Only A Theory: Evolution and the Battle for America's Soul is a 2008 book by the American cell biologist and Roman Catholic Kenneth R. Miller. In the book, Miller examines the battle between evolution and intelligent design (ID), and explores the implications of science in America. The title of the book comes from a misconception of what "theory" means in the context of science and evolution. On June 16, 2008 Miller was interviewed on The Colbert Report discussing the book.