On the basis of Popper's conception of the three worlds, the author proposes a classification of the sciences in which psychoanalysis, the specific science of World 2, the world 'of subjective experiences', occupies a place of its own. The subject of psychoanalytic science gave rise to the creation of a unique methodology centred on the formalized and systematic use of intuition in the service of knowledge. This methodology implies the harmonious utilization of the primary and secondary processes for this knowledge.

The achievement of this appropriate coordination calls for a radical change in the usual way of using the mental apparatus, which is constantly at risk of being lost. Psychoanalysts find themselves compelled to undergo a kind of personal, continuous paradigmatic revolution, which, in the event of failure, gives rise to methodological deviations, which are described.