The Multiple-Computations Theorem and the physics of singling out a computation

Meir Hemmo, Orly Shenker

Research output: Contribution to journalArticlepeer-review


The problem of multiple-computations discovered by Hilary Putnam presents a deep difficulty for functionalism (of all sorts, computational and causal). We describe in outline why Putnam?s result, and likewise the more restricted result we call the Multiple-Computations Theorem, are in fact theorems of statistical mechanics. We show why the mere interaction of a computing system with its environment cannot single out a computation as the preferred one amongst the many computations implemented by the system. We explain why non-reductive approaches to solving the multiple-computations problem, and in particular why computational externalism, are dualistic in the sense that they imply that non-physical facts in the environment of a computing system single out the computation. We discuss certain attempts to dissolve Putnam?s unrestricted result by appealing to systems with certain kinds of input and output states, as a special case of computational externalism, and show why this approach is not workable without collapsing to behaviourism. We conclude with some remarks about the non-physical nature of mainstream approaches to both statistical mechanics and the quantum theory of measurement with respect to the singling out of partitions and observables.
Original languageEnglish
Article number2
Pages (from-to)175–193
Number of pages19
JournalThe Monist
Issue number2
Early online dateJul 2021
StatePublished - 9 Mar 2022

Bibliographical note

Publisher Copyright:
© 2022 The Author(s), 2022. Published by Oxford University Press. All rights reserved. For permissions, please e-mail:


  • Computational theoery of mind
  • indeterminacy of computation
  • physical computation
  • Computational neurscience
  • multiple computations
  • functionalism
  • computational functionalism
  • dualism
  • externalism
  • reductive physicalism
  • identity physicalism
  • non-reductive physicalism

ASJC Scopus subject areas

  • Philosophy


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