John Rawls argues that the basic structure of society ought to be evaluated according to two principles. The first principle concerns liberty; the second concerns social justice.

In a simplified form, leaving off some details, they look like this:

1. The Liberty Principle: Everyone ought to have the most extensive set of basic liberties compatible with a similar scheme for others.
2. The Difference Principle: Social and economic inequalities ought to be to the greatest benefit of the least well off.

Rawls interprets the Liberty Principle a particular way. He doesn’t think all liberties could count as basic. Instead, he gives us a list. The basic liberties include rights to vote and run for office (the political liberties), to exert influence over politics, rights of free speech, free association, freedom of conscience, freedom of occupation choice, rights to own personal property, rights to legal due process, and a few other civil liberties. He thinks rights of freedom of contract, freedom to own and use productive property, freedom to profit from capital, and a number of other economic liberties are not basic. They aren’t protected by the first principle of justice. They don’t make the list. 

How does Rawls determine which liberties make the list and which don’t? In short, he thinks that some liberties, but not others, are necessary to develop and sustain “the two moral powers”. (The two moral powers are the capacity to form and act upon a conception of the good life and a capacity to form and act upon a sense of justice.) According to Rawls, the right to own and use productive property isn’t necessary to develop these two moral powers, but the right to own personal property is.

A neoclassical liberal—especially one who has a roughly Rawlsian framework—will take issue with how Rawls makes his list. For one reason or another, the neoclassical liberal thinks that rights to own productive property, to trade goods, to make contracts, and so on, are more or less morally on par with rights of free speech, legal due process, and so on. Different neoclassical liberals could have different reasons for this belief. As this blog goes on, we’ll discuss some such reasons.

So, a neoclassical liberal differs from a high liberal in part by interpreting the Liberty Principle more broadly, or by having a more demanding version of the Liberty Principle. Plain old classical liberals and libertarians do so as well. However, neoclassical liberals—like Rawls—also endorse some sort of principle of social justice, while plain old classical liberals and libertarians do not.

I haven’t given you any reason to think neoclassical liberalism is true. I’m just explaining what it is in a very generic way.

If I were a high liberal, I’d demand an answer to the following question: If the neoclassical liberal thinks that all sorts of commercial and economic liberties should be protected by the Liberty Principle, doesn’t that completely crowd out and trivialize any principles of social justice? You’ll get an answer to that question, but not today.

One final note: I don't want to give you the impression that neoclassical liberals are all modified Rawlsians. Among the people I consider neoclassical liberals, many are, but many are not. I'm using Rawls as a foil here because his theory of justice is popular and well-known.