Strategic vs. Parametric choice in Newcomb’s Problem and the Prisoner’s Dilemma: Reply to Walker

In Bermúdez 2013 I argued against David Lewis’s well-known and widely accepted claim that Newcomb’s problem and the prisoner’s dilemma are really notational variants of a single problem. Mark Walker’s paper in this journal (Walker, Philosophia, 42, 841–859, 2014) takes issue with my argument. In this note I show how Walker’s criticisms are misplaced. The problems with Walker’s argument point to more general and independently interesting conclusions about, first, the relation between deliberation and decision and, second, the differences between the prisoner’s dilemma, which is a strategic choice problem, and Newcomb’s problem, which is a parametric choice problem.