moreover, I argue that interpreting the wave function as a ray, in agreement many physicists, Galilei invariance (...) 

We critically examine the role and status probabilities, as they enter via the Quantum Equilibrium Hypothesis, play in the standard, deterministic interpretation of deBroglie’s and Bohm’s Pilot Wave Theory (dBBT), by considering interpretations of probabilities in terms of ignorance, typicality and Humean Best Systems, respectively. We argue that there is an inherent conflict between dBBT and probabilities, thus construed. The conflict originates in dBBT’s deterministic nature, rooted in the Guidance Equation. Inquiring into the latter’s role within dBBT, we find it (...) 

In this paper I wish to connect the recent debate in the philosophy of quantum mechanics concerning the nature of the wave function to the historical debate in the philosophy of science regarding the tenability of scientific realism. Being realist about quantum mechanics is particularly challenging when focusing on the wave function. According to the wave function ontology approach, the wave function is a concrete physical entity. In contrast, according to an alternative viewpoint, namely the primitive ontology approach, the wave (...) 

In the first part of the paper I argue that an ontology of events is precise, flexible and general enough so as to cover the three main alternative formulations of quantum mechanics as well as theories advocating an antirealistic view of the wave function. Since these formulations advocate a primitive ontology of entities living in fourdimensional spacetime, they are good candidates to connect that quantum image with the manifest image of the world. However, to the extent that some form of (...) 

The problem of the 3N dimensions of the wave function is of particular interest in the philosophy of physics. In this work, we will recall the main positions about the nature and dimensionality of the wave function and we will introduce a new perspective, coming from quantum chemistry. For this, we will bring to light the formal operations that underlie the independent electron approximation. On this basis, we will point out how quantum chemistry can offer new arguments that contribute to (...) 

In this paper, I introduce an intrinsic account of the quantum state. This account contains three desirable features that the standard platonistic account lacks: (1) it does not refer to any abstract mathematical objects such as complex numbers, (2) it is independent of the usual arbitrary conventions in the wave function representation, and (3) it explains why the quantum state has its amplitude and phase degrees of freedom. / Consequently, this account extends Hartry Field’s program outlined in Science Without Numbers (...) 

Quantum theory plays an increasingly significant role in contemporary earlyuniverse cosmology, most notably in the inflationary origins of the fluctuation spectrum of the microwave background radiation. I consider the two main strategies for interpreting standard quantum mechanics in the light of cosmology. I argue that the conceptual difficulties of the approaches based around an irreducible role for measurement  already very severe  become intolerable in a cosmological context, whereas the approach based around Everett's original idea of treating quantum systems (...) 

I argue that wavefunction realism  the view that quantum mechanics reveals the fundamental ontology of the world to be a field on a highdimensional spacetime, must be rejected as relying on artefacts of toosimple versions of quantum mechanics, and not conceptually wellmotivated even were those toosimple versions exactly correct. I end with some brief comments on the role of spacetime in any satisfactory account of the metaphysics of extant quantum theories. 

In this chapter, I will discuss what it takes for a dynamical collapse theory to provide a reasonable description of the actual world. I will start with discussions of what is required, in general, of the ontology of a physical theory, and then apply it to the quantum case. One issue of interest is whether a collapse theory can be a quantum state monist theory, adding nothing to the quantum state and changing only its dynamics. Although this was one of (...) 

In his recent book Bananaworld. Quantum mechanics for primates, Jeff Bub revives and provides a mature version of his influential informationtheoretic interpretation of Quantum Theory (QT). In this paper, I test Bub’s conjecture that QT should be interpreted as a theory about information, by examining whether his informationtheoretic interpretation has the resources to explain (or explain away) quantum conundrums. The discussion of Bub’s theses will also serve to investigate, more in general, whether other approaches succeed in defending the claim that (...) 

The wave function in quantum mechanics presents an interesting challenge to our understanding of the physical world. In this paper, I show that the wave function can be understood as four intrinsic relations on physical space. My account has three desirable features that the standard account lacks: it does not refer to any abstract mathematical objects, it is free from the usual arbitrary conventions, and it explains why the wave function has its gauge degrees of freedom, something that are usually (...) 



We use the primitive ontology framework of Allori et al. to analyze the quantum informationtheoretic interpretation of Bub and Pitowsky. There are interesting parallels between the two approaches, which differentiate them both from the more standard realist interpretations of quantum theory. Where they differ, however, is in terms of their commitments to an underlying ontology on which the manifest image of the world supervenes. Employing the primitive ontology framework in this way makes perspicuous the differences between the quantum informationtheoretic interpretation, (...) 

Quantum mechanics has always been regarded as, at best, puzzling, if not contradictory. The aim of the paper is to explore a particular approach to fundamental physical theories, the one based on the notion of primitive ontology. This approach, when applied to quantum mechanics, makes it a paradoxfree theory. 