A cat-belling problem for FDT

[AI disclosure: I used Opus 5.5 for light edits after my first draft] Functional decision theory (Yudkowsky and Soares 2017) proposes choosing actions as follows (equation 4 in the paper): Here is the agent's probability distribution, is a graph saying how changing a logical variable affects other variables, is the observation history, and is utility. The underlines denote dequoting: is a variable in the agent's model representing the output of the FDT algorithm on these inputs. In this post, by FDT I mean this specific proposal, not TDT, UDT, logical EDT, or FDT*. (FDT* is a different decision theory defined in the FDT paper, which uses an undefined "true" operator in place of .) FDT, admittedly, relies on a operator applied to a logical statement, which is on shaky philosophical foundations: Equation (4) is sufficient for present purposes, though it rests on shakier philosophical foundations than (3). Pearl (2000) has given a compelling philosophical account of how to deduce the structure of causation from observation and experiment, but no such formal treatment has yet been given to the problem of deducing the structure of other kinds of subjunctive dependence. Equation (4) work