David Hume (1711–1776) was the first philosopher in the Western tradition to construct a system of thought that had no intellectual reliance on God. His atheism was not merely a matter of personal belief, but was based on an application of skepticism to claims that the existence of God could be known by reason. Hume extended that skepticism to the nature of knowledge about the world, as well, and showed how limited our knowledge of both cause and effect, and the future, really is. He was the first, thoroughly modern, naturalistic philosopher.