We present an empirical study aimed at analysing the use of viewpoints in an industrial Concurrent Engineering context. Our focus is on the viewpoints expressed in the argumentative process taking place in evaluation meetings. Our results show that arguments enabling a viewpoint or proposal to be defended are often characterized by the use of constraints. Firstly, we show that, even if some constraints are apparently identically used by the different specialists involved in meetings, various meanings and weightings are associated with these constraints by these different specialists. Secondly, we show that the implicit or explicit nature of constraints depends on several interlocutive factors. Thirdly, we show that an argument often covers not only one constraint but a network of constraints. The type of combination reflects viewpoints which have specific status in the meeting. Then, we will propose a first model of the dynamics of viewpoints confrontation/integration.