Max Heitmann (Worcester College): 'Revisiting Retrocausality in Newcomb’s Problem'
First introduced to the philosophical world by Nozick in 1969, Newcomb’s problem has been much discussed over the last half-century. Surveys show that philosophers are fairly evenly split between taking both boxes (two-boxing), taking just the opaque box (one-boxing), and some form of ambivalence or agnosticism. Standing apart from their disagreements, however, is the view that the contents of the opaque box are counterfactually independent of the Subject’s choice, which has traditionally formed a part of the common ground between one-boxers and two-boxers. In this talk, I’ll re-examine this received view. Building on insights emerging from the philosophical foundations of statistical mechanics, I formulate an argument for the claim that the Subject’s choice whether to one-box or two-box can influence the earlier prediction of that choice, and therefore the contents of the opaque box—provided that the Predictor avails themselves of a certain (rather extreme) method of making their prediction. I confront this argument with a compelling general objection against such claims of retrocausal influence. All this leads us to the conclusion that, in this extraordinary Newcomb problem, the counterfactual situation is indeterminate, neither supporting one-boxing nor two-boxing. Thus, counterfactuals cannot here be used to guide rational choice. Along the way, I’ll explore an ambiguity in a popular account of the relation between the time asymmetry of causation and the so-called “asymmetry of records” (i.e., the observation that we have abundant records of the past but none whatsoever of the future).
