"A functional system is irreducibly complex if it contains a multipart subsystem (i.e., a set of two or more interrelated parts) that cannot be simplified without destroying the system’s basic function. I refer to this multipart subsystem as the system’s irreducible core.
We can therefore define the core of a functionally integrated system as those parts that are indispensable to the system’s basic function: remove parts of the core, and you can’t recover the system’s basic function from the other remaining parts. To say that a core is irreducible is then to say that no other systems with substantially simpler cores can perform the system’s basic function."
Hmm, if he's right, a four bladed propeller on an outboard motor couldn't have any blades cut off and still "perform the system’s basic function".
A monkey cannot climb a tree if it's missing an arm.
A butterfly cannot fly unless all four wings are present and complete.
A millipede, a dog, or a duck cannot walk (propel itself along the ground) if it's missing a leg.
An airplane without landing gear cannot land, or land safely. "Safely' meaning without harm to the occupants.
Of course he would say that some parts are dispensable while some parts are indispensable. Well, I could argue that an elephant without a head wouldn't function but that wouldn't prove that elephant heads are designed, or that they're designed by some imaginary supernatural god.
There's something else to consider:
What are 'parts'? Who determines where the exact line is drawn between 'parts'? Can anyone say that there are parts that can't be reduced to parts? A starter in a car is called a part, but it's made of many parts. A 'one piece' brass propeller is a combination of 'parts' - the atoms within it, and the atoms are a combination of parts. Seems to me that pretty much everything is a combination of parts. The search for the Higgs Boson comes to mind. And if it's found, what part will be looked for then?
Something else that comes to mind is the endless debate about the exact line between 'species'.