Modern constitutional democracy and republicanism were developed during the 17th and 18th century by Enlightenment authors (Locke, Rousseau, and Montesquieu). T

Modern constitutional democracy and republicanism were developed during the 17th and 18th century by Enlightenment authors (Locke, Rousseau, and Montesquieu). They setup some fairly novel concepts for enabling representative government, including the idea that rights derive from the principle of authority (Locke) and the idea of separation of powers to limit authoritarianism (Montesquieu). Ideal is hard to quantify here, but if we focus on maximizing representation and effectiveness at the same time, then it's fair to say that these forms of government were uniquely successful. Despite their flaws and failures, they still seem to be the best at maximizing those two variables. Prior to the U.S., people accepted Plato's sensibility that all forms of democracy devolve into authoritarianism -- which obviously is a meme that persists today. (It's worth pointing out that at the same time the U.S. was forming, France had its democratic revolution which ultimately settled into Napoleonic rule.) The racism of the Enlightenment authors I mentioned is fairly staggering. It's hard to reconcile that with their work, even at the time it was written. Despite that, America now has 100% suffrage and managed to retain its government structure (via a civil war).