Following a long-standing philosophical tradition, impartiality is a distinctive and determining feature of moral judgments, especially in matters of distributive justice. This broad ethical tradition was revived in welfare economics by Vickrey, and above all, Harsanyi, under the form of the so-called Impartial Observer Theorem. The paper offers an analytical reconstruction of this argument and a step-wise philosophical critique of its premisses. It eventually provides a new formal version of the theorem based on subjective probability.

This paper proposes that the particular moral point of view embodied in Adam Smith's ethics, which ultimately follows a model based on the determination of justice, enables him to introduce impartiality as a measure for every virtue, and to posit the equal dignity of all human beings as the justification of his ethics. This moral viewpoint, which I here call the `sympathetic-impartial perspective', is naturally learned by human beings in the course of socialization through the ongoing interaction between the innate (...) impulse to sympathize and practically-informed reason. Moreover, this particular perspective creates a bridge between Smith's moral and political theories, shedding new light upon the moral foundations of his `system of natural liberty'. (shrink)