The Open Thread posted at the beginning of the month has gotten really, really big, so I've gone ahead and made another one. Post your new discussions here!
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 agree that you can turn the handle on a particular piece of mathematics that resembles decisionmaking, but some part of me says that you're just playing a game with yourself: you decide that everything exists, then you put a prior over everything, then you act to maximize your utility, weighted by that prior. It is certainly a blow to one's intuition that one can only salvage the ability to act by playing a game of make-believe that some sections of "everything" are "less real" than others, where your real-ness prior is something you had to make up anyway.
Others also think that I am just slow on the uptake of this idea. But to me the idea that reality is not fixed but relative to what real-ness prior you decide to pick is extremely ugly. It would mean that the utility of technology to achieve things is merely a shared delusion, that if a theist chose a real-ness prior that assigned high real-ness only to universes where a theistic god existed then he would be correct to pray, etc. Effectively you're saying that the postmodernists were right after all.
Now, the fact that I have a negative emotional reaction to this proposal doesn't make it less true, of course.
There is a deep analogy between how you can't change the laws of physics (contents of reality, apart from lawfully acting) and how you can't change your own program. It's not a delusion unless it can be reached by mistake. The theist can't be right to act as if a deity exists unless his program (brain) is such that it is the correct way to act, and he can't change his mind for it to become right, because it's impossible to change one's program, only act according to it.