Thomson's turnabout on the trolley

Abstract

The (in)famous 'trolley problem' began as a simple variation on an example given in passing by Philippa Foot (1967), involving a runaway trolley that cannot be stopped but can be steered to a path of lesser harm. By switching from the perspective of the driver to that of a bystander, Judith Jarvis Thomson (1976, 1985) showed how the case raises difficulties for the normative theory Foot meant to be defending, and Thomson (along with many others after her) compounded the challenge with further variations that created still more puzzles of broader interest. In recent years, her thought experiments have even been co-opted by psychologists engaged in the empirical study of moral judgment (Greene 2001, 2008; Hauser 2006). Yet more than thirty years after launching the trolley problem, Thomson (2008) has now strikingly reversed course, retracting the very claim she had originally used to raise puzzles for Foot. I shall argue that this reversal is a mistake, leading to a needlessly counterintuitive, contrarian position about damagecontrol cases. Instead of overturning her earlier position, her new variations merely uncover a surprising insight about the conditions under which one may permissibly sacrifice another for a good end.