Quantum Theory and the Ontological Status of Non-individuals

Robert R.A. Arnăutu

Valéria Gradinar

The non-relativistic quantum mechanics offers us conditions to consider at least two possible metaphysical packages, but incompatible between themselves: metaphysics of individuals, and metaphysics of non-individuals. In addition, the standard formalism is compatible with both the ontologies, without the theory being decided for either of them. From this particular kind of situation, the thesis of the underdetermination of metaphysics by physics can be established. Actually, it can be found, among scientists and philosophers, defenders of one, or another ontology, as well as those who do not address the issue, given that theory on its own does not decide. This means that if we make a choice for one of these packages, it will be happing in a metaphysical field, increasing a lot the philosophical discussions about individuality of quantic objects in quantum physics. From a naturalized methodological view, we present the issues from those defend the individuality of quantic objects, and from those, include us, defend non-individuality, focusing two approaches: (i) the ontological one, in which the fail of IIP as individuation principle is discussed; and, (ii) the logical one, in which non-reflexive logics, as well as a quasi-set theory became more suitable for representing the non-individuals. In this paper we stand for the choice of non-individuals ontology becomes more plausible, and should be taken in account seriously, opening up possibilities for ontological pluralism.

Gregg S. Jaeger

Andrey A. Gribkov

The article is dedicated to the analysis of the ontological status of the hidden parameter λ in the context of Bell's theorem and quantum correlations. In the standard formulation of Bell's inequalities, the hidden parameter is attributed to an individual pair of entangled particles: it is assumed that λ determines the measurement outcomes for each specific pair and, therefore, serves as the carrier of correlation at the level of a single event. This interpretation gives rise to a well-known dilemma: the violation of Bell's inequalities in an experiment is interpreted as evidence of the impossibility of any local realistic theory, leading to conclusions about the non-locality of nature or a rejection of realism. The subject of this study is the very legitimacy of attributing the hidden parameter to an individual pair of particles. The question is posed: is λ a property of a single pair or a characteristic of a statistical ensemble? The problem is considered in the context of the classical philosophical opposition between the singular and the general, as well as the mereological relationship between parts and the whole in relation to the quantum-mechanical description of reality. A conceptual analysis of the mathematical structure of Bell's theorem is employed, along with a comparison of the ontological assumptions of the standard and ensemble interpretations, as well as a philosophical analysis of the levels of realization of correlation. The scientific novelty of the work lies in the explicit formulation of the question regarding the level of ontological belonging of the hidden parameter—a question that is typically not addressed in standard discussions around Bell's theorem. It is shown that attributing λ to an individual pair of particles represents not an experimentally justified fact, but an ontological assumption embedded in the formalism at the stage of its construction. This assumption predetermines the interpretation of the results: the violation of Bell's inequalities is perceived as a collapse of local realism only under the condition that correlation must be realized at the level of a single pair. If the correlation is realized at the level of the ensemble—through the structure of the distribution ρ(λ)—then the violation of Bell's inequalities indicates not non-locality, but the inadequacy of an individual ontology of the hidden parameter. The conclusion is that the standard interpretation of Bell's theorem conflates two ontological levels of description, and a correct delineation of these levels removes the necessity of choosing between non-locality and a rejection of realism.

Olímpia Lombardi

Edward M. MacKinnon

This article probes the question of what interpretations of quantum mechanics actually accomplish. In other domains, which are briefly considered, interpretations serve to make alien systematizations intelligible to us. This often involves clarifying the status of their implicit ontology. A survey of interpretations of non-relativistic quantum mechanics supports the evaluation that these interpretations make a contribution to philosophy, but not to physics. Interpretations of quantum field theory are polarized by the divergence between the Lagrangian field theory, which leads to the Standard Model of Particle physics and the Algebraic quantum field theory that discounts an ontology of particles. Ruetsche’s interpretation offers a potential for loosening the sharp polarization that presently obtains. A brief evaluation focuses on the functional ontology of quantum field theory considered as an effective theory.