How did the ideas of enlightenment thinkers lead to democratic thought and institutions?

"The ideas of economists and political philosophers, both when they are right and when they are wrong, are more powerful than is commonly understood," wrote John Maynard Keynes in 1936. "Indeed the world is ruled by little else."

Enlightenment philosophy and economic theory had a particularly direct influence on the establishment of democratic government, because several of the Founding Fathers of the United States were quite well-versed in what was at that time absolutely state-of-the-art thought. It is not simply coincidence that the Declaration of Independence and Adam Smith's The Wealth of Nations were published the same year; Thomas Jefferson had very likely read some of Smith's earlier work by the time he was writing the Declaration. The Founding Fathers were also heavily influenced by John Locke, Immanuel Kant, Montesquieu, and Jean-Jacques Rousseau, and you can see some of this influence even in the wording; Locke's "life, liberty, and property" led directly to Jefferson's "life, liberty, and the pursuit of happiness".

While it is wrong to lionize the Founding Fathers and treat them as if they were infallible (they assuredly had many flaws, not least their use and endorsement of slavery), there really is something quite remarkable about the founding of the United States, different from almost every other nation that came before. Most countries came about either organically over centuries of people sort of living together and eventually thinking of themselves as the same, or suddenly and violently by the conquering of one group of people by another. The US separated from Britain violently to be sure; but once it had, the nation that was constructed was not made simply to advance the interests of the leaders of the revolution (as most revolutionary governments are, even today). Instead, they literally sat down together and asked the question: "What would be the greatest kind of government?" They argued and debated over this question for years, drawing from the work of the best philosophers and economists in the world to determine the answer. When they had finally reached some sort of consensus as to what the greatest kind of government would be, they made that government. They consciously set out to make the best nation they could, and applied the best knowledge available in order to do so.

This was a turning point in human history. Monarchy, oligarchy and depotism had been essentially the only major forms of government (even what they called "democracy" in ancient times was really aristocracy), but from that point forward began to be replaced by more and more pluralistic and democratic governments. The process is far from complete, of course; but it all started at that moment near the end of the 18th century, and we owe much of its success to the brilliance of Enlightenment thinkers.