If not, when did the new enlightenment come to pass? Are we smarter than the founders?
Are we smarter? Maybe not, but we (some of us) have a better understanding of what liberty and justice are.
Not "smarter," but different. Slavery is abolished, women aren't property, we have child labor laws, people are educated, etc. All of those improvements to our society would be unthinkable to the Founding Fathers. Doesn't mean it's bad.