 Why might we hesitate before agreeing that in cases such as these, justice requires people to refrain from doing things that they are permitted to do by the public rules of their society (passing on benefits to their children; seeking higher wages)? One reason is that the refraining is only going to have a significant effect if it is practised on a large scale, and individuals have no assurance that others will follow their example; meanwhile they (or their children) will lose out relative to the less scrupulous. A connected reason has to do with publicity: it may be hard to detect whether people are following the required ethos or not (see Williams 1998). Is the person who sends her child to a private school because she claims he has special needs that the local state school cannot meet being sincere, or is she just trying to buy him comparative advantage? How can we tell whether the person who claims more money, but merely, he says, as compensation for the unusual stress that his work involves, is reporting honestly? (for Cohen’s response, see Cohen 2008, ch. 8) It appears, then, that there are principles of justice that apply to what Rawls calls ‘the basic structure of society [as] a public system of rules’ that do not apply in the same way to the personal behaviour of the individuals who live within that structure. Attending to the scope, as well as the content, of justice is important.