The key principle established by Enlightenment thinkers that influenced modern democracies was the concept of individual rights and liberties. Enlightenment philosophers like John Locke and Jean-Jacques Rousseau emphasized ideas such as the social contract, which suggested that governments exist to protect the rights of individuals, including life, liberty, and property. This foundation influenced the development of democratic principles, advocating for representative government, the rule of law, and the idea that legitimate authority derives from the consent of the governed. Enlightenment ideals significantly shaped modern legal and political systems around the world.