Open problems are clearly defined problems1 that have not been solved. In older fields, such as Mathematics, the list is rather intimidating. Rationality, on the other, seems to have no list.
While we have all of us here together to crunch on problems, let's shoot higher than trying to think of solutions and then finding problems that match the solution. What things are unsolved questions? Is it reasonable to assume those questions have concrete, absolute answers?
The catch is that these problems cannot be inherently fuzzy problems. "How do I become less wrong?" is not a problem that can be clearly defined. As such, it does not have a concrete, absolute answer. Does Rationality have a set of problems that can be clearly defined? If not, how do we work toward getting our problems clearly defined?
See also: Open problems at LW:Wiki
1: "Clearly defined" essentially means a formal, unambiguous definition. "Solving" such a problem would constitute a formal proof.
See Wikipedia's list for a few examples.
The distinction between clearly defined and otherwise is somewhat subjective. I have not heard anyone talking about the subject yet, so brought it up.
Since Rationality seems to be strongly related to Bayes' theorem, it makes some sense that a lot of problems could be presented in a fashion where we only have to answer a few questions about priors to understand which actions to take.
I don't know if this answers your question.
It's the best possible kind of answer to my question - a link to a load of interesting stuff - thanks!
I see where I went wrong, in missing out the entire physical universe as a source of questions that can be clearly stated but are about real things rather than mathematical descriptions of them.