Plato and the Idea of Justice

Justice means being the best one can be or reaching one’s highest human potential.


The theory of the state or the Ideal State in Plato’s Republic culminates in his conception of justice. In other words, the central question of the Republic was the meaning of justice or right conduct or morality. Plato critically examines the existing conceptions of justice and gives his own concept of justice in his Republic.

The School of Athens.

Contemporary Theories of Justice and Plato’s Arguments

Basically there are three prima facie theories of justice by Cephalus, Thrasymachus and Glaucon. And, Plato, in his arguments, speaks through Socrates.

Cephalus’ Theory of Justice: Traditionalism

Cephalus and his successor, Polemarchus‘ view on justice represents the traditional ideas of morality of ancient Greece. Cephalus defines justice as telling the truth, and paying one’s debts.”

However, Socrates points out that, in some cases, it might be harmful to speak the truth or return one’s belongings. It may not be just to return weapons to a mad person, or to tell the truth when it is better to conceal it. It should be understood that justice has to be beneficial, or at least, not harmful. Thus, it is suggested that Cephalus’ concept of justice will not be acceptable.

To this, Polemarchus, Cephalus’ son, defines justice in a slightly altered form. By justice, Polemarchus means “giving each man his due” or what was fitting.” Justice is here assumed as an art- an art which gives “good to friends and evil to enemies.”

Socrates dismisses this view and argues that helping friends may also involve ignoble acts like stealing and telling a lie. Secondly, the idea of being good to friends and bad to enemies is difficult to apply. What we think as a friend might be a friend in seeming only, but an enemy in reality. Thirdly, Plato argues that justice is a quality of the soul and a habit of the mind. Any person who has once attained it can act only in one way, which can never be the way of injuring others. A just person should not harm anyone, whether friend or enemy.

Thrasymachus’ Theory of Justice: Radicalism


Thrasymachus is treated as the spokesman of the Radical Sophists. He defines justice as “the interests of the stronger party or the ruler.” In other words, might is right. Each type of government enacts laws that are in its own interests. Democratic states have democratic laws, tyrannical states tyrannical laws, and so on. Rules are always defined by the stronger party and those who deviate from these rulers are punished as lawbreakers or ‘wrongdoers’.

To this, Socrates responds that rulers  might make mistakes by not being able to identify their interests and frame laws contrary to their advantage.

At this point, Clitophon suggests to define justice as “whatever the strong believe to be in their interest.” But, Thrasymachus rejects this idea and replies that rulers are always right. He defines justice as another’s good. He goes further to say that injustice is better than justice, the unjust man is a wiser man than the just.

Socrates, however, argues that justice is not the advantage of the stronger, because the rulers’ duty is to serve the interests of the people. Ruling is an art and a ruler’s only aim is the well being of the citizens.

Insisting on his doctrine of specific functions, he further points out that the virtue or excellence of anything consists in its discharge of its appointed function. Therefore, a ruler, wise, good and knowledgeable cannot be selfish and will serve for the welfare of the people.

Thrasymachus’ definition that justice is the interest of the stronger could not be refuted by Socrates and the fact remains that it is the strongest who sets the standards in society.

Glaucon’s Theory of Justice: Pragmatism

Converse to what Thrasymachus has said about justice, Glaucon defines justice as the interests of the weak. He contends that justice is an artificial thing, the product of convention.

Glaucon, along with Adeimantus, argues that individuals are not willingly just, but out of necessity, in which case injustice is better than justice. They consider justice to be a contract between the strong and the weak. Justice is a mean or a compromise, between the best of all, which is to do injustice and not to be punished, and the worst of all, which is to suffer injustice without the power of retaliation. Justice is the fears of the weak rather than the appetites of the strong.

To this, Socrates points out that justice has to be universal and should be at the interest of all and not for few. When insisted upon, he says that justice exists both in the State and in the individual, but it exists on a larger scale and in a more visible fashion in the State. He gives the example that anything written in  big and bold, in contrast to written in small size, would receive more attention. Thus, justice has to be understood in the State first before it is to the individual.

Plato’s Idea of Justice

Having a different conception from the existing views and revolutionary in approach, Plato explains his conception of justice in the following arguments:

Justice in the State and IndividualAccording to Plato, states and cities arose out of two reasons- mutual need and the differences in aptitudes of individuals. He believes that an individual is an organic entity, an important part of the establishment.

By justice in the individual, Plato means that every individual is assigned a place in society according to one’s natural aptitudes and skills. A just individual is one who does his job and does not interfere in another’s share. It is the having and doing of one’s own and what belongs to oneself.

For example, an artisan will be just if he does the work of production and does not try to involve himself in political decision-making.

Plato gives three arguments in favour of what he calls a just life:

  • a just individual limits his desires, for non-satisfaction of desires lead to unhappiness.
  • only a philosopher can differentiate between the pleasures derived from the pursuit of reason, and those obtained from appetite and sensuality.
  • pleasures derived from the intellect are more genuine and comforting than those derived from senses.

Justice in the State, on the other hand, means that the society should recognise and educate every individual’s talents according to their aptitude. Justice is “one class, one duty; one man one work.”

Plato divides the functions of a society into three- ruling, defence and production, and there should not be any interference between them. For Plato, justice is the bond which holds a society together, a harmonious union of individuals each of whom has found his life-work in accordance with his natural fitness and his training.

The contemporary theories of justice have a common element: these theories have treated justice as if it is something external, an accomplishment, an importation, or a convention. What Plato argues is that justice is a virtue, a human excellence. Justice is internal and it is a human grace. For him, “justice means being the best one can be,” or “reaching one’s highest human potential,” so that the State becomes virtuous; and with individuals fulfilling their obligations to the political community and thereby serving common interest.

NOTE: I wrote this as an assignment for the subject, Western Political Thought (WPT), taught during my undergraduate in Ramjas College, University of Delhi.
The exact question for which I wrote this assignment is given below:
Write an essay on contemporary theories of justice and Plato’s criticism regarding these theories.
The grammatical tense has been changed and some small changes have been made which includes the exclusion of certain portion from the text. You can see the original unedited assignment in the form of gallery towards the end of the article.


Subrata Mukherjee and Sushila Ramaswamy, A History of Political Thought: Plato to Marx.

Ernest Barker, Greek Political Theory: Plato and His Predecessors.

Shefali Jha, Western Political Thought: From Plato to Marx.

George H. Sabine, A History of Political Theory.

Class lectures and notes.

Conceptual bits from:

Bertrand Russell, A History of Western Philosophy.

Richard H. Popkin, Columbia History of Philosophy.

Jostein Garrder, Sophie’s World (Novel).

The Original Assignment

Published by

Heigrujam Premkumar

I love to read. I love to write. On all things I am passionate about. Tweet me at @heigrujampk

Leave a Comment

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s