Joined: Jan. 2007
| Paley writes: If the structural convergence between marsupial and placental wolves argues against common descent as you seem to think, then why did the molecular analysis I cited earlier place the thylacines with other marsupials, in conformance with evolutionary predictions? Is this not an example of a passed test?|
Please be careful. First, I did not say convergence argues against common descent. I'm merely using it to raise questions about a claim of powerful evidence. Second, no one is denying that evolution passes tests (a much weaker claim).
| Deadman writes: I asked other than skin as patagium, what traits do you find so significant in sugar gliders and flying squirrels...if it's to be about pentadactyly v. patagium, you have to admit that the universality of pentadactyly in mammals seems a tad more ...well, UNIVERSAL ( and hence basic) ... than mammals with patagium. Pentadactyly is part of the mammalian bauplan and patagium webbing is not. If you want to say " but this is merely subjective" uh...okay. Gosh, Waterloo! |
For the moment, I feel pretty secure in pointing to pentadactyly and saying " this universal mammalian character carries more weight than non-universal patagium" But I see you have problems with that. Tsk. Then do some work.
All good points, but you are drifting back into a strawman. You and many others have repeatedly argued against falsification. Secondly, universality is not crucial here. It can be forfeited (by evolutionary theory) without sacrificing the claim of homology or this evidential claim.
|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.
|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. 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.
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.
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.
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.
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.