Section 47 opens with a reiteration of the point that the sketch of the system of institutions that satisfies the two principles of justice is now complete. Assuming the basic structure has this form the distribution that results will be just (or, minimally, not unjust) and the analogy here, as is typical of much of the argument of Theory, is with the outcome of a fair game. However, at this point, Rawls turns to consider the question of how the conception of justice as fairness relates to our common sense precepts of justice.
Common sense precepts have within them the problem of priority that Rawls articulated back in Chapter I as arising for intuitionist conceptions and which the various arguments for priority of principles that he gave in the previous sections of Chapter V show a basis for having overcome on the conception of justice as fairness. The two principles of justice are taken to define the basic criterion of how we will understand justice but are themselves arranged in an hierarchical order and contain (in the case of the second principle) sub-parts that themselves need articulating in order.
Rawls now considers various types of "common sense" precept and how they arise. However, he is less interested in these precepts themselves than with how different conceptions of justice lead to different ways of weighing them. The difference between different conceptions of justice is not understood by Rawls to reside in different types of common sense precepts but, instead, in different types of attention to them. A society that provides for fair equality of opportunity (the first part of the second principle of justice) responds differently to common sense precepts once this principle is part of its basic structure than does another society that does not provide for fair equality of opportunity in this way.
For one thing the provision of opportunities according to this principle tends to produce greater levelling of incomes with the result that the precept of rewarding each according to training is given less weight in this society than in alternative ones that have not built the principle of fair equality of opportunity into their basic structure. What this example is meant to show is that the type of generality that common sense precepts possess is the wrong sort for the articulation of principles of justice. This is despite the fact that some common sense precepts do initially appear general enough, such as ones that stress the natural right of property in the fruits of our labour (a kind of Lockean view). However, for this view to really be generally applicable it must be the case that the distribution it refers to is part of a generally just order, it cannot simply define one. It is, after all, just one of many precepts with another, also often appealed to and clearly off-setting this, referring to distribution according to need.
In market situations the general problem, at work in the kind of Lockean conception, is one in which contributions are expected to be rewarded. But what matters for any given kind of contribution is the relation of it to the whole system of norms in question. In this respect the questions of choice of occupation and free association are parts of a system of justice but the overall principle of fair equality of opportunity is one that determines the rewards that would arise in relation to them.
If section 47 articulates the problem that common sense precepts lack sufficient generality to stand in for principles of justice at the level of the basic structure, section 48, by contrast, tackles one specific type of principle that would threaten to reduce questions of justice to questions of virtue. This would be the adoption of a general principle that rewards should be adjusted by connection to virtue or moral worth shown (a kind of "republic of virtue"). Justice as fairness is in opposition to such a notion despite recognising the place of legitimate expectations within systems of justice.
The extent of a contribution someone has made at a given time is often determined impersonally by mechanisms such as markets that price the reward of a given effort in ways that may have little connection to the individual effort involved. This is a problem with viewing the conception of just distributive shares as a process of maximising returns by reference to conscientious effort. It also shows the difficulty of adopting such a principle as a public one. Moral worth, whether defined through conscientious effort or in some other way, is not a principle of distributive justice. Indeed, so little is this the case according to Rawls that there would be something grossly offensive about thinking of justice in this way as he suggests in the following striking comparison: "For a society to organize itself with the aim of rewarding moral desert as a first principle would be like having the institution of property in order to punish thieves".
The reason for this striking analogy concerns the distinction Rawls draws between a conception of reward determined by virtue and one that draws on the correct notion of legitimate expectations. In the latter case the expectations are what arise from doing things encouraged by existing arrangements and these would be best defined, on Rawls' view, by reference to the principle of fairness and the natural duty of justice. Institutions are bound to realise legitimate expectations they have encouraged in relation to these superordinate principles of justice. However, even when we have a system of justice that is governed by such principles there is no way of ensuring that conscientious effort or any other such type of moral worth would lead to higher rewards.
In this respect distributive justice is quite unlike retributive justice. If the purpose of the latter is to uphold basic natural duties through the provision of penalties attached to their violation, the purpose of distributive justice is only to ensure a generally just order and to reward individuals for carrying out generally valued social functions, so the variations in rewards should only be concerned with promoting the general ends of the basic structure, not the elevation of particular individuals in a parallel to the degradation suffered by those who have violated natural duties.
In sum then, Rawls concludes that most common sense precepts of justice are insufficiently general to be possible candidates in the original position for the status of general principles of justice and he specifically rules out views that would conceive of social justice as a wide form of reward for virtue since the latter view conflates the purposes of distributive justice with those of retributive justice.