By major institutions I understand the
political constitution and the principal economic and social
arrangements. Thus the legal protection of freedom of thought and
liberty of conscience, competitive markets, private property in the
means of production, and the monogamous family are examples of major
social institutions. Taken together as one scheme, the major
institutions define men's rights and duties and influence their
life-prospects, what they can expect to be and how well they can
hope to do. (Theory, section #2.)
I think it's important to note that these are only examples. Rawls isn't necessarily assuming the justice of any of these particular institutions.
Rawls
gives some examples of basic structure or major social institutions. Here's a
quote:
