understanding social utility through harsanyi’s argument


clay shentrup
2 min readApr 16, 2023

people often debate whether it's possible to sum individual utilities to create a social utility. there are many traditional arguments against this idea, usually materialist in nature, claiming that utility should ultimately be quantifiable, like the number of dopamine molecules in one's brain. however, for practical purposes, we can avoid these esoteric arguments and look at the issue from the practical perspective of a randomly selected member of society. this person would prefer the state of the world that maximizes net utility, as it is the state most likely to maximize their own expected utility.

the analogy of currency bags

to illustrate this point, let's consider an analogy. imagine you have two bags containing notes of various currencies, such as yen, euros, or dollars. you are allowed to pick a random bill from one of the two bags, knowing only their average bill size. naturally, you would want to choose the bag with the highest average, even if it might actually be worse for you because it contains a lower-value currency. from an expectation standpoint, it's still the better option. it does not matter that the currencies are of differing denominations and thus “cannot be summed” to produce a specific comparable value. it works in expectation.

harsanyi's argument and the concept of social welfare

this is similar to the argument proposed by j.c. harsanyi in a 1953 article. he suggested that "optimizing social welfare" means "picking the state of the world all individuals would prefer if they were in a state of uncertainty about their identity." in other words, if you are equally likely to be anyone, your expected utility would be the summed utility in the world divided by the number of people - that is, the average utility. this idea supports the notion that social utility is, in fact, averaging.


by examining harsanyi's argument, we can gain a better understanding of social utility from a practical perspective. while there are certainly more complex philosophical debates surrounding this concept, harsanyi's approach allows us to appreciate the value of maximizing social welfare in a way that is accessible and relevant to everyday life. his insights highlight the importance of considering the collective well-being of society, rather than focusing solely on individual utilities.



clay shentrup

advocate of score voting and approval voting. software engineer.