The basic idea of irreducible complexity developed by Michael Behe is simple and elegant. Dr. Behe posits that a biological system such as the iconic bacterial flagellum (UD’s mascot – see the picture at the top of our homepage) is irreducibly complex if each part of the system is indispensable to function. In other words, if one removes any part of an irreducibly complex system, one winds up not with degraded function but with no function at all.
This idea is important to the debate over Neo-Darwinian Evolution (NDE), because NDE is grounded absolutely in the notion that every complex biological system evolved from a simpler precursor in a stepwise fashion in which each step provided a net fitness gain.
It is obvious that an irreducibly complex system cannot have evolved in a stepwise fashion for the simple reason that all of the parts must be in place at once for there to be function. By definition, you can’t add the parts one after the other in a stepwise fashion and have function at each step of the process.
An automobile engine is an example of a system with an irreducibly complex core. There are hundreds of parts in an engine, some of which are part of the irreducibly complex core and some of which are not. For example, the bolt holding the battery in place is NOT part of the core. We can remove that bolt, and the battery will flop around, but the car will still run. The battery itself, on the other hand, is part of the irreducibly complex core. As anyone who has ever turned the key on a car with a dead battery knows, no battery equals zero function.
Irreducible complexity poses a serious problem for NDE, which various NDE researchers have attempted to meet (so far unsuccessfully). The latest attempt to address this conundrum comes from Kelly Hughes and David Blair of the University of Utah, two of the world’s leading experts on bacterial flagellar assembly, in chapter 38 of the new book Microbes and Evolution: The World that Darwin Never Saw. They write:
It is clear that the flagellum is a complex structure and that its assembly and operation depend upon many interdependent components and processes. This complexity has been suggested to pose problems for the theory of evolution; specifically, it has been suggested that the ancestral flagellum could not have provided a significant advantage unless all of the parts were generated simultaneously. Hence, the flagellum has been described as “irreducibly complex,” implying that it is impossible or at least very difficult to envision a much simpler, but still useful, ancestral form that would have been the raw material for evolution.
Our JonathanM has a detailed review over at Evolution News and Views. Hughes’ and Blair’s essential idea is that the bacterial flagellum is not irreducibly complex because sub-components within the flagellar structure are homologous to other bacterial organelles. In other words, some of the components of the flagellum can be found in other molecular structures. For example, as JonathanM points out in his review, they correctly point out that the stator proteins MotA and MotB are homologs of ExbB and ExbD, which form part of the TonB-dependent active transport system.
Let’s explore this argument in the context of a vehicle engine. Just as with the flagellum an engine has parts that are, in a sense, homologous with parts in other kinds of machines. Examples abound. An engine has nuts, bolts, a battery, belts, wires, pistons, reservoirs for various fluids. All of these components can be found in other types of machines. Therefore, according to Hughes’ and Blair’s analysis, an engine is not irreducibly complex.
You will say that conclusion is not only wrong, it is laughable, and you will be right. It is glaringly obvious to even the most casual observer that the mere existence of an irreducibly complex system’s parts is a necessary – but far from sufficient – condition for the system’s function. Suppose I have every single component of an engine in my garage. Do I have a functioning engine? Of course not. Suppose further that I take all of those components and put them in a big bag and shake them up. Do I have an engine now? Of course not. Even a child would understand that having the parts is not enough even if all of the parts are in the same place at the same time.
Function requires simultaneous coordination of the parts. Certainly simultaneous coordination can be achieved in a stepwise fashion. Indeed, it is hard to imagine it being achieved any other way. There is no way to build an engine such that all of the parts come together in an instant. The mechanic starts with the block and inserts the pistons and attaches the rods and so on and so on until the engine is built and functions. Notice, however, that each step does not give the engine “a little more function.” Each individual step gives the engine no function at all. There is function only when all of the steps are completed.
The distinction between merely “stepwise” and “stepwise with each step improving function” is vital. A mechanic is an intelligent agent. When he builds an engine he has a distant goal in mind (a functioning engine), and he achieves that goal one step at a time. It makes no difference to him whether he gets a little bit of improved function at each step. Indeed, if there are 500 steps, he is content with zero function for steps 1 through 499. NDE cannot build an engine that way. By definition there must be a net gain in function for steps 1 through 499. Why? Because natural selection “selects” a new trait for one and only one reason – the new trait increases the fitness of the organism. Therefore, if the new trait does not increase the fitness of the organism there is nothing there that natural selection can select for.
In summary, as I mentioned above, any child can see that the idea of irreducible complexity is not defeated by the mere existence of the parts of the system. Why can’t these highly educated biologists see what any child can see? Because they are blinded by their metaphysical suppositions. To them, the bacterial flagellum just had to evolve in a stepwise fashion. It is quite literally unthinkable for it to have come about any other way. And if it had to have happened that way, then any explanation for how it happened that way is sufficient, even if the explanation is patently absurd.
In the first comment in the combox we get this from Neil Rickert:
The battery itself, on the other hand, is part of the irreducibly complex core. Anyone who has ever turned the key on a car with a dead battery knows, no battery equals zero function.
Early automobiles did not have a battery. They were started with a crank. The battery was added later, to allow electrical starting. But the crank remained, and buyers insisted on having it. So, even then, the automobile could be started using the crank and without a battery.
Later, after the electrical starter had proved itself successful, automobiles were built without a crank.
So here, in your own example, we have a system with an appearance of irreducible complexity, yet whose development history was one of stepwise change
Here’s my response:
The fact that an engine designed to start without a battery can get along without a battery has no bearing on whether an engine designed to start with a battery can get along without a battery.
As Joe and BA point out (and as I explained in the OP), both systems were designed. A designer can design a system to accomplish the same thing in various ways. (piston/rotary or battery start/crank start). This says nothing about whether NDE can build an IR system in a stepwise fashion.
You have committed what Phil Johnson calls “Berra’s blunder,” i.e., using an example that is obviously the product of intelligent agency to attempt to make a point about a non-intelligent process.
If you compare a 1953 and a 1954 Corvette, side by side, then a 1954 and a 1955 model, and so on, the descent with modification is overwhelmingly obvious. This is what paleontologists do with fossils, and the evidence is so solid and comprehensive that it cannot be denied by reasonable people…
The point is that the Corvette evolved through a selection process acting on variations that resulted in a series of transitional forms and an endpoint rather distinct from the starting point. A similar process shapes the evolution of organisms.
Tim Berra, Evolution and the Myth of Creationism, 1990, pg 117-119
Of course, every one of those Corvettes was designed by engineers. The Corvette sequence — like the sequence of Beethoven’s symphonies to the opinions of the United States Supreme Court — does not illustrate naturalistic evolution at all. It illustrates how intelligent designers will typically achieve their purposes by adding variations to a basic design plan. Above all, such sequences have no tendency whatever to support the claim that there is no need for a creator, since blind natural forces can do the creating. On the contrary, they show that what biologists present as proof of “evolution” or “common ancestry” is just as likely to be evidence of common design.
Phillip Johnson, Defeating Darwinism by Opening Minds, 1997, pg 63.
Even a moment’s reflection would suffice to make it clear that the “crank to battery/crank to battery only” analogy does not address the argument of the OP. But Mr. Rickert did not take a moment to reflect, because he, like the two Ph.Ds referred to in the OP, has ideological blinders on. These blinders cause him to make analogies that even a child could see have no bearing whatsoever on whether NDE – as opposed to an intelligent agent – can build an irreducibly complex system. Thank you, Mr. Rickert, for illustrating the point of the OP so beautifully.