The argument from irreducible complexity suggests that the removal of a single part from a system destroys the system’s function, ergo evolution is ruled out, ergo the system must have been designed by some external force. This is the basic argument advanced by Michael Behe and his followers. Below I counter some of the claims made by the proponents of irreducible complexity.
- Sometimes the functions are changed so that they do something other than what they did prior to mutation. Such evolutionary development of irreducibly complex systems have been described in the scientific literature in great detail.
- Even if irreducible complexity does preclude Darwinian evolution, the conclusion of design does not follow. Many other possible conclusions can be argued. It is an example of a failed argument from incredulity.
- Systems have been considered irreducibly complex that might not be so. For example:
- Michael Behe’s mousetrap example of irreducible complexity can be simplified by making some minor alterations to the mousetrap. Furthermore, the mousetrap may lose functionality as a mousetrap if a part is removed but then one might craft a fishhook from the spring, turn the nonfunctional mousetrap into a paper weight and so on.
- The bacterial flagellum is not, in fact, irreducibly complex because it can lose many parts and still function, either as a simpler flagellum or as a secretion system.
- The immune system example that Behe is so fond of is not irreducibly complex because the antibodies that mark invading cells for destruction might themselves hinder the function o fthose cells, allowing the system to function (although not as well) without destroyer molecules of the complement system.