At the New York Times' Opinionator blog, Steven Mazie urges Occupy Wall Street to take inspiration from the late, great political philosopher John Rawls:

Rawls’s boldest claim — that inequality in society is only justified if its least well-off members fare better than they would under any other scheme — could provide a lodestar for the protests. Rawls was no Marxist: this “difference principle” acknowledges that a productive, free society will be home to at least some degree of inequality. But the principle insists that if the rich get richer while wages and social capital of the poor and middle class are stagnant or falling, there is something seriously wrong.

I don't believe that this is Rawls' boldest claim. That the basic structure of a society's political economy ought to benefit its least advantaged members as much as any feasible alternative basic structure is not really so bold a claim. It follows almost trivially from the idea that our main institutions ought to tend toward the common interest and mutual benefit. The interests of the "least well-off" have to be protected and advanced; the system must benefit them, too. Rawls' particular formulation of this general idea--his "difference principle"--is uncommonly and, I think, implausibly strong. But I don't want to talk about that because I think most discussions of Rawls', including Steven Mazie's, propagates a fundamental misinterpretation of Rawls' political philosophy by focusing on the difference principle.

Rawls theory of justice has two principles. According to Rawls, the requirements of the first principle absolutely must be satisfied before moving on to the second principle. The difference principle is the last half of the second principle. By the time Rawls gets to the difference principle, most of the important work has already been done.

Rawls' first principle of justice is a principle of maximum equal liberty that doesn't sound that much different from Herbert Spencer's. According to Rawls "each person is to have an equal right to the most extensive basic liberty compatible with a similar liberty for others.” The principle of equal liberty, and its absolute priority over matters of distribution, is what makes Rawls theory of justice liberal.

One might sensibly imagine that if all liberties matter, and that if citizens are to enjoy the most extensive liberty compatible with a similar liberty for others, then economic liberty must matter, and citizens ought to have as much of it as possible. However, Rawls specifically denies that robust economic rights and liberties are in any way implied by his first principle of justice. Economic liberties are not among our basic liberties. This is Rawls' boldest claim.

When Rawls first fleshes out his first principle of justice shortly after introducing it, he omits to mention precisely the sorts of economic liberties one might expect the principle to include.

The basic liberties of citizens are, roughly speaking, political liberty (the right to vote and be eligible for public office) together with freedom of speech and assembly; liberty of conscience and freedom of thought; freedom of the person along with the right to hold (personal) property; and freedom from arbitrary arrest and seizure as defined by the concept of the rule of law.

Political liberty and it’s adjuncts are first among equals in Rawls scheme. The “right to hold (personal) property” is duly mentioned, but it tags along with “freedom of the person,” and Rawls never explains exactly what does and doesn’t count as personal property (t-shirts? wages? stock in Google?), though it eventually becomes clear that it’s not a lot. The freedom to buy and sell, to enter into contracts, to start a business, to hire and be hired, to save and invest, to trade freely across borders -- none of these are among the basic liberties to be established under the first principles. Rawls pushes all this putatively non-basic stuff under the second principle. But why?

I think it's as uncomplicated as this: Because if he didn’t, he wouldn’t get the answer he was looking for. As Samuel Freeman, one of our most eminent Rawlsians puts it, “If unregulated freedom of contract and absolute rights of property are basic liberties, this limits considerably the political liberties and the range of legislation that democratic assemblies can enact.” That is to say, if robust economic rights are included in the list of basic liberties, they're removed, like the rest of our basic rights, from the scope of democratic discretion. As Freeman puts it, this "limits considerably the political liberties," and if certain ideals of strong democratic sovereignty and a worker/voter-managed economy figure prominently in your favorite picture of the good society, such limits simply won't do. But of course taking, say, freedom of speech and liberty of religious conscience off the table and protecting them constitutionally "limits considerably the political liberties" in exactly the same way. The point of basic rights and their priority over distributional matters is to limit the scope of politics.