Parti del Diverso. Genesi di una nozione di negazione nel ‘Sofista’ di Platone

In the Sophist Plato proposed his account of ontological negation. His dialogical definition rested upon a complex philosophical background. This paper aims to retrace that underlying philosophical background in order to fully appreciate Plato’s original solution. Both external and internal theoretical assumptions are identified in the text as conditional, operating constraints. The necessity of avoiding any commitment to absolute non-being, absolute relativism or radical skepticism, or even complete indiscernibility on the matter of negation can be listed among the external constraints at work in the discussion. At the same time, Plato was probably compelled to avoid any commitment to the introduction of the so called ‘negative Forms’ to save his own account from possible inconsistencies that emerged in discussions within his Academy. In particular the critical role played by Aristotle’s De Ideis is envisaged here as the implicit and provocative incitement for the new direction taken by the Sophist in regard of the famous definition of Non-being as Otherness. The constant belonging of each item of reality to the kind of Otherness, whose natural parts for Plato lay at the core of the very notion of negation, will be presented at the end as the only way to provide grounds to the otherwise inconceivable notion of Non-Being. Here it is argued that Plato managed to develop this conclusion despite and beyond all external and internal philosophical constraints that he found along his way towards the daring definition of ‘what is not’.