"Here’s another case that seems to me even weirder. Suppose that you’re reading about some prison camps from World War I. They sound horrible, but the description leaves many details unspecified, and you find yourself hoping that the guards in the prison camps were as nice as would be compatible with the historical evidence you’ve seen thus far. Does this give you, perhaps, some weak reason to be nicer to other people, in your own life, on the grounds that there is some weak correlation between your niceness, and the niceness of the guards?"
I am wondering if this (and most other real-world examples) do not work since you are changing your behaviour precisely because your decision theory assumes that your behaviour has an acausal impact on other peoples’ behaviour. Someone who beliefs in causal decision theory would not factors this into their decisions. So, in every scenario where you would normally choose A but you switch to B because you think this also acausally influences others to choose B you actually have no impact because the other people do not factor in this acausal influence and hence they won’t be more likely to choose B for the same reasons as you did. So, as long as other people use causal decision theories (which I think most people do intuitively, but I don’t have a study to show it) you cannot change their behaviour, since in the attempt of changing them, you apply a sort of reasoning that makes you fundamentally different from them. This causes the original argument of why your decisions can influence them to collapse. This would mean that you can still "magically" influence others but only if you don't try to do it deliberately, or am I overlooking something here?