 Harsanyi may be viewed as the last representative of the old welfare economics, to which he made a major contribution in the form of two arguments. The first one is often called the “impartial observer argument”. An impartial observer should decide for society as if she had an equal chance of becoming anyone in the considered population. This is a risky situation in which the standard decision criterion is expected utility. The computation of expected utility, in this equal probability case, yields an arithmetic mean of the utilities that the observer would have if she became anyone in the population. Harsanyi (1953) considers this to be an argument in favor of utilitarianism. The obvious weakness of the argument, however, is that not all versions of utilitarianism would measure individual utility in a way that may be entered in the computation of the expected utility of the impartial observer. In other words, ask a utilitarian to compute social welfare, and ask an impartial observer to compute her expected utility. There is little reason to believe that they will come up with similar conclusions, even though both compute a sum or a mean. For instance, a very risk-averse impartial observer may come arbitrarily close to the maximin criterion.