From equality to inequality: The Diamond–Sen criticism of Harsanyi's criterion of social justice

It is difficult to resolve conflicts of interests even in a society consisting of identical persons. Such an issue has been perceived as a serious difficulty posed to Harsanyi's axiomatic utilitarianism by Diamond's critique which Sen seemed to approve. Recent treatments tried to resolve this criticism by modifying Harsanyi's analytical framework so as to render it immune to Diamond's view about fairness. This paper shows that Diamond's view of fairness may be read as a "simple form" of Rawls' justice as fairness; and hence its clash with Harsanyi's social welfare criterion reflects the Harsanyi–Rawls debate about social justice. Sen's position on the debate is also discussed. In the case where individual preferences share some common characteristics in the manner described in Harsanyi's 1955 axiomatization of utilitarianism, various conceptions of equal treatment of equals are possible. To each of these conceptions corresponds a specific social welfare function, and there is no way to find which one is the best, from the scientific or ethical points of view.