The on-line encyclopaedia Wikipedia is a pragmatic patchwork, an assemblage of many singular points of view on a given subject, based on rules of clarity and communicability of public statements. Its success reflects a transformation of our relationship with knowledge. In this article the authors use a social map of the conflicts in the on-line encyclopaedia to study the places where discussion tilts into dispute, quarrels and complaints for moral misconduct or disturbance. Based on statistics and focused monographs, they show that the Wikipedia is characterized by the inability to solve certain conflicts through existing procedures, and explore the reasons for this phenomenon.