The political theorist famous for the concept of the "social contract" is Jean-Jacques Rousseau. In his seminal work "The Social Contract," Rousseau posits that individuals enter into an implicit agreement to form societies and governments to protect their rights and promote mutual benefit. He argues that legitimate political authority arises from the consent of the governed, emphasizing the importance of popular sovereignty. Rousseau’s ideas have profoundly influenced modern political thought about liberty, equality, and the role of the state, forming a foundation for later democratic theories and systems of governance.