The interpersonal comparison is a general problem across psychology- not merely a specific problem about comparing welfare

EDIT: Today I happened to reread Angner’s “Is it possible to measure happiness” and it’s probably important to mention that all the basic elements of my argument can be found in Angner’s article, though it isn’t spelt out in quite the same way by Angner.

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One of the pat answers about why it took a while for economics to enthusiastically embrace measurement of happiness and subjective wellbeing is the interpersonal comparison problem, viz, how can I know that your desire/need/happiness etc. is greater or lesser than mine?

Wikipedia sums up Lionel Robbins objection as such:

Lionel Robbins questioned whether mental states, and the utilities they reflect, can be measured and, a fortiori, interpersonal comparisons of utility as well as the social choice theory on which it is based. Consider for instance the law of diminishing marginal utility, according to which utility of an added quantity of a good decreases with the amount of the good that is already in possession of the individual. It has been used to defend transfers of wealth from the “rich” to the “poor” on the premise that the former do not derive as much utility as the latter from an extra unit of income. Robbins (1935, pp. 138–40) argues that this notion is beyond positive science; that is, one cannot measure changes in the utility of someone else, nor is it required by positive theory.

Intuitively this makes a certain sense. It’s difficult to know whether Jessica is really happier than Janet, or whether Jessica simply has a lower threshold to calling herself happy. Beyond this epistemological problem of knowing how to compare utilities, there’s an ontological problem of what it even means to compare these things across individuals. It’s not like they can ever be laid against each other. Your happiness might seem to be denominated in a different quantity to mine.


I’m wondering if there really is a special problem of interpersonal utility comparison, especially if utility is conceived of as happiness or subjective wellbeing, or whether instead, the problem is quite general, and many such interpersonal comparisons can be questioned.

For a lot of people, this thought won’t be new, but for me, it was a revolution in how I think about the problem. I’d always believed that there was a special interpersonal comparision problem for welfare. Seeing that the problems of welfare comparision are really identical to the problems of many other forms of psychological comparision like anger comparision or neuroticism comparison  across persons put a different spin on the problem. It made it less urgent as a problem in welfare economics, and more urgent as a larger philosophical question.

Consider how similar interpersonal comparison problems can arise for both anger and welfare. Bob may yell less than Brad, but this might not be because Bob is less angry than Brad, but simply because Bob has an aversion to showing his anger. Brad may say he is less happy than Bob but this may not be because Brad is less happy, but simply because he has a higher standard for what counts as happiness. The problem is parallel, and similar parallels can be constructed for other problems of interpersonal comparision.

If interpersonal comparison is a fully general problem across psychometric constructs, with no special features related to happiness, this might well give us reason to be less concerned about the problem as it relates to happiness, or it might give us reason to be more concerned about a variety of psychometric constructs. My personal take is that it strengthens my prior conviction that while this problem is real, it shouldn’t affect the practice of economic or sociological theory or decision making. We do not yet have a fully adequate theory of what it means to compare these quantities, but we should no more let this prevent us than our lack of a fully adequate way of knowing we are not being deceived by an evil demon prevents us from practicing physics.

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