Most of these problems only occur when you are a foundationalist about preferences. If you consider degrees of desire (from negative to positive infinity) as basic, and “utilities” representing those desires, preferences are just an emergent phenomenon of an agent desiring some outcome more than another.
The interpersonal comparison problem is then mostly one of calibrating a “utility scale”. Such a scale needs two points: one for u=0 and one for some u≠0 (e.g. 1).
The zero point is already very elegantly handled in Richard Jeffrey’s utility theory: If we axiomatically assume an algebra of propositions/events, excluding the contradictory proposition, with an probability and utility function defined over it, and assume that tautologies have utility zero (or indeed all probability one events), as they are “satisfied desires”, it is provable that indifference between a proposition X and its negation ¬X (i.e. u(X)=u(¬X)) implies that X and ¬X also have utility zero. At which point we have defined an interpersonally comparable zero point—if people are measurably indifferent between getting and not getting something, they assign utility zero to it.
We could then go on to define as, e.g., utility “1” something which all humans—with psychological or neurophysiological plausibility—enjoy approximately the same. For example, drinking a glass of water after not drinking anything for 12 hours. If then someone says they desire something three times as much as said glass of water, we know they desire it more than someone else who desires something only two times as much as the glass of water.
Most of these problems only occur when you are a foundationalist about preferences. If you consider degrees of desire (from negative to positive infinity) as basic, and “utilities” representing those desires, preferences are just an emergent phenomenon of an agent desiring some outcome more than another.
The interpersonal comparison problem is then mostly one of calibrating a “utility scale”. Such a scale needs two points: one for u=0 and one for some u≠0 (e.g. 1).
The zero point is already very elegantly handled in Richard Jeffrey’s utility theory: If we axiomatically assume an algebra of propositions/events, excluding the contradictory proposition, with an probability and utility function defined over it, and assume that tautologies have utility zero (or indeed all probability one events), as they are “satisfied desires”, it is provable that indifference between a proposition X and its negation ¬X (i.e. u(X)=u(¬X)) implies that X and ¬X also have utility zero. At which point we have defined an interpersonally comparable zero point—if people are measurably indifferent between getting and not getting something, they assign utility zero to it.
We could then go on to define as, e.g., utility “1” something which all humans—with psychological or neurophysiological plausibility—enjoy approximately the same. For example, drinking a glass of water after not drinking anything for 12 hours. If then someone says they desire something three times as much as said glass of water, we know they desire it more than someone else who desires something only two times as much as the glass of water.