The alter identicus has dismissed the alter ego in late modernity, with repercussions  for the way psychiatrists view the other. After examining the notions of limit and  situation for each of these two ways of viewing the other, we will examine their  consequences for diagnostic development. We will detail the example of the ADI-R  and the ADOS in the diagnosis of autism spectrum disorders (ASD). We will question  the usefulness of defining very broad markers of belonging (alter identicus) that seem  to miss their target : to understand a neuroconstructivist development process in  which the patient’s creativity (alter ego) contributes significantly to the development  of a divergent trajectory.