In indicating the problem of understanding the question of where the "classical" conception of utilitarianism can turn for its justification Rawls invokes the view of the "impartial spectator" used by Hume and Adam Smith. This notion of impartiality shows a commitment to a form of idealisation that is distinct from that involved in the conception of the "original position". The idea in general is that the "impartial spectator" has a general point of view that enables possession of knowledge of the relevant circumstances. The first point, after identifying this notion, is to work out what kinds of consideration the impartial spectator is concerned with and to see how they relate to those at work in the "original position".
The key difference between the impartial spectator and the original position on Rawls' argument is simply that the former's definition includes no assumptions from which the two principles of justice could be derived. Rawls views the basis for this claim to reside in the more restrictive sense of concern that applies to the impartial spectator. The impartial spectator's definition does not include any reference to deductive provision of reasons to adopt principles.
So the first look at the impartial spectator leads to a kind of "empty formalism" objection to its use. However, rather than stopping with this kind of criticism of the device Rawls looks instead at the means by which it can be given more determinate content. One way would be to supply this spectator with a form of moral psychology such as to give them plentiful supplies of sympathy (thus bending the device in a sentimentalist direction). Once this is done the derivation of "classical" utilitarianism can take place. Rawls points to Hume's account of utility as one example of how the link between the impartial spectator and a classical notion of utilitarianism can take place. On the Humean account there can be supposed increases in pleasure in the impartial spectator as the forms of pleasure felt within the social whole increase. So sympathy is here taken to be a principle that provides us with a psychological ground for impartiality.
The impartial spectator thus works through a form of empathetic identification with members of the society. Impartiality works here to weaken self-interest and knowledge of circumstances and a real capacity for identification guarantees that others are genuinely taken into account. Once the device's role is filled out it becomes apparent that it plays the role for the "classical" utilitarian that the "original position" has been designed by Rawls to play for the contractarian. They are hence competing devices. Interestingly, the appeal to the impartial spectator has also been explicitly made in Sen's recent work The Idea of Justice so Sen, in making this appeal, indicates a commitment to the idealising device that was, in Rawls' view, central to the formulation of "classical" utilitarianism.
If the impartial spectator requires sympathetic identification, the original position, by contrast, supposes nothing similar, instead taking the parties to the agreement to be mutually disinterested (as is the case with Adam Smith's market operators). Further, there is no appeal in the original position to either knowledge (which is generally not possessed due to the "veil of ignorance" with certain exceptions in regard to moral psychology) and, given the notion of mutual disinterest, nothing like the idea of sympathetic identification. Thus, in one sense, the moral psychology presupposed in the "original position" appears less generous than that applied to the "impartial spectator" though, in a different way, that allowed in the "original position" is greater due to the determinate notion of "person" allowed within the "original position". Generality is arrived at in the "original position" not by means of sympathy but instead precisely from the need, given the veil of ignorance, to assume it as a vantage point since one has little else to go on.
The determinate sense of personhood involved in the "original position" is in terms of the general meta-commitment each member of the contracting parties has to protection of their interests including the interest in being able to prosecute their own notions of the good. By contrast, the sense of person in the impartial spectator situation is appropriately "bare" with no indication included either of specific interests or of meta-interests. This is the basis, as Rawls now points out, for the charge that utilitarianism abstracts from the separateness of persons. The capacity for sympathy has replaced all specific interests and, in doing so, has robbed from participants any real sense of selfhood at all.
The abstraction from determinate qualities of persons in the impartial spectator device requires the notion of "impersonality" to fill the requirement of impartiality. Rawls views this as conflating all possible desires into a single system of desire. At this point the real reason why the "classical" utilitarian doctrine would not be adopted in the "original position" becomes evident as a consequence of the moral psychology assumed to be applicable to the contracting parties. Only if the contracting parties were assumed, not to be, as they are, disinterested but instead as perfect altruists, would there arise adoption of the classical principle of utility. "Thus we arrive at the unexpected conclusion that while the average principle of utility is the ethic of a single rational individual (with no aversion to risk) who tries to maximise his own prospects, the classical doctrine is the ethic of perfect altruists." Hence the conception of personhood presupposed in the different formulations of the principle of utility is not equivalent in the two cases.
Having brought out the psychological assumptions underpinning the "classical" utilitarian doctrine Rawls next turns to what these assumptions themselves involve. The perfect altruist of the "classical" doctrine is effectively without any specific desires of their own so they are parasitic upon the existence of others who possess such desires. This is presumably why Sidgwick and others have tended to the view that it might well not be best, from a utilitarian point of view, if all are utilitarians. If all were so assumed to be there would be no place at which any view of distribution could be centred. By contrast, the assumption of mutual disinterest in the original position takes it that there are separate interests which are in conflict and thereby works on the assumption that justice is concerned with the reconciliation with such competing interests.
One of the bases of the utilitarian appeal becomes clear from the considerations of this discussion. It is that it presents an intuitive rendering of the sense that moral judgments involve impartiality. But the device of the "original position" presents this appeal to impartiality in a different way by making different psychological assumptions and the assumptions that the original position requires are ones that Rawls can present as more "realistic" than those of the device of the impartial spectator. Rawls indicates that the interpretation of impartiality by utilitarianism is in terms of impersonality and that it is this interpretation that requires abstraction from the separateness of persons.
The possibility opens at this point in Rawls' discussion of a different theory of justice should the impartial spectator device be adopted but not involve conflation of desires into one system. Philanthropy as a principle, however, runs into similar problems as the adoption of benevolence would if it does not assume conflicting desires are present and if such conflicts exist then it follows that philanthropy will become selective and cease to operate as a general principle. The general point that emerges is that the problem with principles based on sympathy, benevolence or love all face the difficulty that they are second-order notions that are parasitic on first-order commitments. This is a new way of endorsing Kant's objection to pathological emotion as a form of ethical generalisation. Kant objected on the grounds of the instability of feeling. Rawls adds to this the point that feelings are, in any event, generally partial in consideration and to adopt an impartial conception of them is to require the continued existence of partiality and this continued existence of partiality is itself a problem for public adoption of sentimental principles. So "nothing would have been gained by attributing benevolence to the parties in the original position".
However, in conclusion, Rawls does allow the contracting parties in the original position to have a "sense of justice", albeit not one that requires commitment to supererogation almost as a matter of course. The principles of justice, once adopted, are indicated by Rawls to later also be the basis of a sense of virtue. This appears to advert again to his earlier notion of "rightness as fairness" though, as usual, Rawls does not work this through at this point.
With the completion of section 30 Chapter III ends and so also does the first part of Theory, the part itself entitled "Theory". The key philosophical role of this part of the work is evident, not least in Chapter III itself. In the "preface" to the original edition Rawls indicated some parts of Chapter IV were also included in the "essentials" of the text but it is apparent that the first part of the book provides most of the "foundations" of the theory. As such, they have also provided some of the most important philosophical points of dispute with Rawls. It will be necessary, however, to press on in future postings to look in more detail at the ways in which the next parts of the book develop in order to see how Rawls goes on to "introduce order and system into our considered judgments" as he puts in the original introduction.