POSITIVE FEEDBACK IN COLLECTIVE MOBILIZATION: THE AMERICAN STRIKE WAVE OF 1886 MICHAEL BIGGS Department of Sociology and Nuffield College, University of Oxford University of Oxford Discussion paper in Economic and Social History, no. 40, April 2001 ABSTRACT Formal models prove the possibility of positive feedback in collective action; the metaphors of historically minded observers convey the same insight. It is still neglected in the literature on social movements, which emphasizes exogenous factors—above all, political opportunities—rather than endogenous processes. This paper draws on an intensive investigation of strikes for the eight-hour day in Chicago in May 1886. It demonstrates that changes in economic and political circumstances cannot explain the magnitude of the strike wave. More importantly, it provides evidence for positive feedback in collective mobilization, showing how optimistic expectations percolated through the working class in the spring of 1886. As each new group of workers became hopeful enough to organize, the fact of their organization inspired other groups to follow suit. New hopes gave rise to new organization; new organization became evidence that such hopes were justified