Fans of the Transformers may recall the "Constructicons," a group of smaller robots who could join together to form one, large robot: one Constructicon would be the left arm of this larger robot, another would be the right leg, and so on. This is the same sort of principle that Rousseau is applying here. Individual citizens have a life and a will of their own, but in binding themselves to the social contract, they also become a part of the larger life and will of the sovereign. Like the large robot formed by the individual Constructicons, the sovereign is not simply the sum total of its individual members, but is treated by Rousseau as an individual itself.
Just as each part of the body is responsible for working with the rest of the body and ensuring that it functions smoothly, every individual is committed to the sovereign. However, the sovereign owes nothing to its subjects in the same way as a person owes nothing to his pinky finger or his left knee. We try to keep our fingers and knees from harm not because we are bound by some sort of contract, but because our fingers and knees are a part of our body, and in harming them we would be harming ourselves. Similarly, the sovereign owes nothing to its subjects, but will nonetheless work to ensure their well-being.
Rousseau's communitarian point of view can be understood by referring to his contrast between the state of nature and civil society. The freedom we have in the state of nature is the freedom of animals: unconstrained and irrational. By entering into civil society we learn to restrain our instincts and to act rationally. By leaving our natural state of do-as-you-please, we come to recognize that we need reasons to justify our actions. This rationality is what defines our actions as moral. Rationality and morality distinguish us from animals, according to Rousseau, so it is only by becoming a part of civil society that we become human. The community is superior to the individual because it is a community of humans and the individual is just a solitary animal.
Rousseau contrasts the physical freedom of following our instincts with the civil freedom of acting rationally. In civil society, we learn the freedom of self-control. Thus, according to Rousseau, we do not give up our freedom by binding ourselves to the social contract; rather, we fully realize it.
This background may help us understand Rousseau's disturbing claim that recalcitrant citizens should be "forced to be free." If we only gain civil freedom by entering into civil society and binding ourselves to the social contract, any violation of that contract will also violate our civil freedom. We undermine our very rationality and morality by violating the contract that made us rational and moral. By forcing its subjects to obey the social contract, the sovereign essentially forces its subjects to maintain the civil freedom that is part and parcel of this social contract.
If you find yourself uncomfortable with all this, you are not alone. Some commentators have gone so far as to accuse Rousseau of totalitarianism, though this is a bit far-fetched. However, his notion that the community comes first and the individuals in it second is contrary to the notions of individual liberty that characterize most modern democracies, the United States in particular.
To a large extent, Rousseau is motivated by the fear that in modern states where citizens are not actively involved in politics, they become passive witnesses of the decisions that shape them rather than active participants. The civil freedom that comes through active political participation is largely the freedom to determine one's own fate.
Still, if the ##French Revolution##, is any indication, Rousseau's doctrines can be misused. Rousseau's ideas formed an ideological backbone for the French Revolution, but as the evolving chaos of the Revolution so clearly indicates, it may not always be clear how the general will is determined, and in such instances terror and the guillotine can become an attractive means of forcing people to be "free." Though to lay all the extreme excesses of the French Revolution at the feet of Rousseau is unfair, some critics have noted that while Rousseau is usually quite careful in distinguishing between force and right, he blurs that distinction dangerously in saying that people must be "forced to be free."