The September Open Thread, Part 2 has got nearly 800 posts, so let's have a little breathing room.
This thread is for the discussion of Less Wrong topics that have not appeared in recent posts. If a discussion gets unwieldy, celebrate by turning it into a top-level post.
I consider it debatable whether these amendments to naive CDT - CDT plus keeping a commitment, CDT plus cooperating with yourself - really constitute a new decision theory. They arise from reasoning about the situation just a little further, rather than importing a whole new method of thought. Do TDT or UDT have a fundamentally different starting point to CDT?
Well, I'm not sure what you're asking here. The problem that needs solving is this: We don't have a mathematical formalism that tells us what to do and which also satisfies a bunch of criteria (like one-boxing on Newcomb's problem, etc.) which attempt to capture the idea that "a good decision theory should win".
When we criticize classical CDT, we are actually criticizing the piece of math that can be translated as "do the thing that, if I-here-now did it, would cause the best possible situation to come about". There are lots of problems with this. "Reasoning about the situation" ought to go into formulating a new piece of math that has no problems. All we want is this new piece of math.