I argue that wavefunction realism --- the view that quantum mechanics reveals the fundamental ontology of the world to be a field on a high-dimensional spacetime, must be rejected as relying on artefacts of too-simple versions of quantum mechanics, and not conceptually well-motivated even were those too-simple 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.

It is common ground among proponents and detractors of wavefunction realism that the view ‘privileges position’, in the sense that it arbitrarily singles out one among a continuum infinity of wavefunction representations as characterizing the fundamental field: the position representation. This paper shows that, properly understood, wavefunction realism does not involve such an arbitrary choice. First, I argue that, though each wavefunction representation gives rise to a different version of wavefunction realism, the (...) difference between these theories amounts to a mere haecceitistic difference. Second, I argue that wavefunction realists should reconceive of their view as a role-based thesis that is silent about the relevant haecceitistic differences. (shrink)

Traditionally Ψ is used to stand in for both the mathematical wavefunction (the representation) and the quantum state (the thing in the world). This elision has been elevated to a metaphysical thesis by advocates of the view known as wavefunction realism. My aim in this paper is to challenge the hegemony of the wavefunction by calling attention to a little-known formulation of quantum theory that does not make use of the wavefunction in representing the quantum (...) state. This approach, called Lagrangian quantum hydrodynamics (LQH), is not an approximation scheme, but rather a full alternative formulation of quantum theory. I argue that a careful consideration of alternative formalisms is an essential part of any realist project that attempts to read the ontology of a theory off of the mathematical formalism. In particular, I show that LQH undercuts the central presumption of wavefunction realism and falsifies the claim that one must represent the many-body quantum state as living in a 3n-dimensional configuration space. I conclude by briefly sketching three different realist approaches one could take toward LQH, and argue that both models of the quantum state should be admitted. When exploring quantum realism, regaining sight of the proverbial forest of quantum representations beyond the Ψ is just the first step. (shrink)

Functionalism is the view that being x is to play the role of x. This paper defends a functionalist account of three-dimensional entities in the context of Wave Function Realism (WFR), that can explain in detail how we can recover three-dimensional entities out of the wavefunction. In particular, the essay advocates for a novel version of WFR in terms of a functional reductionist approach in the style of David Lewis. This account entails reduction of the upper entities to (...) the bottom ones, when the latter behave appropriately. As applied to WFR, it shows how the wavefunction can turn out to be identical to three-dimensional objects, provided certain conditions. The first major goal of the paper is thus to put forward an improved and more rigorous version of WFR, which dissolves several extant issues about the theory, and can serve as a starting point for future literature on the topic. Moreover, the second major goal of the article is to take WFR as a case study to demonstrate the pros of functional reductionism, especially in the form defended here, thereby helping to bring this view back in the philosophy of science debate. The positive upshots of this paper suggest a possible application of functional reductionism also to other contexts. (shrink)

Much of the the discussion of the metaphysics of quantum mechanics focusses on the status of wavefunctions. This paper is about how to think about wavefunctions, when we bear in mind that quantum mechanics—that is, the nonrelativistic quantum theory of systems of a fixed, finite number of degrees of freedom—is not a fundamental theory, but arises, in a certain approximation, valid in a limited regime, from a relativistic quantum field theory. We will explicitly show how the wavefunctions of quantum mechanics, (...) and the configuration spaces on which they are defined, are constructed from a relativistic quantum field theory. Two lessons will be drawn from this. The first is that configuration spaces are not fundamental, but rather are derivative of structures defined on ordinary spacetime. The second is that wavefunctions are not as much like classical fields as might first appear, in that, on the most natural way of constructing wavefunctions from quantum field-theoretic quantities, the value assigned to a point in configuration space is not a local fact about that point, but rather, depends on the global state. (shrink)

We propose that the ontic understanding of quantum mechanics can be extended to a fully realistic theory that describes the evolution of the wavefunction at all times, including during a measurement. In such an approach the wave equation should reduce to the standard wave equation when there is no measurement, and describe state reduction when the system is measured. The general wave equation must be nonlinear and nonlocal, and we require it to be time-symmetric; consequently, this approach is not (...) a new interpretation but a new theory. The wave equation is an integrodifferential equation (IDE). The time symmetry requirement leads to a retrocausal approach, in which the wave equation is solved subject to initial and final conditions to determine history at intermediate times. We propose that different outcomes from (apparently) identically prepared experiments may result from uncontrolled parameters; both the nonlocality and the retrocausality of the theory imply that Bell’s Theorem cannot rule out such “hidden variables.” Beginning with Hamilton’s principle, we demonstrate the construction of such a theory by replacing the action with a functional designed to give rise to a nonlinear, nonlocal IDE as the wave equation. This IDE reduces to the standard wave equation (a differential equation) in the absence of a measurement, but exhibits state reduction to a single eigenvalue when the system interacts with another system with the properties of a measurement apparatus. We demonstrate several desirable features of this theory; for other properties we indicate their plausibility and possible avenues to a proof. (shrink)

It has been shown that quantum mechanics in its orthodox interpretation violates four different formulations of causality principle endowed with empirical meaning. The present work aims to highlight how even a realistic non-standard interpretation of the theory conflicts with causality in its Cartesian formulation of the principle of the non-inferiority of causes over effects. Such an interpretation, which attributes some form of weak physical reality to the wave function (called empty wave, regarded as a zero-energy wave-like phenomenon), is a sort (...) of precursor of the more recent so-called wavefunction realism. We also discuss a more radical realistic interpretation according to which physical properties can also be assigned to non-metaphysical relative nothing, seen as the simple absence of a particle such as a photon, but not of its corresponding state (no-photon), which is considered real. By interpreting the wave function collapse as a consequence of an interaction with empty waves or of a detection of the no-photon, we will highlight how more real physical effects can derive from lower causes, including relative nothing. Finally, we will show how these interpretations, while violating Cartesian causality in its two variants, do not seem to affect the validity of the principle of a rational explanation that nothing can derive from (absolute) nothing, which does not seem satisfied by the orthodox interpretation. (shrink)

Carnap's conception of linguistic frameworks is widespread; however, it is not entirely clear nor consensual to pinpoint what is the influence of his stance within the traditional realist/anti-realist debate. In this paper, we place Carnap as a proponent of a scientific realist stance, by presenting what he called “linguistic realism”. Some possible criticisms are considered, and a case study is offered with wave function realism, a popular position in the philosophy of quantum mechanics.

I look at the distinction between between realist and antirealist views of the quantum state. I argue that this binary classification should be reconceived as a continuum of different views about which properties of the quantum state are representationally significant. What's more, the extreme cases -- all or none --- are simply absurd, and should be rejected by all parties. In other words, no sane person should advocate extreme realism or antirealism about the quantum state. And if we focus (...) on the reasonable views, it's no longer clear who counts as a realist, and who counts as an antirealist. Among those taking a more reasonable intermediate view, we find figures such as Bohr and Carnap -- in stark opposition to the stories we've been told. (shrink)

Molecular structure is one of the dispositional attributes of the molecule and counted as an example of affordances. This attribute has been systematically exploited through the development of theories and practice of organic chemistry. (Ochiai 2023, pp. 141–149) The question to be addressed in this study is whether we can legitimately claim that this type of attribute is real. To answer the question, we first clarify what is worthy of the word ‘reality’ in scientific arguments. Whitehead claims that a physical (...) substance like electron is a bundle of spatial-temporal experience. (Mesle 2008, p. 36) The contention is that we cognize the causal relationships of the physical world through the experience of events. What we cognize as real is not unchanging matter but various kinds of events we experience. Based on this recognition we examine the nature of affordances. Affordances are the context-relative dispositional attributes of {agent-world} complexes. (Harré 2014, pp. 77–91; Harré and Llored 2018, pp. 167–186) The affordance of a knife becomes actualized through our experience of cutting. In this way affordances are concerned with work or the function of something useful. They are materialized as tools. This suggests that affordances are real, and so is molecular structure. Molecular structure is characterized by a certain function which molecules show in organic synthesis. Other dispositional attributes of molecules that become actualized in the context of organic chemistry are also examined. We refer to the physical significance of wavefunctions as well, which we discussed in the previous study. (Ochiai 2023, pp. 359–367) Creating function, we expand a world we cognize as real. This view of the world we name ‘functional realism.’ Our conceptual scheme is supported by Quine’s holism. (shrink)

Different realistic attitudes towards wavefunctions and quantum states are as old as quantum theory itself. Recently Pusey, Barret and Rudolph on the one hand, and Auletta and Tarozzi on the other, have proposed new interesting arguments in favor of a broad realistic interpretation of quantum mechanics that can be considered the modern heir to some views held by the fathers of quantum theory. In this paper we give a new and detailed presentation of such arguments, propose a new taxonomy of (...) different realistic positions in the foundations of quantum mechanics and assess the scope, within this new taxonomy, of these realistic arguments. (shrink)

Foundational attitudes towards quantum theory have recently thrown off much of the old philosophical baggage largely associated with Niels Bohr to which Einstein famously objected, including the central ‘collapse of the wavefunction’ concept. A ‘neo-Copenhagen’ interpretation, it is suggested, has arisen. This development is placed in its historical context and contrasted to philosophical allegations of anti-realism. The neo-Copenhagen interpretation remains wedded to Heisenberg's uncertainty and observer-dependent values of particles. However a discussion of Nick Herbert's ‘rainbow analogy’ suggests that (...) subatomic particles are emergent from a ‘nonlocal’ level of reality outside the domain of space and time. Critical realism recognizes that emergent systems have an irreducibly ontologically character, and in its combination of epistemological relativism and ontological realism, provides a basis for the proposition that realists who support Einstein's objections must now recognize that their realism must be redefined. (shrink)

I distinguish between two different ways in which the wavefunction might play a role in explaining the behavior of quantum systems and argue that a satisfactory account of quantum ontology will make it possible for the wavefunction to explain the behavior of quantum systems in both of these way. I then show how this constraint has the potential to impact two quite different accounts of quantum ontology.

The information-theoretic approach to quantum mechanics, proposed by Bub and Pitowsky, is a realist approach to quantum theory which rejects the “two dogmas” of quantum mechanics: in this theory measurement results are not analysed in terms of something more fundamental, and the quantum state does not represent physical entities. Bub and Pitowsky’s approach has been criticized because their rejection of the first dogma relies on their argument that kinematic explanations are more satisfactory than dynamical ones. However, little attention has been (...) given to the second dogma. If anything, some have discussed the difficulties the informational-theoretical interpretation faces in making sense of the quantum state as epistemic. The aim of this paper is twofold. First, I argue that a realist should reject the second dogma without relying on the alleged explanatory superiority of kinematic explanation over dynamical ones, thereby providing Bub and Pitowsky with a way to avoid the first set of objections to their view. Then I propose a functionalist account of the wavefunction as a non-material entity which does not fall prey of the objections to the epistemic account or the other non-material accounts such as the nomological view, and therefore I supply the proponents of the information-theoretical interpretation with a new tool to overcome the second set of criticisms. (shrink)

Prime matter plays an indispensable role in Aristotle’s philosophy, enabling him to avoid the pitfalls of both naïve Platonism and nominalism. Prime matter is best thought of as a kind of infinitely divisible and atomless bare particularity, grounding the distinctness of distinct members of the same species. Such bare particularity is needed in symmetrical situations, like a world consisting of indistinguishable Max Black spheres. Bare particularity is especially important in modern physics, given the homogeneity and isotropy of space. With the (...) importance of fields in classical, relativistic, and quantum physics, we have good reason to prefer something like Aristotle’s continuous, infinitely divisible matter over indivisible particles. Mass and energy in relativistic physics also points in the direction of prime matter as the enduring substrate of these quantities. Recent work on Aristotelian interpretations of quantum mechanics, further underscores the contemporary relevance of prime matter. (shrink)

When discussing quantum ontology, the debate has recently focused on comparing and contrasting wavefunction realism and its rivals. Among them one finds the primitive ontology approach, which is often conflated with the local beables program. In this paper I wish to clarify what I take to be the distinction between the notion of primitive ontology and the one of local beable. I argue that the primitive ontology is the local beable which allows for a dynamical, constructive explanation which (...) preserves symmetries. (shrink)

Quantum entanglement has long been thought to be have deep metaphysical consequences. For example, it has been claimed to show that Humean supervenience is false or to involve a novel form of ontological holism. One way to avoid confronting the metaphysical consequences is to adopt some form of antirealism. In this paper we discuss two prominent strands in recent literature—wavefunction realism and “Super-Humeanism”—that appear quite different, but, as we see it, are instances of a more general strategy. In (...) effect, what these attempt to do is to diffuse the puzzle of entanglement by eliminating it. These interpretative movements are advertised as equally realist, but, we claim, fail to take an appropriately realist attitude towards entanglement. What we advocate instead is a genuine metaphysics of entanglement: instead of eliminating entanglement, develop a metaphysics that accounts for and explains it. (shrink)

Monism is roughly the view that there is only one fundamental entity. One of the most powerful argument in its favor comes from quantum mechanics. Extant discussions of quantum monism are framed independently of any interpretation of the quantum theory. In contrast, this paper argues that matters of interpretation play a crucial role when assessing the viability of monism in the quantum realm. I consider four different interpretations: modal interpretations, Bohmian mechanics, many worlds interpretations, and wavefunction realism. In (...) particular, I extensively argue for the following claim: several interpretations of QM do not support monism at a more serious scrutiny, or do so only with further problematic assumptions, or even support different versions of it. (shrink)

This paper investigates the tenability of wavefunction realism, according to which the quantum mechanical wavefunction is not just a convenient predictive tool, but is a real entity figuring in physical explanations of our measurement results. An apparent difficulty with this position is that the wavefunction exists in a many-dimensional configuration space, whereas the world appears to us to be three-dimensional. I consider the arguments that have been given for and against the tenability of wavefunction (...) class='Hi'>realism, and note that both the proponents and the opponents assume that quantum mechanical configuration space is many-dimensional in exactly the same sense in which classical space is three-dimensional. I argue that this assumption is mistaken, and that configuration space can be taken as three-dimensional in a relevant sense. I conclude that wavefunction realism is far less problematic than it has been taken to be. Introduction Non-separability The instantaneous solution The dynamical solution Invariance What is configuration space, anyway? Conclusion. (shrink)

Among the various proposals for quantum ontology, both wavefunction realists and the primitive ontologists have argued that their approach is to be preferred because it relies on intuitive notions: locality, separability and spatiotemporality. As such, these proposals should be seen as normative frameworks asserting that one should choose the fundamental ontology which preserves these intuitions, even if they disagree about their relative importance: wavefunction realists favor preserving locality and separability, while primitive ontologists advocate for spatiotemporality. In this paper, (...) first I clarify the main tenets of wavefunction realism and the primitive ontology approach, arguing that seeing the latter as favoring constructive explanation makes sense of their requirement of a spatiotemporal ontology. Then I show how the aforementioned intuitive notions cannot all be kept in the quantum domain. Consequently, wavefunction realists rank locality and separability higher than spatiotemporality, while primitive ontologists do the opposite. I conclude that however, the choice of which notions to favor is not as arbitrary as it might seem. In fact, they are not independent: requiring locality and separability can soundly be justified by requiring spatiotemporality, and not the other way around. If so, the primitive ontology approach has a better justification of its intuitions than its rival wavefunction realist framework. (shrink)

Many discussions in the metaphysics and philosophy of physics literature aim to use physics as a guide to elucidate what the world really, fundamentally is like. However, we don’t yet have a confirmed fundamental theory of physics—what’s the next best thing we can possibly say about the fundamental that is properly informed by our best theories of physics? This paper offers a starting point to address this question. It focuses on the literature on the ontology of quantum mechanics, where the (...) problem is especially salient: Many proposals aim at drawing the fundamental ontology of the world from quantum mechanics, even though they often focus on a non-fundamental theory such as nonrelativistic quantum particle mechanics. I argue that quantum mechanics can plausibly be informative about the fundamental if it is taken as a general framework theory, which covers a range of specific concrete theories, including nonrelativistic quantum particle mechanics, the Standard Model of particle physics, and string theory. I use Wavefunction Realism as an example to demonstrate what kind of ontological lessons about the world at the fundamental level the quantum framework may teach us. (shrink)

According to the high-dimensional approach to quantum mechanics (a.k.a. wavefunction realism), the fundamental space of our world has an unfathomably large number of dimensions. This account is empirically adequate only if the three-dimensional manifest image can somehow be recovered from high-dimensional reality. A proper understanding of inter-level metaphysics (a.k.a. metaphysical explanation, grounding, etc.) shows that the manifest image can indeed be recovered, and answers the most concerning objections to high-dimensionalism. But it also shows that high-dimensionalism has disturbing consequences (...) about the objectivity of the manifest image. (shrink)

Many agree that the pilot-wave theory is to be understood as a first-order theory, in which the law constrains the velocity of the particles. However, while Dürr, Goldstein and Zanghì maintain that the pilot-wave theory is Galilei invariant, Valentini argues that such a symmetry is mathematical but it has no physical significance. Moreover, some wavefunction realists insist that the pilot-wave theory is not Galilei invariant in any sense. It has been maintained by some that this disagreement originates in the (...) disagreement about ontology, as Valentini, contrary to Dürr, Goldstein and Zanghì, has been taken to endorse wavefunction realism. In this paper I argue that Valentini’s argument is independent of the choice of the ontology of matter: it is based of the notion of natural kinematics for a theory, and the idea that the kinematics should match the dynamics. If so, I also argue that there are several reasons to dispute Valentini’s claim that the kinematical symmetries should constrain dynamical ones. (shrink)

The apparent nonlocality of quantum theory has been a persistent concern. Einstein et al. and Bell emphasized the apparent nonlocality arising from entanglement correlations. While some interpretations embrace this nonlocality, modern variations of the Everett-inspired many worlds interpretation try to circumvent it. In this paper, we review Bell's "no-go" theorem and explain how it rests on three axioms, local causality, no superdeterminism, and one world. Although Bell is often taken to have shown that local causality is ruled out by the (...) experimentally confirmed entanglement correlations, we make clear that it is the conjunction of the three axioms that is ruled out by these correlations. We then show that by assuming local causality and no superdeterminism, we can give a direct proof of many worlds. The remainder of the paper searches for a consistent, local, formulation of many worlds. We show that prominent formulations whose ontology is given by the wave function violate local causality, and we critically evaluate claims in the literature to the contrary. We ultimately identify a local many worlds interpretation that replaces the wave function with a separable Lorentz-invariant wave-field. We conclude with discussions of the Born rule, and other interpretations of quantum mechanics. (shrink)

This paper argues for a broadly dispositionalist approach to the ontology of Bohmian mechanics . It first distinguishes the ‘minimal’ and the ‘causal’ versions of Bohm’s theory, and then briefly reviews some of the claims advanced on behalf of the ‘causal’ version by its proponents. A number of ontological or interpretive accounts of the wave function in BM are then addressed in detail, including configuration space, multi-field, nomological, and dispositional approaches. The main objection to each account is reviewed, namely the (...) ‘problem of perception’, the ‘problem of communication’, the ‘problem of temporal laws’, and the ‘problem of under-determination’. It is then shown that a version of dispositionalism overcomes the under-determination problem while providing neat solutions to the other three problems. A pragmatic argument is thus furnished for the use of dispositions in the interpretation of the theory more generally. The paper ends in a more speculative note by suggesting ways in which a dispositionalist interpretation of the wave function is in addition able to shed light upon some of the claims of the proponents of the causal version of BM. (shrink)

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. (shrink)

This paper presents a new modified quantum mechanics, Critical Complexity Quantum Mechanics, which includes a new account of wavefunction collapse. This modified quantum mechanics is shown to arise naturally from a fully discrete physics, where all physical quantities are discrete rather than continuous. I compare this theory with the spontaneous collapse theories of Ghirardi, Rimini, Weber and Pearle and discuss some implications of these theories and CCQM for a realist view of the quantum realm.

QBism is one of the main candidates for an epistemic interpretation of quantum mechanics. According to QBism, the quantum state or the wavefunction represents the subjective degrees of belief of the agent assigning the state. But, although the quantum state is not part of the furniture of the world, quantum mechanics grasps the real via the Born rule which is a consistency condition for the probability assignments of the agent. In this paper, we evaluate the plausibility of recent criticism (...) of QBism. We focus on the consequences of the subjective character of the quantum state, the issue of realism and the problem of the evolution of the quantum state in QBism. In particular, drawing upon Born’s notion of invariance as the mark of the real, it is argued that there is no essential difference between Einstein’s program of ‘the real’ and QBists’ realism. Also, it will be argued that QBism can account for the unitary evolution of the quantum state. (shrink)

In this article I examine several related views expressed by Robin Hendry concerning molecular structure, emergence and chemical bonding. There is a long-standing problem in the philosophy of chemistry arising from the fact that molecular structure cannot be strictly derived from quantum mechanics. Two or more compounds which share a molecular formula, but which differ with respect to their structures, have identical Hamiltonian operators within the quantum mechanical formalism. As a consequence, the properties of all such isomers yield precisely the (...) same calculated quantities such as their energies, dipole moments etc. The only means through which the difference between the isomers can be recovered is to build their structures into the quantum mechanical calculations, something that is carried out by the application of the Born-Oppenheimer approximation. Consequently, it has been argued by many authors that molecular structure is written in ‘by hand’ rather than derived. Robin Hendry is one such author, but he goes a great deal further by proposing that this situation implies the existence of emergence and downward causation. In the current article I argue that there are alternative explanations which render emergence and downward causation redundant. Such an alternative lies in the notion of quantum decoherence and the appeal to work in the foundations of physics, which posits that the various isomers exist as a superposition until their wavefunctions are collapsed either by observation or by interacting with their environment.Hendry also alludes to a debate among chemists as to whether chemical bonds are real or not, in the sense of directional connections between two or more nuclei in any given molecule. I reject this view and propose that the structural and energetic views of chemical bonding, that have been discussed by some philosophers of chemistry including Hendry, do not refer to any essential ontological differences. I agree that chemists view bonding in a more realistic fashion and may consider bonds to be in some senses real, while physicists may consider bonding in more abstract energetic terms. However, I do not believe that such differences in scientific practice and attitudes should be considered to offer a window as to the ontological status of bonding or whether bonding is real. Finally, I discuss the kinetic energy school of chemical bonding which would seem to challenge any notion of bonds as directional entities, since bonding is no longer regarded as being primarily due to the build-up of electron density between nuclei. (shrink)

Of the many ways of getting at the core of the weirdnesses in quantum mechanics, there’s one which traces back to Schrödinger’s seminal 1935 paper, and has to do with the apparent fuzzy nature of the reality described by the formalism through the wavefunction $$\psi$$ ψ. This issue, which I will be calling the Determinacy Problem, is distinct from the standard measurement problem of quantum mechanics, despite Schrödinger himself ends up conflating the two. I will argue that the Determinacy (...) Problem is an exquisitely philosophical problem, for as it is standard when facing any phenomenon which appears to have indeterminate or fuzzy characteristics, the solutions available are to either blame the deficiencies of our language, or our lack of knowledge, or to blame the world itself. These three attitudes can already be found in the literature on quantum mechanics, either explicitly or implicitly, and they appear to motivate three very distinct research programs: high-dimensional realism, primitive ontology, and quantum indeterminacy. (shrink)

Computationalism provides a framework for understanding how a mathematically describable physical world could give rise to conscious observations without the need for dualism. A criterion is proposed for the implementation of computations by physical systems, which has been a problem for computationalism. Together with an independence criterion for implementations this would allow, in principle, prediction of probabilities for various observations based on counting implementations. Applied to quantum mechanics, this results in a Many Computations Interpretation (MCI), which is an explicit form (...) of the Everett style Many Worlds Interpretation (MWI). Derivation of the Born Rule emerges as the central problem for most realist interpretations of quantum mechanics. If the Born Rule is derived based on computationalism and the wavefunction it would provide strong support for the MWI; but if the Born Rule is shown not to follow from these to an experimentally falsified extent, it would indicate the necessity for either new physics or (more radically) new philosophy of mind. (shrink)

In this article I examine several related views expressed by Robin Hendry concerning molecular structure, emergence and chemical bonding. There is a long-standing problem in the philosophy of chemistry arising from the fact that molecular structure cannot be strictly derived from quantum mechanics. Two or more compounds which share a molecular formula, but which differ with respect to their structures, have identical Hamiltonian operators within the quantum mechanical formalism. As a consequence, the properties of all such isomers yield precisely the (...) same calculated quantities such as their energies, dipole moments etc. The only means through which the difference between the isomers can be recovered is to build their structures into the quantum mechanical calculations, something that is carried out by the application of the Born-Oppenheimer approximation. Consequently, it has been argued by many authors that molecular structure is written in ‘by hand’ rather than derived. Robin Hendry is one such author, but he goes a great deal further by proposing that this situation implies the existence of emergence and downward causation. In the current article I argue that there are alternative explanations which render emergence and downward causation redundant. Such an alternative lies in the notion of quantum decoherence and the appeal to work in the foundations of physics, which posits that the various isomers exist as a superposition until their wavefunctions are collapsed either by observation or by interacting with their environment. Hendry also alludes to a debate among chemists as to whether chemical bonds are real or not, in the sense of directional connections between two or more nuclei in any given molecule. I reject this view and propose that the structural and energetic views of chemical bonding, that have been discussed by some philosophers of chemistry including Hendry, do not refer to any essential ontological differences. I agree that chemists view bonding in a more realistic fashion and may consider bonds to be in some senses real, while physicists may consider bonding in more abstract energetic terms. However, I do not believe that such differences in scientific practice and attitudes should be considered to offer a window as to the ontological status of bonding or whether bonding is real. Finally, I discuss the kinetic energy school of chemical bonding which would seem to challenge any notion of bonds as directional entities, since bonding is no longer regarded as being primarily due to the build-up of electron density between nuclei. (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? 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)

Roderich Tumulka’s GRWf theory offers a simple, realist and relativistic solution to the measurement problem of quantum mechanics. It is achieved by the introduction of a stochastic dynamical collapse of the wavefunction. An issue with dynamical collapse theories is that they involve an amendment to the Schrodinger equation; amending the dynamics of such a tried and tested theory is seen by some as problematic. This paper proposes an alteration to GRWf that avoids the need to amend the Schrodinger equation (...) via what might be seen as a primary set of solutions to the Schrodinger equation that satisfy a normalisation condition over space and time. The traditional Born-normalised solutions are shown to be conditionalisations of these primary solutions. (shrink)