Final answer:
Rousseau supported his thesis in 'The Social Contract' by advocating for a society where the government upholds the collective freedoms based on the general will of the people, as opposed to being ruled by an elite minority or absolute monarch.
Step-by-step explanation:
Jean Jacques Rousseau developed and supported his thesis in "The Social Contract" by proposing a social contract theory that emphasized the general will of the people. He challenged the absolute power of monarchs and critiqued earlier social contract theories, positing that the government must derive its legitimacy from the will of the people, rather than the whims of an elite minority or absolute ruler. Rousseau contended that individuals surrender certain rights to create a society where their collective freedoms are secured and protected by a government that serves the common interest. Through this theory, he advanced the idea that if a government fails to protect the rights and freedom of its people, it loses its legitimacy.