The conversation took many strands, which is never ideal, but I'll try to summarize each one as best I can.
One of the strands included a look at the Argument From Authority Fallacy (AFAF). The chap kindly directed me to a site which details the whole fallacy in detail.
The AFAF goes like this:
1. Person A is (or is assumed/claimed to be) an authority on subject S.
2. Person A makes a claim C about S.
3. Therefore C must be true.
Unfortunately the chap I was chatting to failed to acknowledge much of the fallacy's components in his own argument.
One of the sites included a refutation of vestigiality. According to Dr. Jerry A Coyne, who is an authority on evolution, vestigiality is "diagnosed not by its usefulness, but because it no longer has the function for which it originally evolved" ['Why Evolution Is True' (2009)]
Dr Coyne goes on to describe the fact that humans still have an extensor coccygis muscle attached to our coccyx. This is the exact same muscle which is found in monkeys and other mammals which have tails. In humans the muscle has no function despite it still being attached to our skeleton.
In the article on the Creationist site highlighted above, written by Dr Don Batten and Dr Jonathan Sarfati they state that: "it is in principle not possible to prove that an organ is useless, because there is always the possibility that a use may be discovered in the future." This is clearly not true of the extensor coccygis muscle, unless of course humans have yet to grow tails. To be honest I wasn't sure I was inclined to read any more of this article, but I struggled on.
The next point to be raised was about why emus and ostriches are flightless despite having wings. The article suggests that:
1. they derived from smaller birds which could once fly (which is one form of evolution the Drs claim is acceptable within the Creationist model.)
2. they do have a function other than flight.
3. the Creator uses the same model for all birds regardless, and therefore all birds have wings.
Dr Coyne does not disagree with the second point at all. In fact he explains the exact same thing from an evolutionary standpoint. Ostriches use their wings in courtship displays (as do other birds), and to maintain balance, (as do other birds), and to threaten its enemies, (as do other birds.) So in fact the ostrich has wings which perform all of the function of other birds' wings except flight... perhaps then the problem isn't that the wings are badly adapted for flight, but that the rest of the bird isn't... but that's just my wacky idea!
All flightless birds have wings, but the kiwi has only tiny wings buried deep under its feathers which are just remnants of their flying ancestors' wings. Totally useless for any of the above adaptations.
When Drs Batten and Sarfati try to claim that the fact that a vestigial organ, or limb, undermines evolutionary theory they miss the point entirely. "Evolutionary theory doesn't say that vestigial characters have no function" says Dr Coyne, " It is vestigial not because it's functionless, but because it no longer performs the function for which it evolved... Indeed we expect that ancestral features will evolve new uses: that's just what happens when evolution builds new traits from old ones."
When you admit, as the Creationists do that the wings of the ostrich now have new functions besides flight aren't they saying that these changes are adaptations, and aren't adaptations part of the evolutionary process?
Further in the article the Creationists claim that it is only possible to devolve and not evolve. That means that in the Creationist model it is only possible for organisms to lose function and not evolve new traits which gain function. They argue that once a bird has devolved to become flightless it cannot re-evolve to regain its flight. This is possibly true. I personally don't think I know of any animal which has regained past lost abilities, but then I know that the process of evolution only works in the direction of conferring an advantage to the organism within its current surroundings. So if a bird needs to feed on the ground then it is likely to become flightless. Unless its source of food learns to live arboreally, or fly, the bird is unlikely to ever need to go back to flying! That's just how evolution works.
It's worth going back to the AFAF for a second and take a look at the two sides I've presented here. Dr Jerry Coyne holds a PhD in Evolutionary Biology which he gained from Harvard, one of the USA's premier universities and has authored over 115 refereed scientific papers. He is an authority on evolutionary biology. Now let's see what the other side looks like shall we?
Well... Dr Batten is a horticulturalist, and Dr Sarfati is a physical chemist. Neither of them have any qualifications in evolutionary biology and so are not authorities in the field of evolutionary biology.
So to quote the AFAF web page sent to me by the Creationist on twitter:
"This sort of reasoning (AFAF) is only fallacious when the person is not a legitimate authority in a particular context... If a person makes a claim about some subject outside of his area(s) of expertise, then the person is not an expert in that context. Hence, the claim in question is not backed by the required degree of expertise and is not reliable. It is also very important to note that expertise in one area does not automatically confer expertise in another. For example, being an expert physicist does not automatically make a person an expert on morality or politics." [my emphasis]
So the Creationist has already fallen foul of his own accusation aimed at me that, since I accept the truth of evolution I am committing the Argument From Authority Fallacy, and yet in actual fact, since the authorities I accept my information from are experts in their field I am not committing that fallacy at all... I am merely accepting the word of someone whose accomplishments in the context I am defending are beyond doubt. This is a valid exercise.
I was sent another link to an Answers In Genesis page the author Dr David Menton (an anatomist not a paleornithologist - see above AFAF notes on relevant authorities) writes that Alan Feduccia, a noted paleornithologist has refuted the idea that birds evolved from therapod dinosaurs but if you go back a bit in the article you'll find this:"While evolutionists now agree that birds are related in some way to dinosaurs, they are divided over whether birds evolved from some early shared ancestor of the dinosaurs within the archosauria (which includes alligators, pterosaurs, plesiosaurs, ichthyosaurs, and thecodonts) or directly from advanced theropod dinosaurs (bipedal meat-eating dinosaurs, such as the wellknown Tyrannosaurus rex). " [my emphasis]
So... the article goes on to refute the line of thinking which brings us to an evolution from therapods, and does so quite eloquently and rather convincingly I have to say. Me being no expert and all that. However, I can read, and I noticed that the AIG writer rather skimmed over the line of thinking proposed by one, Alan Feduccia... where have we seen that name?... that birds are evolved from archosaurs. In fact, Prof Feduccia's inclusion in the AIG article is a classic tactic of the Creationist movement. They find the current widely accepted theories and find the one person amongst the throng who disagrees, then elevates them to great heights as the ultimate authority on the issue at hand. Feduccia is in the minority, but his ideas might have merit. Unfortunately for the Creationists Feduccia's main argument is that therapods and birds have a common ancestor in the archosaur, so that means whichever way you look at it modern dinosaurs (birds) did evolve from earlier species, the only contention is which one?
Several times during the AIG article we are told that dinosaurs are reptiles, which is actually a misleading statement, since most of them did not exhibit characteristics that are particularly reptilian at all. It makes you think of scaly, cold-blooded creatures with four legs and flicking tongues. However, most dinosaurs had skin, not scales, walked on two limbs not four and were likely warm-blooded and highly socialized. So comparisons between reptile lungs and avian lungs, and between scales and feathers are invalid. Birds are recognized today as being bona fide dinosaurs by the vast majority of ornithologists and paleontologists. The evidence is there for those who truly want to find it.
So, atheists/skeptics beware when looking at sites such as Answers In Genesis, because the tactics are to seem very technical and scientific, but what they don't tell you is more important than what they do tell you.. and more important still is who is telling you! When talking about the Argument From Authority Fallacy the theists' side of the fence are almost certain to be the biggest culprits, so when they tell you that you are the fallacious one, remember that you are far more likely to find sources appropriate to the argument/discussion than they are.
Thanks for reading. Please comment on this if I've missed anything or made any obvious mistakes.
______________________
"Why Evolution Is True" by Dr Jerry A. Coyne was published in 2009 and is available at all good book shops.
No comments:
Post a Comment