The failure of a way of conceiving and grasping man's being starting from the question of what that being is exactly (the paradigm of production) calls for an ontology capable of thematizing the guiding idea of man that has shaped the development of psychology and psychotherapy. What is suggested, then, is the outlining of a new perspective on man's being, which is to say, of an ontology—that is phenomenological in its method of inquiry—capable of conceptualizing the incompleteness of existence. Phenomenological ontology thus presents psychology and psychotherapy with a new positum, ipseity, and, hence a new method to study it, formal indication. The chapter explores the impact of this ontology in creating a paradigm shift in psychology and therapeutic practices.