Irreducible mechanisms - the enemy of evolution?
Darwin said one thing that was right (I am not saying
that it was the only thing!) and that was that the presence of irriducible mechanisms
would blow Darwinian ideas out of the water.
What Darwin did not know at the time was that there are many such mechanisms in the living
creatures on this planet.
Evolution is the 'survival of the fittest'. Those animals that have an advantage over their competitors are able to do better than their competitors, resulting in the success in survival terms over their competitors. Simply put, those animals who succeed in passing their genetic material to the next generation are the winners in Evolution.
Natural Selection is at work here, those characteristics that do better in the given environment are those that succeed. So they are passed on to the next generation. Those characteristics that are not passed on to the next generation are lost from the genetic pool.
One could imagine that if, say, all the trees and bushes over one foot tall are destroyed, then a giraffe is at a major disadvantage compared to, say, a small deer.
A frequently quoted example are the finches that Darwin observed. In dry weather those birds with tougher, maybe larger, beaks would do better than other finches. They could subsequently produce healthier and more numerous offspring, thus the bigger, better (in these circumstances) beaks become a dominant characteristic.
It is also feasible that, over a few generations, the birds with the smaller beaks could die out completely and that the genes that produce smaller beaks are lost from the gene pool altogether.
It would seem obvious therefore that any mutation or characteristic that served no purpose, or was even a handicap of some sort, would be rapidly removed from the gene pool.
The functioning eye
A functioning eye needs an optic nerve to take the signals to the brain and the control systems
in the brain to interpret the signals to allow conscience decisions to be made. Even a minimalist version of these features could not possibly be created by chance.
The idea that random chance could produce three distinctly separate mechanisms all designed
to work together in a most complex manner, all at the same time, is beyond any rational belief. 
But the key concept for the evolutionist to grasp is that natural selection, an idea that they are very keen on!, cannot produce an irreducible mechanism.
Natural selection says that any adaptation that has not got a purpose will be removed from the gene pool.
So how could a functioning eye be formed over a long period of time when there is no function until the whole system is in place?
It is very simplistic to look at a mechanism such as the eyeball and say that it evolved! What kind of evolutionary process would take place to create an eyeball together with the optic nerve and the necessary brain functions without any knowledge of what vision was?
The flagellar motor
Salmonella and E. coli has a fascinatingt way of moving around. These bacteria have a body size of 1 to 2 microns but they have 'evolved' a propeller to move about. The motor that drives this propeller is a macromolecular assembly with multiple components.
The motor consists of distinct components including; a rotor, stators, a drive shaft, bushing, a rotation switch regulator. The diameter of this 'motor' is just 3nm but it can rotate at around 20,000 rpm and has an energy consumption of around 10 -16 W.
This motor can stop, change direction and reach full speed again within a quarter of a turn.
The idea that this can 'evolve' is beyond belief. The motor has to be complete and working or the bacteria cannot move and would die. The components would have developed over a long period of time and they would be useless during that time. Could the bacteria survive if they were unable to move under their own power?
Justifying irreducible mechanisms
Evolutionists have come up with various concepts such as 'exaptation', 'cooption' and 'preadaptation'. But these need faith to believe in them as well, they are not 'proof'! Just looking for similar mechanisms and saying that one mechanism evolved from a different mechanism is no more than a position of faith!
I would expect a Creator to create a wide range of mechanisms, many of which would overlap in many ways. I would also expect the same basic building blocks to be used again and again. Not evidence of evolution but evidence of design!
Evolutionists need to explain how feathers developed whilst also explaining how the lifeform also developed the required brain functions, muscles, nerves and all the other attributes of birds (including song). If it had taken thousands of generations to achieve the final form then the chances of it happening by pure random chance are lower than zero!
The final nail in the coffin for the concept of natural selection came with the recent discoveries of DNA and how the cells work. The discovery of the most complex and fascinating mechanisms that operate within the cell which simply could not happen by chance and could only exist the result of a designer.
That is why Darwin recognised that his theories could be assigned to the dustbin if any irriducible mechanisms were found to exist!