Andreas_Giger comments on Open Thread, September 30 - October 6, 2013 - Less Wrong

4 Post author: Coscott 30 September 2013 05:18AM

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Comment author: Andreas_Giger 01 October 2013 07:43:17PM 1 point [-]

I don't like the notion of using different decision theories depending on the situation, because the very idea of a decision theory is that it is consistent and comprehensive. Now if TDT were formulated as a plugin that seamlessly integrated into CDT in such a way that the resulting decision theory could be applied to any and all problems and would always yield optimal results, then that would be reason for me to learn about TDT. However, from what I gathered this doesn't seem to be the case?

Comment author: Slackson 01 October 2013 09:33:59PM 3 points [-]

TDT performs exactly as well as CDT on the class of problems CDT can deal with, because for those problems it essentially is CDT. So in practice you just use normal CDT algorithms except for when counterfactual copies of yourself are involved. Which is what TDT does.

Comment author: Vaniver 03 October 2013 07:24:18PM 0 points [-]

I argue that there's an mapping in the opposite direction: if you add extra nodes to any problem that looks like a problem where TDT and CDT disagree, and adjust which node is the decision node, then you can make CDT and TDT agree (and CDT give the "TDT solution"). This is obvious in the case of Newcomb's Problem, for example.

Comment author: IlyaShpitser 04 October 2013 11:27:35AM *  1 point [-]

I guess it's true that CDT needed lots of ideas to work. TDT has one idea: "link counterfactual decisions together." So it is not an unreasonable view that TDT is an addendum to CDT, and not vice versa, since CDT is intellectually richer.