In a conversation with a friend about decision theory, they gave the following rebuttal to FDT:
Suppose there is a gene with two alleles, A and B. A great majority of agents with allele A use FDT. A great majority of agents with allele B use EDT. Omega presents the following variant of Newcomb’s problem: instead of examining the structure of your mind, Omega simply sequences your genome, and determines which allele you have. The opaque box contains a million dollars if you have allele B, and is empty if you have allele A. Here, FDT agents would two-box, and more often than not end up with $1,000, as nothing depends on any prediction of their behavior, only on an external factor their actions have no retrocausal effect on: no matter what they do, they are not “proving Omega wrong” in any sense; their genome does not subjunctively depend on their actions. An EDT agent, however, would one-box, as with regular Newcomb’s problem: they do not care about subjunctive dependence.”If you’re so smart,” a proponent of EDT might ask of a proponent of FDT, “why ain’t you rich?”
One easy out is to simply get one’s genome sequenced prior to the experiment itself. In that case, both EDT and FDT agents know what is in the boxes beforehand, and will two-box accordingly. The EDT agent can no longer obtain any evidence of them having one allele or the other.
What if that’s impossible though? Suppose we don’t know what the allele is, and are by some contrived means kept from finding out, leaving only knowledge of its existence?
One point in favor of FDT: unlike in a regular Newcomb’s problem, a precommitment to one-box prior to the experiment does nothing: even if one does so, this has no effect on Omega’s decision.
Comes the response from a proponent of EDT: No causal effect, perhaps, but such a precommitment is evidence that one carries allele B. Thus, those who make that precommitment are more often than not rewarded!
Consider the multiverse, and the circumstances of an agent’s birth in this scenario. 50% of worlds give them gene A. 50% give them gene B. Regardless of what they do, these probabilities are fixed, as the alleles of an agent are determined at random. Thus, if the agent has a greater propensity for two-boxing in this modified Newcomb’s problem, regardless of their genes, they will overall come out ahead in expected value.
Contrast the regular Newcomb’s problem: the agent has retrocausal control over the probabilities of their being a one-boxer or two-boxer. By one-boxing, they cause the multiverse to have one more one-boxer in it, even if they are one of the small minority that Omega mis-predicts. Thus, from the multiversal perspective, it is the agents further down the line that determine the probability of an agent one-boxing, rather than a random process.
Results: it is hard; harder than meditation. I can get lost in thought easily, though I snapped back often enough to successfully execute the action. I note that any change in the thing I was in the middle of prompted a snapback: no longer lost in thought due to suddenly needing to think about external reality. I expect I will get better at this with time, especially since in this case the action needs to be executed daily.