Philosophy and Phenomenological Research

Volume 57, Issue 1, March 1997

A New Grandfather Paradox?

In a 1994 Scientific American article, physicist David Deutsch and philosopher Michael Lockwood give a defense of the possibility of time travel based on the “Many Worlds” interpretation of quantum mechanics. They motivate their appeal to the Many Worlds interpretation by arguing that the standard formulation of the paradox of time travel in terms of ability is misguided, presenting their own version of the paradox based on an “autonomy principle”, and arguing that this paradox should be resolved by appeal to the Many Worlds interpretation. But whatever the merits of their solution, it is unmotivated, for their new version of the paradox turns out on closer scrutiny to be nothing more than the original ability version of the paradox in disguise.