EN
The paper examines the importance of Protagoras for the development of Plato's political and ethical philosophy by a close look at his dialogue Protagoras named after this sophist. The focus is, firstly, the epideictic speech of Protagoras that raises and answers the questions of the nature, unity, and teachability of virtue (aretē), of the best education (paideia) and of the best political constitution (politeia). Specifically the dispute about the valuation of democracy, the understanding of political art, the relationship between nature and constitution and the anticipation of the later Aristotelian distinction between ethical and dianoetic virtues in the Protagoras are analysed in this context. All of these points can finally demonstrate how much Plato's own way of thinking has been affected by Protagoras: The sophist marks for him on an acknowledged high level and by pursuing an almost paradigmatic way all the wrong philosophical ideas, thus making him the perfect antagonist compared with Plato's own intentions.