Rationalism is the term used to describe writers and philosophers who privilege scientific reason and logical thought over and above everything else. The Rationalists in America were very much influenced by the Enlightenment that was happening in the 18th century in Europe. However, unlike the Enlightenment’s great thinkers and philosophers, the Founding Fathers of America attempted to put the philosophy of the Enlightenment to actual use. This is most likely directly related to the fact that American Rationalists evolved out of the tradition of Puritanism, not the class structure and Feudalism of Europe.
Rationalism is based on the concepts of logic and scientific reasoning, but the Rationalists themselves were not scientists as we think of the term. Science in the 18th century was not a profession it was a hobby. Wealthier Americans who had gone to the universities went back to their homes and began to categorize the flora and fauna of their home regions. Not because they were biologists, but because somebody had to do it, and it might as well be them.
Most American science was based on figuring out how to do things more efficiently (and profitably). Rationalists used the scientific method of identifying the problem, hypothesizing a solution, and testing the hypotheses until you reach a satisfactory conclusion. Benjamin Franklin became one of America’s great scientists, but almost everything that he invented (bifocals, lightning rods, Franklin stoves, etc) were designed to solve specific problems. He was not just “puttering around” or doing experiments willy-nilly.
One side effect of rationalism was that it led to questioning of everything. Instead of following tradition simply because it had always been done that way, rationalists questioned the traditions and made the necessary changes based on what they observed. Thus, because of the rationalist worldview, instead of automatically setting up a government like every other government in Europe, the Founding Fathers asked what sort of government made the most logical sense.
One other significant element of rationalism is their view of religion. As is often pointed out in church/state discussions today, the Founding Fathers made reference to God on a regular basis. However, their view of God and religion was NOT the same as the Puritans. The vast majority of the Founding Fathers and other leading Rationalists were Deists. They believed in God, but it was not a God who was involved in human affairs. The metaphor that was commonly used was the God was like a Clockmaker who had made the universe, wound it up, and was letting it wind down. By referencing God, they were referencing the very notion of a rational, planned universe. Man’s role was to try to make proper use of what God had created, whether it be in political structures, daily life, or even scientific observation. Studying the world scientifically wasn’t in defiance of religion, it was to better understand what God had created.
This is just a very simple beginning explanation of Puritanism. Check out these websites if you want to know more: