In the American founding era, most of the leading thinkers were rationalists. This means that they believed in reason as a top method of determining truth. Note that the general concept of reason has changed since then. 

When most people think of reason today, they tend to mix it with the ideas of logic, science and determinism. In the American colonial and early republican era, this was not the case. 

The term "science" was often used to mean general thinking and the idea of learning, and in this sense it coincided with the rational perspective. 

But today's technical science, based on a general consensus of experts along with the empirical use of the scientific method, is quite the opposite of the rationalist viewpoint. 

And logic, which is actually a branch of mathematics rather than philosophy, is very different than reason.