Refusing both an immanentist approach and methodological eclecticism, the author makes several propositions for a study of the public. He suggests that one confine oneself to a partial rather than comprehensive approach, and that one depart from empirical analysis in order to revert to it more effectively, using an heuristic model. This model will allow one to investigate what happens in terms of modes of production of perceptions and emotions, and in terms of internal or external contextual constraints. For semio-pragmatics, the same film projection generates different texts, depending on the public. Conversely, the same individual viewer is generally at the intersection between different publics. Examples range from the family film at the early cinema to fiction films and new types of projection and viewing (e.g. the Géode or Imax).