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Author
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Topic: Response to Jason Rosenhouse
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Cornelius G. Hunter
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Member # 81
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posted 21. September 2004 18:35
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The question of the secretory system's origin is not off-limits, or a biological given, or any such thing. But it is simply not a response to Musgrave's scenario.
Darel:
Actually, it is a response to Musgrave's scenario. As I explained earlier, the first step in the scenario is "a secretory system arose." (And not just any old secretory system by the way.) The scenario is not merely that the existing secretory system could have evolved into the existing flagellum. The scenario is that the flagellum plausibly could have arisen via evolution. If it is not shown that the flagellum plausibly could have arisen via evolution, then the hypothesis fails.
The secretory system is one of the functional intermediates identified that help define the evolutionary pathway. It is not changing the subject to examine the evolution of the functional intermediates. Is it true that these intermediates plausibly could have evolved? If not, then the flagellum could not plausibly have evolved (at least via the hypothesis in question).
quote:
Behe's assertion -- that IC falls if even one substantial IC example is explained by mutation-selection -- means that evolutionists are not obligated to explain all steps in the appearance of a system. To refute IC, they need only explain the appearance of one irreducible core of components. If the flagellum contains at least one such core that is not in the secretory system, and the steps of Musgrave's scenario are plausible, then he has refuted IC as an anti-evolution argument, irrespective of whether he has the slightest idea where the secretory system came from.
No, this is not true. Now I can see where some of the confusion arises. My comments above should clear this up. Make sense?
[ 21. September 2004, 18:36: Message edited by: Cornelius G. Hunter ]
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Scott
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Member # 1222
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posted 21. September 2004 19:08
Perhaps we can move this along by considering the following.
Suppose that instead of asserting that the secretory system evolved into the flagellum, we move the argument downsteam. Sorry to revert to the use of letters again, but I am not familiar with the details of the proposed evolutionary pathway, so will deal in generalities.
A - the secretory system.
Z - the flagellum
Somewhere in between we have a finite number of intermediates, precursor systems to the flagellum.
Let's say that the argument proceeded from X to Z, rather than from A to Z. According to Daryl, we cannot ask about the origin of X, even though it is a proposed step in the pathway.
In the same way that X is an intermediate step to get to Z, so also is A an intermediate step to get to Z. Why is A not a proposed step in the pathway, just as X would be?
The question seems to be, is it valid to assume the existence of some unexplained precursor, assert that it is a viable precursor, and move forward from there.
If that is valid, then why start with A? Why not start with Y, explain only one step in the process, and claim that Z is not therefore IC?
Why would the latter not be a reasonable refutation of IC?
Also, if the secretory system evolved into, or was changed into, the flagellum, how is it that we know about the secretory system?
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Cornelius G. Hunter
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Member # 81
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posted 22. September 2004 00:20
Good point Scott. By the way, none of this takes away from Musgrave's good work. The problem lies not in Musgrave's work, which is a good first step, but in the notion that this somehow refutes IC.
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RBH
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Member # 380
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posted 22. September 2004 02:54
Scott asked quote:
Also, if the secretory system evolved into, or was changed into, the flagellum, how is it that we know about the secretory system?
This is in the same league as the question "If man evolved from monkeys, why are there still monkeys?" C'mon, Scott. Think about it.
RBH
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Cornelius G. Hunter
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Member # 81
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posted 22. September 2004 06:27
This post is in reponse to Professor Jason Rosenhouse's blog entry for September 21, 2004 at http://evolutionblog.blogspot.com.
Two closely related species of frog, Rana fusca and Rana esculents, have eye lenses which are similar but are formed differently. Did these two similar species evolve their eye lens independently? There are many such similarities that develop differently or arise from different genes and they raise obvious questions about the claim that they arose via common descent.
This and other examples have been pondered by many scientists. The example above comes from Sir Gavin de Beer, embryologist, professor, historian, and Director of the British Natural History Museum. He asked the question, "What mechanism can it be that results in the production of … the same 'patterns,' in spite of their not being controlled by the same genes? I asked this question in 1938, and it has not been answered."
Though these issues do not support evolution, they are not controversial. Designs that appear to be homologous sometimes arise from different embryonic development patterns or from different genes. This is a well known problem. [Alberch, 51, 56; de Beer, 16] As Brian Hall wrote:
quote:
Because there are so many examples of homologous structures arising from nonhomologous development processes, I believe homology can no longer retain its historical links to shared embryonic development. [Hall, 1]
Professor Rosenhouse wonders, however, if there really is an issue here. Isn't there some way that evolution could explain the frog example? Could this be a mere interesting anomaly?
quote:
To determine if Hunter's frog example is something to worry about we would need to know, among other things, the precise manner in which the eye lenses in question develop, how similar the final products are and how different their development is, and the various natural mechanisms that might lead two structures related by common descent to follow different patterns of development. To turn his vague assertion into an actual argument Hunter would need to provide a lot more detail than he provided, exactly as I said in the first place.
In Rana fusca the lens develops from the epidermis on the optic cup. It is the optic cup that induces the epidermis to differentiate into the lense which ends up perfectly fitting. It makes sense that the lens perfectly fits in the optic cup since it is developing from the epidermis. In Rana esculents, however, the lens develops without the presence of the optic cup. As Sir Gavin de Beer put it, the lenses in these two closely related species "differ completely in the mechanism by which determination and differentiation are brought about. This is no isolated example."
Is this an anomaly? No, there are many more examples (they are "the rule rather than the exception." [Alberch, 51] ). How similar are the lenses? Well, put it this way: they were considered to be homologous. How different is their development? Completely different (as de Beer put it). In one case the optic cup is the inducer, in the other case the optic cup is irrelevant. It can be completely cut out. How could evolution explain these examples? One can construct such explanations. For instance, neutral mutations caused a switch in the development path that, nonetheless, left the final design intact and functional. Those mutations eventually became fixed in the gene pool. Of course, this is a just-so story. There is no evidence that such a thing ever did, or even could, happen. These observations are not easily explained by common descent or by convergence. But then again, there's also no evidence that the frogs themselves could have evolved in the first place.
Traditionally one of the important criterion for identifying homologies was shared embryonic development. Obviously, this expectation has failed. Evolutionists can hardly say that Rana fusca and Rana esculents evolved their eyes independently. Did their common ancestor not have eyes? No, evolutionists must now say that genetic and embryonic conservation is not required for homologies -- somehow.
There are plenty of issues here, and these are all interesting questions, but there is one more question. How do these findings from embryology affect the homology evidence for evolution? Homology is a key evidence for evolution. Darwin argued that similarities in similar species (such as the pentadactyl pattern) mandated common descent. The idea is that evolution is constrained to work with the available materials. If it works, it gets used, though it may not be optimal. In the twentieth century, neo-Darwinism elaborated on this, saying that the genetic mutations provide the randomly-generated design changes that could be selected. Hence there is a correlation between the design features (the phenotype) and the genes behind them (the genotype). Similar designs in similar species should arise from the same genes, and the same development pathways. Distant designs in distant species, on the other hand, will arise from genes with greater differences.
But this is not what we are finding. The very argument for why homology so strongly supports evolution is, itself, not supported by the evidence. If evolution is true, then design similarities need not be a consequence of evolution being constrained.
None of this means that evolutionists are being arbitrary in their assigning some similarities as homologies and others as analogies. They are fitting the data to their theory as best they can. The theory has its problems, and there is uncertainty, but it is not completely arbitrary.
Another problem with the homology argument, at the other end of the spectrum, is that similarities show up in distance species. These convergences are well known and common. These weaken the homology argument. If similar designs are present in distant species, where common descent cannot be used to explain those similarities, then common descent need not be invoked to explain similarities in species that are not so distant.
Rosenhouse points out that evolutionists have reasonable methods for distinguishing between analogies and homologies. He erroneously thinks that this makes homologies powerful evidence for evolution. Geocentrism can explain retrograde motion, but this doesn't make it powerful evidence for the theory.
The powerful evidences for evolution are not holding up under scrutiny and we are now told that these are nonetheless powerful evidences. In order to maintain that evolution is a fact, evolutionists must have powerful evidence. This is a tall order in the face of the evidential difficulties. One strategy is to maintain that explanations, no matter how speculative, make for powerful evidences. Rosenhouse has argued this repeatedly. For instance, complex fossil species that appear out of nowhere become powerful evidences because they can be "explained" by punctuated equilibrium. And complexities are not a problem because, after all, complexities can conceivably arise. Evolution is a fact and nothing is a problem for it.
Finally, Professor Rosenhouse resorts to the argument that Hall and the others I've cited are evolutionists. Can these embryonic problems really be so serious if these fellows are evolutionists? Here Rosenhouse puts me in an impossible position. Imagine if I had used quotes from evolution skeptics. Then I would be blamed for not fairly representing the theory. The fact that these evolutionists do not doubt evolution indicates the validity of these concerns. These are not contrived concerns being raised by skeptics of evolution. Whether or not Hall is an evolutionist has no bearing on the evidence. I could have just as easily quoted from an evolution skeptic. Would that, then, have meant that the evidence is against evolution?
Next in my essay I considered molecular homologies. I gave six example functional reasons for the protein sequence patterns we observe (i.e., sequence similarities correlated with morphological similarities). They were speculative and we would need quite a bit more research to learn more about what functional reasons might explain sequence similarities.
I pointed this out when Professor Rosenhouse said that "it is safe to say that no one has a plausible suggestion for what that functional reason might be" for sequence similarities and differences. Rosenhouse was asking about how the specific patterns in hemoglobin differences (for example) that we find across species is explained functionally.
My six (speculative) functional reasons provide potential rational for these patterns (again, big questions are unanswered at this point, the reasons merely indicate possible explanations exist), but Rosenhouse vigorously complained that I missed his point and my six reasons are irrelevant to his concern. He also said my reasons were "only a lot of jargon thrown around for no good purpose," and asks rhetorically: "This essay was included in a volume intended primarily for non-scientists. Do you really think Hunter was trying to bring clarity to scientific issues here?"
Actually, my intention was not to confuse the reader by tossing about meaningless jargon. The reasons, though speculative, are reasonable starting points at addressing the very issue Professor Rosenhouse was asking about. Rosenhouse apparently does not understand this. He questions my motives, but in fact the point was that conceivable functional reasons exist for the observed sequence patterns.
I next pointed out that highly-conserved, non functional regions of the human and mouse genome weaken the case for common descent. Professor Rosenhouse is again, however, says that this is all meaningless. "Suffice it to say," he explains, "that it is more of the same: Hunter offers an idle bit of data (in this case certain similarities in the non-coding regions of human and mouse genomes) and simply asserts, without justification, that it poses a challenge to common descent."
Sorry, but this is science, and science does use data. And this is hardly "an idle bit of data." In fact, though I provided the reference, it doesn't require an expert to see that highly conserved functionless regions in fairly distant species is not what evolution predicted. In fact, before such findings evolutionists used to say that this sort of thing would falsify evolution.
Notes
Alberch, P., "Problems with the interpretation of developmental sequences," Systematic Zoology, 34:46-58, 1985.
de Beer, G., Homology: An Unsolved Problem, 1971.
Hall, B. K., "Homology and Embryonic Development," Evol Biology, 28:1-37, 1995.
[ 22. September 2004, 12:09: Message edited by: Cornelius G. Hunter ]
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Darel R. Finley
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Member # 100
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posted 22. September 2004 09:21
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The scenario is not merely that the existing secretory system could have evolved into the existing flagellum. The scenario is that the flagellum plausibly could have arisen via evolution. If it is not shown that the flagellum plausibly could have arisen via evolution, then the hypothesis fails.
Dr. Hunter,
It seems that we are in a disagreement not over Darwinism-vs.-design, but over the proper way to argue against Darwinism. To avoid a never-ending thread, I'm guessing it's time we agree to disagree, and simply summarize our positions. My position on this is best illustrated by a quote from Behe:
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How about Professor Coyne’s concern that, if one system were shown to be the result of natural selection, proponents of ID could just claim that some other system was designed? I think the objection has little force. If natural selection were shown to be capable of producing a system of a certain degree of complexity, then the assumption would be that it could produce any other system of an equal or lesser degree of complexity. If Coyne demonstrated that the flagellum (which requires approximately forty gene products) could be produced by selection, I would be rather foolish to then assert that the blood clotting system (which consists of about twenty proteins) required intelligent design.
--Michael Behe, "Philosophical Objections to Intelligent Design"
Behe does not specify in this quote exactly what is meant by explaining the flagellum -- every step from non-living chemicals up? -- so I must apply common sense and the context of his argument. To me, this Behe quote implies that IC can be defended in one of two ways:
1. The origin of any IC core resists Darwinian explanation, and any one plausible counterexample will suffice. If Darwinists come up with one, they have defeated IC as an anti-evolution argument.
2. If Darwinists show how one IC core could arise, but haven't explained others, then IC still stands. Potentially, we expect the entire evolutionary chain from non-living chemicals to the modern flagellum (and various other IC systems) to be explained in detail before we will admit defeat.
Behe, I think, is subscribing to defense #1, and makes it clear that defense #2 would be an endless appeal to ignorance as Professor Coyne charges.
So, we have to draw the line somewhere for what an anti-IC Darwinist is required to produce to have removed IC as an obstacle to Darwinism. I say that line should be drawn at the production of any novel, irreducible core of components.
I do not deny that if the flagellum evolved from the secretory system, then the evolution of the secretory system is ultimately part of the overall evolution of the flagellum, and should one day be explained by Darwinists. But if IC is to be defended as something more than an argument from ignorance, we have no choice but to tackle each Darwinist claim (to have explained an IC core) separately, and to make a special point of doing so, since IC is so often accused of being an argument from ignorance.
This means that the most important IC cores to discuss are those that the Darwinists claim to have solved. We are all aware that there are a dozen other cores they don't even claim to have solved, some of which may be necessary precursors to the flagellum. (Could the flagellum have evolved in the absence of the intracellular transport system which Behe discusses in detail in Darwin's Black Box?) Identification of functional IC cores is critical to the whole IC position, and defense #1 requires that we let the Darwinists choose which core we will fight over today.
If I thought that IC could not be defended except by insisting that the appearance of multiple cores be explained together, when one of them already has been, then I would have to renounce IC as a failed argument.
[ 22. September 2004, 13:36: Message edited by: Darel R. Finley ]
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Darel R. Finley
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posted 22. September 2004 14:00
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If that is valid, then why start with A? Why not start with Y, explain only one step in the process, and claim that Z is not therefore IC?
Why would the latter not be a reasonable refutation of IC?
Scott,
It is a reasonable refutation of IC if both of these conditions are met:
* Z contains an IC core of components that is not found in Y.
* Y is known to have existed prior to Z.
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Cornelius G. Hunter
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Member # 81
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posted 22. September 2004 14:27
Darel:
I agree with you that the Behe quote means the origin of any IC core resists Darwinian explanation, and any one plausible counterexample will suffice. If Darwinists come up with one, they have defeated IC as an anti-evolution argument.
What should an anti-IC Darwinist be required to produce to have removed IC as an obstacle to Darwinism? You say that line should be drawn at the production of any novel, irreducible core of components. Agreed. Next you say:
quote:
I do not deny that if the flagellum evolved from the secretory system, then the evolution of the secretory system is ultimately part of the overall evolution of the flagellum
Why do you say "ultimately"? It seems you are making a distinction between pre secretory system evolution and post secretory system evolution. You write:
quote:
This means that the most important IC cores to discuss are those that the Darwinists claim to have solved. We are all aware that there are a dozen other cores they don't even claim to have solved, some of which may be necessary precursors to the flagellum. (Could the flagellum have evolved in the absence of the intracellular transport system which Behe discusses in detail in Darwin's Black Box?) Identification of functional IC cores is critical to the whole IC position, and defense #1 requires that we let the Darwinists choose which core we will fight over today.
But no one is saying this. I agree with you that the evolution of an IC design such as the flagellum is going to depend on other IC structures. But remember, if we can demonstrate that one IC design can evolve, then we can assume the others could evolve too (though evolving multiple IC systems simultaneously might be quite a trick). So while trying to prove the evolution of the flagellum, we can assume, for the moment, the existence of the others. Then, if we succeed, the problem is solved and the IC problem is rejected. But this does not mean that we can pare back the problem of the flagellum evolution to something that it is not.
Consider an arch made of stones that you can walk under. If any of the stones were missing the arch would fall apart. How was it created? Is it unlikely that the arch evolved into place? Consider this hypothesis: The arch was created by using string to suspend each stone a few inches above its designed positions. Then, the string is cut and the stones all fall neatly into place simultaneously, forming the arch. There is no doubt such a pathway could work.
Now imagine that future research demonstrates that the latter part of Musgrave's pathway starting from the secretory system to the flagellum is indeed plausible. The known components could have come together to form the flagellum via empirically observed processes. This would mean that the initial conditions were rather remarkably arranged, such that these different components could assemble and work together, and be performing this new function. This would be quite a bit of serendipity. A better solution would be to show is that there is something fundamental at the molecular level that accommodates this degree of interchangeability despite the enormous degrees of freedom in these structures. This indeed may be so, but we have little evidence of it right now.
Interchangeability degrades with complexity. If I am building simple structures with simple components (e.g., wooden blocks), then often I will be able to interchange different blocks that are not the same size or shape. If I am building supersonic jet fighter aircraft with components that have hundreds or thousand of degrees of freedom, then interchangeability isn't going to come naturally. Can you imagine using a rudder component from one fighter in the nosecone of another? I don't think so. If we were to find some fundamental reasons to believe that this is generally the case in biology, then that would be very interesting. And this would be one way to solve IC.
[ 25. September 2004, 03:28: Message edited by: Cornelius G. Hunter ]
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Scott
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posted 22. September 2004 15:40
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RBH: This is in the same league as the question "If man evolved from monkeys, why are there still monkeys?" C'mon, Scott. Think about it.
Perhaps to you it is in the same league, but not to me. Afaik, no one asserts that monkeys evolved into men, or that man evolved from monkeys. That's the standard evolutionist's response to that question, isn't it?
And yet here, isn't it being asserted that some system evolved into a different system?
Also, I see a difference between populations and biochemical structures or systems.
It's not a vacuous question. It deserves an answer. I can think of one:
The secretory system did not evolve into the flagellum.
So what are we left with? I can think of alternatives. Frankly though, I don't think this is the thread to take that up in. I think that's getting a bit off topic.
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Salvador T. Cordova
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Member # 959
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posted 24. September 2004 11:12
Dr. Hunter,
You may hear about this at Dr. Rosenhouse's blog. By a strange set of circumstances we met at James Madison University for the first time at a meeting of the JMU Freethinkers.
We had a very pleasant conversation, and the Freethinkers invited us to have a panel discussion about these topics in the future.
In the spirit of brainstorms, I hope we will continue to work with the critics of the design hypothesis to strengthen our arguments.
I point this out because this thread will likely be receiving more attention than you may have ever envisioned. I'm appreciative that an ISCID fellow like yourself would spend time posting here, and I wanted to publicly express my thanks, espcially now that Dr. Rosenhouse and I will be having informal and likely formal panel discussions at JMU on the issues you have cited in this thread.
Thank you again, Dr. Hunter.
Salvador
PS
Dr. Rosenhouse is a really nice guy in person. I hope you have the privilege of meeting him someday.
[ 24. September 2004, 11:12: Message edited by: Salvador T. Cordova ]
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Cornelius G. Hunter
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Member # 81
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posted 24. September 2004 11:24
Salvador:
Thank you for the kind note. I appreciate your posts. Also, thanks for pointing out that Nishikawa paper -- very interesting.
[ 24. September 2004, 11:25: Message edited by: Cornelius G. Hunter ]
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