Abstract Quantum entanglement poses a challenge to the traditional metaphysical view that an extrinsic property of an object is determined by its intrinsic properties. So structural realists might be tempted to cite quantum entanglement as evidence for structural realism. I argue, however, that quantum entanglement undermines structural realism. If we classify two entangled electrons as a single system, we can say that their spin properties are intrinsic properties of the system, and that we can have knowledge about these intrinsic properties. Specifically, we can know that the parts of the system are entangled and spatially separated from each other. In addition, the concept of supervenience neither illuminates quantum entanglement nor helps structural realism.
Abstract Quantum entanglement poses a challenge to the traditional metaphysical view that an extrinsic property of an object is determined by its intrinsic properties. So structural realists might be tempted to cite quantum entanglement as evidence for structural realism. I argue, however, that quantum entanglement undermines structural realism. If we classify two entangled electrons as a single system, we can say that their spin properties are intrinsic properties of the system, and that we can have knowledge about these intrinsic properties. Specifically, we can know that the parts of the system are entangled and spatially separated from each other. In addition, the concept of supervenience neither illuminates quantum entanglement nor helps structural realism.
In this chapter it is argued that the decisive argument against the reducibility of causal relations comes from quantum physics. Bell’s theorem proves that no dynamics based on the local, intrinsic properties of quantum objects can yield the empirical predictions of quantum mechanics. Nonetheless, it is argued that quantum entanglement by no means implies that we have to abandon an ontology of objects in favour of an ontology of structures. All extant proposals for a quantum ontology of matter in spacetime are committed to objects, whose dynamics are determined not by their local, intrinsic properties, but by an holistic property instantiated by all the objects together—a structure that takes all the objects in the universe as its relata. The view set out in this chapter combines ontic structural realism with an ontology of objects that can be conceived as substances.
The paper sides with the primitive ontology approach to quantum physics, as exemplified notably in Bohmian mechanics. It argues that the objects of the primitive ontology of quantum physics are structurally individuated by the spatial relations in which they stand. They neither have a primitive thisness (haecceity) nor intrinsic properties (such as mass or charge), but only stand in spatial relations. These relations make it that they are physical objects. Furthermore, in virtue of these relations, they are individuals, being absolutely discernible. Ontic structural realism thus plays a twofold role in the philosophy of quantum physics: it comes in not only at the level of the dynamics (structures of entanglement), but already at the level of the objects (primitive ontology) that instantiate the structures of entanglement, these objects being individuated by spatial relations.
Abstract In quantum mechanics, entangled states are not exotic or rare. Rather, entanglement is the norm and so the metaphysical consequences of entanglement are a central issue for anyone wishing to provide an ontological interpretation of the various formulations of quantum mechanics. This chapter presents the argument for wave function realism from quantum entanglement, which says that wave function realism is necessary if one wants an ontological interpretation that does not conflate distinct quantum states. It explains quantum entanglement and how postulating a wave function in higher dimensions can help to metaphysically ground the phenomenon. The chapter ultimately concludes that the argument from quantum entanglement fails as there are several rival positions that can also explain quantum entanglement and recover the distinctions between different entangled states. These include the primitive ontology approach, various other holisms, ontic structural realism, spacetime state realism, and the multi-field approach.
As far as classical physics is concerned, it is possible to trace causal relations between physical objects (i.e. particles in this case) back to intrinsic properties of these objects (such as their mass and charge). On this view, causal relations turn out to be internal instead of external relations, supervening on intrinsic properties of the relata (as proposed by Heil and Lowe). However, one can raise doubts about this view already in Newtonian mechanics. The decisive blow to this view comes from quantum physics, with Bell’s theorem proving that no dynamics based on local, intrinsic properties of quantum objects can yield the empirical predictions of quantum mechanics. Nonetheless, quantum entanglement by no means implies that we have to abandon an ontology of objects (i.e. substances such as particles) in favour of an ontology of structures (as claimed by French and Ladyman). Any of the known proposals for a quantum ontology of matter in space-time is committed to objects. However, on any of these proposals, what determines the dynamics of these objects are not local, intrinsic properties, but a global or holistic property instantiated by all the objects together – that is, a structure that takes all the objects in the universe as its relata. The view set out in this paper thus amounts to combining ontic structural realism with an ontology of objects that can be conceived as substances. This suggestion is illustrated by drawing on the ontology of quantum physics worked out by Bohm and Bell. 1.
The paper attempts to convince that the orthodox interpretation of quantum mechanics does not contradict philosophical realism by throwing light onto certain properties of quantum systems that seem to have escaped attention as yet. The exposition starts with the philosophical notions of realism. Then, the quantum mechanics as it is usually taught is demoted to a mere part of the theory called phenomenology of observations, and the common impression about its contradiction to realism is explained. The main idea of the paper, the physical notion of intrinsic properties, is introduced and many examples thereof are given. It replaces the irritating dichotomy of quantum and classical worlds by a much softer difference between intrinsic and extrinsic properties, which concern equally microscopic and macroscopic systems. Finally, the classicality and the quantum measurement are analyzed and found to present some still unsolved problems. A possible way of dealing with the Schrödinger cat is suggested that is based on the intrinsic properties. A simple quantum model of one classical property illustrates how our philosophy may work.
The metaphysics of quantum entanglement has been a subject of interest among philosophers of physics in recent decades. Entanglement is commonly described as a relation that does not depend on the intrinsic properties of its relata. This feature has led some authors to propose that the quantum reality is fundamentally relational and/or holistic. Moreover, it has been employed to support various influential metaphysical perspectives within the metaphysics of science, including structuralism, monism, and, recently, coherentism. This paper advocates a non-reductionist approach to internal relations, drawing on Fine’s analysis of propositions involving essential properties. Assuming the pervasiveness of quantum entanglement, it is argued that treating it as an internal relation is the most compelling option. Under this interpretation, entanglement can be accommodated within different metaphysical frameworks: (1) as a fundamental internal relation, it aligns with structuralism; (2) as a derivative internal relation, it is compatible with monism; and (3) as a relation of dependence, it supports coherentism.