“Intelligent design begins with a seemingly innocuous question: Can objects, even if nothing is known about how they arose, exhibit features that reliably signal the action of an intelligent cause? To see what’s at stake, consider Mount Rushmore. The evidence for Mount Rushmore’s design is direct—eyewitnesses saw the sculptor Gutzon Borglum spent the better part of his life designing and building this structure. But what if there were no direct evidence for Mount Rushmore’s design? What if humans went extinct and aliens, visiting the earth, discovered Mount Rushmore in substantially the same condition as it is now?
In that case, what about this rock formation would provide convincing circumstantial evidence that it was due to a designing intelligence and not merely to wind and erosion? Designed objects like Mount Rushmore exhibit characteristic features or patterns 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. “
-- William A. Dembski, Ph.D.