This article is concerned with the concept of ambiguity in argumentation. Ambiguity in linguistics lies on the coexistence of two possibly interpretations of an utterance, while the role of contextual factors and background/encyclopedic knowledge within a specific society seems to be crucial.  From a systemic point of view, Halliday has proposed three main language functions (meta-functions): a) ideational function, b) interpersonal function, c) textual function. Language could reflect speaker’s experience of his external and internal world, interpersonal relationships and organization of text, respectively. Lexico-grammatical choices under a micro-level perspective and context (the environment of language) may lead to inconsistent interpretations through semantic or syntactic ambiguities. In philosophy and argumentation logic, strategies of ambiguity have been investigated by Aristotle, since the first sophistic movement. In his Topics, Metaphysics and Rhetoric, has pointed out the notion of “τὸ διττῶς / διχῶς λεγόμενον”, meaning that a term can have different senses and double interpretation. In this paper we discuss how we reconstruct the meaning of an utterance in dialogue through the mechanism of interpretation and how we analyze and construe ambiguities, combining the insights of argumentation theory and text linguistics. Research results show that in case of misunderstanding, the “best interpretation” is the less defeasible one according to contextual presumptions.