The inaugural division between the consciente and the unconscious alludes to a duality in the psychoanalysis, which founds its ontology and reflects on its notions, models and scientificity criteria. This duality should be approached from a specific rationality, a logic of paradox, which allows us to apprehend its contraries as complementary: not as excluding. The author tries to understand how the intertwinement between the same and the other becomes so complex that it far exceeds a citar rational understanding, and removes all definite limits between a sense load and another new one. This, that, according to the author, is the creative capacity of the notions in psychoanalysis, is necessary to outline an object that never stops offering resistance and to undertake a reflection about the specificity of the models in psychoanalysis and of the interdisciplinary dialogue. The author believes that the paradoxality (as well as the negative) sets up a specific epistemology for the psychoanalysis, and that when it is integraied into the university environment, the explicitation of its models and the logical way in which these are used may feed the very reflection with etements that contribute to the specificity of the investigation methodotogy.