It's not obvious to me how tragedy of the commons/prisoner's dilemma is isomorphic to Newcomb's problem, but I definitely believe you that it could be. If TDT does in fact present a coherent solution to these types of problems, then I can easily see how it would be useful. I might try to read the pdf again sometime. Thanks.
They aren't isomorphic problems, however it is the case that CDT two-boxes and defects while TDT one boxes and co-operates (against some opponents).
r/Fitness does a weekly "Moronic Monday", a judgment-free thread where people can ask questions that they would ordinarily feel embarrassed for not knowing the answer to. I thought this seemed like a useful thing to have here - after all, the concepts discussed on LessWrong are probably at least a little harder to grasp than those of weightlifting. Plus, I have a few stupid questions of my own, so it doesn't seem unreasonable that other people might as well.