For a specialist in linguistic studies the existence of ouais raises quite a simple question: should it be considered as equivalent to oui or not ? Most of the time it is accepted that the origin of the interjection is the adverb. Although this hypothesis is easily broken by convenient arguments two major drawbacks can be mentioned. Firstly one may wonder why ouais was first associated with surprise and not with agreement. Secondly if language levels are not taken into consideration, why can’t we replaced ouais with oui in all types of context ? The author of this article assumes that it can be easily explained if we consider ouais as a specific morpheme. He draws a chart of the different meanings of ouais and shows that they illustrate a regular basis depending on the link between the interjection and its context. As a consequence he changes thoroughly the link which is usually established between linguistic rules and language levels. The author does not intend to know whether ouais is familiar or not, which is a question with no answer. He prefers to ask the following question, which he can answer: why does the speaker with the highest status forbids others to use ouais. Thus he finds that changing his point of view on the links between linguistic and pragmatic fields enables him to come to the cause and the consequence of the information he gives about the functions of ouais.