Rawls describes an alleged feature of utilitarianism as follows:
A rational and impartial sympathetic spectator is a person who takes up a general perspective: he assumes a position where his own interests are not at stake and he possesses all the requisite information and powers of reasoning.
So situated he is equally sympathetic to the desires and satisfactions of everyone affected by the social system. Responding to the interests of each person in the same way, an impartial spectator gives free reign to his capacity for sympathetic identification by viewing each person’s situation as it affects that person.
Thus he imagines himself in the place of each person in turn, and when he has done this for everyone, the strength of his approval is determined by the balance of satisfactions to which he has sympathetically responded. When he has made the rounds of all the affected parties, so to speak, his approval expresses the total result. Sympathetically imagined pains cancel out sympathetically imagined pleasures, and the final intensity of approval corresponds to the net sum of positive feeling. (163)
Utilitarianism was never meant to apply to individual conduct, as in “you shall act so as to maximize global welfare”; not even rule utilitarianism (“you shall act according to rules following which generally promotes global welfare”).
It rather acknowledges a certain division of labor between the lawgivers and the people. It is true that natural law must be wisely discovered, and positive law, prudently made. But the judges and legislators are passive. They make the law and then just sit there waiting.
The first thing they wait for is for people to refuse, perhaps shortsightedly, to honor the incentives generated thereby, in which case the authorities jump out and pounce on the lawbreaker like a snake on its prey and punish him — also utilitarian-ly.
The second, is also for the citizens to respond to the same incentives, but this time properly. This is because the governed, on the contrary, are active. Even so, they are not required to make any utilitarian calculations but are permitted simply to pursue their own self-interest in whatsoever it may consist. This self-interest can explicitly, through charity, include the happiness of others, but it does not have to; all actions guided by good law tend to redound to the social good and indeed, global welfare.
It is only the judges and legislators who should pay heed to utilitarianism. Moreover, they can’t predict how the citizens will act. They cannot predict who will be the next Thomas Edison or Henry Ford, or whether. They can at best, to repeat the quote of Mises in a post below, “provide an environment which does not put insurmountable obstacles in the way of the genius.” Whether there will be geniuses to whom the road will be open in such an environment is up to God and His genetic random person generators.
As a result, we don’t need an impartial sympathetic spectator who compares utilities intersubjectively. For in the imaginary world before the law is laid down, there are no citizens yet. The morality of Edison is not being compared with the morality of Ford, such that whoever creates more happiness is ordered to act. No one is ordered to do anything; only punishments for crimes are specified. Once this is done, people are left in the command of their own counsel, free to pursue whatever pleasures they fancy.
This humble method turns out to be the most reliable way of creating “the greatest good for the greatest number.”