The Second International Congress of the History of Science, held in London in 1931, is chiefly remembered for the surprise appearance of the Soviet delegation and the lasting imprint that Boris Hessen’s Marxist reading of Newton’s Principia has left on the history of social constructivist thought in science studies and the history of science. This paper will revisit the story of the Congress, taking the history of this event out of the disciplinary historiography of the history of science and considering the preoccupations of its participants with the unity of knowledge articulated by international scholars in Europe, the US, and post-revolutionary Russia, driven by a spectrum of political and epistemic commitments. The paper will focus, in particular, on the least noticed member of the Soviet delegation, Nikolai Vavilov, whose work, in the view of the Congress’ participants, has bridged the gaping divides between written history and that of the unscripted era, between human history and geohistory, and between the historians and the scientists. Paradoxically, the collective memories of the Congress as the turning point in historiography of science, as well as those of Nikolai Vavilov as a martyr of genetics and the founder of biodiversity research, have reproduced the very disciplinary divisions that many Congress’s organizers and participants sought to dissolve.
