 The problem for Rawls, however, is to show that the principles that would be selected in such an original position are in fact recognizable as principles of justice. One might expect the parties to calculate how to weigh the primary goods (which Rawls catalogues as ‘rights and liberties, opportunities and powers, income and wealth’) against each other, and then to choose as their social principle ‘maximise the weighted sum of primary goods, averaged across all persons’. This, however, would bring the theory very close to utilitarianism, since the natural method of weighing primary goods is to ask how much utility having a given quantity of each is likely, on average, to bring (for the claim that utilitarianism would be chosen in a Rawlsian original position, see Harsanyi 1975). Since Rawls wishes to reject utilitarianism, he has to adjust the psychology of the parties in the original position so that they reason differently. Thus he suggests that, at least in developed societies, people have special reason to prioritise liberty over the other goods and to ensure that it is equally distributed: he argues that this is essential to safeguard their self-respect. In later writing his argument is less empirical: now the parties to the contract are endowed with ‘moral powers’ that must be exercised, and it is then fairly easy to show that this requires them to have a set of basic liberties.