Intelligent Design begins with the observation that intelligent causes can do things which undirected natural causes cannot. Undirected natural causes can place scrabble pieces on a board, but cannot arrange the pieces as meaningful words or sentences. To obtain a meaningful arrangement requires an intelligent cause. This intuition, that there is a fundamental distinction between undirected natural causes on the one hand and intelligent causes on the other, has underlain the design arguments of past centuries. Throughout the centuries theologians have argued that nature exhibits features which nature itself cannot explain, but which instead require an intelligence over and above nature.
Design arguments are old hat.
Indeed, design arguments continue to be a staple of philosophy and religion courses. Though intuitively appealing, Paley's argument had until recently fallen into disuse. This is now changing. In the last five years design has witnessed an explosive resurgence. Scientists are beginning to realize that design can be rigorously formulated as a scientific theory.