 This method of construction of an index of inequality, often referred to as the ethical approach to inequality measurement, is most useful when the argument of the social welfare function, and the object of the measurement of inequality, is the distribution of individual well-being (which may or may not be measured by income). Then the social welfare function is indeed symmetrical (by requirement of impartiality) and its aversion to inequality reflects its underlying ethical principles. In other contexts, the method is more problematic. Consider the case when social welfare depends on individual well-being, and individual well-being depends on income with some individual variability due to differential needs. Then income equality may no longer be a valuable goal, because the needy individuals may need more income than others. Using this method to construct an index of inequality of well-being is fine, but using it to construct an index of inequality of incomes would be strange, although it would immediately reveal that income inequality is not always bad (when it compensates for unequal needs). Now consider the case when social welfare is the utilitarian sum of individual utilities, and all individuals have the same strictly concave utility function (strict concavity means that it displays a decreasing marginal utility). Then using this method to construct an index of income inequality is amenable to a different interpretation. The index then does not reflect a principled aversion to inequality in the social welfare function, since the social welfare function has no aversion to inequality of utilities. It only reflects the consequence of an empirical fact, the degree of concavity of individual utility functions. To call this the ethical approach, in this context, seems a misnomer.