Rousseau's Social Contract
One of the most important books on politics written during the Enlightenment was Rousseau's Social Contract (1762). The basic idea is that people, as individuals, have natural liberty, but they cannot preserve that liberty on their own. So they agree to live under the authority of a government, in exchange for the security that the government will find a way to protect their liberty with laws. The question, then, becomes to decide how to make those laws so that they assure that all citizens will have liberty and be free.
For this to happen, he wrote, government would have to be based on something other than the will of the king (as in absolutism) or even the will of a majority of the people, as expressed through elections (as in, say, Britain). Instead, such a government had to be governed by a consensus of everyone in the society, which he called the general will. It has generally been thought to be a radically democratic idea because it means that not only does everyone have the right to vote but everyone has the right to win every vote and thus be fully free!!
Only a society in which everyone was truly virtuous would be able to achieve this ideal of reaching a consensus on all important matters. But what if most people agreed but a few did not? Should the society decide to adopt the "will of the majority" and hope the minority agrees to follow that law? (This of course is the basic principle of democratic government, as ordinarily understood.)