Wait -- so you think tractable approximations of TDT will still lead to the right conclusion, but that Psy-Kosh still shouldn't use it, even for practice?

No. I advised him of the output of me running my tractable approximation of TDT: focus on the right thing for the presented case.

In any case, yes, at the appropriate level of granularity, there are relevant correlations between yours and others decision processes -- specifically, at the level of whether you deem it optimal to use discretion to bend application of laws in ways that favor your values. See komponisto's and my long comments on this discussion for more detail.

This is incorrect. Suppose you and other humans start out using variations CHDT (Crazy Human Decision Theory), which have some level of correlation with each other, but do not take this correlation into account when making decisions. Then you learn about TDT, think it is a good idea, and incorporate some of its ideas into some variation THDT (Timeless Human Decision Theory), which ends up being something like run CHDT but override some decisions if principles derived from TDT make it seem like a good idea. So you look at this jury nullification problem, and start running CHDT which returns that it seems like a good policy. But TDT says that if your decisions with others are correlated with other agents, you should take that into account. And you don't like what you predict would happen if everyone embraced jury nullification, so you change your decision. At this point you have destroyed the correlation between your decision and the normal CHDT using humans because you overrode the component of your decision theory that works the same way.

This could work if the other humans are also using THDT, because then they could override their CHDT answers for the same reasons you do. But we are talking about juries drawn from a population of mostly non-rationalists who have never heard of TDT. The decisions you make differently because you know about TDT do not correlate with their decisions.