Not every unjust action makes the one who does it necessarily be an unjust person. So, for instance, a person might sleep with the spouse of another, and know that it was wrong, but they are carried away by passion, and do not make a choice that is cold-blooded. While it still is bad, it would have been worse if they had acted in a cold-blooded way. So, while this person does act unjustly, still they are not necessarily an unjust person. Likewise, someone may at one time steal something, but that does not now mean that the person lives out all their days as a thief.

Now, it may be plain to us what would be just (e.g. what would make for a fair deal), but making justice be done is another thing altogether. We have to deal with human beings, and so we must look to what makes for political justice (and not some ideal, or absolute justice). By political justice, we mean the justice that comes from just laws and just rulership.

There can be no justice without law. Justice in a society comes from its laws being enforced. This species of justice is called legal justice. Legal justice involves taking the laws on the books and the cases that come to court, and deciding right from wrong, what is just and unjust. And the reality of the world is that justice only exists between people that are equals and have the power to do unjust acts to each other; and if there were no political justice to hold the city together, there would instead be injustice between the people, and that would drive them apart.

When there is injustice between people, they do unjust acts to each other. (Though just because an unjust act occurs once, that does not now necessarily mean that there is injustice between people. Injustice between people means that they never do right by each other, but are instead always looking to prey upon each other.) The unjust action we are talking about is taking too much for oneself and not giving other people their due. This why people hate tyrants, because that is what tyrants do: set themselves up in a position of power, and then use force to take what should belong others.

What people want is for there to be law and order. It should be the law that rules and the person in office that upholds the law. Such people are, again, called magistrates, and they have a lot of power to do good or ill for a society in their decisions. Just laws, by themselves, are not enough to make for a just society. In order to have a just society, we must have just outcomes. And in order to have just outcomes, we must have someone actually doing the just actions. Now part of that will be the citizens following the laws, but that is only part of it. The rest will be the cases where someone breaks the law or cases where it is not clear how the law covers the matter in question. And so we need rulings, and we need magistrates: just rulings made by just magistrates.

But what makes a magistrate make a just ruling? We can tell that it does not come from giving people what they want because they want it. It does not come from favoritism or being sentimental, and certainly not from bribery either. Just rulings come from magistrates who rule by reason. Such magistrates use their minds, think things through carefully, figure out what would be the just thing, and then render their verdict.

Again, it is the magistrate that is supposed to make sure that justice is done. But if the magistrate is just, then that means that the magistrate will not get the gains that they would have got if they were instead a tyrant, and took from people. Really, a just magistrate works for the benefit of the community; everyone gains from being able to live in a just society. The magistrate should gain as well from for all the time and effort that they put into their office. And so, a salary is given to the magistrate, and honors and privileges. And yet this is still not enough for some people, and they make themselves into tyrants.

There is a difference between the justice that exists among fellow citizens and that between parent and child or master and slave. Now, justice is another's good. And there are injustices where one person's loss is another's gain. But is it possible for one and the same person to do an injustice to themselves and both gain and lose from it? No. A person cannot steal from themselves and a person cannot act liberally toward themselves. Well, slaves and children (until they are grown and are their own person) are considered to be a person's property, and the property of a person is considered to be a part of that person. No one chooses to hurt themselves, and so no one would choose to do ill to slaves or children. And this is not to say that one may do anything one likes with them, but rather that the justice that does exist is not the same kind as political justice. This justice, instead, comes from one taking care of what is one's own.

But the justice between citizens comes through the law; there is no law between master and slave. It is true that some citizens rule and others are ruled, but this is done by law. We could say that the justice between husband and wife is more like this (viz. the justice between citizens), but even this household justice is not the same as political justice.