Anyway, here's a petard for Mr. LLLICHY:
Petard!
That overstates the case, but I'll let it slide, since the larger errors in this post greatly overshadow this one.
so will it will be either unchanged due to its criticality for its present function(maximum fitness and "unavailable" for cooption) or be driven towards criticality for that function(seeking maximum fitness and "unavailable" for cooption) as predicted by Darwinian evolution.
It never ceases to amaze me how often the creationists on these threads grossly misrepresent what is actually "predicted by Darwinian evolution". I'm often left wondering whether they're ignorant of the field, or dishonest about it. But neither option inspires confidence, and they could of course be both.
This part of LLLICHY's post is so riddled with errors it's difficult to know where to begin.
Error #1: Note the rhetorical sleight-of-hand in the middle of the sentence, which magically changes from talking about how a component must be *useful* enough to be maintained, to (abracadabra) being *critical* and thus so indispensible that the organism can't survive without it performing its current function. Presto, chango, nothing up my sleeve! Nice try, but while it's (generally) true that components aren't retained (for extremely long periods, anyway) unless they perform *some* useful function, that's ENTIRELY different from presuming that all retained components or features are "critical" to the existence of the organism and could not possibly be turned to another use without making the organism unviable. For example, the protruding external ear on humans is *useful*, but not *critical* -- we could continue to live without them, hearing through a simple hole in our heads into the ear canal like birds do.
Error #2: The above passage presumes, incorrectly, that a component must have one-and-only-one function (and that it is "locked into" performing that one function, as explained in #1). Nonsense. Even gradeschool children can spot the flaw in this (so what's LLLICHY's excuse?) What child does not know that the human nose is used for respiration *and* smelling? And most high-school students know that the nose also performs filtering (nose hairs catch airborne debris before they reach the lungs), heat exchange (air is warmed by blood vessels in the nose before it reaches the lungs, protecting the lungs from cold damage), moisturizing (turbinates in the nose release moisture into the incoming air so as not to dry out the lungs), and so on.
Error #3: Conversely, LLLICHY (incorrectly) presumes that a component "must" be locked into its one "critical" function because if it ceases to perform that function, there won't be anything else to "fill the need". Again, even a child knows better. For example, the nose is used for breathing -- but the mouth can be too. Biological systems are replete with examples of redundancy and duplication of function.
Error #4: Not only do different components often perform or contribute to the same function, but the *same* component can diverge and go down *two* functional pathways, one of which continues to perform the original function while a "copy" is co-opted to some other use. This mechanism, gene duplication, has been known and studied since at least the 1960's. I'm sorry that LLLICHY is more than three decades behind on his reading in this field. Perhaps he might want to come up to speed before he attempts to critique this topic again. Through gene duplication, the descendants inherit *two* (or more) copies of the gene for the feature they code for. Initially both copies simply crank out copies of the feature as usual. However, the key point is that if one mutates or is selected in some other direction (e.g. to some other function), there's no problem, since the *other* copy of the gene continues to fulfill the original function. In short, the "spare" copy of the gene is *entirely free* to evolve away from the original function towards something else, since the other copy is still present. For just one real-world case out of literally thousands, see for example Positive Darwinian selection after gene duplication in primate ribonuclease genes.
Error #5: LLLICHY launched into this fallacious argument just days after he had already been informed of the flaws in it. Selective amnesia, or intellectual dishonesty? From this post of mine in response to his same mistakes six days ago:
First, stubbornly sticking to the "cars can only go to one destination" aspect of the flawed analogy not only doesn't "answer" RWP's point, it ignores *his* point, which is that fitness involves the fine-tuning of *multiple* functions in an organism, not just one-and-only-one.And lest he attempt the "oh, I must have missed that reply" excuse, I'd like to point out that he posted replies in a thread which was entirely devoted to the topic of gene duplication: Genome Evolution | First, a Bang Then, a Shuffle , so he *is* well aware of the mechanism. Why, then, does he pretend not to be aware of its consequences to his "components are locked into to one function" argument here? Inquiring minds want to know.Second, the whole "one car on one road" analogy is fundamentally flawed as a model of genetic evolution on several counts, the primary one being that due to gene duplication, genes most certainly *CAN* and *DO* go down "two (or more) roads at once" without having to "abandon" the "original destination" (i.e. current function). And even without gene duplication, a single copy of a gene can perform more than one function, yet again making the "single car" analogy ludicrously unsuitable and grossly misleading as a mental model of genetics and evolution.
Error #6: Not only is LLLICHY wrong on the facts, and using a bait-and-switch argument, but he's wrong about what is "predicted by Darwinian evolution". Not only does the modern field of evolution not match his straw-man version of it, but even *Darwin's* original presentation of evolution explicitly predicted the opposite of what LLLICHY claims it predicts. Rather than predicting that components must be "driven to criticality", Darwin actually predicts that they can remain free to change function:
Numerous cases could be given amongst the lower animals of the same organ performing at the same time wholly distinct functions; [my point #2 -- Ich.] thus the alimentary canal respires, digests, and excretes in the larva of the dragon-fly and in the fish Cobites. In the Hydra, the animal may be turned inside out, and the exterior surface will then digest and the stomach respire. In such cases natural selection might easily specialise, if any advantage were thus gained, a part or organ, which had performed two functions, for one function alone, and thus wholly change its nature by insensible steps. Two distinct organs sometimes perform simultaneously the same function in the same individual; [my point #3 -- Ich.] to give one instance, there are fish with gills or branchiae that breathe the air dissolved in the water, at the same time that they breathe free air in their swimbladders, this latter organ having a ductus pneumaticus for its supply, and being divided by highly vascular partitions. In these cases, one of the two organs might with ease be modified and perfected so as to perform all the work by itself, being aided during the process of modification by the other organ; and then this other organ might be modified for some other and quite distinct purpose, or be quite obliterated.LLLICHY is over 140 years behind on his understanding of evolution's predictions, apparently. And so is Behe, for the same reason.The illustration of the swimbladder in fishes is a good one, because it shows us clearly the highly important fact that an organ originally constructed for one purpose, namely flotation, may be converted into one for a wholly different purpose, namely respiration. The swimbladder has, also, been worked in as an accessory to the auditory organs of certain fish, or, for I do not know which view is now generally held, a part of the auditory apparatus has been worked in as a complement to the swimbladder. All physiologists admit that the swimbladder is homologous, or 'ideally similar,' in position and structure with the lungs of the higher vertebrate animals: hence there seems to me to be no great difficulty in believing that natural selection has actually converted a swimbladder into a lung, or organ used exclusively for respiration.
-- Charles Darwin, "On the Origin of Species", 1859.
Six major errors in one sentence (seven if you count the one I let slide). Impressive.
And as Behe makes clear, you build a straw man and knock it down by your mischaracterization of his argument.
Untrue. Steve-b's summary of Behe's core argument is entirely accurate (see below). Anyone who disagrees is free to present their own version of "Behe's argument" (instead of just sob, "is not!") so that we can A) compare it against what Behe actually wrote, and B) see if that version holds any water either.
Premise two is a false representation of his argument.
No. Here is premise two from Steve-b's post: "2)possession of only a subset of those parts conveys no advantage and thus is not preferred by natural selection". Compare to Behe's own words:
Irreducible complexity is just a fancy phrase I use to mean a single system which is composed of several interacting parts, and where the removal of any one of the parts causes the system to cease functioning. [...] An irreducibly complex system cannot be produced directly by numerous, successive, slight modifications of a precursor system, because any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional. [...] Since natural selection can only choose systems that are already working, then if a biological system cannot be produced gradually it would have to arise as an integrated unit, in one fell swoop, for natural selection to have anything to act on.That's exactly what Steve-b's shorter version says. Where's the alleged "straw man"?
He again has clearly stated above "The system can have its own function, different from any of the parts. Any individual function of a part does not explain the separate function of the system."
This is just Behe trying to have it both ways, and in the process invalidating his first argument. Hardly convincing.
Compare these two claims from Behe:
Claim A: "An irreducibly complex system cannot be produced directly by numerous, successive, slight modifications of a precursor system, because any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional. ... Since natural selection can only choose systems that are already working, then if a biological system cannot be produced gradually it would have to arise as an integrated unit, in one fell swoop, for natural selection to have anything to act on."A or B -- pick one, you can't have both. Well, not and be intellectually honest, you can't.Claim B: "The system can have its own function, different from any of the parts. Any individual function of a part does not explain the separate function of the system."
Either natural selection doesn't "have anything to act on" until the component is completely finished (claim A), *OR* it *does* have something to act on in the form of the functional-for-a-different-purpose subcomponents (claim B).
They're mutually exclusive.
If Behe wants to admit the truth of claim B -- and he knows he has to -- then he must abandon claim A. But he hasn't. Thus the criticisms against his self-defeating argument.
Anyway, here's a petard for Mr. LLLICHY:
The creationists vary in every other degree but they all leave you asking this question.