What is the principle of Plato about Just and Unjust in his Dialogue (Plato’s Dialogue)?

Socrates offers three argument in favor of the just life over the unjust life: (i) the just man is wise and good, and the unjust man is ignorant and bad (349b); (ii) injustice produces internal disharmony which prevents effective actions (351b); (iii) virtue is excellence at a thing’s function and the just person lives a happier life than the unjust person, since he performs the various functions of the human soul well (352d).  Socrates is dissatisfied with the discussion since an adequate account of justice is necessary before they can address whether the just life is better than the unjust life (354b).

Glaucon is not persuaded by the arguments in the previous discussion (357a).  He divides good things into three classes: things good in themselves, things good both in themselves and for their consequences, and things good only for their consequences (357b-d).  Socrates places justice in the class of things good in themselves and for their consequences.

Glaucon renews Thrasymachus’ argument to challenge Socrates to defend justice by itself without any consideration of what comes from it (358b ff.).  Glaucon gives a speech defending injustice: (i) justice originates as a compromise between weak people who are afraid that suffering injustice is worse than doing it (358e-359a);  (ii) people act justly because this is necessary and unavoidable, so justice is good only for its consequences (story of the ring of Gyges’ ancestor, 359c-360d); (iii) the unjust person with the reputation for justice is happier than the just person with the reputation for injustice (360d-362c).

Adeimantus expands Glaucon’s defense of injustice and attack on justice by asserting: the reputation of justice is better than justice itself, so the unjust person who is able to keep the reputation of being just will be happier than the just person; discussion of various ways that the unjust can acquire the reputation for justice (362d-366d).

Socrates is asked to defend justice for itself, no…………..