Wikipedia: "Liberal democracy, also referred to as Western democracy, is the combination of a liberal political ideology that operates under a democratic form of government. It is characterised by elections between multiple distinct political parties, a separation of powers into different branches of government, the rule of law in everyday life as part of an open society, a market economy with private property, and the equal protection of human rights, civil rights, civil liberties and political freedoms for all people... Liberal democracy traces its origins—and its name—to the European 18th-century, also known as the Age of Enlightenment. At the time, the vast majority of European states were monarchies, with political power held either by the monarch or the aristocracy."
Without exception, America's "Founding Fathers" were rooted in the philosophy of The European Enlightment.
Useful links:
Liberal Democracy - https://en.wikipedia.org/wiki/Liberal_democracy
The European Enlightenment and The Founding Fathers: https://www.khanacademy.org/humanities/us-history/colonial-america/colonial-north-america/a/the-enlightenment