The third reflection concerns whether a just society (just, that is, according to Justice as Fairness) can be a society in which disabled people, or better people with certain deviations from standard human functioning can all be among the worst off (in terms of expectations of primary goods).
Consider deviations from standard human functioning such as deafness or a particularly short height (notice that such deviations do not impair a person's capacity human functioning necessariy, or at least it would be controversial to say so). Let us imagine a society that treats a good hear or tallness as qualifications for many jobs, systematically. (It should not be a society so difficult from ours.) In other words, it would discriminate against short and deaf people (in the morally neutral sense of "discriminate", meaning "distinguish from the rest and reject", not "illegitimately or immorally distinguish from the rest and reject"). This society may:
1. fulfill the clause of fair equality of opportunity: people with similar talents/abilities and willingness to use them would have similar life chances. In a society characterized by the total lack of attention for the special needs deriving from deviations from standard human functioning, deaf and short people will lack an important talent or ability (for that society) and all end up with little life opportunities; [remember that Rawlsian talents are society-relative]
2. contain institutions that are not improvable from the standpoint of the difference principle: it might be that no change in its institutions can reduce inequality without worsening the position of the worst off members of society, measured in terms of income and wealth.
Notice the opposition with the case of racial discrimination. A society that does not violate the principle of fair equality of opportunity can hardly manage to discriminate people in relation to their skin color (that is, treat skin color as a relevant qualification for a social position) if it is also, at the same time, a society that satisfies the difference principle. For, as far as our knowledge of production and exchange tells us, it might be possible to either reduce inequality or to raise the life-prospects of the worst off members by simply allowing people with the usual productive talents (productivity, organization skill, fantasy, will, etc) discriminated because of their skin color to take position where they "fit", according to their marginal productivity. To put it in another way, a productive society must select people according to qualities connected to marginal product, and skin color is not one of those: hence skin color cannot be treated systematically as a qualification for a job, if a society wants to be productive. Since fair equality of opportunity is in place, and this forbids the arbitrary exclusions of people meeting (what in a given social arrangement counts as) the relevant qualifications for position (whatever these happen to be, in a society), a just society cannot simply afford treating skin color as a qualification. The same reasoning cannot probably be done for a property such as deafness and shortness. A society can probably systematically discriminate people that have such traits, place them in the least rewarding social roles, and justify this via increased productivity to the very people it discriminate against, as there could be no way to reduce this discrimination without worsening deaf and short people's expectations of wealth and income.
Two conclusion follow:
A. being not-deaf and being not-short may both qualify as Rawlsian talents
B. a society in which the worst off members of society are all deaf and short might be just according to Rawls's criteria.
The only way from escaping this conclusion, it might seem, is to introduce the social basis of self-respect in the index we use to measure who is the worst off in society. Self-respect is indeed a primary good according to Rawls, but Rawls uses only income and wealth to evaluate social positions. And for good reasons: it is very difficult to measure trade-offs between a good such as self-respect and goods such as income and wealth. So the way out of the difficulty seems very difficult one to take.