Binmore, Kenneth (2009) Interpersonal Comparisons of Utility View Download
[Some of this material is a reworking of sections of my book Natural Justice (Binmore [5]
and its earlier two-volume incarnation Game Theory and the Social Contract (Binmore [3, 4]).
My Playing for Real, which is forthcoming with Oxford University Press, contains many details
omitted in this article.]
’Tis vain to talk of adding quantities which after the addition will
continue to be as distinct as they were before; one man’s happiness
will never be another man’s happiness: a gain to one man is no gain
to another: you might as well pretend to add 20 apples to 20 pears.
Jeremy Bentham
INTRODUCTION:
There are at least as many views on how the welfare of individuals should be compared
as there are authors who write on the subject. An indication of the bewildering
range of issues considered relevant in the literature is provided by the book Interpersonal
Comparisons of Well-Being (Elster and Roemer [8]). However, I plan to
interpret the topic narrowly. Although I shall review some traditional approaches
along the way, my focus will be on the questions:
What do modern economists mean when they talk about units of utility?
How can such utils be compared?
It is widely thought that that the answer to the second question is that utils assigned
to different individuals cannot sensibly be compared at all. If this were true, I share
the view expressed by Hammond [11], Harsanyi [14] and many others that rational
ethics would then become a subject with little or no substantive content.