xell (and I could ask Giltwist the same question): why is that good? See, it makes sense to ask "Is what society considers good good?" But that means that good must be something other than merely what society considers to be good, otherwise the question would have no sense. (That is, it makes no sense to ask "Is x y?" if x is the same thing as y.)
Oh, and sorry, I missed the one sentence thing. Hopefully this is short enough.