Choice, Determinism, and Cooperation

A goal-pursuing agent must somehow ascertain when an action would serve as a means to achieving a goal. Various criteria (causal, evidential, counterfactual) have been proposed (e.g. Joyce 1999). Examining Newcomb’s Problem (Nozick 1969) and more-mundane thought experiments, I argue for an acausal but non-evidentialist counterfactual criterion (but without invoking the “possible worlds” of e.g. Lewis 1973) for means-end recognition: an agent acts for the sake of what the outcome would then be, not necessarily for what the action causes. Newcomb’s Problem posits an imaginary situation in which a large reward was (irrevocably) set up for you if and only if a reliable prediction anticipated that you would now make a choice which (apart from the large reward) is slightly unfavorable to you. A paradox arises as to whether to make the choice that (almost certainly) implies that you reap the reward. Newcomb’s Problem bears on the compatibility of choice with determinism. Further, Lewis (1979) and others argue that the Prisoner’s Dilemma (e.g. Shubik 1982), a thought experiment that bears on the rationality of altruistic cooperation, reduces to Newcomb’s Problem. I propose a radical variant of Newcomb’s Problem in which the already-inalterable reward outcome is also already visible to you, yet (I claim) you are still correct to act in pursuit of that outcome. I argue that the radical variant is key to reconciling choice with determinism, and that it suggests a foundation for cooperative behavior that goes substantially beyond what a resolution of the Prisoner’s Dilemma alone would provide.