So you've deleted the posts you've made in the past. This is harmful for the blog, disrupts the record and makes the comments by other people on those posts unavailable.

For example, consider these posts, and comments on them, that you deleted:

• 11 core rationalist skills (39 points, 33 comments, promoted)
• The Terrible, Horrible, No Good, Very Bad Truth About Morality and What To Do About It (23 points, 108 comments, promoted)
• Supporting the underdog is explained by Hanson’s Near/Far distinction (20 points, 18 comments, promoted)
• Max Tegmark on our place in history: "We're Not Insignificant After All" (14 points, 68 comments)

I believe it's against community blog ethics to delete posts in this manner. I'd like them restored.

The idea is that universal prior is really about observation-predicting algorithms that agents run, and not about prediction of what will happen in the world. So, for any agent that runs a given anticipation-defining algorithm and rewards/punishes the universal prior-based agent according to it, we have an anticipation-computing program that will obtain higher and higher probability in the universal prior-based agent.

This by the way again highlights the distinction between what will actually happen, and what a person anticipates - predictions are about capturing the concept of anticipation, an aspect of how people think, and are not about what in fact can happen.

What machine???

I don't believe it's particularly controversial. There is a question of whether humans retain preference about counterfactual worlds, but decision-theoretically, not-updating in the usual sense is strictly superior, because you get to make decisions you otherwise wouldn't be able to.

Bayesian updating is the wrong thing to do in counterfactual mugging, and the reason TDT goes wrong on that problem is that it updates.

Pray tell, what is the right thing to update?

I can't quite place "you need a notion of event, and that is determined by your prior", but I guess the mapping between sample space and possible observations is what you meant.

Prior evaluates, but it doesn't dictate what is being evaluated. In this case, "events happening" refers to subjective anticipation, which in turn refers to prior, but this connection is far from being straightforward.

But if you fix a language L for your universal prior, then there will be a more powerful metalanguage L' that allows finitely describing some structure, which can't be finitely described in the base language, right? So don't we still have the problem of the universal prior not really being universal?

It can still talk about all structures, but sometimes won't be able to point at a specific structure, only a class containing it. You only need a language expressive enough to describe everything preference refers to, and no more. (This seems to be the correct solution to ontology problem - describe preference as being about mathematical structures (more generally, concepts/theories), and ignore the question of the nature of reality.)

(Clarified the second part of the previous comment a bit.)

Why "new terms"? If the language can finitely express a concept, my scheme gives that concept plausibility. Maybe this could be extended to lengths of programs that generate axioms for a given theory (even enumerable sets of axioms), rather than lengths of individual finite statements, but I guess that can be stated within some logical language just as well.