This article is intended to analyse the part of the dispute between Thrasymachus and Socrates in Book A of "Republic", in relation to the preceding part of the book, i e Polemarchus' definition of "justice" and Socrates' criticism of it Polemarchus defines "justice" as "to do good to the friends and to do evil to the enemies" This principle of the right action is composed of two rules, opposite to each other and applied in each case to only one of the two groups of men Socrates, in his criticism, expelling "to do evil" from "justice" and extending over the whole the rule applied to the friends by Polemarchus, seems to suggest "to do good (to everybody)" as the general principle, advocating, as it were, the cause of "justice" On the contrary, Thrasymachus recommends "to do evil to others", i e "injustice" as the punciple, applying to everyone except oneself the rule that Polemarchus has done to one's enemies only In Thrasymachus' view, "to do evil to others" is one's own good (as it were, justice, δικαιον), while "to be righteous" is another one's (i e the stronger man's) good and one's own evil From Socrates' standpoint again, if we might infer so, "to do evil to others" is the gravest evil to oneself, and despite his unerring skill in the art of evil, an unjust man is in the grandest error in mistaking it for a good and is possessed of grossest ignorance, and he is less strong and more unfortunate in the true sense than a righteous man The problem of justice is, on the other hand, treated by Thrasymachus in relation to the law and the ruler who makes it, and thus is given a public meaning (not only a private one) in the whole state or community But the two disputants differ diametrically from each other as to what the ruler and his τεχνη essentially consist in Throughout the whole of their dispute, Socrates appears to be triumphant, but we should rather think that the question is, in reality, of the difference of standpoint between Socrates, who thinks a man always does good when he knows good and evil and who considers the whole community to be a world all composed of brothers, and Thrasymachus, who again regards the society as a battlefield where everyone fights with others for his own good, which is nothing but another's evil When refuting Thrasymachus, however, Socrates is found showing in the sharpest contrast his own views and their implications, by means of treating from his own point of view the problems presented by his opponent