Justice demands that we treat equals equally and unequals in proportion to their inequality-so we need a measure for (in)equality, a basis of desert or a criterion for eligibility as a recipient of justice. We now have our archpoint; the time has come to apply this device to these questions.
In this and the ensuing two chapters I shall introduce the elements of a measure of social justice separately and systematically, slowly erecting a multi-storey building. The present chapter starts by asking who or what the recipient of minimal justice ought to be. In fact, it deals with three different but inseparable questions: the criteria for recipiency, the criteria for calling someone a recipient of social justice in particular, and the criteria for ordering the recipients' claims to social justice. The reason for treating these three questions in one single chapter is that the answer to each of these questions depends on the identification of relevant differences: differences between rocks and humans, between members and strangers, between the fortunate and less fortunate.
Principles of distributive social justice determine who will give what to whom, on what grounds and in what quantities. 'From each according to his capacity, to each according to his needs', is perhaps the best classic example of a measure of justice. However, a formula like this leaves much unspecified: who exactly is 'each', what are needs and capacities, how are they to be measured? The same ambiguity would be present in a fictitious Lockean constitution giving each person an equal share in political power. The formula looks innocent enough until one realizes that in Locke's view servants and women could not count for real persons as they lack autonomy: they are expected to follow the will of their husbands and masters. Clearly, if it is our intention to present sensible and defensible principles of justice, we cannot dodge the issue of the criteria for attributing recipiency (that is the quality of being a potential recipient of justice). Should the concept of social justice be extended to include themes, persons and