Folks, we covered that already! "You should open the door before you walk trough it." means "Your utility function ranks 'Open the door then walk through it' above 'Walk through the door without opening it'". *YOUR* utility function. "You should not murder." is *not* just reminding you of your own preferences. It's more like "(The 'morality' term of) my utility function ranks 'You murder' below 'you don't murder'.", and most "sane" moralities tend to regard "this morality is universal" as a good thing.