This is pure abstraction with no relationship to reality. The opposite is shown to be true in reality.If I can freely kill you on account of misconduct toward me you will not misconduct yourself, you will absolutely maintain civility. . . .
People can be notoriously biased and jump to conclusions. When the former Yugoslavia broke apart, all kinds of people who had lived together peacefully suddenly got paranoid. Some had intermarried, many lived in the same apartment buildings. But suddenly, nationalistic fears were roused; and people grew suspicious of other nationalities. The idea became it was safer to shoot them before they could shoot you, and every act of violence added to the paranoia.
Cultures without governments that look after the rights of their citizens are frequently tribal. If your tribe is more powerful and the neighboring tribe has assets you want, you go kill the people and seize their assets. With no government at all, anyone who wanted your house and land could come kill you and take them.
The United States went a period of something similar in some areas where government was weak -- where families would fall into feuding. The feuds would go on and on.
I subscribe to John Locke's idea on government. We start with the individual's right to own property and to defend himself. In practice that sounds great, but it doesn't work that well; so people form a social contract to give up their right of self defense because a government can do it better. A government should exist then, not to oppress people, but to protect them from aggressive neighbors within the country and from military aggressors. If it does this well, people are happy. If it does it poorly, people will become dissatisfied and want to revolt.
In theory courts can be less biased than individuals who are involved in conflicts. Both parties in a conflict think, "I'm right and he's wrong." Both are apt to be biased in favor of their own interests. Again in theory courts can be less biased; but we see in practice they often demonstrate this bias or that. That kind of breakdown in the impartiality of the courts also leads to discontent with the result that people often feel they won't find justice in the courts, encouraging them to take justice into their own hands.