8/20/2007

VOX DEI BATE #6

Vox has replied, and his response is substantive. I have to admit that I am surprised to the degree that our thinking is convergent on certain points. I will reply at length to the new observations he makes, but for right now I want to focus on the points of agreement, to make sure that there is no misunderstanding.

(sigh) Hopefully, no one will accuse me of equivocating, but we'll see. Vox writes:

"...(2) Scott's genetic definition of evolution differs from the conventional definition based on fossil-based speciation which one commonly encounters in discussions with pro-evolution laymen. (3) I am not attempting to make a proactive case for an alternate theory of speciation or genetic evolution, I am simply defending my position as an evolutionary skeptic.

I agree with (2), though I note that there is greater cross-talk between those who study genetic evolution and the fossil record than ever before, and that 'molecular clocks' and phylogenetic trees derived from the former tend to accord with the latter within an order of magnitude. Those cases that don't aren't being shoved under the rug, either: they are active areas of research.

I also agree with (3) in the paragraph: Vox's skepticism is entirely a negative argument against the prevailing model, not an attempt to foist an alternative model on the rest of us. What I and some others would like to know is where Vox stands on the the question of whether any account presuming natural causes could prove sufficient. How about it, Vox? Is your skepticism on this point confined to TENS (the Theory of Evolution by Natural Selection) alone, or does it extend to any model which confines itself to natural causes?

Anyway, more Vox:

Second, I wish to note a few points that Scott has graciously conceded. (1) There is no clear evidence of speciation in the fossil record. (2) One cannot claim that the Theory of Evolution by Natural Selection (TENS) is the truth and speak as a scientist. (3) Those who attempt to enlist TENS as proof for things which cannot be tested have left the domain of science."

Gulp! I'm going to offer a caveat for (1), since it could easily be misinterpreted.

I don't think any paleontologist would claim that any particular sequence (A-> B-> C) of transitional forms actually unequivocally documents an episode of speciation. We can't know if A is actually an ancestor of B, or if B is actually an ancestor of C. We have to keep in mind that in individual cases other possible explanations for the apparent transition in question might exist. The population represented by A might've co-existed with B, for example, but flourished in greater numbers earlier in the history of life than B (thus leaving more fossils of greater antiquity), and vice-versa, given the impression that population A was ancestral to B when in fact both shared another common ancestor.

So, yes, no clear-cut case of speciation can be demonstrated in any individual fossil sequence. To put it another way, organisms fossilize, but the moment their populations diverge from others (the speciation event) does not. But the inference that speciation occurs doesn't rely upon individual cases, but upon the entire fossil record, and obviously I am persuaded that the inference as a whole is correct. I suspect Vox does, too! So while in a sense I agree with (1), keep in mind my language lacked the necessary precision the topic deserves, and it should not be taken as evidence that I think the fossil record doesn't support the evolution of species, because I do.

More Vox:

(2) One cannot claim that the Theory of Evolution by Natural Selection (TENS) is the truth and speak as a scientist.

This is true, if one is speaking of 'truth' in a non-tentative, dogmatic way, 'Truth' with a capital 'T', the kind of truth the Nazarene says will set you free. Like I said, I'm not in the truth business. The models we build in science are always tentative, always held provisionally. Individual scientists know better than to suggest otherwise, but (especially in popularizations) they often forget that their enthusiasm for this or that proposition comes across as dogmatic, especially when they are being read by someone who defines his or her self in terms of a belief system. Small wonder we scientists are often accused of peddling our own belief system! Most of the time, Vox, I honestly believe that scientists are innocent of this charge. But, you know, I tend to be hyper-optimistic, as PZ observed.

More Vox:

(3) Those who attempt to enlist TENS as proof for things which cannot be tested have left the domain of science."

I agree, obviously. That doesn't make them right or wrong, of course. It just means that such declarations are not science. It's difficult for pro-evolution advocates to steer a middle course here, given the tendency of creationists to insist that their untestable source of Truth trumps our difficult (but not impossible)-to-test model. Unabashed advocacy is a good political strategy, but doesn't necessarily lead to the best science. I can say with authority that scientists tend to speak far more conservatively in our formal pronouncements---that's just the way science is done. Where we often stumble is in popularizations, and (especially) in public debate with the unscrupulous.

Well, that's enough for now. A future post will address Vox's new claims and some points of disagreement. Many have expressed doubts that anything positive can come from such exchanges. I've certainly been frustrated by some of the commenters at Vox's place, but I also have to tip my hat to Starwind (a VD regular), who has demonstrated more genuine intellectual curiousity on the comments section of this blog than many partisans on both sides ever do---and that's refreshing.

7 comments:

Anonymous said...

who has demonstrated more genuine intellectual curiousity on the comments section of this blog than many partisans on both sides ever do

If he had been genuinely curious he wouldn't have been so resistant to look up the terms the was tossing around to see what they actually meant. As the anonymous guy he was arguing with it just got more and more depressing until I figured I could walk away from the keyboard or start typing slowly and in all-caps.

And where you quote vox as saying:
Second, I wish to note a few points that Scott has graciously conceded. (1) There is no clear evidence of speciation in the fossil record. (2) One cannot claim that the Theory of Evolution by Natural Selection (TENS) is the truth and speak as a scientist. (3) Those who attempt to enlist TENS as proof for things which cannot be tested have left the domain of science."

this is exactly the kind kind of quotemining they live for - the misusing of terms like Proof and Truth to get soundbites they can wave around. "See, an evolutionist agreed that there's no clear proof of speciation and that no-one speaking as a scientist can calim that The Theory of Evolution is true!"

You walked into that one. They don't.do.nuance. They aren't interested in learning what a theory is, or the nature of proof in a scientific context. They just want to win on whatever Sophistic terms they possibly can.

Jim RL said...

2) One cannot claim that the Theory of Evolution by Natural Selection (TENS) is the truth and speak as a scientist.

This is just an overly philosophical abuse of language. Science doesn't deal in "Truth" or proof. Science deals in evidence, and Evolution by Natural Selection conforms to all of the available evidence. The entire field of biology only makes sense through the lense of evolution via natural selection. I have to agree with anonymous that you walked into that one. The quote could just as well be you can't talk about anything as "Truth" as a scientist. I doubt Vox will respect the subtlety.

Scott Hatfield . . . said...

The entire field of biology only makes sense through the lense of evolution via natural selection. I have to agree with anonymous that you walked into that one. The quote could just as well be you can't talk about anything as "Truth" as a scientist. I doubt Vox will respect the subtlety.

You guys aren't wrong about my stepping in it. I screwed up there, I agree. I could definitely be 'quote-mined' and I'm a little nervous about it. I can only hope that Vox has more integrity, and more appreciation for nuance, than his critics suspect.

Anonymous said...

You aren't the first TENS supporter who has said it, and you probably won't be the last. You need to get over your anxiety, because it is politically oriented. Like any writer and educator, you can only be responsible for your words in context.

--emerod

Dennis said...

I am a Geologist. The fossil record does show speciation events. In fact very many speciation events, I would recommend any book on trace fossils, there are many good ones in the geology section of your university library. It will supply a good description of the fossil, the changes, and the timeline.

The only thing left to question is the mechanism that drove the change. That can only be explained through other sciences, Geologists don't do those studies. Geologists use the fossil evidence to describe a soil horizon and do some preliminary dating (not final dating). Geology texts won't answer why something evolved just show evidence that it did.

Evidence of speciation is actually more revelent in existing species. There, not only do we see the outward expression of the change but can examine the environmental factors and biological mechanisms enacting the change.

There are many examples of ongoing speciation. If you can accept the simplification that speciation occures when there is a change in chromasome number, however this is not the whole story. Look at dogs they all have something like (I am going from memory here) 72 chromasomes all dogs can mate including wolves and excluding foxes, and produce offspring. However you cannot mate a very large dog with a small dog and get a good result they will have disasterous congenital defects, you can mate down using intermediaries and get all good dogs. Big and small dogs are sexually differentiated but not genetically differentiated. Horses 44 chromasomes and donkeys 42 chomasomes are genetically differentiated but can produce a good offspring, a mule 43 chromasomes except the mule is always sterile because the X and Y chomasomes do not match up. All cats have 38 chomasomes except South American cats they have 36. You couldn't tell the difference between a South American Leopard and an African or Asian Leopard but they cannot mate they are completely speciated, this is a good example of convergent evolution. You can mate a lion 38 with a tiger 38 and get a liger but the liger is always steril just like a mule and in the same way lions and tigers are just a genetically differentiated as horses and donkeys, don't let that chromasome number fool you pigs also have 38 chromasomes. Currently being actively studied are the north African short necked giraffe they are in the middle of speciation and have members with 40, 41, and 42 chromasomes they all can interbreed and produce completely viable offspring because the genes that are fusing have to do with the neck.

To get an idea how this happens look at the following link
http://www.talkorigins.org/origins/postmonth/jul05.html#hon

So you question whether speciation can be proven I think you are looking at the wrong evidence.

Scott Hatfield . . . said...

Dennis:

Thank you for your comment. I'm actually the pro-evolution science teacher guy in this exchange. I have no doubt that speciation events are very common and I know of several instances where they have been documented---the earliest example that I'm aware of being Moore's work with the leopard frog in the 1940's. I live in the San Joaquin Valley, which is 'ringed' by the Ensantina complex of incipient salamander species. And so on, and so forth: I am completely satisfied that speciation now and in the past is well-demonstrated.

Where I would part company with you is the claim that speciation events are preserved in the fossil record. Instead, what we have is a general demonstration of the fact of evolution and powerful evidence for common descent. We can't say anything definitive about whether the lineage of fossil 'A' is actually ancestral to the lineage of fossil 'B', no matter how many ways we look at the artifacts.

Anonymous said...

"I can only hope that Vox has more integrity, and more appreciation for nuance, than his critics suspect."

Is this meant to be ironic? Read his latest column on WorldNetDaily and weep tears of despair.