# Four-Dimensionalism **Domain:** Metaphysics / Persistence / Personal Identity **Doc Type:** Theory Node **Classification:** Temporal-Parts Account **Maturity:** Established Debate **Related:** [[wiki/Durable Identity|Durable Identity]], [[wiki/Personal Identity|Personal Identity]], [[wiki/Fission and Fusion of Persons|Fission and Fusion of Persons]] --- ## Position **Four-Dimensionalism** holds that persisting things extend through time as well as space and have temporal parts or stages. A person is not wholly present at each instant in exactly the same way; a life is a temporally extended entity composed of related stages. ## Branching Interpretation Some four-dimensional accounts treat fission as overlapping persons that share pre-branch stages and diverge later. This can preserve transitivity: there were two temporally extended persons all along, coinciding before the branch rather than one person becoming numerically identical to two. ## Continuity Consequence The view reframes migration from moving one enduring object to establishing relations among temporal stages. It can model branching cleanly, but it does not prove that a computational stage is part of the same person, settle consciousness or determine which continuers receive legal authority. Stage relations still require criteria. ## Sources - [Stanford Encyclopedia of Philosophy — Personal Identity and Ethics](https://plato.stanford.edu/entries/identity-ethics/) - Theodore Sider, *Four-Dimensionalism* (Oxford University Press, 2001). ## See Also [[wiki/Durable Identity|Durable Identity]] · [[wiki/Closest Continuer Theory|Closest Continuer Theory]] · [[wiki/Substrate Transition|Substrate Transition]]