It seems to me that the original UDT already incorporated this type of approach to solving naturalized induction. See here and here for previous discussions. Also, UDT, as originally described, was intended as a variant of EDT (where the “action” in EDT is interpreted as “this source code implements this policy (input/output map)”. MIRI people seem to mostly prefer a causal variant of UDT, but my position has always been that the evidential variant is simpler so let’s go with that until there’s conclusive evidence that the evidential variant is not good enough.
LZEDT seems to be more complex than UDT but it’s not clear to me that it solves any additional problems. If it’s supposed to have advantages over UDT, can you explain what those are?
I hadn’t seen these particular discussions, although I was aware of the fact that UDT and other logical decision theories avoid building phenomenological bridges in this way. I also knew that others (e.g., the MIRI people) were aware of this.
I didn’t know you preferred a purely evidential variant of UDT. Thanks for the clarification!
As for the differences between LZEDT and UDT:
My understanding was that there is no full formal specification of UDT. The counterfactuals seem to be given by some unspecified mathematical intuition module. LZEDT, on the other hand, seems easy to specify formally (assuming a solution to naturalized induction). (That said, if UDT is just the updateless-evidentialist flavor of logical decision theory, it should be easy to specify as well. I haven’t seen people UDT characterize in this way, but perhaps this is because MIRI’s conception of UDT differs from yours?)
Anyway, my reason for writing this isn’t so much that LZEDT differs from other decision theories. (As I say in the post, I actually think LZEDT is equivalent to the most natural evidentialist logical decision theory — which has been considered by MIRI at least.) Instead, it’s that I have a different motivation for proposing it. My understanding is that the LWers’ search for new decision theories was not driven by the BPB issue (although some of the motivations you listed in 2012 are related to it). Instead it seems that people abandoned EDT — the most obvious approach — mainly for reasons that I don’t endorse. E.g., the TDT paper seems to give medical Newcomb problems as the main argument against EDT. It may well be that looking beyond EDT to avoid naturalized induction/BPB leads to the same decision theories as these other motivations.
It seems to me that the original UDT already incorporated this type of approach to solving naturalized induction. See here and here for previous discussions. Also, UDT, as originally described, was intended as a variant of EDT (where the “action” in EDT is interpreted as “this source code implements this policy (input/output map)”. MIRI people seem to mostly prefer a causal variant of UDT, but my position has always been that the evidential variant is simpler so let’s go with that until there’s conclusive evidence that the evidential variant is not good enough.
LZEDT seems to be more complex than UDT but it’s not clear to me that it solves any additional problems. If it’s supposed to have advantages over UDT, can you explain what those are?
I hadn’t seen these particular discussions, although I was aware of the fact that UDT and other logical decision theories avoid building phenomenological bridges in this way. I also knew that others (e.g., the MIRI people) were aware of this.
I didn’t know you preferred a purely evidential variant of UDT. Thanks for the clarification!
As for the differences between LZEDT and UDT:
My understanding was that there is no full formal specification of UDT. The counterfactuals seem to be given by some unspecified mathematical intuition module. LZEDT, on the other hand, seems easy to specify formally (assuming a solution to naturalized induction). (That said, if UDT is just the updateless-evidentialist flavor of logical decision theory, it should be easy to specify as well. I haven’t seen people UDT characterize in this way, but perhaps this is because MIRI’s conception of UDT differs from yours?)
LZEDT isn’t logically updateless.
LZEDT doesn’t do explicit optimization of policies. (Explicit policy optimization is the difference between UDT1.1 and UDT1.0, right?)
(Based on a comment you made on an earlier past post of mine, it seems that UDT and LZEDT reason similarly about medical Newcomb problems.)
Anyway, my reason for writing this isn’t so much that LZEDT differs from other decision theories. (As I say in the post, I actually think LZEDT is equivalent to the most natural evidentialist logical decision theory — which has been considered by MIRI at least.) Instead, it’s that I have a different motivation for proposing it. My understanding is that the LWers’ search for new decision theories was not driven by the BPB issue (although some of the motivations you listed in 2012 are related to it). Instead it seems that people abandoned EDT — the most obvious approach — mainly for reasons that I don’t endorse. E.g., the TDT paper seems to give medical Newcomb problems as the main argument against EDT. It may well be that looking beyond EDT to avoid naturalized induction/BPB leads to the same decision theories as these other motivations.