I think decadence in the West is a result of a gradual change in the goals government pursues and the way government operates. The basis of Western Civilization, and arguably any civilization, is the rule of law. Without predictability, economic investments with long term payoffs are impossible to make. Our current prosperity began with John Locke’s idea, from his 1690 “Two Treatises on Government,” that government required the consent of the governed and that government’s purpose was to secure the life, liberty and property of the people it governed. The way Western "democratic" governments operate today is to have experts make regulatory decisions for people without their consent. Government makes people follow rules that it thinks are good for them, and redistributes property in the name of social justice, which usually means buying votes with entitlements.
English history from 1600 to 1700 was very important to the Founders who set up the United States. The Declaration of Independence was the American Colonies’ formal withdrawal of our consent to be governed by King George III. This was especially important because King George III was King of England by the Act of Settlement passed in 1701, which chose the Hanoverians over the Stuarts to be Kings of England. In other words, King George II was King of England by consent of the governed. There were several contemporary claimants to the throne of England with better rights of descent than George III.
The Constitutional requirement that the president see “that the laws be faithfully executed” was a reaction to Charles I (1600-1649) and James II (1633-1701), who ignored parliamentary laws whenever they found the laws inconvenient. The 2nd Amendment right to bear arms was an attempt to prevent military dictatorship, like the one imposed by Oliver Cromwell from 1653 to 1658.
The economic enlightenment started by Adam Smith (1723-1790), which Frederic Bastiat (1801-1850) extended, argued that economic prosperity required minimal government interference beyond a stable legal framework to enforce commercial contracts. Common practice at the time they wrote was for the government to grant huge monopolies to private companies, like the British East India Company, which was granted India. Government granted monopolies then are very similar to crony capitalism today. Smith and Bastiat argued against government granted monopolies. They said the economy would do better without heavy handed government interference.