Having for its aim the analysis of the emergence and evolution of different theorizations of language, the history of linguistics bears a particular interest regarding the study of the concepts that underlie these theoretical approaches. Thus a part of the examination of these concepts consists in questioning their origin by determining whether they are the result of a pure linguistic reflection or have borrowed from another disciplinary domain. Indeed linguistics, like all other sciences, has no tightly sealed borders, and many theoretical approaches to language – like pragmatics – have been developed by borrowing concepts from other disciplines. Faced with the co-optation of a concept belonging to another scientific domain, the historian of linguistics can – in order to reveal all the presuppositions contained within the definition of this concept – create a kind of " archeology " (in Foucault's sense) by retracing its transdisciplinary path from its attested origin. In doing so, the historian of linguistics offers himself the possibility of making manifest the implicit theoretical crystallizations contained in the definition of the concept and explaining its limitations or its interest related to linguistics. The purpose of this communication will be to argue that one of the roles of the history of linguistics is to carry out a dynamic diagnosis of the definitional content of concepts by analyzing their development from a diachronic and transdisciplinary point of view. To support this thesis, I will focus on the concept of speech act and will show the influence that its passage through theology and law has had on its current definition and the problems that are related to it. This analysis will then lead us to better understand why linguistics is making parsimonious use of this concept, thus offering contemporary linguistics avenues to either render the concept more adequate or to give preference to another concept instead.