Fundamentality and levels in Everettian quantum mechanics

Alastair Wilson

Research output: Chapter in Book/Report/Conference proceedingChapter (peer-reviewed)peer-review


Distinctions in fundamentality between different levels of description are central to the viability of contemporary decoherence-based Everettian quantum mechanics (EQM). This approach to quantum theory characteristically combines a determinate fundamental reality (one universal wavefunction) with an indeterminate emergent reality (multiple decoherent worlds). In this chapter I explore how the Everettian appeal to fundamentality and emergence can be understood within existing metaphysical frameworks, identify grounding and concept fundamentality as promising theoretical tools, and use them to characterize a system of explanatory levels (with associated laws of nature) for EQM. This Everettian levels structure encompasses and extends the ‘classical’ levels structure. The ‘classical’ levels of physics, chemistry, biology, etc. are recovered, but they are emergent in character and potentially variable across Everett worlds. EQM invokes an additional fundamental level, not present in the classical levels picture, and a novel potential role for self-location in interlevel metaphysics. When given a modal realist interpretation, EQM also makes trouble for supervenience-based approaches to levels.
Original languageEnglish
Title of host publicationQuantum Mechanics and Fundamentality
Subtitle of host publicationNaturalizing Quantum Theory between Scientific Realism and Ontological Indeterminacy
EditorsValia Allori
Number of pages19
ISBN (Electronic)9783030996420
ISBN (Print)9783030996413
Publication statusPublished - 28 Jul 2022

Publication series

NameSynthese Library
ISSN (Print)0166-6991
ISSN (Electronic)2542-8292

Bibliographical note

Publisher Copyright:
© 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.


  • fundamentality
  • levels
  • dependence
  • Everett
  • many worlds
  • quantum

ASJC Scopus subject areas

  • Logic
  • History
  • Language and Linguistics
  • History and Philosophy of Science


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