Using AI tools to research collective amnesia: California Senator Broderick as a case study

In 1859, U.S. Senator David C. Broderick, a leading anti-slavery figure in California, was mortally wounded in a duel with David S. Terry, the pro-slavery former Chief Justice of the California Supreme Court. His death became a major political event, helping shape California’s Unionist alignment, which changed the course of the Civil War and American history at large. Yet today Broderick is nearly absent from public memory. This paper asks how such absence was produced. Drawing on computational social science studies of collective memory, I use AI-assisted analysis of California newspapers to trace Broderick’s visibility and meaning. The paper reveals the contingent and structural factors that prevented Broderick from escaping a broader pattern of declining public attention, while also conceptualizing two new mechanisms of historical amnesia: semantic narrowing, the transformation of the meanings attached to Broderick’s memory; and hollowed-out commemoration, whereby acts of remembrance leave little mark on cultural memory.