“Might is Right” by Thrasymachus
Thrasymachus recommends that we regard justice as the advantage of the stronger; those in positions of power simply use their might to decree what shall be right.
(a) Why does Plato reject this?
Plato claimed that for one thing, if the ruling party mistakenly legislates to its own disadvantage, justice will require the rest of us to perform the opposite feat of both doing what they decree and also doing what is best for them. More importantly, Socrates argues that the best ruler must always be someone who knows how to rule. Thus, good rulers must try to do what is best for those who have trusted in them, rather than seeking their own welfare.
(b) What is Plato's alternative definition of justice for the state (in other words, what is his explanation of political justice)?
Plato defines justice in the two ways which are “Justice is Harmony” and “Justice is Doing one’s own job”.
Finding these two phrases, however, is hardly enough to get a clear sense of what justice is.
Plato's definition of justice is that justice is the having and doing of what is one's own. A just man is a man in just the right place, doing his best in the duty he has received. This applies both at the individual level and at the universal level. Plato offers two main likenesses to examine the definition of justice.
The division of parts in the soul as well as the parts of the state. A person's soul has three parts– the appetitive, spirited and the rational (stated in question number 6). Similarly, the state is also divided into three types of people, the guardian (rulers), the soldiers (enforcers)