In its origin, liberalism had no ambition to be universal either in the sense of claiming to be valid for everyone and every human society or in the … - Raymond Geuss

The actual effect of Rawls’s theory is to undercut theoretically any straightforward appeal to egalitarianism. Egalitarianism has the advantage that gross failure to comply with its basic principles is not difficult to monitor, There are, to be sure, well-known and unsettled issues about comparability of resources and about whether resources are really the proper objects for egalitarians to be concerned with, but there can be little doubt that if person A in a fully monetarized society has ten thousand times the monetary resources of person B, then under normal circumstances the two are not for most politically relevant purposes “equal.” Rawls’s theory effectively shifts discussion away from the utilitarian discussion of the consequences of a certain distribution of resources, and also away from an evaluation of distributions from the point of view of strict equality; instead, he focuses attention on a complex counterfactual judgment. The question is not “Does A have grossly more than B?”—a judgment to which within limits it might not be impossible to get a straightforward answer—but rather the virtually unanswerable “Would B have even less if A had less?” One cannot even begin to think about assessing any such claim without making an enormous number of assumptions about scarcity of various resources, the form the particular economy in question had, the preferences, and in particular the incentive structure, of the people who lived in it and unless one had a rather robust and detailed economic theory of a kind that few people will believe any economist today has. In a situation of uncertainty like this, the actual political onus probandi in fact tacitly shifts to the have-nots; the “haves” lack an obvious systematic motivation to argue for redistribution of the excess wealth they own, or indeed to find arguments to that conclusion plausible. They don't in the same way need to prove anything; they, ex hypothesi, “have” the resources in question: “Beati possidentes.”

One obvious way to specify what it is that is “due” to someone is to appeal to existing legal codes, but what they will prescribe will vary enormously from one time and place to another. A second account of justice might appeal to some notion of merit or desert. The third approach is Aristotle’s “general” conception, which simply identified “justice” with the sum of all the virtues and excellences. A fourth conception of justice is the idea that justice is in some way to be connected to equality of shares, resources, or outcomes. Finally there is the idea of fairness or impartiality of procedure. One might think that Rawls’s view derives some of its apparent plausibility because of a gradual slide between the various senses of “justice.” People start from a vague intuition that justice as a “general” concept (in the third sense above) is extremely important for the proper functioning of a society; they then find it easy to shift from this to a particular conception that connects “justice” with fairness of procedure and (a certain kind of limited) equality.

The general point that a political theory is, among other things, a partisan intervention, is well taken. So question about the actual political implication of a theory cannot be excluded as, in principle, irrelevant.