This paper argues that the literature on contemporary social movements is essentially circular, representing a political reductionism within which the analysis of these movements in terms of (individual, collective, societal) instrumental rationality appears both as a premise and as a conclusion. This in effect treats the theorist's own local form of rationality as universal, rather than taking the question of the modes of rationality operating in these contexts as an open question for research. By restricting the analytic and explanatory value of the social movement concept to the narrow field identified as relevant by this methodology, its common use for more wide-ranging analyses of the nature of contemporary social change is fatally und...