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Irreducible complexity

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The divine comedy
Icon creationism.svg
Running gags
Jokes aside
Blooper reel
So I'm going to give you a condensed version of an Intelligent Design creationist lecture. It'll be very entertaining:

"Complexity, complexity, complexity complexity. Oh look, there's a pathwayWikipedia's W.svg — it's very complicated. Complexity! Complexity, complexity complexity — complexity. And did you know that cells are really, really complicated? But we're not done — complexity! Complexity (complexity complexity). And you're gonna be blown away by the bacterial flagellum — it's like a little machine! And it's really, really complicated! Complexity-complexity complexity. Complexity. We need more cells, they're really complicated. You just get blown away by these things, they are just so amazingly complicated. Complexity. Therefore; design."

You've heard it all now — that's the root of their argument.
P.Z. Myers[1]

Irreducible complexity is a concept popularized by noted pseudoscientist Michael Behe in his 1996 book Darwin's Black Box to support intelligent design. Intelligent design pushers argue that while some systems and organs can be explained by evolution, those that are irreducibly complex cannot, and therefore an intelligent designer must be responsible.[2]

Irreducible complexity stems from the claim that some biological systems appear to be too complex to have arisen by natural selection. Specifically, it argues that if you take a part away from an organism and it stops functioning (analogous to taking the engine out of a car) then it must be irreducibly complex and cannot have evolved. It is one of the main arguments of the Intelligent Design movement.

The concept is considered to be mostly bollocks when applied to evolution because it fails to take into account numerous other pathways that a particular ability can evolve through — it assumes that evolution must go through "additive" processes to achieve its conclusion and this isn't the case. Most evolutionary biologists do not consider it science by any stretch of the imagination because the idea relies on personal incredulity and unwarranted assumptions.


I think I have now finally understood what "irreducibly complex" really means: a statement, fact or event so simple it cannot be simplified any further, but still too complex to be grasped by a creationist.
—Björn Brembs, biologist[3]

"Official" definition[edit]

There is a slightly different definition of "irreducible complexity" related to emergent phenomena in systems theory and computational complexity theory. However, a full explanation of this is beyond the scope of this article.[4]

It is believed that Michael Behe has basically taken some of the ideas found within this theory and rehashed it slightly to apply to evolution. Behe's definition[5] is that an irreducibly complex form is:


While surrounded by some fancy words and the language of science, this is just incredulity that the world could arise through naturalistic processes. The argument is no more advanced or "evolved" than William Paley's "Watch Argument" which stated that as a watch looked created, it must have a creator. Essentially, Behe is stating "because I can't see a natural explanation, Goddidit" — this ignores any possibility that a naturalistic explanation or evolutionary pathway will later be discovered.


Probability Analysis[edit]

In calculating the probability for a mutation, one must consider not merely the probability that the mutation will arise, but the number of opportunities for that mutation. So if a mutation has only a one-in-a-million chance of happening, it's still very likely that the mutation will eventually occur if the species has millions of members. So now the question arises: if there are several different mutations under consideration, do we multiply all the probabilities together, and then compare the probability to the number of opportunities, or do we compare each probability to the number of opportunities, and then multiply the adjusted probabilities together? Evolutionary theory (and mathematical probability theory) tell us that we should do the latter;[citation needed] each mutation can arise independently, spread through the population by natural selection, and combine through sexual reproduction (or gene transfer in simpler organisms). Proponents of irreducible complexity assert that in most cases, the individual mutations do not provide any advantage by themselves,[citation needed] and so are not operated on by natural selection, and we must multiply the probability of all of the mutations first before considering the number of opportunities.[citation needed]

Examples of flawed arguments[edit]

The core of their argument is this; that complexity can only be created by design. That's the first premise they offer up.

And then what they do, in their lectures, is they tell you over and over again; "biology is really complex". And then that means; "biology was created by design".

Now, I suspect there are a few philosophers out there in the audience — if you ever want to teach your students about the fallacy called begging the question? Send them to the Discovery Institute webpage. That's what it is — this is a big exercise in circular logic; in begging the question.
—P.Z. Myers[6]

Frequently, believers in irreducible complexity cite the eye as an example of something too complex to have evolved. They frequently introduce the argument with a question of the type, "What use is half an eye?". However if the question is recast as "Given a choice, would you prefer to be completely blind or have 50% of your present vision?", then it becomes clear that the question is badly formed, especially when keeping in mind that many species manage to survive with significantly less-advanced eyes. Examples include the polychaete worms, which can distinguish between light and dark;[7] the simple eye-cup of the flatworms, for finding the direction of a light source; jellyfish and scallops, with simple eyes for detecting movement;[8] the famous compound eyes of the insects, which can make out simple shapes, and ultimately the sophisticated single-lens eyes of the molluscs and vertebrates.

Another famed and also flawed example references "the watch on the beach". It goes as follows: "If you find a watch on the beach, do you assume it got there by chance, or do you assume it was made by an intelligent designer?" The example is flawed because watches and their parts do not reproduce or mutate. (And if they did, they could be produced by random mutation.[9]) Moreover, nobody would assume that the watch had simply been summoned into existence by some mystery force; they would not only assume a watchmaker, but a whole history of work in associated technologies by hundreds if not thousands of individuals. Oddly, no ID advocate has ever argued that the "designer" is a giant committee of unrelated inventors.

The above arguments appeal to the common sense of the "Average Joe". Popular support is, however, not part of the scientific method; bear in mind that a significant part of the world's population believes in astrology.

Although proponents offer irreducible complexity as evidence of intelligent design, this conclusion is questionable. Robustness is generally considered to indicate good design, not precariousness. Which parachute would you consider better designed — one which ceased to function if a single part was missing, or one which has a back-up pullcord? Irreducible complexity, if accepted as evidence of design, suggests at best crappy design.

Behe also has defined and redefined irreducible complexity:

In response to these demonstrations however, IDC proponents belatedly "reinterpret" their initial claims in order to lift them out of the critic's reach. A first strategy to this end consists in shifting the burden of proof from plausible evolutionary pathways to the actual evolutionary story, maintaining that the broad outlines of a plausible evolutionary account amounts to nothing more than Darwinian wishful thinking and speculation. The same bait-and-switch technique can be discerned here: IC is constantly boasted as a point of principle for ruling out the possibility of evolutionary explanations, but as soon as it is challenged on that ground, through a discussion of plausible evolutionary scenarios, ID creationists pretend that they were talking about actual evolutionary pathways all along. When they are confronted with tangible evidence of actual evolutionary history, IDC theorists resort to a second strategy, shifting their design claims to the remaining parts of the evolutionary puzzle, as if the "real" problem was always there. For example, Kenneth Miller (2004) beautifully demonstrated the structural similarities between one component of the flagellum and the so called type III-secretory system. He convincingly argued that the former is a very plausible evolutionary precursor of the latter, which has been co-opted by evolution to perform a new function. In response to this embarrassing demonstration, Behe (2001:689-690) simply shifted his attention to the complexity of the newly discovered system by itself, and at the same time stubbornly insisted that the assemblage of these precursors into the flagellum system is still impossible without the helping hand of a Designer (Behe, 2004:359).[10][11]

In a famous early instance of an argument from "irreducible complexity" (although not by that name), Herbert Spencer (1820-1903) argued that the huge antlers of the Irish elkWikipedia's W.svg together with the other bodily structures needed to support them formed a combination that could not have arisen by natural selection alone. "(I note in passing that Spencer's is exactly the argument that contemporary advocates of Intelligent have used to rejuvenate sclerotic Scientific Creationism; they seem to hope this infusion of monkey glands will unleash a new powerful refutation of Darwinian evolutionary theory.)"[12] Spencer was not a creationist. Even though he advanced this argument against Darwin's mechanism of evolution, Spencer thought that he had a better mechanism (something like Lamarckism). He didn't see the elk as evidence for divine intervention. (Needless to say, today's advocates of "irreducible complexity" do not address Spencer's position.)

Another obvious counterpoint is that irreducible complexity can easily be demonstrated in technology, and the ID argument becomes utterly ludicrous when applied to the real process of design: for example, a modern steel-mill makes steel, but has vital components that are themselves made of steel. The ID claim, applied to this example, would go: "a designer must have magically created the steel components of the first mill", rather than imagining that perhaps the first steel was not made in a modern steel mill. (One might note that even children realize that simply invoking Santa Claus is not enough to account for the appearance of Christmas presents. There must be a crew of manufacturing elves and a reindeer-driven sleigh delivery-system, not to mention the North Pole.)

So who designed God?[edit]

Arguments from irreducible complexity must also take into account the question of whether or not God himself is a being of irreducible complexity:

  • Answering "Yes" sends you flying into an infinite regress of who-designed-God's-designer, who-designed-the-designer's-designer... (and so on, ad inifinitum). Keeping in mind that suddenly insisting "God designed himself!" would mean you allow for self-design — making the very existence of any designer superfluous to begin with.
  • Answering "No" means that life and the Universe couldn't have been intelligently designed either — because if even almighty God (read: the most "specified and complex" and thus most intelligently designed entity ever) fails to meet the criteria of the design inference, then nothing else will.

How "Irreducibly complex" structures form[edit]

In early April 2006 a long study at the University of Oregon was published in the journal Science. Based on the reconstruction of ancient genes from extinct animals, the researchers were able to show how the nontheory of "irreducible complexity" is a joke.

Protein molecules, they found, slowly employed trial and error, reusing and modifying existing parts, to act in a key-and-lock manner and switch discrepant hormones "on" and "off." This genetic march was blindly inaugurated 450 million years ago, before life left the ocean and before the evolution of bones.

We now know things about our nature that the founders of religion could not even begin to guess at, and that would have stilled their overconfident tongues if they had known of them.
Christopher Hitchens, God Is Not Great: How Religion Poisons Everything[13]

One way in which "Irreducibly complex" structures could develop is via a process known as scaffolding, wherein a structure gains in complexity via duplication and mutation of parts, then parts are knocked out via mutations, leaving a structure with no direct linear development from the original, basic structure. Other paths by which irreducibly complex structures may form include cooption of parts from other structures. Both of these can be seen in the case of the bacterial flagellum, which includes many parts taken from a secretory pump.

Another is "function shift" or exaptation, which can also explain how irreducibly complex structures may evolve. During evolution, a feature may shift from one function to another — a classic example is the feathers of a bird. They originally evolved in dinosaurs as a way to keep warm, but birds then evolved to use them for flight. Half a wing might not be useful for flying, but it will still keep you warm. Our arms are another example-they were originally legs, but evolved into arms when we became bipedal.


In a nutshell[edit]

QualiaSoup adresses some of the classic flaws in the creationist reasoning regarding irreducible complexity.

And just in case you didn't get the above video the first time...

See also[edit]

External links[edit]


  3. Björn Brembs — I CAN HAZ UR BEKTEERYA?
  4. See Wikipedia: Irreducible complexity (Emergence)Wikipedia's W.svg
  5. Micheal Behe — Darwin's Black Box: The Biochemical Challenge to Evolution
  7. Buchsbaum, R. Animals Without Backbones (Penguin 1958); vol.1, plate 64
  8. Scallop eyes
  9. Evolution IS a Blind Watchmaker: Video of a clock-'evolving' simulation
  10. Irreducible incoherence and intelligent design: a look into the conceptual toolbox of a pseudoscience by Maarten Boudry et al. Q. Rev. Biol. 2010 Dec;85(4):473-82.
  11. Irreducible Incoherence and Intelligent Design – a look into the conceptual toolbox of a pseudoscience full text of Maarten Boudry et al.
  13. Page 87.