To understand Plato’s Republic as a whole, we must know his notion of injustice as well as that of justice, since he makes a comparison between the life of justice and the life of injustice. Prior to his detailed analyses of injustice in Books IV, VIII, and IX, Plato discusses injustice philosophically even in Book I. In this paper I deal with 351b-352b where Plato clarifies the function of injustice by appeal to the analogy between city and individual. According to (...) Plato, injustice in the city causes hatred in each citizen, which results in the civil war and fighting among them, leading to the destruction of the city. Analogously, Plato discusses the function of injustice in the individual, showing that hatred is the most fundamental function of injustice. Plato’s analogy, though, includes two remarkablediscrepancies between city and individual. First, justice in the individual causes a conflict among beliefs and desires, which makes him incapable of doing anything, while social injustice still allows the city lacking its unity to do something. Second, hatred or hostility social injustice engender in each citizen is directed toward others, whereas injustice in the individual produces self-disgust of the whole soul, functioning as the destructive principle of the soul. This is howthis argument serves to foreshadow Plato’s analyses of injustice in the remainder of the Republic. (shrink)