I asked you to specify which version of IC you were referring to anyways, because this really changes how it needs to be responded to. After a side track covering my views on the origin of life (where I hope you see a great deal of common ground with me), you finally get around to answering my question. You apparently do not even know that there are more than one definition. You proposed the IC1 definition…
a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning.
And this is where we find ourselves now.
Before we move forward, let’s just remember the context of all this. Despite your doubts, I certainly do understand the ID case. The issue is not that I am clueless about it. Rather, I am not convinced by the argument.
So what is the next definition of IC, which I will call IC2? In 2000 Behe writes a different definition, that he carries forward to this day in the Edge of Evolution.
An irreducibly complex evolutionary pathway is one that contains one or more unselected steps (that is, one or more necessary-but-unselected mutations). The degree of irreducible complexity is the number of unselected steps in the pathway.
Now this definition suffers greatly compared to IC1, because it is not longer objective and directly measureable. Instead, we need to understand something of the evolutionary pathway, which is not directly observable.
Still, for the IC2, most knowledgeable scientists agree that IC2 systems exist in nature too. Similar to IC1 systems, we are convinced that evolution can evolve IC2 systems also. Embedded in this definition is an important straw man. He writes “one or more unselected steps.” Here, into the IC2 definition is being smuggled a strict enforcement of “Darwinian” evolution. Now, anyone following biology at a basic level of competence knows that strict-Darwinian evolution was falsified a long time ago, in the 1970s. We now know that a large proportion of changes are near neutral or even slightly deleterious in the short term. So this dominant pathway of change is intrinsically ruled out by Behe’s definition.
So, with that in mind, it is correct to say that modern biology agrees that IC2 systems appear throughout biology, because we thinking neutral mutations are often the evolutionary path to the systems we see, and they are not selected. Of course, this is all beside the point, because we are convinced that evolution can evolve IC2 systems using unselected steps (like neutral drift and draft, or even slightly deleterious steps).
Now, we could define a new version of IC (IC3 if you humor me here) that allows for all changes by neutral mechanisms. How might that fair? Unfortunately, this definition is even more unhinged from objective evaluation than IC2. We have moved entirely away from the concrete brilliance of IC1, to a fundamentally theoretical classification that is not directly testable in any way.
Well, no one has yet demonstrated that any system in biology is IC3. The claim that IC1 = IC3 is clearly false. So is the claim that IC2 = IC3. But how do we demonstrate that a biological system is IC3, and not just IC1 or IC2? No one knows. No one has proposed a way that seems remotely plausible to anyone outside the “already convinced” ID crowd. Instead we have a lot of sloppy arguments that somehow treat all classes as if they are the same thing.
Honestly, I do not know how to solve this problem. But I am not an ID advocate, so that isn’t my job. The fundamental problem for IC arguments is that biologists already agree that IC1 and IC2 systems exist, and we have even demonstrated their evolution directly in the laboratory.