Society can only function to the extent that people have interests in common: the end goal of any state is the common good. Rousseau argues that the common good can only be achieved by heeding the general will as expressed by the sovereign. The sovereign is inalienable: it cannot defer its power to someone else, or be represented by a smaller group. It expresses the general will, which will never coincide exactly with any particular private will. As the will of the people, the sovereign can only exist so long as the people have an active and direct political voice.
Nor is sovereignty divisible: the sovereign always and necessarily expresses the will of the people as a whole, and not of some part. An expression of the general will takes the form of law, whereas the expression of a particular will is at best an application of law. Rousseau accuses other philosophers of failing to understand this distinction. They take particular acts (administration, declarations of war, etc.) to be acts of sovereignty, and since these acts are not undertaken by the people as a whole, they conclude that sovereignty is divisible. This conclusion permits thinkers such as Grotius to then invest sovereign power in the particular will of a single monarch, thus robbing the people of their rights.
Though the general will always tends toward the common good, Rousseau concedes that the deliberations of the people do not always necessarily express the general will. He draws an important distinction between the general will and the will of all, stating that the latter is simply the sum total of each individual's desires. These particular interests usually balance each other out unless people form factions and vote as a group. Rousseau insists that no factions form within a state, and that each individual should think for himself.
While he claims that the sovereign has absolute power over all its subjects, Rousseau is careful to carve out a space for private interests as well. A citizen must render whatever services or goods are necessary to the state, but the state cannot demand more than what is necessary from the citizen. Furthermore, the sovereign is only authorized to speak in cases that affect the body politic as a whole. Cases that deal only with individuals or particularities do not concern all citizens, and so do not concern the sovereign: the sovereign deals only with matters that are of common interest. As a result, each citizen is free to pursue private interests, and is only bound to the sovereign in matters that are of public concern.
Rousseau supports the death penalty, arguing that the sovereign has the right to determine whether its subjects should live or die. His strongest reason for this position is the claim that wrongdoers, in violating the laws of the state, are essentially violating the social contract. As enemies of the social contract, they are enemies of the state, and must either be exiled or put to death. It is possible to pardon criminals, but both pardons and punishments are signs of weakness: a healthy state has few criminals.
The concepts of the sovereign and of the general will had currency before Rousseau, but not in the form that Rousseau gives them. A sovereign is the ultimate authority with regard to a certain group of people. It is the voice of the law, and all people under its authority must obey it. It is also independent of any outside influences.