Finally, although the theoretical elaboration of "objective happiness" uses an "observer" to make time-tradeoff judgments so as to cardinalize hedonic utilities, the "observer" is not to be found in Kahneman's empirical studies, and even the theoretical elaboration fails to allow for heterogeneity in observer judgments/preferences.
In order to cardinalize momentary utilities, Kahneman introduces an "observer.
In his empirical implementation of the "objective happiness" approach, Kahneman has not actually surveyed an observer or observers to rank hedonic profiles and thereby cardinalize hedonic utilities.
111) The idea, in economists' terms, is to cardinalize
A's and B's preferences so that A's gain from the project can be compared with B's loss.