How to Reconcile Identity and What Matters in Survival: Y-Shaped Space-Time Worms

• Author / Creator

  Yildiz, Ceren

• Derek Parfit (1984) challenges our notion of personal identity as a criterion of survival by offering a thought experiment in which one goes through fission and survives as both postfission persons while being identical to neither of them since identity is a one-one relation. Parfit thereby argues that identity is not what matters in survival, and what matters is psychological continuity and connectedness which is a one-many relation. David Lewis (1983) offers a worm theorist solution by explaining fission in terms of multiple occupancy; that is to say that both post-fission persons (two distinct space-time worms) exist before fission by co-occupying the same pre-fission person stages. Theodore Sider (1996) points out the implausibility of the overlap of persons and offers the stage view as a solution. Thus, we can interpret fission as the overlap of two worms but not the overlap of two persons, for persons are not worms but the instantaneous stages of the worms, according to the stage view. I agree with Sider on the grounds that worm view and multiple occupancy view are not compatible. However, I will argue that we can keep the worm view and drop the multiple occupancy view instead, and interpret fission as a Y-shaped space-time worm. I will defend that two post-fission persons bear an identity relation to each other. In order to do so, I will suggest that we should redefine our notion of psychological connectedness. Fission forces all of us to give up something. Parfit sacrifices the criterion of identity for survival. Lewis keeps the criterion of identity for survival but sacrifices the criterion of uniqueness for identity by arguing that there is an overlap of two persons before fission. Sider avoids this problem but he sacrifices our notion of person, which ordinarily refers to a spacetime worm, by arguing that persons are stages. I will offer a more reasonable sacrifice and argue that we should give up the direct causal relation requirement for psychological connectedness. I will discuss the advantages of interpreting fission as a Y-shaped space-time worm, and answer to possible objections.

• Subjects / Keywords

  • metaphysics
  • philosophy of time
  • persistence
  • identity
  • four-dimensionalism
  • worm view

• Graduation date

  Spring 2019

• Type of Item

  Thesis

• Degree

  Master of Arts

• DOI

  https://doi.org/10.7939/r3-wmjb-wc58

• License

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