Grammatically unacceptable utterances are communicatively accepted by native speakers, why are they ?

This paper aims at redefining the generally accepted notion of unfinished or elliptic sentence, which appears to be crucial in defining in turn the notion of fluency itself. It will be shown that a large part of utterances which a regularly trained linguist would consider as unacceptable and revealing some kind of disfluency of the speaker who produced them, are in fact fully accepted by the participants of a regular verbal interaction. This apparent contradiction will be explained by the fact that linguists base their judgments of well formedness of the utterances on their grammatical structure, whereas speakers interact basically by means of communicative units, which are not necessarily made up of grammatically well formed parts.