During the eighteenth century, many educated Americans began to be influenced by the outlook of the European Enlightenment. This philosophical movement, which originated among French thinkers and soon spread to Britain, sought to apply to political and social life the scientific method of careful investigation based on research and experiment. Enlightenment ideas crisscrossed the Atlantic along with goods and people. Enlightenment thinkers insisted that every human institution, authority, and tradition be judged before the bar of reason. The self-educated Benjamin Franklin’s wide range of activities—establishing a newspaper, debating club, and library; publishing the widely circulated Poor Richard’s Almanack, and conducting experiments to demonstrate that lightning is a form of electricity—exemphfied the Enlightenment spirit and made him probably the best-known American in the eighteenth-century world.
One inspiration for the Enlightenment was a reaction against the bloody religious wars that racked Europe in the seventeenth century. Enlightenment thinkers hoped that “reason,” not religious enthusiasm, could govern human life. The criticism of social and political institutions based on tradition and hereditary privilege rather than the dictates of reason could also be applied to established churches. John Locke himself had published The Reasonableness of Christianity in 1695, which insisted that religious belief should rest on scientific evidence. During the eighteenth century, many prominent Americans moved toward the position called Arminianism, which taught that reason alone was capable of establishing the essentials of religion. Others adopted Deism, a belief that God essentially withdrew after creating the world, leaving it to function according to scientific laws without divine intervention. Belief in miracles, in the revealed truth of the Bible, and in the innate sinfulness of mankind were viewed by Arminians, Deists, and others as outdated superstitions that should be abandoned in the modern age.
In the seventeenth century, the English scientist Isaac Newton had revealed the natural laws that governed the physical universe. Here, Deists believed, was the purest evidence of God’s handiwork. Many Protestants of all denominations could accept Newton’s findings while remaining devout churchgoers (as Newton himself had). But Deists concluded that the best form of religious devotion was to study the workings of nature, rather than to worship in organized churches or appeal to divine grace for salvation. By the late colonial era, a small but influential group of leading Americans, including Benjamin Franklin and Thomas Jefferson, could be classified as Deists.