Published online by Cambridge University Press: 01 April 2022
A “symptomatic act” is an act that is evidence for a state that it has no tendency to cause. In this paper I show that when the evidential value of a symptomatic act might influence subsequent choices, causal decision theory may initially recommend against its own use for those subsequent choices. And if one knows that one will nevertheless use causal decision theory to make those subsequent choices, causal decision theory may favor the one-box solution in Newcomb's problem, and may recommend against making cost-free observations. But if one can control one's future choices, then causal decision theory never recommends against cost-free observation.
This paper was written during my tenure as a fellow with the Michigan Society of Fellows. It is based on research supported by the National Science Foundation under Grant SES-8708168. I am grateful to Howard Sobel for helpful comments.