Einstein's criticism of quantum mechanics and humean philosophy

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Vassilios Karakostas

The pros and cons of various forms of atomism and holism that are applicable both in physical science and today’s philosophy of nature are evaluated. To this end, Lewis’ thesis of Humean supervenience is presented as an important case study of an atomistic doctrine in philosophical thought. It is shown that Lewis’ ontological doctrine of Humean supervenience incorporates at its foundation the so-called separability principle of classical physics. In view of the systematic violation of the latter within quantum mechanics, it is argued that contemporary physical science posits non-supervenient relations over and above the spatiotemporal ones. Depending on the mode of assignment of states to physical systems — unit state vectors versus statistical density operators — we distinguish between strongly and weakly non-supervenient relations. It is demonstrated that in either case the relations of quantum entanglement constitute prototypical examples of irreducible physical relations that do not supervene upon a spatiotemporal arrangement of Humean qualities, weakening, thereby, the thesis of Humean supervenience. It is examined, in this respect, the status of Lewis’ recombination principle, whereas his conception of lawhood is critically investigated. It is concluded that the assumption of ontological reductionism, as expressed in Lewis’ Humean doctrine, cannot be regarded as a reliable code of the nature of the physical world and its contents. It is proposed instead that due to the undeniable existence of non-supervenient relations a metaphysic of relations of a moderate kind ought to be acknowledged as an indispensable part of our understanding of the natural world at a fundamental level.

Neil Dewar

There has recently been debate in the literature over whether the metaphysical doctrine popularly known as Humean supervenience can be reconciled—in whole or in part—with certain empirical facts about quantum entanglement. In this paper, I undertake a critical analysis of Humean efforts to effect such a reconciliation. I begin with a discussion of the relationship between Humeanism and quantum mechanics; I suggest that there are some difficulties even when considering single-particle quantum mechanics, but agree that the real problems come when considering many-particle quantum mechanics. I then review the available strategies for overcoming this problem, and find them wanting.

Christoph Lehner

Tomasz Bigaj, Antonio Vassallo

An important part of the influential Humean doctrine in philosophy is the supervenience principle (sometimes referred to as the principle of separability). This principle asserts that the complete state of the world supervenes on the intrinsic properties of its most fundamental components and their spatiotemporal relations (the so-called Humean mosaic). There are well-known arguments in the literature purporting to show that in quantum mechanics the Humean supervenience principle is violated, due to the existence of entangled states. Recently, however, arguments have been presented to the effect that the supervenience principle can be defended in Bohmian mechanics. The key element of this strategy lies in the observation that according to Bohmian mechanics the fundamental facts about particles are facts about their spatial locations, and moreover, for any proper subsystem of the world its state may non-trivially depend on the spatial configuration of the rest of the universe. Thus quantum-mechanical states of subsystems do not represent their intrinsic properties but rather characterize their relations with the environment. In this paper we point out the worry that this Bohmian strategy --known as Bohumianism-- saves the letter but not the spirit of the Humean doctrine of supervenience, since it prima facie violates another seemingly important Humean principle, which we call Strong Supervenience and whose denial implies the existence of necessary connections among distinct individuals. We argue that the best defense for Bohumians is to question the fundamental existence of complex physical systems and their states by treating any reference to them as a convenient description of the underlying collection of Bohmian particles. We consider several pros and cons of this strategy.

Michel Paty