That's all that a priori knowledge is: stuff you know without knowing why. Or to make the levels of abstraction more explicit, a priori beliefs are beliefs you have without knowing why. Once you start thinking about them, asking why you believe something and finding reasons to accept or reject it, it's no longer a priori.

This is a nice concise statement of the idea that didn't easily get across through the posts A Priori and How to Convince Me That 2 + 2 = 3.

Not sure, this came up in a few previous conversations. If an agent is almost certain that it's completely indifferent to everything, the most important thing it could do is to pursue the possibility that it's not indifferent to something, that is to work primarily on figuring out its preference on the off chance that its current estimate might turn out to be wrong. So it still takes over the universe and builds complicated machines (assuming it has enough heuristics to carry out this line of reasoning).

Say, "Maybe 1957 is prime after all, and hardware used previously to conclude that it's not was corrupted," which is followed by a sequence of experiments that test the properties of preceding experiments in more and more detail, and then those experiments are investigated in turn, and so on and so forth, to the end of time.

This calls for a link to simulated annealing, an optimization heuristic. Here, initial sampling is "provocation" and the jumps later in the process of cooling are "movement".

It's like with dreams of true universal objective morality: even if in some sense there is one, some agents are just going to ignore it.

This comment was written 3 days before the post komponisto linked to, which discussed the issue of account deletion feature having been broken at that time (Apr 2011); the comment was probably the cause of that post. I don't see where it indicates the state of this feature around summer 2010. Since "nothing happens" behavior was indicated as an error (in Apr 2011), account deletion probably did something else before it stopped working.

Since "report" buttons currently don't appear in most places, the lists of reported items go without update for months, so there's not much incentive to look at them. The last reported item in Main is of 12 June 2011. But I've got the pages bookmarked, so if the feature is resurrected it'll serve its purpose.

See this ticket. Currently, one of the moderators has to notice personally, though you could for example send a PM to me.

what is actually meant by "sentient life to continue"

"Planet" is a "planet", even if you should be working on something else, which is what I meant by usual concepts breaking down.

I don't think it was even possible for users to delete their own accounts on the old version of LW. (See here.)

That post discusses the fact that account deletion was broken at one time in 2011, and a decision was being made about how to handle account deletion in the future. It doesn't say anything relevant about how it worked in 2010.

SilasBarta discovered Roko in the process of deleting his comments, before they had been completely deleted.

"April last year" in that comment is when LW was started, I don't believe it refers to incomplete deletion. The comments before that date that remained could be those posted under a different username (account), automatically copied from overcomingbias along with the Sequences.

I believe that at least one unanimous extrapolated wish exists - for (sentient) life on the planet to continue.

Maybe there are better plans that don't involve specifically "sentient" "life" continuing of a "planet", the concepts that could all be broken under sufficient optimization pressure, if they don't happen to be optimal. The simplest ones are "planet" and "life": it doesn't seem like a giant ball of simple elements could be the optimal living arrangement, or biological bodies ("life", if that's what you meant) an optimal living substrate.