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Mike PSS

Posts: 428
Joined: Sep. 2006

(Permalink) Posted: Jan. 31 2007,23:21   

Quote (Cornelius Hunter @ Jan. 30 2007,11:42)
Mike PSS writes: First, the evolutionary claim is made that pentadactyl pattern found within mammals is the result of common descent.  You do know that this means the common ancestor of mammals had pentadactyl pattern limbs.  And that this trait is carried by ALL mammals.

No, it need not be carried by all mammals.

Common Descent = Nested Hierarchy
ALL mammals (extant and extinct) exhibit the pentadactyl limb pattern.
Please find me one example where a mammal (extant or extinct) doesn't have pentadactyl limbs or limb precursors.
If you want to discuss nested hierarchies then I'll probably have to channel Zachrial to this thread as he has numerous recent posts trying to explain this subject to a JoeG (over on the UD thread).
Mike PSS writes: Second, the evolutionary claim is made that the morphological similarities between thylacine and wolves are developmental in nature because of similar environmental influences during each evolutionary event.  You do know that this means that an environmental niche was "available" for evolution to "fill" by RM+NS+time (+other factors) and that the "available" niche was duplicate at seperate and isolated geographic locations.  And that the resident species "eligible" to fill this niche within these geographic locations were different.

I dispute your analogy here because without further explanation about how pentadactyl limb development is comparable to thylacine/wolf morphological development.  You need to show either...
How did available environmental niche influence the development of pentadactyl limbs.
What genetic similarities were developed between thylacine and wolf as a result of environmental nich development.

The problem here is that you are placing the burden of disproof on me when you are making the evidential claim.

My questions are NOT burden of proof questions.  The questions are based on sound logic so that your argumentary claims can be logically LINKED to one another.  Without some type of answer (notice that you only have to answer one of them) then you don't have a linked comparative argument.  You just have two seperate observations that result in seperate answers.  There is NO claim you can make by comparing the two observations without some logical (NOTE: NOT EVIDENTIAL BUT LOGICAL) underpinnings to your statements.
I'm merely asking how those similarities, that happen to fit the evolutionary pattern, are supposed to count as powerful evidence. Of course evolution has an explanation, as you outlined above.

So you agree that my answers count as powerful evidence?
If you don't agree then you have to answer one of my questions to logically link the statements.
The answer to my question, according to standard evolutionary theory is, as Theobald concisely put it: "In one case we have structural similarity that has a functional explanation (wolves).  In the other case, we have the much more puzzling phenomenon of structural similarity in spite of functional diversity (pentadactyl limbs)."

In other words, for homologies such as the pentadactyl pattern, there doesn't seem to be a good reason why the same design would be used for different functions. This is puzzling for evolutionists.

I beg to differ with your conclusion here based on Theobold's quote.  You better parse or reference Theobold a little bit better to fit your conclusion you just made.  In fact I think the next paragraph you quoted (but didn't include) from the Theobold paper actually gives Theobold's answer to his "puzzling" statement.  Context in quoted phrases is important.

Maybe in your world view there has to be a "reason" associated with the use of similar design.  However, as the answers I gave above indicate there is NO puzzle to the functional dissimilarity of the pentadactyl homology in mammals.

There are several problems with this evidential claim, but I would like to focus on just two of them. First, the claim relies on an unproven premise. The premise is that the pentadactyl pattern is, at least in some cases, not an optimal or efficient design. The reasoning here is intuitive. It shows up for different functions, and it seems unlikely that one design can be the best for such different functions (digging, flying, grasping, etc.). That is all well and good, but we do not know this to be true.

First, no one but IDists seem to claim "optimum or efficient design".  I know I don't in my answer (nor does Theobold).  The only evolutionary claim made is that the pattern need only have enough function to support the organism.  This function, over time, may be "optimized" where version 2 (being a slight modification of version 1 due to evolutinary mechanisms) is better adapted to the function when compared to version 1.  However this is not "optimum design" nor does it have to be "efficient design".  There is no "best design" in the evolutionary pentadactyl pattern, only usefull function.
Darwin made the claim a century and a half ago with nothing to back him up but intuition, and today nothing has changed. Take one look at the different pentadactyl designs (eg, in the horse and bat) and one can see it comes in very different shapes and sizes, and seems to function OK. Who knows, perhaps it is efficient. Perhaps the extent of structural similarity which we observe (which often isn't very much) makes sense for the given functional diversity. So this popular and important evidential claim entails a premise that is not known to be true. It may seem puzzling to us, but perhaps we should not throw up our hands and give up. It is certainly a very interesting observation, but hardly supports the claim that this is powerful evidence.

And this is a strawman argument that you tried to create by claiming that pentadactyl limbs need to have "optimal or efficient design".

I'm blowing your straw down and you should look at my counter-point to your "optimal or efficient design" claim above and answer this first before making any conclusions based upon your "optimal or efficient design" claim.
A second problem is that the claim is not scientific. Regardless of whether or not homologies such as the pentadactyl pattern are inefficient, this claim entails an "ought" premise. That is, the argument entails a premise about what biological designs ought to be like. This is metaphysical, and it makes the evidential claim impenetrable and outside of science, for one cannot use science to address opinions about what ought to be. One cannot argue against the metaphysical beliefs of evolutionists.

I don't see how your making this metaconclusion from the evolutionary claim for pentadactyl limbs (common descent).  Please explain in some more detail how saying "common descent" as an answer can lead you to believe there is some "ought premise" put forward.  I'm confused with this response.

Mike PSS

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