A large number of chemical reactions are involved in blood clotting, and – here is the crucial point – if even one of these reactions does not occur, the blood will not clot. Therefore, claims Behe, the mechanism for blood clotting could not have evolved gradually through a series of mutations, with each mutation providing an additional survival advantage to

the animal. Each such mutation would, by itself, be useless. All the mutations have to be present to be of any use to the animal because every one of the reactions involved in blood clotting must occur Inhibitors,research,lifescience,medical or the blood will not clot. The mechanism for blood clotting is called “irreducible” because it cannot be reduced to a series of steps with each step affording an additional survival advantage. Rather, the complete blood-clotting mechanism had to appear in the species gene pool all at once. According to Behe, this implies design – “Intelligent Design.” It is important to note that even a relatively simple system, consisting of only two parts, can be an irreducibly complex system, if Inhibitors,research,lifescience,medical both parts are necessary for the system to function. Behe discusses the mousetrap as a classic example Inhibitors,research,lifescience,medical of an IC system. There is clearly nothing very complex about a mousetrap. This example serves to confirm that Behe’s assertion that ID has nothing at all

to do with the argument from design. UNCONVINCING REFUTATIONS OF ID Some of the proposed refutations of ID are rather unconvincing. Consider the following refutation (which has many adherents, just look in Google), proposed by biologist Robert Dorit7: “Many of the proteins Inhibitors,research,lifescience,medical of the eye lens, for example, began their careers doing something completely different and unrelated to vision. selleckchem evolution is a creative scavenger, taking what is available and putting it to new use. The correct metaphor for the Darwinian process Inhibitors,research,lifescience,medical is not that of a First World engineer, but that of a Third World auto mechanic who will get your car running again, but only if the parts already lying around can be used for the repair” (emphasis added). There is a very important implication in the italicized words. What only if the necessary

parts were not already lying around? Dorit’s argument implies that it would then be impossible to produce the corresponding IC system by Darwinian evolution. This would be an enormous limitation to the evolutionary process. Evolutionary biologist H. Allen Orr8 dismisses the above proposed refutation of ID: “We might think that some of the parts of an irreducibly complex system evolved step by step for some other purpose and were then recruited wholesale to a new function [which is precisely what Dorit proposed]. But this is unlikely. You may as well hope that half your car’s transmission will suddenly help out in the airbag department. Such things might happen very, very rarely, but they surely do not offer a general solution to irreducible complexity.