This article aims to show how the procedure followed by Aristotle in one of its scientific treatises – Aristotle’s On the Soul– is a clear demonstration of the primary and indispen-sable role of dialectics in scientific investigation. The idea is to show, from the study and the contrast between the scientific and the dialectical procedure in De Anima, that the dialectics in Aristotle plays an affirmative role that goes beyond the purely negative one (that traditionally associates with it). For this, the work will focus primarily on the defi-nition and description of the dialectics given in Topics (I and VIII); properly in De Anima(DA) and in Witt’s and Irwin’s works in the matter.