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.
In Rousseau's time, the sovereign was generally an absolute monarch. These rulers assumed absolute control over their states, both property and inhabitants. Louis XIV, the archetypal absolute monarch, is rumored once to have said, "I am the state." Within France, whatever the king said was law and had to be obeyed, and no outside force could exert any influence either on Louis or his state.
Rousseau holds on to the essential notion of sovereignty--that it is a power with absolute and inalienable influence over its subjects--but rejects the idea that a single person or elite group can act as sovereign. His goal in The Social Contract is to determine how people can maintain their freedom within the confines of political association, so the idea of a single monarch with absolute power over his subjects runs totally contrary to his ideal. The only way people can be subjected to a sovereign power without losing their freedom is if they themselves are this sovereign power. Thus, Rousseau turns the idea of sovereignty on its head, asserting that the people, and not the king, are sovereign.
In the case of absolute monarchy, sovereign authority is expressed in the will of the king. In Rousseau's ideal republic, sovereign authority is expressed in the general will. Just as a king uses authority to gain what is best for him, the people acting together use authority to gain what is best for all.
The general will, unlike the will of a king, is not the will of any particular individual. In fact, Rousseau thinks it is impossible that any single person's will should coincide with the general will in all cases. Rousseau draws an important distinction between the general will and the "will of all." The will of all is simply what we get when we add up everything that each individual wants. The general will aims at the common good. Rousseau suggests that citizens should vote with the general will, and not their private interests, in mind. In modern democracies, voters tend to pursue their own interests: the rich favor tax cuts, the poor favor social programs, and so on. In Rousseau's ideal republic, each person will vote with the interest of achieving what is best for all: the rich will recognize that taxation for social programs will help those in need, the poor will recognize that lower taxes can spur the economy, and so on.
The general will and the will of all often coincide to a great extent, and Rousseau even seems to suggest that private ballot is the best means of determining both. This raises the question of how we can distinguish one from the other. The only clear indication we get is that the general will is free of factionalism. If a significant number of people band together because of shared private interests and agree to promote these interests by voting as a block, they will manage to unbalance the general will. Rather than aiming evenly toward the common good, the state will begin aiming unevenly toward the good of the most powerful faction.
In a state free of factions, the difference, it seems, rests entirely in the attitude with which citizens vote. In a healthy republic, each citizen votes with the interest of securing what is best for the state. Paradoxically, this requires that each citizen think for himself rather than consult with fellow citizens on what they think is best. A private ballot is essential to avoiding factionalism.
We should not take Rousseau's insistence that citizens disregard their private interests when voting as a sign that he disregards private interests altogether. He is quite clear that the sovereign only has authority in matters that affect and are of interest to the body politic as a whole. In these matters, it is important that citizens think of the common good rather than their own interests. However, the sovereign has no authority over matters that affect only a portion of the body politic. When dealing with matters outside sovereign authority, it is obviously important that each citizen do what he thinks is best for himself.