Enlightenment thinkers such as Thomas Paine, Jean Jacques Rousseau, and Montesquieu developed governmental theories.
These governmental theories such as 'social contract', 'natural rights', and 'separation of powers' all influence government systems in modern times by providing a pathway, or base, for the ideas presented in our U.S. Constitution.
It is suspected that the founding fathers borrowed many ideas introduced in the Enlightenment -- For instance, separation of powers was an idea developed by Charles Montesquieu. It stated that political power should be separated amongst multiple so that no one could assume complete power over government. This idea was borrowed and is the basis of our U.S. government today.