I get why in examples where you can see each others' source code this can be the case, and I do one-box on Newcomb where a similar situation is given, but I don't see how we can presume that there is this kind of instrumental value. All we know about this person is he is a flat earther, and I don't see how this corresponds to such efficient lie detection in both directions for both of us.
What does the source code really impart? Certainty in the other process' workings. But why would you need certainty? Is being a co-operator really so extraordinary a claim that to support it you need overwhelming evidence that leaves no other possibilities?
The problem is that there are three salient possibilities for what the other player is:
Between co-operator and deceiver, all else equal, you should expect the evidence given by co-operator to be stronger than evidence given by deceiver. Deceiver has to support a complex edifice of his lies, separate from reality, while co-operator can rely on the whole of reality for support of his claims. As a result, each argument a co-operator makes should on average bring you closer to believing that he really is a co-operator, as opposed to being a deceiver. This process may be too slow to shift your expectation from the prior of very strongly disbelieving in existence of co-operators to posterior of believing that this one is really a co-operator, and this may be a problem. But this problem is only as dire as the rarity of co-operators and the deceptive eloquence of deceivers.
We clearly disagree strongly on the probabilities here. I agree that all things being equal you have a better shot at convincing him than I do, but I think it is small. We both do the same thing in the Defector case. In the co-operator course, he believes you with probability P+Q and me with probability P. Assuming you know if he trusts you in this case (we count anything else as deceivers) you save (P+Q) 2 +(1-P-Q) 1, I save (P) 3+(1-P) 1, both times the percentage of co-operators R. So you have to be at least twice as successful as I am even if there ...
I spoke yesterday of the epistemic prisoner's dilemma, and JGWeissman wrote:
To which I said:
And lo, JGWeissman saved me a lot of writing when he replied thus:
I make one small modification. You and your creationist friend are actually not that concerned about money, being distracted by the massive meteor about to strike the earth from an unknown direction. Fortunately, Omega is promising to protect limited portions of the globe, based on your decisions (I think you've all seen enough PDs that I can leave the numbers as an excercise).
It is this then which I call the true epistemic prisoner's dilemma. If I tell you a story about two doctors, even if I tell you to put yourself in the shoes of one, and not the other, it is easy for you to take yourself outside them, see the symmetry and say "the doctors should cooperate". I hope I have now broken some of that emotional symmetry.
As Omega lead the creationist to the other room, you would (I know I certainly would) make a convulsive effort to convince him of the truth of evolution. Despite every pointless, futile argument you've ever had in an IRC room or a YouTube thread, you would struggle desperately, calling out every half-remembered fragment of Dawkins or Sagan you could muster, in hope that just before the door shut, the creationist would hold it open and say "You're right, I was wrong. You defect, I'll cooperate -- let's save the world together."
But of course, you would fail. And the door would shut, and you would grit your teeth, and curse 2000 years of screamingly bad epistemic hygiene, and weep bitterly for the people who might die in a few hours because of your counterpart's ignorance. And then -- I hope -- you would cooperate.