In order to ground and reinforce his theory of primary goods, J. Rawls introduces the idea of the "Aristotelian principle" in 65 of A Theory of Justice. The article discusses the difficulties entailed by the acceptance of this notion, as well as the limitations of the idea of the good underlying that principle. The objective is to show that the conception of the good presented by Rawls is affected by "moral in-sufficiency" and to argue in support of the thesis that his approach to the idea of the good overshadows the practical dimension of rationality.