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Two Quantum-Mechanical Arguments against the Metaphysical Equivalence between Substratum and Bundle Theories of Individuality

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  • Raoni Arroyo,
  • Jonas R. Becker Arenhart
Raoni Arroyo
Graduate Program in Philosophy, Federal University of Santa Catarina, Florianopolis, Brazil.
Jonas R. Becker Arenhart
Department of Philosophy, Federal University of Santa Catarina, Florianopolis, Brazil / Graduate Program in Philosophy, Federal University of Maranhão, São Luís, Brazil.
DOI: https://doi.org/10.36446/af.e1203

Published 2026-01-06

Keywords

  • Metaphysical Equivalence,
  • Metametaphysics,
  • Metaphysics of Quantum Mechanics,
  • Substratum and Bundle Theories of Individuality,
  • Metaphysical Underdetermination
  • Equivalencia metafísica,
  • Metametafísica,
  • Metafísica de la mecánica cuántica,
  • Teorías de substrato y de haces sobre la individualidad,
  • Indeterminación metafísica
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Abstract

It is a widespread consensus among metaphysicians that the bundle and substratum theories are substantially different metaphysical theories of individuality. In a realist stance towards metaphysics, they cannot both track the truth when describing fundamental reality, thus they’re rival metaphysical theories. Against that consensus, Jiri Benovsky has advanced a metametaphysical thesis that they are in fact metaphysically equivalent. This paper challenges Benovsky’s equivalence thesis with two counter-arguments based on the metaphysics of quantum mechanics: quantum metaphysical indeterminacy and wavefunction realism. As we shall argue, while both substratum and bundle theories arguably fail in standard quantum mechanics, they fail in different ways. Hence, given Benovsky’s own notion of metaphysical equivalence, they are not equivalent.

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