Carlo Zappia and I have been asking the same question of each other, and now turn to the list: Daniel Ellsberg graduated from Harvard "under" John Chipman whom he "acknowledged" in his first academic article in the Economic Journal (1954, fn. 3). As for his Ph.D Thesis, the 2001 print (Garland Press) does provide information about who discussed parts of the thesis (Savage is acknowledged to have had a prominent role), but there is no mention of Chipman. However none of the people quoted is indicated as having been the supervisor, nor is there mention of any committee. My own reading of Samuelson's Harvard thesis shows no mention of a "supervisor", and no published source indicates any such person, or committee (although E. B. Wilson is thanked in several places). Which suggests the question: was it Harvard's practice in the interwar and immediate postwar period to have Economics dissertations accepted collectively, with no formal committees, or supervisors? Any information would be appreciated. E. Roy Weintraub