Assertion 4.5: Evolutionists cannot tell us exactly how most organisms and biological structures arose.
Analysis:
Evolutionists can account for many biological structures with considerable ease, as long as they are not held to the unreasonable standard of absolutely exact knowledge. For instance, as Douglas J. Futuyma writes,
One of the most amazing aspects of evolution is how easy it is to account for major transformations through rather simple changes in developmental processes. Most of the differences among different kinds of mammals are quite simply accounted for by changes in the relative rates of growth of different parts of the body. Speed up the elongation of fingers to get a bat wing; slow down the development of teeth or legs to reduce or eliminate them in whales; slow down the growth of the lateral toes and increase that of the middle one to get a horse's hoof. (Futuyma 1982:63-64)
References
Futuyma DJ. 1983. Science on Trial: The Case for Evolution. New York: Pantheon.