Irreducible Complexity

[Fist and Faith]

I'd really like to hear about the purely scientific arguments to this. Kins, you wrote:

Irreducible complexity does not exist. This was presented several years ago as untested speculation then quickly defeated through actual testing and later refuted by its own creator.

I've read a couple of arguments against. One was very emotional and unconvincing, and one was pretty well thought out and expressed. I'll try to track them down. I'm particularly interested in Behe's own refutation of it.

Again, here's the first thing Behe said about it. I'll add more quotes when I'm not late for work.

Darwin knew that his theory of gradual evolution by natural selection carried a heavy burden:

If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.

It is safe to say that most of the scientific skepticism about Darwinism in the past century has centered on this requirement. From Mivart's concen over the incipient stages of new structures to Margulis's dismissal of gradual evolution, critics of Darwin have suspected that his criterion of failure had been met. But how can we be confident? What type of biological system could not be formed by "numerous, successive, slight modifications"?

Well, for starters, a system that is irreducibly complex. 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. 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.

[Prebe]

Irreducible complexity is a result of human lack of imagination. We "could not imagine" how an organ as complex as the eye could be formed by gradual evolution. This is easy-peasy today.

From a molecular perspective, it is hard for us to imagine how complex enzymes have developed their functionality. Often this is because we don't have the imagination to see, that the enzyme is a complex of several subunits, that have previously served other purposes by themselves.

I don't know this Behe guy, but I see what he is getting at. Even if I think that I could refute it with some ease (I started above), I would be interested in seing his own official supplication

[Zarathustra]

Lack of imagination. Exactly, Prebe. And the conclusion drawn in the midst of that void of understanding is even less scientific. It's the classic, ". . . and then a miracle happened . . . " explanation, which is not an explanation at all. Irreducible complexity is just a sophisticated way to say, "the impossible exists, therefore it must be supernatural." I don't think the world is impossible. I'm not ready to throw up my hands just because things seem complicated. It's not time to insert magic in our explanations just becuase the world requires yet a little more thought.

If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.

If Darwin actually said this, then he's wrong (wouldn't be the first time). Evolution doesn't break down on the discovery of a counter example to this claim. Not every evolutionary "advance" is made by numerous, successive, slight modifications. Sometimes a single mutation can lead to a radical reorganization of an organisim, bringing about a change that is both orderly, symmetrical and observable on a macro-level. We've witnessed this in insects, for instance, where a single genetic change can cause them to have a completely different leg structure that is mirrored on both sides of their bodies.

And Prebe is right in saying that nature can turn previous features to new uses, so that a lung, for instance, doesn't have to spring into being fully developed in order for an organism not to suffocate.

[Kinslaughterer]

The complexity argument ignores examples of less complex forms in nature. Basically the idea is, for instance, the eye is too complicated to work if it was any less advanced therefore it must be an example of intelligent design (which is a creationist idea, or more rightly a creationist trojan horse of antiscience). Unfortunately simpler forms of the eye exists such as light sensing organs, proto-eyes which only pick up movement, and blind, seemingly useless eyes.

The problem with both creationist and intelligent designers is they are offering no legitimate alternative to evolution that has any sort of scientifc rigor. Why teach intelligent design when you have no basis for it?






Quote:
Unfortunately but honestly Behe later stated: "Demonstration that a system is irreducibly complex is not a proof that there is absolutely no gradual route to its production" (21), thereby undermining the beauty and power of his falsificator. But Behe did more to undermine his falsificator of Darwinism. In an article in the journal Biology and Philosophy (29) Behe stated "A weak point of Darwinian theory is its resistance to falsification. What experimental evidence could possibly be found that would falsify the contention that complex molecular machines evolved by a Darwinian mechanism? I can think of none". I can think of none? This is an extremely amazing claim. Behe forgets his own mousetraps! What was the point of writing Darwin's Black Box? What was the point of the concept 'irreducible complexity'? What was the point of the bacterial flagellum and the blood clotting system, if not refuting their Darwinian origin?





www.stephenjaygould.org/ctrl/pennock_ ... 899.asp

1. Evolution is only a theory. It is not fact or a scientific law

The National Academy of Science regards scientific theory as a well substantiated explanation of some aspect of the natural world that can incoporate facts, laws, inferences, and tested hypotheses. No amount of validation changes a theory into a law. Actually one can regard evolution as a fact of science as NAS refers to fact as something that has been repeatedly and independently confirmed.

2. If Humans descended from monkeys, why are there still monkeys?

First off evolution states that humans and non-human primates had a common ancestor. Its kind of like asking "if children come from adults why are there still adults?"


3. Natural Selection is based on circular reasoning: the fittest are those who survive and those who survive are the fittest.

Natural selection is more a conversational way of explaining survival of the fittest, the key is that adaptive fitness ran be defined without reference to survival. For instance large beaked finches are better adapted to crushing seeds but may be slow breeders so they survive with a single adaptive trait while fast breeding finches survive with another trait and nature affects which of these traits are better adaptive to given environmental circumstances.

4. Mathematically it is inconceivable that anything as complex as a protein, let alone a living cell or a human, could spring up by chance.

Chance plays a small role in evolution but natural selection is anything but chance rather it harnesses nonrandom change by preserving adaptive traits and eliminating non-adaptive ones. Essentially it builds off effective adaptations to make more and more sophisticated creatures better suited to survive.

5. Living things have fantastically intricate features that could not function if they were any less complex. The only prudent conclusion is that they are the products of intelligent design.

Many cite the eye as a sturucture that could not have evolved. Critics say that its function depends on the prefect arrangement of its parts. Thus natural selection could never favor transitional forms of the eye. Unfortunately for creationists, biology has successfully identified numerous examples of primitive eyes and light sensing or color sensing organs and even shown were eyes have evolved by independent means in other species.

[Prebe]

(Suzuki, D.T., Griffiths, A.J.F., Miller, J.H. and Lewontin, R.C. in An Introduction to Genetic Analysis 4th ed. W.H. Freeman 1989 p.704)

Cool! That was my textbook on evolutionary biology.

[Avatar]

Good posts, Malik and Prebe especially...lack of imagination...I like it.

--A

[Prebe]

Why teach intelligent design when you have no basis for it?

Exactly Kins. This is where discussion always end with ID proponents. So it is probably better to just pop the question first time round, the next time someone wants to discus creation vs. evolution. Would save us a lot of time.

But then again, people like you or I would not have the opportunity to defend the evolution theory with such pride and eloquence would we ?