The concept of justice, or law, comes into being as soon as any kind of social relationship is created. For example, Robinson Crusoe, living alone, had no need for laws. There was no one with whose rights he could interfere by exercising his own freedom of action. But as soon as his man Friday appeared, there was a chance of conflict between his rights and those of his servant. Law then became necessary.

The purpose of law is to set down and to make clear the social relationships among individuals and, between the individual and Society. It tries to give to each person as much liberty of action as fits in with the liberty of others.