It also worries me quite a lot that eliezer’s post is entirely symmetric under the action of replacing his chosen notions with the pebble-sorter’s notions. This property qualifies as “moral relativism” in my book, though there is no point in arguing about the meanings of words.
My posts on universal instrumental values are not symmetric under replacing UIVs with some other set of goals that an agent might have. UIVs are the unique set of values X such that in order to achieve any other value Y, you first have to do X. Maybe I find this satisfying because I have always been more at home with category theory than logic; I have defined a set of values by requiring them to satisfy a universal property.
I suspect that there are many people in this world who are, by their own standards, better off remaining deluded. I am not one if them; but I think you should qualify statements like “if a belief is false, you are better off knowing that it is false”.
It is even possible that some overoptimistic transhumanists/singularitarians are better off, by their own standards, remaining deluded about the potential dangers of technology. You have the luxury of being intelligent enough to be able to utilize your correct belief about how precarious our continued existence is becoming. For many people, such a belief is of no practical benefit yet is psychologically detrimental.
This creates a “tradgedy of the commons” type problem in global catastrophic risks: each individual is better off living in a fool’s paradise, but we’d all be much better off if everyone faced up to the dangers of future technology.