Blackwell's own oral-history testimony, read in full, names an extensive RAND social network but never Rufus Isaacs or John Nash

rand-corporationdavid-blackwellrufus-isaacsjohn-nashoral-historyprimary-verificationnegative-findingcold-war-science

David Blackwell's 2002–2003 oral history for UC Berkeley's Regional Oral History Office (Bancroft Library) devotes substantial portions of two interview sessions — "Summers at the Rand Corporation" and "Playing games at Rand" — to his RAND years, independently corroborating the "three summers between 1948 and 1950" dating already in the vault via MacTutor (claim-isaacs-rand-colleagues-nash-blackwell-confirmed-overlap). In his own words, Blackwell names as RAND colleagues or game-playing partners: Abe Girshick ("Yes, Abe Girshick and I worked together quite a bit at Rand, on various problems"), Richard Bellman, Jimmie Savage, Lloyd Shapley, Marian Shapley and Julia Robinson ("Julia Robinson and Marian Shapley, that's Lloyd Shapley's wife, and I were all at Rand"), Olaf Helmer, Alex Mood, and Henri Bohnenblust and Seymour Sherman. The full transcript — both the UC Berkeley digital-collections copy (192 pp.) and an identical Tufts-hosted mirror (124 pp.) — was read start to finish. Neither Rufus Isaacs nor John Nash is named anywhere in it.

This is a negative finding from a source that could have confirmed the direct-colleague claim and did not. It is not proof the two men never interacted with Blackwell — an interview taken roughly fifty years after the fact, driven by an interviewer's specific prompts, can omit a real acquaintance the subject simply wasn't asked about — but it means the strongest Blackwell-authored primary located this session does not corroborate the "direct colleague" framing carried in claim-isaacs-rand-colleagues-nash-blackwell-confirmed-overlap, which rests on Tier 3–4 secondary sources only.