Predictor is not the agent that is making a decision. (Also, unpack the last sentence.)
By "tit for tat" I am referring to the notable strategy in the iterated prisoner's dilemma. Agents using this strategy will keep cooperating as long as the other person cooperates, but if the other person defects then they will defect too. It's an excellent strategy by many measures, beating out more complicated strategies, and we probably have something like it built into our heads.
By analogy, a "tit for tat" strategy in Newcomb's problem with transparent boxes would be to one-box if the Predictor "cooperates," and two-box ...
I have not seen any place to discuss Eliezer Yudkowsky's new paper, titled Timeless Decision Theory, so I decided to create a discussion post. (Have I missed an already existing post or discussion?)