Here is my understanding. I was not really involved in the events, so, take this with a grain of salt; it’s all third hand.
FDT was attempting to be an umbrella term for “MIRI-style decision theories”, ie decision theories which 1-box on Newcomb, cooperate in twin prisoner’s dilemma, accept counterfactual muggings, grapple with logical uncertainty rather than ignoring it, and don’t require free will (ie, can be implemented as deterministic algorithms without conceptual problems that the decision theory doesn’t provide the tools to handle). The two main alternatives which FDT was trying to be an umbrella term were UDT, and TDT (timeless decision theory). However, the FDT paper leaned far toward TDT ways of describing things—specifically, giving diagrams which look like causal models, and describing the decision procedure as making an intervention on the node corresponding to the ouput of the decision algorithm. This was too far from how Wei Dai envisions UDT. So FDT ended up being mostly a re-branding of TDT, but with less concrete detail (so FDT is an umbrella term for a family of TDT-like decision theories, but, not an umbrella large enough to encompass UDT).
I think of TDT and UDT as about equally capable, but only if TDT does anthropic reasoning. Otherwise, UDT is strictly more capable, because TDT will not pay in counterfactual mugging, because it updates on its observations.
FDT cannot be directly compared, because it is simply more vague than TDT.
I’m new here. May I ask what’s the core difference between the UDT and the FDT? Also, which is better and why?
Here is my understanding. I was not really involved in the events, so, take this with a grain of salt; it’s all third hand.
FDT was attempting to be an umbrella term for “MIRI-style decision theories”, ie decision theories which 1-box on Newcomb, cooperate in twin prisoner’s dilemma, accept counterfactual muggings, grapple with logical uncertainty rather than ignoring it, and don’t require free will (ie, can be implemented as deterministic algorithms without conceptual problems that the decision theory doesn’t provide the tools to handle). The two main alternatives which FDT was trying to be an umbrella term were UDT, and TDT (timeless decision theory). However, the FDT paper leaned far toward TDT ways of describing things—specifically, giving diagrams which look like causal models, and describing the decision procedure as making an intervention on the node corresponding to the ouput of the decision algorithm. This was too far from how Wei Dai envisions UDT. So FDT ended up being mostly a re-branding of TDT, but with less concrete detail (so FDT is an umbrella term for a family of TDT-like decision theories, but, not an umbrella large enough to encompass UDT).
I think of TDT and UDT as about equally capable, but only if TDT does anthropic reasoning. Otherwise, UDT is strictly more capable, because TDT will not pay in counterfactual mugging, because it updates on its observations.
FDT cannot be directly compared, because it is simply more vague than TDT.
See here: https://www.lesswrong.com/posts/2THFt7BChfCgwYDeA/let-s-discuss-functional-decision-theory#XvXn5NXNgdPLDAabQ