As we saw in the previous posting in this series, the whole theory of social justice rests on the assumption that the common good, contrary to the claims of traditional philosophers, can be accessed directly by ordinary people, not just indirectly by people acting virtuously or the State passing good laws and people obeying them.
The difference between social justice and individual justice (aside from the fact that individual justice looks to individual good and social justice looks to the common good, i.e., humanity's capacity to acquire and develop virtue) is that access to the common good, a network of institutions is not possible for individuals as individuals. It is only possible for individuals as members of groups, that is, of institutions or "corporate bodies," also variously translated as "corporations," "vocational groups," and so on.
Membership in these groups, however, is only open to people who share equal political status. As Pius XI emphasized, these groups must be free (he says it seven times in one paragraph, § 87) — and that necessarily implies that they are based on contractual agreements between people of equal status. You can't be free if you are not equal, and you can't be equal if you are not free:
"Moreover, just as inhabitants of a town are wont to found associations with the widest diversity of purposes, which each is quite free to join or not, so those engaged in the same industry or profession will combine with one another into associations equally free for purposes connected in some manner with the pursuit of the calling itself. Since these free associations are clearly and lucidly explained by Our Predecessor of illustrious memory, We consider it enough to emphasize this one point: People are quite free not only to found such associations, which are a matter of private order and private right, but also in respect to them "freely to adopt the organization and the rules which they judge most appropriate to achieve their purpose." The same freedom must be asserted for founding associations that go beyond the boundaries of individual callings. And may these free organizations, now flourishing and rejoicing in their salutary fruits, set before themselves the task of preparing the way, in conformity with the mind of Christian social teaching, for those larger and more important guilds, Industries and Professions, which We mentioned before, and make every possible effort to bring them to realization."
The power to enter into contracts without coercion (which would not be contracts if coerced) depends on equality of political status, which in turn depends on the power vested in the owner of capital. You cannot ordinarily become a member of a group without some form of coercion if you do not own capital, and you cannot carry out an act of social justice unless you are a member of a group. Thus, social justice depends on free association/contract, and free association/contract ordinarily depend on capital ownership.
The philosophical/theological basis for equality of political status in civil society is along the same lines. Every human being has an "analogously complete" capacity to acquire and develop virtue — this defines us as human, and every human being is as fully human, and is human in the same way as every other human.
As we may have noted once or twice before, we acquire and develop virtue by exercising our natural rights within the limits of the common good — ordinarily we may not use our rights — our power/ability for doing — in a way that harms other individuals, groups, or the common good itself. The exercise of rights necessarily implies political equality within the common good, for everyone is equally human, and therefore necessarily has the same rights as everyone else. No one is above the law.
Then she came back and said she didn't understand a word of it. We cannot change things now. Equality is based on the liberalism of John Locke, Adam Smith and other fiends. The United States was founded as a result of the illegal overthrow of the British Crown by an anti-Catholic Masonic-Jewish conspiracy. End the Fed. Free silver (and no doubt Willy). The Apocalypse is coming. Afterwards property will be abolished and we will have the civilization of love envisioned by John Paul II.
We gave up.