Troubles with Time Travel
Grey (William)
Source: Philosophy, Jan 1999; 74(287): 55-70
Paper - Abstract

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Philosophers Index Abstract

  1. Talk about time travel is puzzling even if it isn't obviously contradictory. Philosophers, however, are divided about whether time travel involves empirical paradox or some deeper metaphysical incoherence.
  2. The possibility of time travel is addressed (mainly) from within the Parmenidean four-dimensionalist metaphysical framework accepted by David Lewis in his defense of time travel. It is argued that time travel raises formidable difficulties which are not resolved by Lewis's ingenious defense.
  3. Objections to time travel considered include:
    1. travel to other times is impossible because there is nowhere (or "nowhen") to go;
    2. in setting out on a journey to the past a time machine will collide with itself;
    3. time travel generates a mysterious temporal dualism between experiential time and physical time;
    4. travel to the past would permit reverse causation1, raising the possibility of causal loops and the attendant problems arising, for example, from the prospect of empirical contradiction and the possibility of someone being one of their ancestors.


Hard copy of on-line version filed in "Various - Papers on Logic & Metaphysics Boxes: Vol 2 (F-N)".

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