This article deals with two aspects of dialectic science present in a very hard passage of the Sophist that has raised a vast variety of readings. The need of a dialectic science facing the problem of the communication of the genera, and the main features of dialectical thought by virtue of which the dialectician can manage different situations where the relationship between the one and the many is to be thought about. Dixsaut claims that it is possible to think about dialectics without identifying it with the subordination of species to genera. Moreover, she holds Plato has provided a way to think about the multiple as free, not necessarily determined by the one.