The distinction between the three dimensions of the subject, Organic Supply, Function, and Functioning, from Lacanian psychoanalysis, offers fertile ground for heuristic exploration. Based on this trilogy, we formulate the hypothesis of an epistemological and an ontological heterogeneity among the various dimensions of the human being. Our methodology is to confront these three dimensions with Freud’s theoretical aporias developed in A Project for a Scientific Psychology. Our results reveal that the distinction between Organic Supply, Function, and Functioning results in a paradoxical emergence. The conception of the subject as emergent is a necessary paradox: it reinstates the epistemological heterogeneity between neuroscience and psychoanalysis, and accounts for the ontological discontinuity of the subject with his experience. The human capacity to attribute meaning to life events through deferred action produces a retroactive effect on his Organic Supply, with implications for the causality of the subject. Our conclusions suggest that paradox is essential for understanding the functioning of the subject, who is conditioned by his material properties. Therefore, the meaning he ascribes to his existence challenges the common premise in neurosciences that the subject is merely a product of his brain.