Similarly, if I were to figure out that defecting is correct, that’s what I can expect my opponent to do. This is similar to my ability to predict what your answer to adding a given pair of numbers would be: I can merely add the numbers myself, and, given our mutual competence at addition, solve the problem. The universe is predictable enough that we routinely, and fairly accurately, make such predictions about one another. From this viewpoint, I can reason that, if I were to cooperate or not, then my opponent would make the corresponding choice- if indeed we are both correctly solving the same problem, my opponent maximizing his expected payoff just as I maximize mine. I therefore act for the sake of what my opponent’s action would then be, even though I cannot causally influence my opponent to take one action or the other, since there is no communication between us. Accordingly, I cooperate, and so does my opponent, using similar reasoning, and we both do fairly well.
One problem with the Prisoner’s Dilemma is that the idealized degree of symmetry that’s postulated between the two players may seldom occur in real life. But there are some important generalizations that may apply much more broadly. In particular, in many situations, the beneficiary of your cooperation may not be the same as the person whose cooperation benefits you. Instead, your decision whether to cooperate with one person may be symmetric to a different person’s decision to cooperate with you. Again, even in the absence of any causal influence upon your potential benefactors, even if they will never learn of your cooperation with others, and even, moreover, if you already know of their cooperation with you before you make your own choice. That is analogous to the transparent version of Newcomb’s Problem: there too, you act for the same of something that you already know is already obtained.
Anyways, as many authors have noted with regards to the Prisoner’s Dilemma, this is beginning to sound a little like the Golden Rule or the Categorical Imperative: act towards others as you would like others to act towards you, in similar situations. The analysis in terms of counterfactual reasoning provides a rationale, under some circumstances, for taking an action that causes net harm to your own interests and net benefit to others’ interests although the choice is still ultimately grounded in your own goals because of what would be the case because of others’ isomorphic behavior if you yourself were to cooperate or not. Having a deriveable rationale for ethical or moral behaviour would be desirable for all sorts of reasons, not least of which is to help us make the momentous decisions as to how or even whether to engineer the Singularity.
There’s about 2 more minutes of his presentation before he finished, but it looks like he just made some comparisons with TDT, so I’m too lazy to copy it over.