Both during and after the Cold War, the U.S. government supported initiatives that brought international scientists together outside formal political channels, whether in the form of academic conferences or cooperative research initiatives, like the European Organization for Nuclear Research (CERN). Beyond the nuclear realm, scientists have informally assisted U.S. officials in negotiating treaties on issues as diverse as climate change and exploration rights in Antarctica.

This strategy, commonly known as “science diplomacy,” has limitations. Scientists are not elected officials, and nothing in their scientific training is designed to prepare them for the subtleties of international political negotiations. The premise of science diplomacy risks putting power in the hands of technical experts whose personal interests may or may not match those of their national governments. And yet: There is no evidence to suggest that the elected head of government — Donald J. Trump — possesses the finesse needed to negotiate a nuclear crisis, either.

In 1955, scientists like Joseph Rotblat hoped to use their personal connections and technical expertise to avert a nuclear apocalypse. For the leaders of Pugwash, the point of an international scientists’ movement wasn’t so much to displace official negotiations between governments as to keep a line of communication open in the event of a crisis. The idea was that private citizens could maintain personal relationships even if their countries had severed formal relations, in much the same way that bipartisan dinner parties used to grease the wheels of government in Washington.