Advocates of intelligent design argue that the biological evidence presents serious problems for macroevolution. For example, all the major types of animals appeared at the same time in the fossil record, with no evidence of common ancestry--a pattern inconsistent with Darwin's theory.
They also argued that complex organs that cannot function without all their parts provide evidence for a cause having intelligence. Usually, this intelligence is attributed to God.
This may be considered an outgrowth of the concept that some biological developments are too complex to have come about without having been designed--this latter concept is known as Irreducible complexity, and the related argument from design.
Proponents of Intelligent Design point to complex biological structures such as the eye, bird's wings, the existence of mitochondria, etc., arguing that such structures could not have possibly have developed due purely to random mutations, even with the aid of natural selection. Symbiotic relationships, such as plants who can only be pollinated by a specific species of insect, which in turn can only reproduce by using the plant, could not have arisen, they argue--a typical chicken-and-egg problem. It is argued that these kinds of biological features are by their very nature too interdependent to come into existence independently through a natural process and then become as intricately intertwined.
Some Intelligent Design arguments fall to later scientific study. For example, the development of mitochondria was once puzzling, but Lynn Margulies's theory of their evolution from endosymbiotic bacteria, once rejected even by biologists, has amassed enough evidence that it is now widely accepted. Evolutionary development of such structures as eyes and wings has been simulated in computers. Studies of fig wasps have revealed how symbotic species can evolve. Most scientists assume that all "problems" that Intelligent Design proponents show will be similarly resolved with further progress of science and assert that proponents of intelligent design fall victim to the fallacy of argument by lack of imagination.
However, the term "intelligent design" has a broader usage than that given in the Intelligent Design Theory. It can refer simply to the belief that God designed the universe, without any specific claim as to how or when he did so. Many people consider this belief entirely compatible with standard Darwinian evolution, with no divine intervention -- life could be produced by a purely natural process, evolution, designed by God. God might merely have written the laws of physics, or chosen the fundamental constants, and left the universe to run like clockwork afterwards. The belief that the laws of the universe were constructed to allow for the existence of intelligent life is known as the Anthropic Cosmological Principle.
Not all people who believe that God was involved in the design of the Universe also adhere to the specifics of the Intelligent Design belief as proposed by Creationists.
Intelligent Design has lately been a controversial subject, particularly in American schools. After years of Judicial rejection of Creationist teaching--on the grounds that Creationism is a religious, not a scientific theory--many Creationists have begun to promote Intelligent Design as a non-religious, scientifically acceptable alternative to the theory of Evolution.
- Entry about ID in the "The Skeptic's Dictionary" by Robert Todd Carroll:
- Intelligent Design FAQ