INTELLIGENT DESIGN studies features of objects that signal the action of an intelligent cause. Designed objects, like Mount Rushmore, exhibit characteristic features that point to an intelligence. Such features or patterns constitute signs of intelligence. Proponents of intelligent design, known as design theorists, purport to study such signs formally, rigorously, and scientifically. Intelligent design may therefore be defined as the science that studies signs of intelligence.

Intelligent design is controversial because it purports to find signs of intelligence in nature and specifically in biological systems. According to the evolutionary biologist Francisco Ayala (2004), Charles Darwin's greatest achievement was to show how the organized complexity of organisms could be attained apart from a designing intelligence. Intelligent design therefore directly challenges Darwinism and other naturalistic approaches to the origin and evolution of life. Leading proponents of intelligent design include Michael Behe, Phillip Johnson, and William Dembski. Leading critics include...