This article is part of a research project that seeks to determine a class of disagreements understandable as a field of arguments that do not obtain due to misunderstandings but because of the nature of some social phenomena. This paper approaches this field through the notion of essentially contested concepts (Gallie), and argues that one can understand this kind of disagreement successfully, following classical rhetoric, as a field constituted by a class of questions of definition. This article has two parts: the first explains Gallie's notion of essentially contested concept and some notes on its reception. The second part clarifies the notion of field of argumentation, the debate on how to understand this notion, and the question of how to understand the field of argumentation related to essentially contested concepts.