Hi Holden, thanks for this very nice overview of Harsanyi’s theorem!
One view that is worth mentioning on the topic of interpersonal comparisons is John Broome’s idea (in Weighing Goods) that the conclusion of the theorem itself tells us how to make interpersonal comparisons (though it presupposes that such comparisons can be made). Harsanyi’s premises imply that the social/ethical preference relation can be represented by the sum of individual utilities, given a suitable choice of utility function for each person. Broome’s view is that this provides provide the basis for making interpersonal comparisons of well-being:
As we form a judgement about whether a particular benefit to one person counts for more or less than some other particular benefit to someone else, we are at the same time determining whether it is a greater or lesser benefit. To say one benefit ‘counts for more’ than another means it is better to bring about this benefit rather than the other. So this is an ethical judgement. Ethical judgements help to determine our metric of good, then. (220).
And: “the quantity of people’s good acquires its meaning in such a way that the total of people’s good is equal to general good” (222).
I don’t think Broome is right (see my Aggregation Without Interpersonal Comparisons of Well-Being), but the view is worth considering if you aren’t satisfied with the other possibilities. I tend to prefer the view that there is some independent way of making interpersonal comparisons.
On another note: I think the argument for the existence of utility monsters and legions (note 17) requires something beyond Harsanyi’s premises (e.g., that utilities are unbounded). Otherwise I don’t see why “Once you have filled in all the variables except for U_M [or U_K], there is some value for U_M [or U_K] that makes the overall weighted sum come out to as big a number as you want.” Sorry if I’m missing something!
Hi Holden, thanks for this very nice overview of Harsanyi’s theorem!
One view that is worth mentioning on the topic of interpersonal comparisons is John Broome’s idea (in Weighing Goods) that the conclusion of the theorem itself tells us how to make interpersonal comparisons (though it presupposes that such comparisons can be made). Harsanyi’s premises imply that the social/ethical preference relation can be represented by the sum of individual utilities, given a suitable choice of utility function for each person. Broome’s view is that this provides provide the basis for making interpersonal comparisons of well-being:
And: “the quantity of people’s good acquires its meaning in such a way that the total of people’s good is equal to general good” (222).
I don’t think Broome is right (see my Aggregation Without Interpersonal Comparisons of Well-Being), but the view is worth considering if you aren’t satisfied with the other possibilities. I tend to prefer the view that there is some independent way of making interpersonal comparisons.
On another note: I think the argument for the existence of utility monsters and legions (note 17) requires something beyond Harsanyi’s premises (e.g., that utilities are unbounded). Otherwise I don’t see why “Once you have filled in all the variables except for U_M [or U_K], there is some value for U_M [or U_K] that makes the overall weighted sum come out to as big a number as you want.” Sorry if I’m missing something!