I am going to comment first on your response to me, and then on a few items in your responses to Papias.
NOTE: I wrote this last night and then could not post it when CF went down, so it overlaps with the most recent message from Papias
So, I'm curious what your background is with respect to biology.
Like Papias, I have no formal qualifications in biology. In fact, in high school I didn't even like science and took only the bare minimum of courses required for graduation. My last formal instruction in science was a freshman biology course for students majoring in the arts--so you can appreciate how simplified it was.
And the prof even skipped the chapter on evolution.
However, I read it myself, as by this time I had heard from a number of sources that evolution was incompatible with Christian faith. It was not a long chapter and I read it in one evening. Do you know what my first thought was on reading it through?
"Wow! So that's how God did it! That's really neat!" (You have to remember I was only 18 at the time.) I really found it interesting and sensible and nothing faith-threatening about it at all. So, I didn't understand what the fuss was about.
I still didn't dig science generally, completed my BA specializing in language and literature and went on to teach French and English. It wasn't until about two decades later when I was married with small children that I even thought about science or evolution again.
I married an evangelical Baptist and shortly after we made a commitment to an evangelical Baptist church, I was invited to hear a preacher who had "scientific proof" the earth was only 6,000 years old. I was frankly flabbergasted. I knew some people had problems with evolution, but I had never before heard of anyone disputing the geological estimates of age of the earth before ("old earth creationism is historically older than "young earth creationism" and I had only heard OEC ideas when I was younger. YEC was brand new to me.)
Well, I found Mr. Gish amusing but not convincing; however I was worried about my kids getting a bad theological grounding in a congregation that encouraged their young people to listen to Gish. And I began for the first time to actually study evolution-related science as much as I could on my own.
But I only really got into it when I got access to the internet about 20 years ago. A lot of what I learned I found right here on Christian Forums. I have supplemented that with other sources such as talkorigins, Understanding Evolution 101 and through lots of reading--beginning with Finding Darwin's God by Kenneth Miller. I have been interested as well in looking at theological approaches that accept evolution such as the Evangelical Dialogue on Evolution, Biologos and again relevant books. Now my personal library contains two long shelves devoted to nothing but evolution and evolutionary creation.
I have even read a few actual scientific papers though that is fairly hard-going for me. Takes a lot of time to look up unfamiliar vocabulary and I never was good at math. But, with my background in language, I have found it relatively easy to pick up the basic framework of a professional scientific paper and follow the logical flow. I end up skipping much of the middle part, which is usually a description of method and detailed data and concentrate on the first part which defines the issue to be studied and then move to the analysis and conclusions at the end.
Further, what's your take on Genesis?
I assume you are referring to the creation accounts in particular and possibly to the account of the flood. Once we get to Abraham, the setting is clearly historical even if the story is not.
My take on Genesis was set when I read Mere Christianity by C.S. Lewis in my early teens (several years before I read that biology text on evolution). It is what Lewis calls "true myth". That is, in a literary sense, it is myth, but in a doctrinal sense it is truth. The myth is there to teach us truth.
What it clearly is not, is physical, empirical fact.
That is a conclusion I came to on my own from the text itself, long before I began to look into the evolution question. And it is also a conclusion for which I have since found additional evidence as I learned more about the ANE culture and the characteristics of various genres of literature.
It's certainly possible I misunderstood something, but a further issue I have with biology is the imprecise nature of its definitions and the heavy dependence on the qualitative. This is an example because the impression I get from Koonin is quite different from what you said. In his review of Theobald he says, "The alternative to UCA is convergent evolution of highly similar sequences of the universal proteins."
Let me come back to this when you cite the whole paragraph for Papias.
Again, I need to challenge your phrasing, which involves some circularity. I would agree were it said: The statement applies to the theory of evolution, not to the observed data.
I would consider that a friendly amendment, as long as it is understood that the observed data are data of evolutionary change. That is, at the most basic level, it is observed that the distribution of alleles in the population under study has changed over a number of generations. (It may also be observed that there have been mutations.) Evolution is defined as "a change in the proportional distribution of alleles in a population over generations". So the data observed are data of evolutionary change.
Does that take the circularity out of it?
Indeed, that is one of the open questions, isn't it.
In part. It is known that natural selection (as Darwin proposed) is a driver of evolutionary change. It is also known that genetic drift plays a role. And there is considerable interest now in the role of development as it influences the course of evolution. Open questions in this area are about such matters as "Under what circumstances does natural selection prevail over genetic drift and vice versa?" and "are there additional drivers of the evolutionary process we have not discovered yet?"
Note that these questions don't challenge the conclusion that there is an evolutionary process and they don't touch on the question of UCA.
To be sure. I meant it only as a milestone, and since we have passed that milestone science talks of what is currently the best theory, confidences levels for known data, and what has not been falsified. It does not claim any absolute proofs.
Yes. That is a good way to put it. Btw have you ever taken a look at Bayesian reasoning? Essential, I think, to understanding much scientific discourse today.
First, let me clarify that my comment referred to UCA, not to evolution in general. In that regard it seems you would call UCA an inference.
Yes, I think that the most appropriate term. Evolution implies, at the very least, a limited number of originating ancestors and is open to a single common ancestor. Darwin observed that much. Many factors discovered since his time (especially some of those noted in the link Papias gave you to 29+Evidences for Common Descent) have led to the consensus that a single common ancestor is more probable that a even a small number of originating ancestors. So on several grounds scientists infer a common ancestor of all living species. Inference, of course, does not establish fact directly.
Regardless, this is a bit of a semantics game. An assumption is something for which there is no (or insufficient) supporting data. Once one proposes a test, the assumption becomes part of a hypothesis. If one offers no data and no test, but expects the assumption to be taken as a given, it is typically called a postulate or an axiom. If one is filling the gaps in the data, the inferences are typically called deductions (for interpolations) or inductions (for extrapolations).
The word "speculation" is a bit of a pejorative. I don't accept self-evident truths in science. As such, everything rests on an assumption (or a postulate if you prefer).
Well, semantics is close to my home turf and there are certainly many semantic pitfalls in the creo/evo conversations. I don't find "speculation" a particularly pejorative word. And as it is used by many anti-evolution speakers "assumption" may as well be a four-letter word unfit to print in a decent article.
I think one has to accept some "self-evident" truths in any field. Axioms, if you like. For example, it is axiomatic in science that there is a physical world outside of our skins to be explored and understood. Anyone schooled in philosophy can tell you that is really not a proposition for which there is proof and some philosophies dispute it. But pragmatically, we all take it as self-evident.
Somewhat less self-evident, yet also axiomatic and assumed by scientists without proof or test is the accessibility and intelligibility of the physical world beyond us. Since Descartes and Kant no one has really provided an effective refutation of solipsism. But again, we take for granted that we are not brains in a vat experiencing an illusory existence in a Matrix-like situation. Moreover, we trust that our sensory organs provide us with accurate data about a world not of our own mental making and that said world will yield data which we can analyze rationally. When you think about it, those are astonishing claims: yet we take them for granted without test or proof. Science could not function without these "self-evident" truths.
Regardless of the word we use, I still maintain that UCA has not been established. Theobald did not succeed, and I'm not aware of anything being offered in its place. As I read the literature, some biologists are still looking for alternatives.
Well, since formally nothing in science is established, that applies to UCA as well. Given the evidence, however, and the lack of any alternative so far, it deserves provisional confidence. Especially as it allows for fruitful research. In that respect it is highly useful to scientists as a framework concept to deal with subordinate questions.
I certainly don't think the science of evolution will fall apart if it is ever established that archaea and bacteria did not have a common ancestor. And if it is only at such a remote period that the concept of common ancestry fails, that won't be of any comfort to those who oppose evolution because of the way they interpret Genesis.
Now in regard to your exchanges with Papias...
Yes.
It varies from the subtle to the direct. Starting at the subtle end, I would note "Alternative Designs and the Evolution of Functional Diversity" by Marks and Lechowicz, where they say that evolution "... anticipates only one optimal combination of trait values in a given environment, but it is also conceivable that alternative designs of equal fitness in the same environment might evolve."
Frankly I am really puzzled by the authors claim that evolution "anticipates only one optimal combination of trait values in a given environment" I agree with them that alternative designs of equal fitness could evolve in the same environment, but I have never heard any scientist propose what they say evolution proposes.
I hope this is not an example of refuting a claim that was never made in the first place. (That is found too often among those who reject evolution.)
In the middle is the work of Yonezawa and Hasegawa. In "Some Problems in Proving the Existence of the Universal Common Ancestor of Life on Earth" they call UCA an open question, and in "Was the universal common ancestry proved?" they call evidence for UCA circumstantial.
For some reason it is a common perception that circumstantial evidence is sub-par. But ask any forensic scientist or any lawyer depending on it, and you will soon find that circumstantial evidence is often much preferable to other evidence, especially eye-witness evidence which is often contradictory. Circumstantial evidence is often clearer and more conclusive than witnesses can ever be. And it can't lie.
I think what they are saying is the same thing I was saying when I referred to UCA as an inference.
On the more direct end is "Looking for the Last Universal Common Ancestor (LUCA)" by Koskela and Annila the statement is, "... it becomes apparent that the quest for the last universal common ancestor is unattainable."
If they mean pinpointing which population was the LUCA, they are probably correct. But that does not mitigate against the evidentiary case that a LUCA did exist.
In some areas quantitative analysis has matured, but (and here I'm deviating from talking specifically of UCA) with respect to the larger claim of a descent of species, it remains qualitative and shifting. The term "species" itself has not been settled, so I wonder what exactly it is that is supposed to have descended. Consider Mallet's article, "Subspecies, Semispecies, Superspecies".
That's one reason I prefer to speak of "populations". Whether the population under study is a species, subspecies, semispecies, etc. is always debatable. Of course "population" itself is a vague term in general, although in research one can delimit the particular population one is working with.
OK, now I see it is too long for one post, so I will continue in a second post.....