Abstract
The essay analyzes the conflict which opened after the French Revolution between public opinion and ideology. In this space of reflection the second seemed sometimes as the hidden face of the first one. Public opinion historically represented the institutionalization of the possibility of a disagreement on the legitimacy of the body politic. It has thus made possible a speech on the political detached from religion. As is clear from the controversy of Napoleon against the ideologues and the Marxian critique, ideology does not get to be the science of social discourse and its alienation, to become a set of sophistry on social conditions. Discussing the arguments of Tocqueville, Bourdieu and Reynié about the deficit of reflexivity of public opinion, the author affirms its distance from the ideology, because it requires anyway an investment for religious believe his propositions