The answer is the society.
Economics is focused on the problem of the society which is created by a world with limited resources and people with unlimited needs and wants.
The idea of the social contract theory comes from Jean Jacques Rousseau's book the Social Contract but one of the most prominent philosophers that discussed the idea was Thomas Hobbes who describes social contract as a contract between the individuals and the government, whose authority comes from the people. The people would cede some of their rights to the government for protection and the sovereign is bound by the wishes of the people as it is they that govern his decisions.
So the question of John Stuart Mill relate to the theory of the social contract very much. The main issue is exactly how many rights would the people have to cede and what would be the right balance between the independence and the obedience to the social contract. That is a very thin and tricky line to navigate.
Answer:
James Madison was the 4th president
Explanation:
I know this because I searched the order of presidents from the first to now the 4th one one James Madison. I hope that this helped you! :)