Who are the least advantaged?

The difference principle, introduced by Rawls (1971, 1993), is generally interpreted as leximin, but this is not how he intended it. Rawls explicitly states that the difference principle requires that aggregate benefits (e.g., average or total) to those in the least advantaged group be given lexical priority over benefits to others, where the least advantaged group includes more than the strictly worst off individuals. We study the implications of adopting different approaches to the definition of the least advantaged group and show that, if acyclicity is required, several seemingly plausible approaches lead to something close to leximin. We then show that significant aggregation is possible, if the least advantaged group is defined as those with those with less benefits than some strictly positive transform of the lowest level of benefits. Finally, we discuss the implications of requiring that, in comparing two alternatives, the cutoff for the least advantaged group of one alternative be the same as that for the other alternative.