The social contract gives life to the body politic, but the law carries out the general will. According to Rousseau, a law is a decision that considers the state as a whole, and cannot be made with particular individuals in mind. For example, the law can create a royal government and a hereditary line of succession, but it cannot elect a royal family. The right to appoint political leaders is an executive power.
Because the populace often does not know how to pursue the common good, Rousseau asserts that there must be a guide to help the people in making the law. This guide, who Rousseau calls the "legislator," ensures that the law supports the preservation of the state. The legislator protects the law from being manipulated by private wills, and also aids the people in weighing the short-term benefits of a decision against its long-term costs. The legislator must thus be an extraordinary person in many respects. He must be extremely intelligent and able to resist the passions of the people while still taking an interest in their happiness. He must also be able to consider the present and future when making the law. The legislator is in a position to transform human nature, to substitute a moral existence for a physical one in the state of nature, and to strengthen the power of the state. Although the legislator is of a superior intellect, the people must approve his proposals before they become laws. The people cannot give up this legislative right, because only the general will can bind private individuals.
Because sovereignty remains with the people, the legislator must make the law comprehensible to the masses and must compel the people to obey the law without using violence. For this reason, lawgivers throughout history have referred to a divine authority to persuade people to support the law. Rousseau claims that religion and politics do not have the same purpose, but that in the beginning stages of a nation, religion can serve as a powerful political tool.
Rousseau begins Chapter VI by defining a law. A law is a decision made by the entire populace that affects the entire populace. In the American political system, the Constitution is a group of laws. A decree is different from a law in that it considers particular groups or individuals. The appointment of a political leader or the punishment of a specific criminal is a decree. Rousseau's definition of law answers many of the questions that political philosophers have raised throughout history. It is no longer relevant to determine who should make the law, because it is defined as an expression of the general will, nor can it be argued that a prince is above the law's jurisdiction because he is a member of the state. Furthermore, the law cannot be deemed unjust, because the people are its author.
Although Rousseau gives legislative power to the people, he has several concerns about them exercising sovereignty. He believes that the common man can be shortsighted, is easily manipulated, and is often unaware of his own needs. The legislator helps to correct the flaws of a popular, legislative process while keeping sovereignty with the people.
For Rousseau's political society to function, citizens must prioritize the general will over their private interests. This is a very difficult demand, and Rousseau acknowledges that a legislator will have to help the people pursue the common good. Rousseau describes the legislator as having almost divine qualities. He must have the intelligence and persuasive abilities required to effect moral change in the state so that citizens will of others before themselves. Many critics of Rousseau's political theory have focused on the impossibility of finding such a legislator.
It is unclear whether Rousseau believes that the people can handle the demands of lawmaking without the legislator's guidance. The legislator helps the people to weigh short-term benefits against long-term risks. He also gives lawmaking a sense of time and place, and prevents private interests from the distorting the articulation of the general will. These are all crucial functions of the legislative process, and without the help of the legislator, it would be very difficult to preserve the state.
Rousseau believes very strongly in the power of the laws. Laws transform human nature by substituting natural freedom for civil freedom, and by making the individual a part of a larger whole. Whereas the state of nature allowed man to do whatever he wished, laws give him a sense of civic duty and morality.