Experiment #110 · Thought experiment

Williams' Self and the Future

Body-swap intuitions cut both ways

Bernard Williams · 1970 · Personal identity

First published: B. Williams, "The Self and the Future", *Philosophical Review* 79 (1970): 161–180.

Tell the same body-swap story two ways — once psychologically, once first-personally — and intuition flips.

Williams presents the same body-swap scenario from two angles. First, third-personally: "your psychology is transferred into another body" — most readers feel they have moved with their psychology. Second, first-personally: "tomorrow you will be tortured, but first you will be made to believe and remember you are someone else" — most readers feel they remain in the original body, unfortunately about to be tortured. Same physical setup, opposite intuitive verdicts. The case is the central objection to easy psychological-continuity views and the most influential anti-Lockean intervention since Reid.

Formulation

Setup: bodies A and B; psychologies swapped. Description 1 (psychological framing): "your mind moves into B." Intuition: you are now in B. Description 2 (somatic framing): "tomorrow you will be tortured in body A, but first your memories will be replaced." Intuition: you remain in A. Same physical events, opposite verdicts.

Compare this experiment

Dimensions Engaged

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Observer

Observer · Number: does identity follow psychology or body? Williams shows the question may have no theory-independent answer.

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Matter

Bears on Matter · Ontological Status: bodies as bearers of personhood vs as vessels.

Responses — How Schools Engage

Affirms / takes the bait 2

Hylomorphism

The somatic framing tracks substantial-form persistence: the person is the embodied soul, not the transferable psychology. Williams's case vindicates Aristotelian intuitions.

Buddhism

There is no person to swap; the cases show only that conventional designations track different streams in different framings. Anatta dissolves the puzzle.

Reframes the question 3

Naturalism

Animalist naturalism wins the second framing: we are biological organisms whose persistence is somatic. The first framing is misleading because of how the swap is described.

Realism

Common-sense intuition is inconstant; the case shows that ordinary identity concepts cannot survive radical hypothetical pressure without modification.

Dualism

The case is genuinely puzzling for dualism: a clean mind-body dualist might expect the psychological framing to be definitive, but the second framing presses bodily intuitions hard.

Holds it inconclusive 1

Analytic Metaphysics / Logical Atomism

A canonical pressure point: the case forces psychological-continuity theorists to refine their criterion, and reveals how thought-experiment intuitions are framing-sensitive.