by Todd Elder at Exploring Creation
The Intelligent Design concept is a relatively recent idea in the creation / evolution debate. However, its base goes back to the teleological 'Arguments from Design' that were created in the late 1700's in an effort to prove the existence of the Almighty. Officially, the Intelligent Design movement does not take a stand on creation nor is it concerned with a literal interpretation of the Scriptures. Thus, for example, it accepts the theory of long ages for the earth's existence. One difficulty of Intelligent Design is that, of itself, it tends to be more of a concept than a testable scientific theory.
There are many common examples of intelligent design that are used as examples. The watchmaker example uses the intricate gears and parts of a watch that function together to accurately measure time as something that would not happen by chance or by small changes by natural processes. The faces of the presidents on Mt. Rushmore are shown to be by the work of man and not by any erosional process. This same idea is extrapolated into the intricate workings of the universe and to living creatures and states that such systems show great amount of design and function and therefore must have had a designer.
The idea of Intelligent Design has been heavily linked to the theory of irreducible complexity. This theory states that complex systems with inter-related parts or functions could not have arisen piece by piece but must have been made or created as a complete unit.
When confronted with this, evolution theory came back with its own ideas on how even complex systems might be able to evolve piece by piece. These include the self-organizing nature of biochemical systems, redundancy of organic structures, and versatile exploratory processes.