Agreed, what I said wasn't literally true. If you get 2 utils from caffeine and -1 util from pain, and if despite this you don't want to drink MD, then it's rational to self-modify to want to drink MD. But the point I meant to make is that it's not rational to self-modify to assign 0 utils to the same pain instead (because you don't care about utils, you care about things using utils), which is what I (mis)interpreted conchis as saying.