Professor of History, Emeritus
1932 – 2011
Roger Hahn was a distinguished member of the first cohort of historians of science trained in the programs established in the United States after World War II. As an undergraduate in physics and history at Harvard (AB, 1953), he had an opportunity of hearing T.S. Kuhn and I.B. Cohen. After obtaining a master’s degree in teaching at Harvard (1954), he went to Paris on a Fulbright to prepare himself more pertinently in the seminars of Alexandre Koyré and René Taton. From Koyré he took an interest in philosophical questions; from Taton, an interest in the dissemination of science.
On returning to the US in 1955, Roger was called to the military service he had postponed to take his fellowship. He soon found himself back in Paris, as an interpreter at SHAPE (Supreme Headquarters of Allied Powers in Europe) and a participant in the seminars of Taton and Koyré. When he entered the graduate program in history of science at Cornell in the fall of 1957, he had had a full exposure to the French form of his profession. In contrast, his thesis advisor, Henry Guerlac, was trying to expand the subject and its explanatory basis to include the social and institutional circumstances of the historical actors. Guerlac’s main field of historical investigation was 18th-centruy France. Roger took to the subject. It demanded sensitivity to the challenges of surviving revolutionary change, an understanding of the tensions in French culture and, of course, a command of the relevant languages.
Roger had most of these qualifications by birthright. He was born in Paris to a Jewish family and schooled there until the age of nine. In 1941 the family fled the German occupation of France and settled in New York, where Roger attended public schools and became an American. He knew at first hand the problems of having to choose when young between competing cultures and worldviews. (Later he would apply these insights in his biography of 18th- and early 19th-century French scientist and statesman Pierre Simon Laplace.) The “sense of adventure and limitless opportunity” that Guerlac saw in his vision of the field was sharpened by competition for funding then newly available to the discipline. The National Science Foundation’s research grants and fellowships enabled Roger to go to France to deepen his archival research on the old Paris Academy of Sciences. This was the subject of his doctoral thesis and of his now classic book, “The Anatomy of a Scientific Institution,” published in 1971 with a dedication to Guerlac. In it Hahn explains how the compact between French academicians and the state affected the nature of their interactions, the course of their work and, ultimately, the causes and circumstances of the suppression of their institution.
The reviews of Hahn’s “Anatomy” were everything a young scholar could want: an “extraordinarily significant book....a major event in the maturation of the history of science;” “a social history of a scientific institution which must surely become a model for further work;” a “publication [that]...has greatly enriched the history of science.” Reviewers praised the depth of research, the bibliographical control, the sophisticated analysis, and the persuasive argumentation. Perhaps best of all, reviewers commended the book as “a framework for further research into the organization of science in France during the late 18th and 19th centuries.”
Hahn agreed with the assessment but did not follow the suggestion. He had begun the work that would occupy him for the rest of his life. Instead of writing a sequel to his corporate history, he chose to pursue an individual for whom social history seemed the least productive approach. For one thing, many of the documents needed to support a conventional biography of Pierre Simon Laplace had gone up in flames in the chateau of a descendant. For another, Laplace’s fame rested on mathematics, which is notoriously resistant to the sociology of knowledge. Against this could be set the challenges, welcome to Roger, of discovering enough archival information for a biography and of bringing Laplace’s scientific interests into contact with wider concerns of the Ancien Régime. Laplace also drew Roger through the principle that all biography is autobiography. Hahn’s last considered opinion of the Newton of France might have been a self-portrait: a “private man, guarded, constantly rational and deliberate, undramatic,” a family man, “placid, serene, and resolute.” Roger, too, was private, guarded, placid, and resolute. As a family man he outdid Laplace, who at 39 married a girl half his age. Roger married in his early twenties. His cultivated and spirited wife Ellen, a musician, was a support and encouragement to him for almost sixty years. Like the Laplaces, the Hahns had two children; at the time of Roger’s death, they had three grandchildren.
In 1961 Hahn accepted a position in the Department of History at UC Berkeley. A year after he arrived in Berkeley, Thomas Kuhn, who had come to UCB only a few years earlier, took a three-year leave to direct a project to salvage and create documentation of the early history of quantum physics. Roger strove to fill the instructional gap in the History Department. Together with John Heilbron, a student of Kuhn’s who joined the UCB faculty in 1967, Roger built up the campus’ program in history of science by networking, for which he had a natural genius, and by helping to create a research group. He worked tirelessly to enhance the library’s collections, in print and manuscript, related to the history of science and technology. Among his notable accomplishments in this line were his acquisition of the extensive unpublished correspondence of the 18th-century Jesuit polymath Roger Boscovich and the establishment, with funds from the Hewlett Foundation, of a program for interviewing scientists and engineers active in the San Francisco Bay Area and obtaining their papers for the Bancroft Library.
Hahn was a founding member and served as director of the Office for History of Science and Technology from 1993 to 1998. He also served as co-chair of the French Studies Program from 1987 to 1990, and was chair of the selection committee for the France-Berkeley Fund. Throughout his career Hahn served on numerous committees in the Department of History, the College of Letters and Science, the Academic Senate, the University of California system, and the Office of the President.
In his biography of Laplace, “Pierre Simon Laplace 1749-1827: A Determined Scientist” (2005), Hahn drove two main connected themes: the calculus of probabilities and the truth of religion. Their connection for Laplace was the problem of the evaluation of the evidence for the life and miracles of Jesus. Hahn’s searches disclosed that although Laplace considered the problem for many years, he held to the agnosticism of Christophe Gadbled, with whom he had studied mathematics when young. Earlier treatments of Laplace, such as that by Charles Gillispie, described him primarily as a mathematician. Hahn’s Laplace is a being in the round, with a family, friends, and enemies, a place in society, and an interest in politics. He does his mathematics discretely off-stage and dies secure in the knowledge that the probability of life hereafter is infinitesimally small.
Although much of Hahn’s work might be labeled “social history of science,” that is not the way he regarded it. He insisted that just as historians of science should not separate the technical from the social, they should not consider the social apart from the technical. In a lecture delivered in Italy in 1975, he pointed to the danger he saw in the then burgeoning field of science studies and the imperialism of the newly founded Society for Social Studies of Science. He worried that the new field would “displace the research front in the profession and to so transform it as to overshadow years of patient labor that have brought it into a state of respectability.” In these balanced remarks Roger captured the discipline at a relative high when, by its studies of the institutional interface between science and the wider society, it was gaining reputation among historians. Those were good and exciting times in the profession both nationally and internationally and Roger helped to make them so.
Roger died on May 30, 2011, en route to Paris, where he was to hold an early celebration of his 80th birthday. During a stopover in New York, he contracted a respiratory disease that overwhelmed an immune system weakened by years of battling cancer. In his baggage was a large manuscript, finished apart from a few minor details, containing Laplace’s known correspondence and the significant records about him that Roger had uncovered during almost fifty years of resourceful searching. This definitive book is now in press.
Roger was a true cosmopolitan. Through his extensive connections, particularly in France and Italy, he eased the path of many American scholars in Europe. France awarded him the order of the “Palmes Académiques” for his contributions to French culture abroad. He was a vice-president of the Académie Internationale d’Histoire des Sciences at the time of his death. His juggling of micro and macrocosms reached its acme in 1985, when he brought the macrocosm to Berkeley in the form of the XVIIth International Congress of the History of Science. The success of this meeting of 1000 independently minded academics owed much to Roger’s reserves of Laplacian placidity. He rarely said a disparaging word about anyone though he could sometimes belittle himself. His passion about the things that count, his wide knowledge and interests, his quiet kindness and willingness to serve made him a generous colleague, a perfect university citizen, and a rare friend.
Roger Hahn is survived by his wife, Ellen Hahn of Berkeley, daughters Elisabeth Hahn of New York City, and Sophie Hahn Bjerkholt of Berkeley, and three grandchildren. He is also survived by his brother, Pierre M. Hahn of San Francisco.
John Heilbron (Chair)
 Resp., F.L. Holmes, in Journal of the history of medicine, 26 (1971), 456-9; Keith Baker, in Minerva, 10 (1972), 502; and Maurice Crosland, in Isis, 63 (1972), 407.
 J.B. Morrell, in British journal for the history of science, 6 (1972), 202.
 Roger Hahn, Pierre Simon Laplace (Cambridge: Harvard University Press, 2005), 205.
 Roger Hahn, “New directions in the history of science,” Physis, 17 (1975), 205-18, on 206.