Not true, TA. Behe argued for common descent in his second book. He does not reject evolution. He rejects the idea that it all happened via random mutations. But the question is how to decide that question. He hopes that it can be decided by analyzing the possibilities at the molecular level. This means considering “simple” molecular machines.
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The basic IC argument applies to any system, be it at the molecular level or at the macroscopic level.
The idea is that such a system can’t evolve through a pathway where the individual parts would have a selective advantage. Instead, the whole system has to appear at once if it is going to evolve through random mutations and selection. That is the argument.
Therefore, finding macroscopic IC systems that do have function without some of the parts or predecessors that have different functions counters the argument. There are examples in the fossil record, such as the evolution of the irreducibly complex mammalian middle ear evolves two of the required parts from bones in the reptilian lower jaw.
What Behe’s argument boils down to is an argument from ignorance. Behe can’t think of an indirect pathway by which these systems can evolve, therefore they didn’t. This is why he sticks to molecular systems because he doesn’t have to worry about transitional forms being dug up.
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Dr. Swamidass, I am a layperson. So I rely on experts to try to help me sift through the evidence. It helps me when Behe publicly debates the experts. He has done this in the past. From what I can tell, Behe usually carries the day. However, I could be mistaken about that. What would help is if an expert, such as yourself, were to evaluate Behe’s debates. For example, you could read through the debate he had with Moran in 2014 and offer your opinion. Or you could read through the debate he had with Miller in 2015 and do the same. Or his debate with Thornton (2012, I think) and do the same. That would be very helpful.
And I hope Behe eventually engages with you publicly. I would look forward to reading both sides.
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TA, it’s not just that Behe can’t think of intermediate forms. Nobody can think of intermediate forms. Or so he argues. If the theory is that such systems evolved by random mutation, then one should be able to offer a plausible pathway by which it could have happened. If nobody can, then why insist that it happened that way? It makes Darwinian evolution into a religion, instead of a science.
To belabor a point already made on these threads: Do you believe that Lewis and Clark’s expedition traveled from St. Louis to the Pacific Ocean and back? Nobody knows the exact path and daily day-by-day progress (although their log notes were quite impressive and come close). And as you said, at best one may only be able to offer “plausible pathways by which it could have happened.” Yet, no doubt our understanding of such will improve as the discoveries are made and the evolutionary processes better understood.
Is something utterly false in science until the piles of evidence reach a certain height? How many excellent hypotheses in science were far less well attested a century ago than they are now? Did that make those hypotheses “religion instead of science” until they reached a level that suddenly became science?
Meanwhile, Darwinian evolution hasn’t been the standard in a very long time. It was never a religion. It was a step along the way of continually clearer understandings of evolutionary processes. There is much yet to be understood—but that doesn’t make evolutionary biology a religion. Not even close.
It would be far easier to argue that various of Behe’s claims are closer to “religion”. (I put religion in quotation marks because I’m using the word in this context more like you are using it, even though I don’t normally use it that way. As an academic, I’m more prone to apply the word religion in its religious studies definition of that which involves reverence towards that which is transcendent.)
That’s what makes it an argument from ignorance.
I don’t see why this is true. It is entirely possible for systems to evolve and us humans being ignorant of how it evolved.
Behe is also shifting the burden of proof. It isn’t enough to challenge evolution. Behe needs to offer positive evidence for his own claims. For example, Behe needs to show us the generation before these IC systems appeared and the generation after these same systems appeared. He then needs to show all of the genetic changes that resulted in the emergence of this system, and then show how these changes were guided.
We tend to think that IC systems evolved because of all the other evidence that supports evolution.
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I assume that we can offer plausible pathways that Lewis and Clark used. If we couldn’t, then I think it would be reasonable to doubt that they did indeed make such a trip.
If we insist that Darwinian evolution, or random evolution, or non-intelligently guided evolution, happened, when we aren’t able to posit plausible pathways, then I think we have reason to doubt it. To insist that we accept it regardless is to make it into something other than science. Call it religion or superstitution, or whatever term you prefer. Just not science.
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“We tend to think that IC systems evolved because of all the other evidence that supports evolution.”
Behe tends to think they evolved, also. But he tends to think they evolved via intelligent guidance.
So was it non-intelligent or intelligent guidance? I think the evidence favors intelligent guidance. But I’m willing to entertain other hypotheses.
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Behe accepts common descent and even the idea that human descended from other primates. So do you consider that position of Behe’s to be a scientific position or is it just “religion or superstition” as you call it?
That is a good idea @bilbo. You proposed a few. Can you link the documents associated with these debates and others? Based on brevity and salience, this might be a very useful effort, that might at least clarify where things stand.
I consider it to be a scientific position.
Okay, I’ll work on it.
And I’ll be using the list here:
We have laboratory confirmation that simple IC systems are evolvable. It’s very plausible that experiments testing longer chains of stepwise mutations could be tested as well:
https://www.sciencedirect.com/science/article/pii/S0022283607010297
The problem I see is not so much demonstrating a feasible stepwise pathway, but rather which pathway was it out of millions of possibilities. Speculating about specific pathways doesn’t help, because we have little information about the conditions under which that pathway may have evolved.
Where is the evidence for intelligent guidance?
Hi Dan, I wasn’t able to access the whole paper, but the abstract was fascinating. Chen maintains that there already is an IC system, where all of the parts are required. But then through selective mutations, they are able to get rid of protein B…replacing it with another external scaffolding protein? It isn’t clear.
So it seems that there is already one IC system, where one of the parts is replaced with a different part? Am I misinterpreting it?
If not, then it doesn’t seem to have shown how an IC system evolved. It does seem to show how an IC system can evolve into a slightly different IC system. That hardly seems to be a refutation of Behe’s point, does it?
I would say the evidence is from our experience of how machines are invented…including on the nano scale.
How many of our machines are produced by two other machines getting together and making a baby machine?
Bilbo, did you know that IC1 is not an all or none concept? We are supposed to count the number of components that must be required to measure the degree of ICness. This is important. If we can show we can move from IC1 degree 10 to 11, the same mechanisms can explain from degree 9 to 10, from 8 to 9, and so on.
Good question. I wouldn’t know. But do you doubt that the original machines were intelligently designed?