1. Plato’s Republic Introduction, Polemarchus, and Thrasymachus
陳斐婷 清華大學哲學研究所專任助理教授

2. Plato’s Republic Introduction

3. Change the world for the better
Throughout his life he hoped, with varying degrees of optimism, that philosophy might change the world for the better. His writing reflect the ups and downs of this belief. The Republic is often thought to represent a high point of optimism, indeed to be a blueprint for a coming society; but in fact Plato’s attitude is not so simple.
As we read the book, we can hardly avoid asking various pertinent questions. Does Plato seriously believe that philosophers can be rulers? How realistic are his proposals for their education meant to be? What is the point of their highly theoretical knowledge, and how is it to be applied in practice?

4. Plato’s disillusionment
Thirty oligarchs in 404BC when Athens surrendered to Sparta
The death of Socrates in 399BC, ostensibly for corrupting the young by his teaching, but really because he had been associated with some of the most notorious enemies of the democracy.
Three visits to Sicily, in 387, 367, and 362. The last two visits to Dionysius II, the new ruler of Syracuse. If Plato did attempt to do anything like realize the plan of the Republic, it failed completely.

5. νόμος vs. φύσις
Plato’s dialogues are nearly all set in the late fifth century (much earlier than the time of their composition).
Great attention was devoted to the question of the roles in human life of nomos (νόμος) and phusis (φύσις)—usually translated ‘convention’ and ‘nature.’
The movement of the sophists who nearly all taught the skills of speech-making and debating necessary for someone aiming at a public career.
In Plato’s view the sophists’ influence tended to produce relativism and skepticism about questions of value, and to replace the question of how to live a good life with the question of how best to get on in the world.

6. The challenge of Thrasymachus
The job he saw as primary was that of showing, against the sceptics, that there are objective moral truth.
The bulk of the book is put forward as an attempt to answer Thrasymachus, who claims that the life of injustice is more worthwhile than the life of justice. Thraysmachus derides conventional moral standards.
Glaucon and Adeimantus reformulate this view as the challenge Socrates has to meet.

7. δικαιοσύνη δικαιοσύνη (righteousness, justice)
Does the concept of justice really correspond to that of δικαιοσύνη? Does the Republic give us a theory of justice in the way that, for example, Rawls’s A Theory of Justice does?
δικαιοσύνη, it is sometimes claimed, can cover a wider area than justice, and be used for right conduct in general. Plato appears to support this idea when he makes Socrates at 352d describe the search for justice as a search ’for the right way to life.’ Hence it is often suggested that δικαιοσύνη should be translated as ‘righteousness’ or the like, and that it corresponds more closely to ‘morality’ than to ‘justice.’

8. Two senses of δικαιοσύνη
Justice as a particular virtue rather by means of the notions of equality and of keeping to what is one’s own. The vice it is opposed to is called πλεονεξία—having and wanting more than one is entitled to. The ordinary view, in the person of Polemarchus, is that justice is giving everyone what is owing, that is, that is due or appropriate.
Justice as morality, for the area of practical reasoning carried on by an agent which is concerned with the best way for a person to live.

9. The narrow sense of δικαιοσύνη
In the Republic itself, the challenge that Socrates is set at the beginning of Book 2 concerns the narrow notion: Thrasymachus had claimed that it is better to be unjust, meaning by this, having more than one’s rightful share, and Glaucon renews the point in the context of equality and fairness, justice and injustice being characterized as abstaining, or not abstaining from what is another’s (360b,d). And Plato’s own analysis of justice does not let it usurp the role of virtue as a whole; it is carefully distinguished from another social virtue, moderation, which appears to cover the same ground.

10. The broad sense of δικαιοσύνη
By the time we get to the end of the Republic we have had more than a theory of justice in the narrow sense. We have been told a good deal about the good life in general. This is because Plato has what can be called an expansive theory of justice. He does not think that matters of what is just and unjust can be settled in a way which will leave untouched other central moral questions that arise in a society.
A society is unjustly run if it fails wider moral requirements, for example if wealth is honored more than desert. Hence the needs of justice require wholesale moral reform.

11. The broad sense of δικαιοσύνη
Justice is a virtue which regulates our relations with others. An expansive theory of justice will therefore make our relations with others central to moral life, and tend to stress the individual’s relations in society as partly constitutive of moral attitudes.

12. Plato’s Republic Polemarchus and Thrasymachus

13. Polemarchus Justice is giving a man his due (e.g., good, harm).
Thrasymachus (1) Justice is merely the advantage or interest of the stronger. (2) Justice is obeying the laws. (3) Justice is “another’s good,” i.e. behavior which benefits another, whereas injustice benefits the agent.
Is Thrasymachus consistent in his view?

14. Justice is the interest of the stronger
338c Justice is merely the interest of the stronger.
342c-d Then medicine does not consider the interest of medicine, but the interest of the body?  True, he said.  Nor does the art of horsemanship consider the interests of the art of horsemanship, but the interests of the horse; neither do any other arts care for themselves, for they have no needs; they care only for that which is the subject of their art?  True, he said.  But surely, Thrasymachus, the arts are the superiors and rulers of their own subjects?  To this he assented with a good deal of reluctance.  Then, I said, no science or art considers or enjoins the interest of the stronger or superior, but only the interest of the subject and weaker? 

15. Justice benefits another, whereas injustice benefits the agent.
343c-d …justice and the just are in reality another's good; that is to say, the interest of the ruler and stronger, and the loss of the subject and servant; and injustice the opposite; for the unjust is lord over the truly simple and just: he is the stronger, and his subjects do what is for his interest, and minister to his happiness, which is very far from being their own.
Socrates’ response: government, like any other form of professional skill, has its own standard of achievement, and is not merely a matter of profit-making or exploitation.
The pursuit of self-interest or injustice pays better than that of justice.

16. Conventionalism Justice is nothing but obeying the laws.
It is misleading because it leads us into thinking that there is something over and above conformity to the laws which exists in all cases of such behavior and which has an independent value. But in fact talk about justice is really, if we look at the facts, talk about power and who holds powers.

17. Immoralism Injustice is better.
In the dialogue Gorgias, Callicles claims that by nature it is just for the strong to rule and exploit the weak; it is only by convention that it is just for the weak to restrain the strong.
Superior strength and intelligence in themselves entitle their possessor to whatever he or she can get by exploiting them. The Nietzschean view.

18. Interpretation of the transition
“But, as I see it, he is not presented as basically changing in his mind, but as being driven from a muddled and misleading formulation of what he holds to a clearer and more defensible statement which reveals the core of his position more obviously. His real position is the immoralist one, but he begins by stating it in a confused way…” (Julia Annas, 1981, 37)