L’importanza del “non”: Platone, i nemici delle idee e il nulla

Three Platonic passages are examined in this paper: Theaet. 153a5-7, soph. 246a8-b3 (with the subsequent lines 247c5-7), Crat. 429e3-430a5. Their common denominator is the way by which a presocratic world-view is presented by Plato: the supporters of such a conception (mobilists, materialists) are characterised by a dogmatic attitude of refusal. In fact, they reject any consideration of an ontological domain that could be thought beside the domain of what in their opinion deserves the name “being”. The aim of the cross-analysis of these passages is to show that through this recurring scheme Plato intends to highlight an aspect of the background ontology of the mobilistic and materialistic thesis: the reduction of the domain of being to the perceptible, which is in turn the outcome of the disavowal of the problem of not-being. From a Platonic point of view, this “blindness towards the not-being” is a particularly serious fault: it frustrates a deeper conception of the empirical realm and, along with this, prevents a truthful understanding of the nature of being, because it preclude the comprehension of both the positive and the negative side of dynamis.