stevestory
Posts: 13407
Joined: Oct. 2005
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on the thread Jack mentions above:
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53
parlar
09/09/2008
4:57 pm
DaveScot,
This response became too long, sorry about that.
I recognize that there are many things about biology that we don’t understand. One thing that really puzzles me, for example, is the relative short time that life had to get started. But that doesn’t mean that I instantly buy religious (or the ID proxy) arguments for how it happened.
Admittedly, a significant problem in evolutionary theory (which IDists take careful note of) is that historical events cannot be proved, simply because we cannot turn back time to see what actually happened. It is likewise clear also that major evolutionary feats happen extremely rarely, often just once, in an earth-sized test tube over billions of years, which make probabilities difficult to estimate. We’re also kind of biased by the end result. Most of the time, however, we can quite easily reconstruct plausible chains of events of how things likely could have happened.
I did my homework regarding ‘irreducible complexity’ (IC), and found that I indeed had misunderstood the concept, please excuse my ignorance.
Here is the definition that I found:
“By irreducibly complex I mean a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning. An irreducibly complex system cannot be produced directly (that is, by continuously improving the initial function, which continues to work by the same mechanism) by slight, successive modifications of a precursor system, because any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional. An irreducibly complex biological system, if there is such a thing, would be a powerful challenge to Darwinian evolution.” (Darwin’s Black Box p39.)
Thus, if the ORIGINAL function of a complex structure disappears by the removal of one subpart of it, then that would establish that evolution couldn’t have done it. (indirectly supporting that a maker must have constructed it.)
The reasoning of this argument is appealing if you are inclined to accept the concept of a creator, but is logically flawed as I’ll demonstrate. The more conservative connotation that I intuitively thought it had, namely that subparts of the system would at all not be allowed to have other (previous) functions, actually made more sense. It would still suffer from the same logical flaw, but it would be more impressive.
The logical flaw lies in the test implied in the first sentence of the cited paragraph. The principal reason comes from the fact that a molecular complex (AB) evolves together. Original functionality in one part A is likely to disappear if a second part B exists that performs that function more efficiently. If B did not perform it more efficiently, evolution would not have promoted this complex AB. The reason why A doesn’t keep the function is that (purifying) selection pressure is required to maintain protein functions; otherwise they are degraded by genetic drift. And if B does the job, selection doesn’t make A keep the function. Simple enough. So, if you remove B and test the function of A, you will often find that it cannot do anything.
Behe’s argument can therefore not be used as an evolutionary test.
I can now imagine arguments that purifying selection and genetic drift is just Darwinist complicated wish-thinking, but I assure you that these are well-established facts with tons of concordant evidence behind.
Just to briefly re-connect to the previous discussion on the flagellum: the paper that you refer to from the year 2000 was written and coordinated (last name authorship) by Milton Saier Jr., who was also last name on the review in Microbe by Wong et. al. (2007) that I referred to earlier in this conversation. Apparently, he changed his mind.
Actually, I’m not really sure what this significance is of the progression of these appearances. If the flagellum appeared first (I’ll gladly admit that it very well might), and that the T3SS then would be partly derived from flagellum components, wouldn’t that still require evolution? Or how does ID then explain that the T3SS later came about? How does this support the ID case?
To really disprove evolution, you would have to find a credible way to deal with the massive amounts of data that supports it in all corners of biology and paleontology. How can the progressions in fossil records be dealt with in a credible way? What about the real-time observations that we make every day on the spreading of antibiotic resistance (adaptive phenotypes)? What about data that demonstrates increased genetic drift in small populations? What about data that demonstrates how new pathogens have come into existence by import of pathogenicity traits (such as genes for T3SSs). Actually, what about molecular data that demonstrates phylogenetic relationships between taxa? From an ID perspective, this must be extremely weird. Homology must be devastating.
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Enjoy it while it lasts parlar. It won't last long.
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