Irreducible Complexity

-
First we begin by defining the concept of irreducible complexity.

Dr. Michael Behe discussed irreducible complexity in his book “Darwin’s Black Box” (1996). He said irreducible complexity refers to “a single system which is composed of several well-matched, interacting parts that contribute to the basic function, and where the removal of any one of the parts causes the system to effectively cease functioning.”

Wm. Dembski updated what Dr. Behe said in "No Free Lunch":

Irreducible Complexity: 

IC- A system performing a given basic function is irreducibly complex if it includes a set of well-matched, mutually interacting, non-arbitrarily individuated parts such that each part in the set is indispensable to maintaining the system’s basic, and therefore original, function. The set of these indispensable parts is known as the irreducible core of the system. Page 285 NFL

Numerous and Diverse Parts If the irreducible core of an IC system consists of one or only a few parts, there may be no insuperable obstacle to the Darwinian mechanism explaining how that system arose in one fell swoop. But as the number of indispensable well-fitted, mutually interacting,, non-arbitrarily individuated parts increases in number & diversity, there is no possibility of the Darwinian mechanism achieving that system in one fell swoop. Page 287

Minimal Complexity and Function Given an IC system with numerous & diverse parts in its core, the Darwinian mechanism must produce it gradually. But if the system needs to operate at a certain minimal level of function before it can be of any use to the organism & if to achieve that level of function it requires a certain minimal level of complexity already possessed by the irreducible core, the Darwinian mechanism has no functional intermediates to exploit. Page 287

As Dembski went on to explain these structures- well all structures requiring multiple parts- are discrete combinatorial objects. And these DCO's require at least 3 things:
1- The origin of the parts (and the correct quantities)
2-  The location (and timing)
3- The proper configuration

For example any bacterial flagella is made up of a number of different proteins, each expressed in specific quantities, called subunits. Miss ONE protein and you are out of a number of required components. And without those components you don't have movement from the appendage. You most likely won't have the appendage. You lose.

Many biologists recognize that irreducible complexity exists in biology. But what they may insist is that it isn't an obstacle: Evos choking on IC

"An irreducibly complex system can be built gradually by adding parts that, while initially just advantageous, become-because of later changes-essential. The logic is very simple. Some part (A) initially does some job (and not very well, perhaps). Another part (B) later gets added because it helps A. This new part isn't essential, it merely improves things. But later on, A (or something else) may change in such a way that B now becomes indispensable. This process continues as further parts get folded into the system. And at the end of the day, many parts may all be required." Orr 1996

"... gradual Darwinian evolution can easily produce irreducible complexity: all that's required is that parts that were once just favorable become, because of later changes, essential. " Orr 1997

If only the narrative were science.

There are many biological structures and systems that meet the definition of irreducible complexity. And there aren't any non-telic mechanisms that can account for them.