A diversity of modes of quantification in contemporary societies have now been explored, following the path of scholars who inspired this field, such as Alain Desrosières. This introduction to the special issue of the Revue d'Anthropologie des Connaissances on the politics of calculation argues that there remains a gap between different strains of the sociology of quantification - one that emphasizes the governmentality it embodies and the discipline it establishes, the other that pays attention to the collective mobilization capacities it offers. It is suggested that public policy and governance is a good field of investigation, to understand how these two “regimes of quantification” are articulated together, and evaluate the extent to which actors external to the networks that control public policies can influence them by recalculating both the problems addressed and the effects of policy programs. Combining the sociology of science and technology and political sociology, this special issue thus hypothesizes that calculation is one of the ways of building coalitions in governance, and one of the objects of what is being debated in its arenas; and, conversely, that governance is one of the contexts in which contemporary forms of calculation are forged and algorithms invented.