The Delusional Misidentification Syndromes (MDS) are a group of monothematic delusions where the process of misidentification affects selectively people, objects and places. Their common denominator is a disturbance of the identification of the object, final stage of the mechanism of perception.

From the context of DMS, and specifically of the personal identification delusions (PID) whose main characteristics are recalled, the objective is here to study the basic elements of the concept of identity.

Two main basis for self-recognition are detailed: the body and the subject’s name. The body is the privileged place where the identity of the subject appears in its singularity. Merleau-Ponty regarded it as the stable structure of existence, “place of appropriation of the world”, allowing the existence of objects. It appears in two ways as a support of the identity, while linking it on one hand to the subject about who feels it like its own, and on the other hand to others who recognize it as the one of the subject. The name acts as a “classifier of lineage” according to Levi-Strauss, by locating the subject and its family from the rest of the social group. It enrolls the individual in a temporality punctuated by the difference between generations.

The feeling of identity appears as an inner certitude which impregnates all experience. Mental illness can question it, like delusions centered on identity by referring to the fundamental question of the origin.