A fair point, but given the facts of the matter, I'd say that the qualification "guaranteed" needs to be toned down only slightly to make the utterance reasonably modest. (And since I'm writing on LW, I should perhaps be explicit that I'm not considering the hypothetical future appearance of some superhuman intelligence, but the regular human social life and organization.)
I think what's going on is you're getting annoyed by naive applications of utilitarian reasoning such as Yvain's in the offense thread, then improperly generalizing that annoyance to even sophisticated applications.
I'd like to see book reviews of books of interest to LW. Some suggestions:
ADDED: I don't mean I'd like to see reviews in this thread. I'd like each review to have its own thread. In discussion or on the "new" page is up to you.