Irreducible Complexity


Irreducible Complexity was the main point of Michael Behe’s book “Darwin’s Black Box”. What is irreducible complexity? Irreducible complexity is a term used to describe a characteristic of certain complex systems whereby they need all of their individual component parts in place in order to function. In other words, it is impossible to reduce the complexity of (or to simplify) an irreducibly complex system by removing any of its component parts and still maintain its functionality.

he otherwise benign concept of irreducible complexity incites fierce controversy when it is applied to biological systems. This is because it is seen as a challenge to Darwinian evolution, which, needless to say, remains the dominant paradigm in the field of biology. Charles Darwin conceded, “If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down” (Origin of Species, 1859, p. 158). Behe argues, “An irreducibly complex system cannot be produced directly (that is, by continuously improving the initial function, which continues to work by the same mechanism) by slight, successive modifications of a precursor system, because any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional” (Darwin’s Black Box, 1996, p. 39). And since it would be non-functional, natural selection would have no reason to preserve it. In fact, natural selection usually eliminates things that have no function or are weak. This is called “survival of the fittest”. The strong survive while the weak perish. This is seen in cases like the finch beaks on the Galapagos islands. The finches with the shorter and duller beaks couldn’t get inside the little hard shelled fruit while the finches with the sharper and longer beaks could. The finches with the shorter and duller beaks died off and the ones that survived passed on the longer, sharper beak to its descendents. That’s what natural selection does. The long, sharp beak was preserved because it was useful while the short, dull beak was eliminated because it was useless and was actually detrimental to the finch that had it. If Irreducibly Complex machines are non-functional, natural selection will eliminate them. But the only way for these systems to be useful is if all of the parts are already put together.

But Darwinism works on numerous, slight modifications and irreducibly complex molecular machine cannot be produced gradually, as is needed for Darwinian evolution because it will be non-functional until it has all of its parts thrown together. Natural Selection is more than likely to eliminate the system before it finally has all of its part put together so it can function.

Well, what are these irreducibly complex machines this biologist Michael Behe touts as powerful evidence against evolution and for Intelligent Design?

This is the bacterial flagellum. The bacterial flagellum is composed of many parts that make it function, it has a stator, it has a rotor, it has ujoint, it has a drive shaft, it has a propeller. If even one of these parts were missing, the bacterial flagellum would not be able to function. What is its function? It actually functions like an outboard motor! Its propeller can 1000 rpms and stop instantly and start spinning at 1000 rpms in the other direction. This movement of the spinning propeller causes the bacterial flagellum to move forward. Moreover, it has built in sensors so that it manuver throughout the cell efficiently and doesn't crash into other flagellums or the walls of the cell. If the bacterial flagellum were missing its filament (a.k.a propeller), it wouldn't be able to go anywhere. It it were missing the rotor, there would nothing to spin the propeller and so...you've still got a motionless flagellum. This type of system cannot be built step by tiny, darwinian step because it won't function unless all of its parts are in place. So, because of that  Natural Selection is more than likely to eliminate the flagellum before it finally has all of its part put together so it can function. So because naturalistic machanisms and/or chance can't produce the bacterial flagellum, I think the best explanation is that it was designed by an intelligent being. 

Now before you accuse me of a God-Of-The-Gaps argument, let me explain why an intelligent agent had to be behind the design of the bacterial flagellum. You see, we have only have 2 possible explanations as to how biochemical systems could have arose. Either natural selection plus chance, or Intelligent Design. If one cannot explain it, it must be the other explanation. If Intelligent Design is not the best explanation, then the Darwinian mechanism is. If the darwinian mechanism can't explain it, the perhaps we should conclude design. Of course, there may be a third alternative that I'm not mentioning...but as far as I can see, those are only 2 explanations. 

Moreover, why should we think that a system that functions exactly like an outboard motor would be put together by chance anyway? I mean, after all, do we ever see outboard motors on boats get assembled piece by piece through natural selection plus chance? No. But we HAVE seen outboard motors being assembled by intelligent beings and so by the principle of uniformitatianism, I think Intelligent Design should be preferred. Uniformitarianism is the assumption that the same natural laws and processes that operate in the universe now, have always operated in the universe in the past and apply everywhere in the universe. It has included the gradualistic concept that "the present is the key to the past" and is functioning at the same rates. So even apart from the fact that the bacterial flagellum is irreducibly complex, I think the bacterial flagellum is powerful evidence for Intelligent Design just based on the fact that it both looks and functions as an outboard motor.

And now, for another irreducibly complex system; the blood clotting mechanism.


Normally blood clots form in response to injuries which cause bleeding. Clot formation helps to concerve the body's supply of blood so that small cuts don't end up draining the body of all of its blood. The body's process for stopping the bleeding by forming a clot is called hemostasis. The blood vessels contain red blood cells, white blood cells, platelets, and tiny proteins called clotting factors. These components of the blood float together in a straw colored liquid called plasma. When the vessel wall is torn open by an injury, blood begins to escape. In response to this damage, the vessel quickly constricts reducing the flow of blood. This constriction lasts only for a few minutes as the body puts in place a plug to stop the bleeding. Platelets soon recognize the injury and begin to stick to the damaged surfaces. This is called platelet adhesion. The adhering platelets change shape and release chemicals which the keep the vessel constricted and draw more platelets into the damaged area. These platelets are said to be activated. Additional platelets arrive and begin to stick to one another so that a loose plug is formed. This is called platelet aggrigation. When tissue is torn apart during an injury, blood is exposed to a chemical called "tissue factor" which naturally reside on the surface of tissue cells or may also be displayed on the inner lining of the blood vessel wall. This tissue factor sets into motion the chemical reaction of the clotting factors found floating in the nearby blood. 

Around a dozen different chemicals called "clotting factors" circulate inactively within the blood. When called upon, these clotting factors will participate in a complex sequence of chemical reactions to ultimately produce tiny strands of strong material called "Fibrin". Fibrin strands form in and around the plug of platelets and eventually form mesh work which tightly binds the plug together. This mesh work keeps platelets from being washed away by the flow of blood and makes it more watertight. Red blood cells and white blood cells become trapped in the meshwork that forms giving the plug its characteristic red color. The overall process of forming these fibrin strands to solidify the clot is called coagulation. So within a matter of minutes a sterdy plug is formed to arrest the outflow of blood, but too much coagulation activity allows the clot to grow much larger than it should. 2 groups of the body's own naturally produced chemicals help to limit the size of the clot. The first group blocks coagulation. These substances are known as coagulation inhibitors. When these chemicals interfere with the reactions among the clotting factors, fibrin formation is blocked and no new fibrin strands are available to hold additional cells to the clot. In this way clot growth is kept to a minimum. 

The other group of chemicals keep clot growth under control by cutting the fibrin strands and actually dissolving part of the clot. These chemicals are called fibrinolysis. Fibrinolysis occurs when chemicals known as plasminogen activators are slowly released from the inner lining of the damaged vessel wall. these plasmenogin activators trigger the destruction of the fibrin strands that hold the clot together. So coagulation inhibitors can only stop the growth of the clot. But fibrinolysis can actually dissolve part or all of the clot. In fact, when the vessel is completely healed, the remaining clot is dissolved by means of this second group of chemicals. To sum up then, rapid clot formation is essential for a conservation of the body's supply of blood. We've seen the constriction of the blood vessel, the formation of platelet plug, thec strengthening of that plug by the addition of fibrin strands, and the body's protective systems preventing too much clot growth. 

If even one of these crucial steps in the blood clotting cascade were missing, the blood clot would not be formed and the animal or person would bleed to death. This phenomenon is far too complex to be put together by accident. The rational person must conclude that this is the result of Intelligent Design.