Departing from the debate between Julia Kristeva and Daniel Stern that produced a predictably intense polemic, the author tries to conceptualize the very different models of psychoanalysis that emerge. On the basis of the irreducibility between natural sciences and social sciences, these models are shown. They are situated in a historical context, paying attention to the epistemological debates that have accompanied psychoanalysis for many years. Differences are exemplified through the exploration of Kristeva's and Stern's perspectives about the functions of the mother figure. The debate between Stern and Kristeva took place in the context of the 2010 IFPS Forum.