In an earlier post I spent some time trying to determine what the major sources were of Rawls's knowledge of the history of classical political economy. I noted that Rawls refers several times in A Theory of Justice to Mark Blaug's important history of economic thought, Economic Theory in Retrospect , and speculated that this might have been an important source of knowledge for Rawls.
Since then I've learned that there is more direct evidence of Rawls's study of Blaug. Eric Schliesser posted several interesting items last fall at the time of Mark Blaug's death. The first post provides PDFs of several pages of notes and annotations in Rawls's hand in a copy of Economic Theory in Retrospect, thanks to David Levy. It is evident from these pages that Rawls paid close attention to the book.
The second post goes into some detail about Blaug's career.
Schliesser also links to a fascinating hour-long interview with Blaug in 2006. Thanks to Offsetting Behaviour for linking to the interview. It is fascinating to hear about the drama of Blaug's life and career, including his encounter with the McCarthy committee in the 1950s.
Economic Theory in Retrospect was an important book for me as well during graduate school in the early 1970s, and I have admired Blaug's work ever since.
Since the earlier post I've also learned that the seminar and reading course that Rawls attended in 1950 with William Baumol at Princeton had substantial readings from the classical of political economy, including several selections from Marx. Baumol has shared with others that Rawls seemed to be impressed with Marx when he read him.