The influential philosopher known for his work on social contract theory during the Enlightenment was Jean-Jacques Rousseau. In his seminal work, "The Social Contract," published in 1762, Rousseau introduced the concept that legitimate political authority derives from a social contract agreed upon by the governed. He argued that individuals achieve true freedom by participating in the collective will or "general will" of the community. Rousseau's ideas significantly impacted political thought, inspiring later revolutions and movements advocating for democracy, individual rights, and social equality, shaping modern democratic theories and practices.