On 12 October 1968, at the Strasbourg Congress organised by the Paris Freudian School, Michel de Certeau questioned the contemporary use of the function of the father, inherited from Freud. Jacques Lacan intervened to underline its decline in modern times and its future consequences, namely, the rise of racism and the extension of segregation processes. I propose to examine this thesis. The author begins by taking up Freud’s analysis of “A seventeenth century demonological neurosis”, evoked by Michel de Certeau, to demonstrate how the roots of hatred of the other lie in the rejection of castration. Then, the Lacanian construction of discourses between 1968 and 1972 allows her to highlight a generalised foreclosure of castration as an effect of modernity. Finally, she looks at today’s large groups in which the paradigm of our time can be deciphered: a society of solitudes that unfolds in a new cartography of segregated identities.