About the Unicity of the Difference Principle and the Complementarity of Economics and Philosophy on the Question of Justice. Part 1: About the Unicity of Rawls’s Difference Principle

Alain Boyer

Table of Contents


Between (2,3) and (2,4), does the Difference Principle (DP) select the first one, the second one, or is it indifferent? That last interpretation is confirmed by Rawls’s use of the curve of the perfectly complementary goods. It admits curves of indifference. Once the worst off is maximized, one is indifferent between all the corresponding states. Leximin selects the second state: it iterates the Maximin on the “last” worst off. Sure, Leximin prefers (2, 10) to (2,3), and there is an intuitive point according which it is unjust that only the richest win anything; it cannot be called a “just” improvement, even if is a Pareto-improvement. In a co-operation, the poorest would be a “sucker”. My proposal is that an improvement can be called “just” iff it improves the situation of all (strong Pareto-improvements). Rawls (1999 [1971], § 17) noticed that if it is possible to go from (2,3) to (2,4), it is “surely” possible to go from (2,3) to (2+n, 4-n’), an improvement implied by Maximin, which is only the lexically first rule of justice of DP, to which one adds the secondary rule “Minimize inequality”. The curves in L are the curves of Maximin: DP has no indifference curves. There is an absence of ambiguity in DP. We are unable to generalize its univocity. Our intuitions on justice amid intermediate classes are vague. A component of justice is the solidarity of all. Nobody should stay alone in the same situation while only the situation of others improves.


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