Benjamin Rush and his friends on human nature.

The 18th century writers explored the nature of man and decided mankind was divided into six subdivisions. Studying man from a naturalistic viewpoint raised doubts about God's primary role, a questioning totally unacceptable to Benjamin Rush. Rush considered all of mankind as originating from God's original pair, but bearing a deficiency and vulnerability from their original sin. He viewed man as a physiologist, as a materialist, and as a monist. Modifying the Scottish philosophers extensive faculty psychology, he accepted nine mental faculties and of these considered the moral sense essential. Rush and his friend, Thomas Jefferson, shared this belief which enabled them to be more optimistic than their friend John Adams who thought man to be driven by a need for distinction and thereby requiring control from a strong central government.