The definition of justice in Plato\'s Republic

In this master\'s thesis, we propose an interpretation of Book IV of Plato\'s Republic, which defends the formula to ta hautou prattein, or \"to do what is proper\", as a plausible definition of justice. The quest for such a definition mobilizes the basis of Plato\'s thought, for it touches on the Socratic-type question \"what is it?\", inserts it in the metaphysical context of the Middle Dialogues and demands the sense of a moral virtue. The central problem discussed in this research is to understand Plato\'s answer - based on \"things\" (en autois Rep. 444A4-6) - to the question \"what is justice\", in contrast to the claim that there is \"the Form of justice in itself \", κατ' αὐτὸ τὸ τῆς δικαιοσύνης εἶδος, (Rep. 435b2). The main objective of this investigation is to reconstruct the assumptions that give justice the definitional formula \"to do what is proper\" (Rep. 443c-444a to ta hautou prattein). Our reading tests the hypothesis that there is, indeed, a definition of justice in the Republic, investigating whether the expression \"doing what is proper\" appropriately fulfills the definitional role and explains the moral content of that virtue. We conclude that \"doing what is proper\" is a paradigmatic definition. Considering that this formula is the construction principle of justice perfect examples, we meet the formal criteria of generality and equality between definiens and definiendum - as demanded by the the Socratic dialogues -, while we fulfill the ontological criterion of adopting a Form as a referent - as required by the metaphysics of the Middle Dialogues. As for the explanatory function of the definition of justice, the formula precisely delimits the meaning of the virtue sought because it points to the most exemplary case of justice, in the best possible world. In this way, the research contributes to a more unitarian interpretation of the Platonic corpus by suggesting that the project of finding a universal, unified and explanatory definition was not completely abandoned in the Middle Dialogues. (AU)