Decision, Causality, and Pre-Determination

Boris Kment (Princeton University )

Abstract: The two dominant appraches in philosophical decision theory are evidential and causal decision theory (EDT and CDT). EDT tells you that you ought to choose the option that provides the best evidence for an outcome you value. By contrast, CDT holds that you should pick the option that you believe to be most likely to cause such an outcome. Many philosophers think that EDT gets so-called “Newcomb cases” wrong and that CDT gets them right. However, the opposite seems to be true in other examples, which include several cases recently constructed by Arif Ahmed. I propose a new theory that is intended to yield the correct results in all of these examples. On my account, the value of an option is a weighted average of the values that CDT and EDT assign to it. The weights depend on your credence that your action is determined by facts beyond your control. I argue that this theory enjoys independent motivation. Moreover, it agrees with CDT in Newcomb cases and with EDT in Ahmed’s examples, thereby yielding the right verdict in both types of case.