In current-day participatory processes, expressions like “citizen knowledge”, “user knowledge” or “ordinary knowledge” are overused. This article clarifies these expressions by analysing three epistemic sets that are applicable to the dynamics of participation: ordinary reason, citizen expertise and political knowledge. It explores the political implications of the investment in these specific forms of knowledge and contributes to the renewal of the classic opposition between elitist and “participatory” theories of democracy. Although the reduction of the knowledge of professional politicians to a more generic political knowledge is improbable, isn’t the dependence on citizen knowledge likely to help revitalize politics as a whole.