Abstract. After some suggestions about how to clarify the confused metaphysical distinctions between dispositional and non-dispositional or categorical properties, I review some of the main interpretations of QM in order to show that – with the relevant exception of Bohm’s minimalist interpretation – quantum ontology is irreducibly dispositional. Such an irreducible character of dispositions must be explained differently in different interpretations, but the reducibility of the contextual properties in the case of Bohmian mechanics is guaranteed by the fact that the positions of particles play the role of the categorical basis, a role that in other interpretations cannot be filled by anything else. In Bohr’s and Everett-type interpretations, dispositionalism is instrumentalism in disguise.
Abstract. After some suggestions about how to clarify the confused metaphysical distinctions between dispositional and non-dispositional or categorical properties, I review some of the main interpretations of QM in order to show that – with the relevant exception of Bohm’s minimalist interpretation – quantum ontology is irreducibly dispositional. Such an irreducible character of dispositions must be explained differently in different interpretations, but the reducibility of the contextual properties in the case of Bohmian mechanics is guaranteed by the fact that the positions of particles play the role of the categorical basis, a role that in other interpretations cannot be filled by anything else. In Bohr’s and Everett-type interpretations, dispositionalism is instrumentalism in disguise.
The paper points out that the modern formulation of Bohm's quantum theory known as Bohmian mechanics is committed only to particles' positions and a law of motion. We explain how this view can avoid the open questions that the traditional view faces according to which Bohm's theory is committed to a wave-function that is a physical entity over and above the particles, although it is defined on configuration space instead of three-dimensional space. We then enquire into the status of the law of motion, elaborating on how the main philosophical options to ground a law of motion, namely Humeanism and dispositionalism, can be applied to Bohmian mechanics. In conclusion, we sketch out how these options apply to primitive ontology approaches to quantum mechanics in general.
The article sets out a primitive ontology of the natural world in terms of primitive stuff—that is, stuff that has as such no physical properties at all—but that is not a bare substratum either, being individuated by metrical relations. We focus on quantum physics and employ identity-based Bohmian mechanics to illustrate this view, but point out that it applies all over physics. Properties then enter into the picture exclusively through the role that they play for the dynamics of the primitive stuff. We show that such properties can be local (classical mechanics), as well as holistic (quantum mechanics), and discuss two metaphysical options to conceive them, namely, Humeanism and modal realism in the guise of dispositionalism.
The article sets out a primitive ontology of the natural world in terms of primitive stuff—that is, stuff that has as such no physical properties at all—but that is not a bare substratum either, being individuated by metrical relations. We focus on quantum physics and employ identity-based Bohmian mechanics to illustrate this view, but point out that it applies all over physics. Properties then enter into the picture exclusively through the role that they play for the dynamics of the primitive stuff. We show that such properties can be local (classical mechanics), as well as holistic (quantum mechanics), and discuss two metaphysical options to conceive them, namely, Humeanism and modal realism in the guise of dispositionalism.
Given the controversial status of the various interpretations of non-relativistic quantum mechanics (QM for short), it may seem crazy to use the philosophy of quantum physics to try to learn some lessons about the prevailing problems in the literature on dispositions and causal powers. However, such an attempt seems worthwhile for at least three reasons. The first is more internal to the philosophy of QM. Apart from a seminal paper by Robert Clifton and Constantine Pagonis (1995), who investigated the issue of dispositional properties in Bohmian mechanics, very little has been done to shed This neglect seems particularly surprising, especially if one considers that some of the founding fathers of quantum physics, notably Werner Heisenberg, have made direct reference to Aristotelian potentiae to refer to and interpret the elusive nature of the atomic and subatomic world ‘in se’, that is, before measurement: ‘Such a probability function [i.e. the statistical algorithm of quantum theory] combines objective and subjective elements. It contains statements on possibilities, or better tendencies (“potentiae” in Aristotelian philosophy), and such statements are completely objective, they don’t depend on any observer the passage from the “possible” to the Some years before, Henry Margenau3 had already characterized the properties of quantum systems as merely latent, in contrast to the properties intervening in the description of classical systems, which are always definite even when they are merely dispositional. Similarly, Karl Popper4 and Nicholas Maxwell5 have defended some sort of a propensity interpretation of probability, and a view of quantum reality essentially characterized by irreducibly probabilistic propensities. Influenced by this tradition, Michael Redhead’s influential textbook on the philosophy of QM distinguishes among three different interpretations of the theory, the second of which presupposes real propensities and potentialities and attributes to measurements the function of ‘converting latent values in possessed values’.6 Clearly, for this second interpretation to make less than an instrumentalistic sense, one needs to construe potentialities and dispositions as real properties of systems. Consequently, it seems important to try to get a firmer grasp of the sense in which QM might need irreducible dispositions to shed light on the nature of the properties of quantum systems before measurements, in particular when the state of such systems is not an eigenstate of the relevant physical observable.
The article points out that the modern formulation of Bohm’s quantum theory, known as Bohmian mechanics, is committed only to particles’ positions and a law of motion. We explain how this view can avoid the open questions that the traditional view faces, according to which Bohm’s theory is committed to a wave-function that is a physical entity over and above the particles, although it is defined on configuration space instead of three-dimensional space. We then enquire into the status of the law of motion, elaborating on how the main philosophical options to ground a law of motion, namely Humeanism and dispositionalism, can be applied to Bohmian mechanics. In conclusion, we sketch out how these options apply to primitive ontology approaches to quantum mechanics in general. 1 Introduction2 What is the Ontological Status of the Wave-Function?3 Humeanism about Laws4 Laws Grounded in Dispositions5 Advantages of Dispositionalism6 Conclusion
Standard quantum mechanics poses serious challenges to some principles deeply entrenched in traditional metaphysics. In particular, the theory defies the ontological category of individual object through three of its features: contextuality, non-separability, and indistinguishability. The difficulties have prompted the development of non-traditional ontological frameworks intended to account for the quantum domain. Some approaches advocate replacing the classical conception of a realm of objects endowed with properties by an ontology that either dispenses with the category of object altogether or treats it as a derivative notion. The Modal-Hamiltonian Interpretation (MHI) of quantum mechanics and Ontic Structural Realism (OSR) exemplify this position. MHI proposes an ontology in which quantum systems are non-objectual bundles of properties linked by definite physical relations. The OSR defends the ontological primacy of structures, within which objects are construed as nodes of relations. The aim of this article is to compare these two ontological approaches, highlighting both their points of convergence and their divergences, particularly in light of the ontological challenges posed by quantum mechanics. With this aim, the article is structured as follows. Section 2 outlines the ontology of MHI, introducing the distinction between type-properties and case-properties, characterizing quantum systems as non-objectual bundles, and analyzing the role of symmetry groups in providing physical content to the theory and governing actualization. Section 3 turns to OSR, examining its motivations, its distinction between physical and mathematical structures, and the modal character of structures. Section 4 offers a systematic comparison of the two approaches, considering their respective motivations and scope, their shared commitment to an object-free ontology, the role played by symmetry groups within each framework, and their contrasting interpretations of modality. Finally, Section 5 presents some concluding remarks.