Initial interaction with Thrasymachus.
Plato shows his distaste for Sophists and Thrasymachus himself, saying that he: "sprang upon us like a wild beast as if he wanted to tear us in pieces"
Thrasymachus criticises Socrates' dialectics "Socrates can play his usual tricks, never giving his own views and when others give theirs criticising and refuting them" and "this is the wisdom of Socrates: he won't teach anyone anything, but goes round learning from others and is not even grateful"
Socrates retorts with sarcasm "you'll see in a moment how ready I am to praise a good answer, for I'm sure the one you're going to give me will be good"
Thrasymachus eventually says his thesis, that "justice or right is simply what is in the interest of the strongest party"
Socrates takes his meaning literally "Polydamas the athlete is stronger than us" and Thrasymachus clarifies that ""right" is the same thing in all states, namely the interest of the established government". This pedantic correction isn't really an objection to his argument, it just attempts to undermine Thrasymarchus himself.
Socrates first criticism of Thrasymachus
Thrasymachus admits that rulers "are, of course, liable to make mistakes"
Socrates presses on, saying that "if they do it well the laws will be in their interest, and if they do it badly they won't" and therefore "it is right not only to do what is in the interest of the stronger party but also the opposite" because "rulers mistakenly give orders that harm them".
For example when Blair declared that he would send troops into Iraq (which can be argued to harm him, given that half of Britains want him to be tried as a war criminal), everyone should have done the opposite.
Socrates ends the dialogue concluding "my dear Thrasymachus...it must follow that it is "right" to do the opposite of what you say is right". This is a fairly successful correction because it undermines all of Thrasymarchuses argument, and it appeals to our experiences of the world, as no ruler is actually infallible.
Socrates concludes that "at this stage of the argument it was obvious to everyone that his definition of justice had been reversed"
Thrasymachu's goes into a long speech typical of Socrates' stereotype of sophists claiming that "in any business relations between them you won't find the just man better off at the end of the deal than the unjust" and that "you can see it most easily if you take the extreme of injustice and wrongdoing which brings the highest happiness to its practitioners and plunges its victims and their honesty in misery". He proposes "tyranny" and "wholesale plunder, sacred or profane, private or public" shows the that "injustice, given scope, has greater strength and freedom and power than justice". Tyrants appear to be in a far better place than the just. This "proves" his argument that "justice is in the interest of the stronger party, injustice the interest and profit of oneself".
Despite this Socrates argues that "you have not convinced me" because even a tyrant wants his society to progress: "the shepard's skill is devoted solely to the welfare of his flock" and that "no profession or art or authority provides for its own benefit". For example, looking after the shepards sheep would lead to the greatest profit for the shephard. Socrates' is more successful in proving that justice is not "in the interest of the stronger party" than refuting Thrasymarchus' claim that "injustice is a particular excellence of the mind".
Thrasymachus' second definition and its criticism
Thrasymachus redefines a ruler as one who "makes no mistake, and so infallibly enacts what is best for himself"
Socrates shows that "each activity needs another to look after its interests" and therefore they help each other which does not make them intrinsically weak "medicine therefore looks to the interest not of medicine but for the body"
"no science studies or enforces the interets of the controlling or stronger party, but rather that of the weaker party subjected to it"
the "doctor prescribes with a view not to his own interest but that of his patient"
Therefore "no ruler of any kind...exercises his authority....with his own interest of view"
Instead "it is his interest and his subject's proper interest to which he looks in all he says and does".
Once again, Socrates' is appealing to our understanding of the world and our rulers.
Socrates second criticism
Socrates argues against Thrasymachus' decision to "rank injustice with wisdom and excellence, and justice with their opposites".
Socrates shows that "the just man does not compete with his like, but only his unlike, while the unjust man competes with both his like and unlike", meaning that he resembles "the man who has no knowledge (who) will try to compete both with the man who has and the man who has not". In contrast, the knowledgeable man does not attempt to constantly outdo other men with knowledge, whereas the unjust man tries to beat everyone. Socrates attempts to lead Thrasymachus to the conclusion that "justice implies excellence" and continues to the second half of his argument.
However, an implication is less convincing than actually "proving" whether the "man who has knowledge" is similar to the just man. Another issue with Socrates' implication is that people do compete when they have knowledge, shown in sports competitions or music competitions.
All of this means that Socrates' idea that "justice implies excellence" is not really convincing.
More convincing criticisms of Thrasymarchus
Justice appears to be good because it enables people to work together, thieves should work together because "if they wrong each other that will breed hatred and dissension" whereas they can work efficiently if they trust each other.
However, this only really shows that being just is best for society. This doesn't actually prove that justice is good in itself, simply that it has good effects. This leads onto Glaucon and Adeimantus' criticisms.
Socrates continues to show the profitable effects of justice as "the unjust man is an enemy of the gods, and the just man their friend". This is particularly true in contempary society, which could be a good criticisms of Glaucon and Adeimantus' criticisms.
Finally, Socrrates concludes that as "justice is a peculiar excellence of the mind" tend to have a better quality of life, which means that the "just man is happy, and the unjust man miserable".
This is ambiguous, and is not really proven in our world. Just because Socrates believes that justice implies excellence does not mean that excellence and justice are actually equatable.
Glaucon revives the case for injustice
Socrates, when asked, views justice "in the highest category, which anyone who is to be happy welcomes both for its own sake and for its consequences". Glaucon comments that they were "normally put into the painful category, of goods which we pursue for the rewards they bring and in the hope of a good reputation, but which in themselves are to be avoided as unpleasant". This adds the distinction that Socrates must prove that good is good in itself.
Glaucon argues that we are just because "the disadvantages of suffering it (injustice) exceed the advantages of inflicting it". Should we give all men true freedom, as in the case of Gyges and his ring of invisibility "we shall catch the just man red-handed in exactly the same pursuits as the unjust".Ultimately "the just man would differ in no way from the unjust" because "no man is just of his own free will, but only under compulsion".
Unlike in Thrasymachus' arguments, the unjust man is "if he is to be thoroughly unjust, must be able to avoid detection in his wrongdoing" so that "our perfectly unjust man may be perfect in his wickedness". The unjust man "always comes off best" especially as his sacrifices to the gods are "far better than those of the just man" so that the gods love him more than the unjust man
In contrast, the unjust man who is "to be and not to seem good" is "scourged, tortured and imprisoned" and learns that "one should want not to be, but to seem just".
Glaucon's case II
He states that people are just "not because they value justice for itself, but for the good reputation it brings", and that "wrong on the whole pays better than right".
Glaucon addresses Socrates' criticism of Thrasymarchus, that "if a man stands well with heaven there is a whole list of benefits for the pious" by mentioning how the anthropomorphic Greek Gods could be "turned from their course by sacrifice" as the "absolution of sins may be had by sacrifices and pleasant trivialities". This undermines Socrates brief defense of justice.
He also responds to the inevitable criticism that it would take time to run the facade of respectibility, and gain a reputation of justice whilst doing unjust acts by arguing that: "nothing worthwhile is easy". This has some truth, but it is still possible to respond saying that it is significantly harder for the unjust to hide their actions than for the just, with nothing to hide.
His refutations add a lot of weight to his claim that: "if I am just it will bring me no advantage...unless I also have a reputation for justice". However, his comparison between the just and unjust man has been criticsed as being excessive, or ridiculous. A man might not be "scouged, had his eyes put out..." unless in special circumstances. He would respond saying that if they had a reputation for injustice then actually they would experience these trials.
Finally Adeimantus (Gaucon and Plato's brother) adds another point to Glaucon's argument. This focuses on Socrates' argument that acting justly is somehow good in itself.
He argues that if good was intrinsically beneficial then no man would do wrong becuase "he would be afraid that by doing wrong he was doing himself a grave and lasting injury". For example, very few people know that they will experience pain if they do an action and proceed to do this action.
Socrates' could respond saying that people don't always understand the benefits of doing good (such as a clear conscience) and do bad things because of a lack of knowledge.
Adeimantus would respond arguing that the benefits of a clear conscience are those that are taught to people by society, rather than an actual benefit.
Therefore, Adeimantus poses a significant challenge to Socrates, and demands that Socrates prove that "one (act) is good and the other evil because of its inherent effects on its possessor"