In contemporary literary metadiscourse, the reference to investigation replaces another, also borrowed from scientific vocabulary: that of experimentation. Hence the shift from a paradigm based on the life sciences to one associated with the humanities and social sciences. A comparative lexicographical analysis reveals the existence, in several European languages, of a dual paradigm of inquiry: two sets of meanings of the term that correspond to two distinct scientific imaginaries. In the first, investigation, associated with the resolution of an enigma, aims to gather evidence. In the second, investigation is a form of research that is not determined by a prior objective, and is aimed above all at advancing our understanding of a phenomenon. The "investigative effect" theorized in this article, with reference to Barthes's "effet de réel", thus deserves to be seen as a legitimizing device that participates in a redistribution of authority to describe the world; but it also questions the authority linked to any discourse of knowledge. A claim such as "this narrative is an investigation" invites us to re-examine the works from the angle of method and responsibility: what metadiscours legitimize the investigative approach? how does it avoid, or not, adding symbolic violence to historical dominations? what does it do with the fantasies that scientific methods aim to keep at bay, and which return when they are evacuated?