Paul Langevin was a French physicist who developed Langevin dynamics and the Langevin equation. He was one of the founders of the Comité de vigilance des intellectuels antifascistes, an anti-fascist organization created after the 6 February 1934 far right riots. Being a public opponent of fascism in the 1930s resulted in his arrest and being held under house arrest by the Vichy government for most of World War II. Langevin was also president of the Human Rights League (LDH) from 1944 to 1946, having recently joined the French Communist Party.

The 6 February 1934 crisis was an anti-parliamentarist street demonstration in Paris organized by multiple far-rightist leagues that culminated in a riot on the Place de la Concorde, near the building used for the French National Assembly. The police shot and killed 17 people, nine of whom were far-right protesters. It was one of the major political crises during the Third Republic (1870–1940). Leftist Frenchmen claimed it was an attempt to organize a fascist coup d'état. According to historian Joel Colton, "The consensus among scholars is that there was no concerted or unified design to seize power and that the leagues lacked the coherence, unity, or leadership to accomplish such an end."