Hans Halvorson Physics, Logic, Philosophy

Fragmentalism in Special Relativity

Introduction

Fragmentalism is a metaphysical view developed by Kit Fine, according to which reality consists of distinct, possibly incompatible “fragments” that reflect different perspectives or aspects of the world. This idea becomes especially provocative when applied to special relativity, which challenges the classical idea of a single, objective present.

Fine’s framework allows for a realist account of tense and temporal becoming, even in the context of relativistic physics, by treating each relativistic frame as indexing its own fragment of reality.

Key Source

Kit Fine: Tense and Reality

Fine introduces his fragmentalist metaphysics in the essay:

Fine argues that the world can be understood as a plurality of partial realities, each reflecting a different perspective on what is real—such as what is present according to a particular time or frame.

Applications to Special Relativity

Fine’s approach has inspired both support and critique, especially in its application to special relativity:

  • Hofweber, Thomas, and Marc Lange. “Fine’s Fragmentalist Interpretation of Special Relativity.” Noûs 51, no. 4 (2017): 871–883. DOI: 10.1111/nous.12150

  • Hofweber, Thomas, and Marc Lange. “Fragmentalism and Special Relativity.” Teorema 38, no. 3 (2019): 5–16.

  • Lipman, Martin A. “On the Fragmentalist Interpretation of Special Relativity.” Philosophical Studies 177 (2020): 21–37. DOI: 10.1007/s11098-018-1178-4

  • Lipman, Martin A. “On Fine’s Fragmentalism.” Synthese 198 (2021): 6317–6334. DOI: 10.1007/s11229-019-02471-0

  • Slavov, Matias. “Eternalism and Perspectival Realism About the ‘Now’.” Foundations of Physics 50 (2020): 1398–1410. DOI: 10.1007/s10701-020-00385-x

  • Rovelli, Carlo. “Neither Presentism nor Eternalism.” Foundations of Physics 49, no. 12 (2019): 1325–1335. DOI: 10.1007/s10701-019-00312-9

    Rovelli argues for a relational interpretation of temporal structure, rejecting both presentism and eternalism. While Rovelli does not endorse fragmentalism per se, his approach shares with Fine’s view a sensitivity to the perspectival nature of temporal facts. Both authors seek to make room for a notion of becoming within the relativistic framework—Fine through metaphysical fragmentation, Rovelli through observer-dependent temporal structure. The similarities suggest a convergence toward models of time that emphasize relational or perspectival ontologies over monolithic block-universe metaphysics.

Summary

Fragmentalism offers a bold metaphysical strategy for reintroducing tense and temporal perspective into modern physics. Whether this approach is tenable in the face of the relativistic rejection of absolute simultaneity remains an open question—but it continues to be a source of rich philosophical debate.

Philosophers such as Carlo Rovelli explore alternative relational frameworks that similarly emphasize the perspectival nature of temporal existence without committing to a fragmented ontology. The intersection of metaphysics and physics remains a fertile field for further exploration.

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This page is part of an ongoing effort to document metaphysical responses to relativity on this site. For related topics, see Eternalism and Presentism.