Under the Microscope/Prof William Reville:Natural theology studies what can be known rationally about God and develops rational arguments for the existence of God.
Probably the best argument for the existence of God was the argument from design, most ably enunciated by the 18th-century clergyman William Paley (1743-1805). That argument was fatally wounded in 1858 by the theory of evolution through natural selection. The argument from design was recently resurrected and is now called Intelligent Design (ID).
ID is championed by fundamentalist Christians and proposes that evolution cannot account for the development of "irreducibly complex" molecular structures in the cell. However, biochemistry has clearly demonstrated that evolution through natural selection can account for "irreducible complexity".
William Paley argued as follows: suppose you are out walking and pick up a stone. You can explain its features by the natural processes of weathering etc and, for all you know, the stone might have lain there forever. Now you pick up a pocket watch. You see the complicated interlocking wheels and the coiled spring powering their movement.
You see the whole mechanism connected to the hands that move across the face of the watch to tell the time. You are clearly looking at a designed article and you logically conclude that it was produced by an intelligent designer.
Paley then looked at the living world which abounds with exquisite design. Consider, for example, the eye, a complex apparatus clearly designed to form images. Paley concluded that such biological devices are obviously designed by a supreme intelligence - God.
Paley's argument was very good, given the level of biological understanding at the time. The young Charles Darwin (1809-1882) was impressed, but the same Darwin, together with Alfred Russel Wallace (1823-1913), later destroyed Paley's argument with the theory of evolution through natural selection. This showed how design in the biological world is unconsciously and naturally produced.
Darwin and Wallace pointed to the variety that naturally exists within a species. Some variants have traits that allow them to procreate better than their fellows. These characteristics will be naturally selected and will appear in increased proportions in the next generation. And this proportion will increase generation after generation so that, over many generations, it transforms into a new species well fitted to its environment.
The biological world is designed, but the designer is blind, unconscious and natural. Darwin and Wallace didn't understand the mechanism of heredity and knew nothing of the structures within the biological cell. In the mid-20th century the mechanism of heredity was discovered to reside in the long, information-packed molecules of DNA. DNA controls the day-to-day chemistry of the cell and also comprises the hereditary material that is copied and passed onto the daughters of the cell when the cell divides. Information in the DNA determines the traits expressed by the whole animal.
DNA occasionally suffers damage and mistakes can be made during copying. When this happens, altered information (mutations) can enter the DNA which is copied and passed onto the next generation. Most mutations are harmful, but sometimes a mutation confers a new trait that helps it survive better than its fellows who do not have the mutation.
In the 1980s, the argument from design was revived in America as Intelligent Design (ID). The principal argument is based on the complex molecular structures found in the biological cell. ID claims that many of these "irreducibly complex" structures could not have arisen through evolution.
ID's main example of irreducible complexity is the bacterial flagellum. Bacteria whip these long appendages about to propel themselves through their watery environment. The long flagellum is connected through a universal joint to a complex motor sructure in the membrane of the bacterial cell. The motor assembly is made from dozens of different proteins and it is an intricate jig-saw of interlocking and interacting parts. It can only work when all the parts are in place simultaneously. Remove one part and the mechanism fails.
A core principle of evolution is that change occurs gradually, by minor modifications of pre-existing structures, driven by natural selection of improved function. But ID asserts that structures such as the flagellum cannot arise by modification of a pre-existing structure, since the smallest modification of the flagellum would render it useless. ID concludes that the flagellum is "irreducibly complex" and was designed de novo by a super-intelligent designer.
If the flagellum was designed de novo, one would not expect each of its individual components to have other separate useful functions in the cell. But, when you look at the several individual components of the flagellum, this is exactly what you find. For example, a whole section of the base of the motor has an independent existence in the cell as the 'Type III Secretory Apparatus' used by some bacteria to inject poison into other bacteria.
It is well established in biochemistry that evolution builds complex molecular machines by combining various simpler components that already exist in the cell but used for different functions. ID fails to stand up against the theory of evolution by natural selection, just as Paley's argument failed 150 years ago.
William Reville is associate professor of biochemistry and public awareness of science officer at UCC, http://