Irreducible complexity
Encyclopedia
Irreducible complexity (IC) is an argument
by proponents of intelligent design
that certain biological systems are too complex to have evolved
from simpler, or "less complete" predecessors, through natural selection
acting upon a series of advantageous naturally occurring, chance mutations. The argument is central to intelligent design, and is rejected by the scientific community
at large, which overwhelmingly regards intelligent design as pseudoscience
. Irreducible complexity is one of two main arguments used by intelligent design proponents, the other being specified complexity
.
Biochemistry professor Michael Behe
, the originator of the term irreducible complexity, defines an irreducibly complex system as one "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". These examples are said to demonstrate that modern biological forms could not have evolved naturally. Evolutionary biologists have shown that such systems can evolve, and that Behe's examples constitute an argument from ignorance
. In the 2005 Kitzmiller v. Dover Area School District
trial in the United States
, Behe gave testimony on the subject of irreducible complexity. The court found that "Professor Behe's claim for irreducible complexity has been refuted in peer-reviewed research papers and has been rejected by the scientific community at large."
Supporters of intelligent design use this term to refer to biological systems and organs that they believe could not have come about by any series of small changes. They argue that anything less than the complete form of such a system or organ would not work at all, or would in fact be a detriment to the organism, and would therefore never survive the process of natural selection. Although they accept that some complex systems and organs can be explained by evolution, they claim that organs and biological features which are irreducibly complex cannot be explained by current models, and that an intelligent designer must have created life or guided its evolution. Accordingly, the debate on irreducible complexity concerns two questions: whether irreducible complexity can be found in nature, and what significance it would have if it did exist in nature.
A second definition given by Behe (his "evolutionary definition") is as follows:
Intelligent design advocate William Dembski gives this definition:
for God (the argument from design or from complexity). This states that because certain things in nature are very complicated, they must have been designed. William Paley
famously argued, in his 1802 watchmaker analogy
, that complexity in nature implies a God for the same reason that the existence of a watch implies the existence of a watchmaker. This argument has a long history, and can be traced back at least as far as Cicero
's De Natura Deorum
ii.34.
(1st and 2nd centuries AD) wrote about the large number of parts of the body and their relationships, which observation was cited as evidence for creation. The idea that specifically the interdependence between parts would have implications for the origins of living things was raised by writers starting with Pierre Gassendi
in the mid 17th century and John Wilkins
, who wrote (citing Galen), "Now to imagine, that all these things, according to their several kinds, could be brought into this regular frame and order, to which such an infinite number of Intentions are required, without the contrivance of some wise Agent, must needs be irrational in the highest degree." In the late 17th century, Thomas Burnet
referred to "a multitude of pieces aptly joyn’d" to argue against the eternity
of life. In the early 18th century, Nicolas Malebranche
wrote "An organized body contains an infinity of parts that mutually depend upon one another in relation to particular ends, all of which must be actually formed in order to work as a whole," arguing in favor of preformation, rather than epigenesis
, of the individual; and a similar argument about the origins of the individual was made by other 18th century students of natural history.
In his 1790 book, The Critique of Judgment, Kant
is said to argue that "we cannot conceive how a whole that comes into being only gradually from its parts can nevertheless be the cause of the properties of those parts"
Chapter XV of Paley's Natural Theology discusses at length what he called "relations" of parts of living things as an indication of their design.
Georges Cuvier
applied his principle of the correlation of parts to describe an animal from fragmentary remains. For Cuvier, this was related to another principle of his, the conditions of existence, which excluded the possibility of transmutation of species
.
While he did not originate the term, Charles Darwin identified the argument as a possible way to falsify a prediction of the theory of evolution at the outset. In The Origin of Species, he wrote, "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. But I can find out no such case." Darwin's theory of evolution challenges the teleological argument by postulating an alternative explanation to that of an intelligent designer—namely, evolution by natural selection. By showing how simple unintelligent forces can ratchet up designs of extraordinary complexity without invoking outside design, Darwin showed that an intelligent designer was not the necessary conclusion to draw from complexity in nature. The argument from irreducible complexity attempts to demonstrate that certain biological features cannot be purely the product of Darwinian evolution.
In the late 19th century, in a dispute between supporters of the adequacy of natural selection
and those who held for inheritance of acquired characters
, one of the arguments made repeatedly by Herbert Spencer
, and followed by others, depended on what Spencer referred to as co-adaptation of co-operative parts, as in: "We come now to Professor Weismann
's endeavour to disprove my second thesis — that it is impossible to explain by natural selection alone the co-adaptation of co-operative parts. It is thirty years since this was set forth in "The Principles of Biology." In §166, I instanced the enormous horns of the extinct Irish elk
, and contended that in this and in kindred cases, where for the efficient use of some one enlarged part many other parts have to be simultaneously enlarged, it is out of the question to suppose that they can have all spontaneously varied in the required proportions." The history of this concept in the dispute has been characterized: "An older and more religious tradition of idealist thinkers were committed to the explanation of complex adaptive contrivances by intelligent design. ... Another line of thinkers, unified by the recurrent publications of Herbert Spencer, also saw coadaptation as a composed, irreducible whole, but sought to explain it by the inheritance of acquired characteristics."
, in the early 20th century, discussed a concept similar to irreducible complexity. However, far from seeing this as a problem for evolution, he described the "interlocking" of biological features as a consequence to be expected of evolution, which would lead to irreversibility of some evolutionary changes. He wrote, "Being thus finally woven, as it were, into the most intimate fabric of the organism, the once novel character can no longer be withdrawn with impunity, and may have become vitally necessary."
In 1974, Young Earth Creationist Henry M. Morris
introduced a similar concept in his book Scientific Creationism in which he wrote; "This issue can actually be attacked quantitatively, using simple principles of mathematical probability. The problem is simply whether a complex system, in which many components function unitedly together, and in which each component is uniquely necessary to the efficient functioning of the whole, could ever arise by random processes."
A book-length study of a concept similar to irreducible complexity, explained by gradual, step-wise, non-teleological evolution, was published in 1975 by Thomas H. Frazzetta. "A complex adaptation is one constructed of several components that must blend together operationally to make the adaptation "work". It is analogous to a machine whose performance depends upon careful cooperation among its parts. In the case of the machine, no single part can greatly be altered without changing the performance of the entire machine." The machine that he chose as an analog is the Peaucellier machine, and one biological system given extended description was the jaw apparatus of a python. The conclusion of this investigation, rather than that evolution of a complex adaptation was impossible, "awed by the adaptations of living things, to be stunned by their complexity and suitability", was "to accept the inescapable but not humiliating fact that much of mankind can be seen in a tree or a lizard."
In 1981, Ariel Roth, in defense of the creation science position in the trial McLean v. Arkansas
, said of "complex integrated structures" that "This system would not be functional until all the parts were there ... How did these parts survive during evolution ...?"
In 1985 Cairns-Smith
wrote of "interlocking", "How can a complex collaboration between components evolve in small steps?" and used the analogy of the scaffolding called centering
used to build an arch then removed afterwards: "Surely there was 'scaffolding'. Before the multitudinous components of present biochemistry could come to lean together they had to lean on something else." However, neither Muller or Cairns-Smith claimed that their ideas were evidence of something supernatural.
An essay in support of creationism
published in 1994 referred to bacterial flagella as showing "multiple, integrated components", where "nothing about them works unless every one of their complexly fashioned and integrated components are in place" and asked the reader to "imagine the effects of natural selection on those organisms that fortuitously evolved the flagella ... without the concommitant control mechanisms".
An early concept of irreducibly complex systems comes from Ludwig von Bertalanffy
, a 20th-century Austrian biologist. He believed that complex systems must be examined as complete, irreducible
systems in order to fully understand how they work. He extended his work on biological complexity into a general theory of systems in a book titled General Systems Theory
.
After James Watson
and Francis Crick
published the structure of DNA
in the early 1950s, General Systems Theory lost many of its adherents in the physical and biological sciences. However, Systems theory remained popular in the social sciences long after its demise in the physical and biological sciences.
Michael Behe
developed his ideas on the concept around 1992, in the early days of the 'wedge movement
', and first presented his ideas about "irreducible complexity" in June 1993 when the "Johnson-Behe cadre of scholars" met at Pajaro Dunes in California. He set out his ideas in the second edition of Of Pandas and People
published in 1993, extensively revising Chapter 6 Biochemical Similarities with new sections on the complex mechanism of blood clotting and on the origin of proteins.
He first used the term "irreducible complexity" in his 1996 book Darwin's Black Box
, to refer to certain complex biochemical cellular
systems. He posits that evolutionary mechanisms cannot explain the development of such "irreducibly complex" systems. Notably, Behe credits philosopher William Paley
for the original concept, not von Bertalanffy, and suggests that his application of the concept to biological systems is entirely original.
Intelligent design advocates argue that irreducibly complex systems must have been deliberately engineered by some form of intelligence
.
In 2001, Michael Behe
wrote: "[T]here is an asymmetry between my current definition of irreducible complexity and the task facing natural selection. I hope to repair this defect in future work." Behe specifically explained that the "current definition puts the focus on removing a part from an already functioning system", but the "difficult task facing Darwinian evolution, however, would not be to remove parts from sophisticated pre-existing systems; it would be to bring together components to make a new system in the first place". In the 2005 Kitzmiller v. Dover Area School District trial
, Behe testified under oath that he "did not judge [the asymmetry] serious enough to [have revised the book] yet."
Behe additionally testified that the presence of irreducible complexity in organisms would not rule out the involvement of evolutionary mechanisms in the development of organic life. He further testified that he knew of no earlier "peer reviewed articles in scientific journals discussing the intelligent design of the blood clotting cascade," but that there were "probably a large number of peer reviewed articles in science journals that demonstrate that the blood clotting system is indeed a purposeful arrangement of parts of great complexity and sophistication." (The judge ruled that "intelligent design is not science and is essentially religious in nature".)
According to the theory of evolution, genetic variations occur without specific design or intent. The environment "selects" the variants that have the highest fitness, which are then passed on to the next generation of organisms. Change occurs by the gradual operation of natural forces over time, perhaps slowly, perhaps more quickly (see punctuated equilibrium
). This process is able to adapt
complex structures from simpler beginnings, or convert complex structures from one function to another (see spandrel
). Most intelligent design advocates accept that evolution occurs through mutation and natural selection at the "micro level
", such as changing the relative frequency of various beak lengths in finches, but assert that it cannot account for irreducible complexity, because none of the parts of an irreducible system would be functional or advantageous until the entire system is in place.
Behe uses the mousetrap as an illustrative example of this concept. A mousetrap consists of five interacting pieces—the base, the catch, the spring, the hammer and the hold-down bar. All of these must be in place for the mousetrap to work, as the removal of any one piece destroys the function of the mousetrap. Likewise, he asserts that biological systems require multiple parts working together in order to function. Intelligent design advocates claim that natural selection could not create from scratch those systems for which science is currently unable to find a viable evolutionary pathway of successive, slight modifications, because the selectable function is only present when all parts are assembled.
In his 2008 book Only A Theory
, biologist Kenneth R. Miller
challenges Behe's claim that the mousetrap is irreducibly complex. Miller observes that various subsets of the five components can be devised to form cooperative units, ones that have different functions from the mousetrap and so, in biological terms, could form functional spandrels
before being adapted to the new function of catching mice. In an example taken from his high school experience, Miller recalls that one of his classmates
Other systems identified by Miller that include mousetrap components include the following:
Behe has responded, "What Miller actually means is that if you take away some components and then go on to, say, twist a couple of metal pieces in just the right way and add a few staples in the correct positions, you can construct a new kind of working trap, which may superficially resemble the starting trap. That, however, is intelligent design. Neither Miller nor anyone else has shown that the mousetrap I pictured in my book can be constructed by a series of small changes, one at a time, as Darwinian evolution would have to do."
of E. coli, the blood clotting cascade, cilia, and the adaptive immune system
.
Behe argues that organs and biological features which are irreducibly complex cannot be wholly explained by current models of evolution
. In explicating his definition of "irreducible complexity" he notes that:
Irreducible complexity is not an argument that evolution does not occur, but rather an argument that it is "incomplete". In the last chapter of Darwin's Black Box
, Behe goes on to explain his view that irreducible complexity is evidence for intelligent design
. Mainstream critics, however, argue that irreducible complexity, as defined by Behe, can be generated by known evolutionary mechanisms. Behe's claim that no scientific literature adequately modeled the origins of biochemical systems through evolutionary mechanisms has been challenged by TalkOrigins
. The judge in the Dover trial wrote "By defining irreducible complexity in the way that he has, Professor Behe attempts to exclude the phenomenon of exaptation
by definitional fiat, ignoring as he does so abundant evidence which refutes his argument. Notably, the NAS
has rejected Professor Behe’s claim for irreducible complexity..."
cascade in vertebrates is a complex biological pathway which is given as an example of apparent irreducible complexity.
The irreducible complexity argument assumes that the necessary parts of a system have always been necessary, and therefore could not have been added sequentially. However, in evolution, something which is at first merely advantageous can later become necessary. Natural selection
can lead to complex biochemical systems being built up from simpler systems, or to existing functional systems being recombined as a new system with a different function. For example, one of the clotting factors that Behe listed as a part of the clotting cascade was later found to be absent in whales, demonstrating that it is not essential for a clotting system. Many purportedly irreducible structures can be found in other organisms as much simpler systems that utilize fewer parts. These systems, in turn, may have had even simpler precursors that are now extinct. Behe has responded to critics of his clotting cascade arguments by suggesting that homology
is evidence for evolution, but not for natural selection.
The "improbability argument" also misrepresents natural selection. It is correct to say that a set of simultaneous mutations that form a complex protein structure is so unlikely as to be unfeasible, but that is not what Darwin advocated. His explanation is based on small accumulated changes that take place without a final goal. Each step must be advantageous in its own right, although biologists may not yet understand the reason behind all of them—for example, jawless fish accomplish blood clotting with just six proteins instead of the full 10.
is a famous example of a supposedly irreducibly complex structure, due to its many elaborate and interlocking parts, seemingly all dependent upon one another. It is frequently cited by intelligent design and creationism advocates as an example of irreducible complexity. Behe used the "development of the eye problem" as evidence for intelligent design in Darwin's Black Box. Although Behe acknowledged that the evolution of the larger anatomical features of the eye have been well-explained, he claimed that the complexity of the minute biochemical reactions required at a molecular level for light sensitivity still defies explanation. Creationist Jonathan Sarfati
has described the eye as evolutionary biologists' "greatest challenge as an example of superb 'irreducible complexity' in God's creation", specifically pointing to the supposed "vast complexity" required for transparency.
In an often misquoted passage from On the Origin of Species, Charles Darwin
appears to acknowledge the eye's development as a difficulty for his theory. However, the quote in context shows that Darwin actually had a very good understanding of the evolution of the eye. He notes that "to suppose that the eye ... could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree". Yet this observation was merely a rhetorical device
for Darwin. He goes on to explain that if gradual evolution of the eye could be shown to be possible, "the difficulty of believing that a perfect and complex eye could be formed by natural selection ... can hardly be considered real". He then proceeded to roughly map out a likely course for evolution using examples of gradually more complex eyes of various species.
Since Darwin's day, the eye's ancestry
has become much better understood. Although learning about the construction of ancient eyes through fossil evidence is problematic due to the soft tissues leaving no imprint or remains, genetic and comparative anatomical evidence has increasingly supported the idea of a common ancestry for all eyes.
Current evidence does suggest possible evolutionary lineages for the origins of the anatomical features of the eye. One likely chain of development is that the eyes originated as simple patches of photoreceptor cells that could detect the presence or absence of light, but not its direction. When, via random mutation across the population, the photosensitive cells happened to have developed on a small depression, it endowed the organism with a better sense of the light's source. This small change gave the organism an advantage over those without the mutation. This genetic trait would then be "selected for" as those with the trait would have an increased chance of survival, and therefore progeny, over those without the trait. Individuals with deeper depressions would be able to discern changes in light over a wider field than those individuals with shallower depressions. As ever deeper depressions were advantageous to the organism, gradually, this depression would become a pit into which light would strike certain cells depending on its angle. The organism slowly gained increasingly precise visual information. And again, this gradual process continued as individuals having a slightly shrunken aperture
of the eye had an advantage over those without the mutation as an aperture increases how collimated the light is at any one specific group of photoreceptors. As this trait developed, the eye became effectively a pinhole camera
which allowed the organism to dimly make out shapes—the nautilus
is a modern example of an animal with such an eye. Finally, via this same selection process, a protective layer of transparent cells over the aperture was differentiated into a crude lens
, and the interior of the eye was filled with humours to assist in focusing images. In this way, eyes are recognized by modern biologists as actually a relatively unambiguous and simple structure to evolve, and many of the major developments of the eye's evolution are believed to have taken place over only a few million years, during the Cambrian explosion
.
Behe maintains that the complexity of light sensitivity at the molecular level and the minute biochemical reactions required for those first "simple patches of photoreceptor[s]" still defies explanation. Other intelligent design proponents have pointed to the difficulty of the entire visual system evolving rather than the eye alone.
The flagella of certain bacteria constitute a molecular motor requiring the interaction of about 40 complex protein parts. Behe asserts that the absence of any one of these proteins causes the flagella to fail to function, and that the flagellum "engine" is irreducibly complex as in his view if we try to reduce its complexity by positing an earlier and simpler stage of its evolutionary development, we get an organism which functions improperly.
Scientists regard this argument as having been disproved in the light of research dating back to 1996 as well as more recent findings. They point out that the basal body of the flagella has been found to be similar to the Type III secretion system
(TTSS), a needle-like structure that pathogenic germs such as Salmonella
and Yersinia pestis
use to inject toxin
s into living eucaryote cells. The needle's base has ten elements in common with the flagellum, but it is missing forty of the proteins that make a flagellum work. Thus, this system negates the claim that taking away any of the flagellum's parts would render it useless. On this basis, Kenneth Miller
notes that, "The parts of this supposedly irreducibly complex system actually have functions of their own."
. One science writer called it a "full-blown intellectual surrender strategy."
Niall Shanks and Karl H. Joplin, both of East Tennessee State University
, have shown that systems satisfying Behe's characterization of irreducible biochemical complexity can arise naturally and spontaneously as the result of self-organizing chemical processes. They also assert that what evolved biochemical and molecular systems actually exhibit is "redundant complexity"—a kind of complexity that is the product of an evolved biochemical process. They claim that Behe overestimated the significance of irreducible complexity because of his simple, linear view of biochemical reactions, resulting in his taking snapshots of selective features of biological systems, structures and processes, while ignoring the redundant complexity of the context in which those features are naturally embedded. They also criticized his over-reliance of overly simplistic metaphors, such as his mousetrap. In addition, research published in the peer-reviewed journal Nature
has shown that computer simulations of evolution demonstrate that it is possible for irreducible complexity to evolve naturally.
It is illustrative to compare a mousetrap with a cat, in this context. Both normally function so as to control the mouse population. The cat has many parts that can be removed leaving it still functional; for example, its tail can be bobbed, or it can lose an ear in a fight. Comparing the cat and the mousetrap, then, one sees that the mousetrap (which is not alive) offers better evidence, in terms of irreducible complexity, for intelligent design than the cat. Even looking at the mousetrap analogy, several critics have described ways in which the parts of the mousetrap could have independent uses or could develop in stages, demonstrating that it is not irreducibly complex.
Moreover, even cases where removing a certain component in an organic system will cause the system to fail do not demonstrate that the system couldn't have been formed in a step-by-step, evolutionary process. By analogy, stone arches are irreducibly complex—if you remove any stone the arch will collapse—yet we build them easily enough, one stone at a time, by building over centering
that is removed afterward. Similarly, naturally occurring arches
of stone are formed by weathering away bits of stone from a large concretion that has formed previously.
Evolution can act to simplify as well as to complicate. This raises the possibility that seemingly irreducibly complex biological features may have been achieved with a period of increasing complexity, followed by a period of simplification.
In April 2006 a team led by Joe Thornton, assistant professor of biology at the University of Oregon's Center for Ecology and Evolutionary Biology, using techniques for resurrecting ancient genes, scientists for the first time reconstructed the evolution of an apparently irreducibly complex molecular system. The research was published in the April 7 issue of Science.
It may be that irreducible complexity does not actually exist in nature, and that the examples given by Behe and others are not in fact irreducibly complex, but can be explained in terms of simpler precursors. There has also been a theory that challenges irreducible complexity called facilitated variation
. The theory has been presented in 2005 by Marc W. Kirschner, a professor and chair of Department of Systems Biology at Harvard Medical School
, and John C. Gerhart, a professor in Molecular and Cell Biology, University of California, Berkeley
. In their theory, they describe how certain mutation and changes can cause apparent irreducible complexity. Thus, seemingly irreducibly complex structures are merely "very complex", or they are simply misunderstood or misrepresented.
(derived from a jawbone) and the panda
's thumb (derived from a wrist bone spur) are considered classic examples. A 2006 article in Nature demonstrates intermediate states leading toward the development of the ear in a Devonian
fish (about 360 million years ago). Furthermore, recent research shows that viruses play a heretofore unexpectedly great role in evolution by mixing and matching genes from various hosts.
Arguments for irreducibility often assume that things started out the same way they ended up—as we see them now. However, that may not necessarily be the case. In the Dover trial an expert witness for the plaintiffs, Ken Miller, demonstrated this possibility using Behe's mousetrap analogy. By removing several parts, Miller made the object unusable as a mousetrap, but he pointed out that it was now a perfectly functional, if unstylish, tie clip.
(professor of evolutionary biology at the University of Chicago
) and Eugenie Scott
(a physical anthropologist
and executive director of the National Center for Science Education
) have argued that the concept of irreducible complexity, and more generally, the theory of intelligent design
is not falsifiable, and therefore, not scientific.
Behe argues that the theory that irreducibly complex systems could not have been evolved can be falsified by an experiment where such systems are evolved. For example, he posits taking bacteria with no flagellum and imposing a selective pressure for mobility. If, after a few thousand generations, the bacteria evolved the bacterial flagellum, then Behe believes that this would refute his theory.
Other critics take a different approach, pointing to experimental evidence that they believe falsifies the argument for Intelligent Design from irreducible complexity. For example, Kenneth Miller
cites the lab work of Barry G. Hall on E. coli, which he asserts is evidence that "Behe is wrong."
Other evidence that irreducible complexity is not a problem for evolution comes from the field of computer science
, where computer analogues of the processes of evolution are routinely used to automatically design complex solutions to problems. The results of such Genetic Algorithms are frequently irreducibly complex since the process, like evolution, both removes non-essential components over time as well as adding new components. The removal of unused components with no essential function, like the natural process where rock underneath a natural arch
is removed, can produce irreducibly complex structures without requiring the intervention of a designer. Researchers applying these algorithms are automatically producing human competitive designs—but no human designer is required.
and God of the gaps
argument.
Eugenie Scott
, along with Glenn Branch
and other critics, has argued that many points raised by intelligent design proponents are arguments from ignorance. Behe has been accused of using an "argument by lack of imagination", and Behe himself acknowledges that a failure of current science to explain how an "irreducibly complex" organism did or could evolve does not automatically prove the impossibility of such an evolution.
Irreducible complexity is at its core an argument against evolution. If truly irreducible systems are found, the argument goes, then intelligent design
must be the correct explanation for their existence. However, this conclusion is based on the assumption that current evolution
ary theory and intelligent design are the only two valid models to explain life, a false dilemma
.
Behe conceded that there are no peer-reviewed papers supporting his claims that complex molecular systems, like the bacterial flagellum, the blood-clotting cascade, and the immune system, were intelligently designed nor are there any peer-reviewed articles supporting his argument that certain complex molecular structures are "irreducibly complex."
In the final ruling of Kitzmiller v. Dover Area School District, Judge Jones specifically singled out Behe and irreducible complexity:
Critical
Argument
In philosophy and logic, an argument is an attempt to persuade someone of something, or give evidence or reasons for accepting a particular conclusion.Argument may also refer to:-Mathematics and computer science:...
by proponents of intelligent design
Intelligent design
Intelligent design is the proposition that "certain features of the universe and of living things are best explained by an intelligent cause, not an undirected process such as natural selection." It is a form of creationism and a contemporary adaptation of the traditional teleological argument for...
that certain biological systems are too complex to have evolved
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
from simpler, or "less complete" predecessors, through natural selection
Natural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....
acting upon a series of advantageous naturally occurring, chance mutations. The argument is central to intelligent design, and is rejected by the scientific community
Scientific community
The scientific community consists of the total body of scientists, its relationships and interactions. It is normally divided into "sub-communities" each working on a particular field within science. Objectivity is expected to be achieved by the scientific method...
at large, which overwhelmingly regards intelligent design as pseudoscience
Pseudoscience
Pseudoscience is a claim, belief, or practice which is presented as scientific, but which does not adhere to a valid scientific method, lacks supporting evidence or plausibility, cannot be reliably tested, or otherwise lacks scientific status...
. Irreducible complexity is one of two main arguments used by intelligent design proponents, the other being specified complexity
Specified complexity
Specified complexity is an argument proposed by William Dembski and used by him and others to promote intelligent design. According to Dembski, the concept is intended to formalize a property that singles out patterns that are both specified and complex...
.
Biochemistry professor Michael Behe
Michael Behe
Michael J. Behe is an American biochemist, author, and intelligent design advocate. He currently serves as professor of biochemistry at Lehigh University in Pennsylvania and as a senior fellow of the Discovery Institute's Center for Science and Culture...
, the originator of the term irreducible complexity, defines an irreducibly complex system as one "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". These examples are said to demonstrate that modern biological forms could not have evolved naturally. Evolutionary biologists have shown that such systems can evolve, and that Behe's examples constitute an argument from ignorance
Argument from ignorance
Argument from ignorance, also known as argumentum ad ignorantiam or "appeal to ignorance" , is a fallacy in informal logic. It asserts that a proposition is true because it has not yet been proven false, it is "generally accepted"...
. In the 2005 Kitzmiller v. Dover Area School District
Kitzmiller v. Dover Area School District
Tammy Kitzmiller, et al. v. Dover Area School District, et al. was the first direct challenge brought in the United States federal courts testing a public school district policy that required the teaching of intelligent design...
trial in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, Behe gave testimony on the subject of irreducible complexity. The court found that "Professor Behe's claim for irreducible complexity has been refuted in peer-reviewed research papers and has been rejected by the scientific community at large."
Definitions
The term "irreducible complexity" was coined by Behe, who defined it as applying to:A single system which is composed of several interacting parts that contribute to the basic function, and where the removal of any one of the parts causes the system to effectively cease functioning. (Darwin's Black BoxDarwin's Black BoxDarwin's Black Box: The Biochemical Challenge to Evolution is a book written by Michael J. Behe and published by Free Press in which he presents his notion of irreducible complexity and claims that its presence in many biochemical systems indicates therefore that they must be the result of...
p39 in the 2006 edition)
Supporters of intelligent design use this term to refer to biological systems and organs that they believe could not have come about by any series of small changes. They argue that anything less than the complete form of such a system or organ would not work at all, or would in fact be a detriment to the organism, and would therefore never survive the process of natural selection. Although they accept that some complex systems and organs can be explained by evolution, they claim that organs and biological features which are irreducibly complex cannot be explained by current models, and that an intelligent designer must have created life or guided its evolution. Accordingly, the debate on irreducible complexity concerns two questions: whether irreducible complexity can be found in nature, and what significance it would have if it did exist in nature.
A second definition given by Behe (his "evolutionary definition") is as follows:
An irreducibly complex evolutionary pathway is one that contains one or more unselected steps (that is, one or more necessary-but-unselected mutations). The degree of irreducible complexity is the number of unselected steps in the pathway.
Intelligent design advocate William Dembski gives this definition:
A system performing a given basic function is irreducibly complex if it includes a set of well-matched, mutually interacting, nonarbitrarily individuated parts such that each part in the set is indispensable to maintaining the system's basic, and therefore original, function. The set of these indispensable parts is known as the irreducible core of the system.
Forerunners
The argument from irreducible complexity is a descendant of the teleological argumentTeleological argument
A teleological or design argument is an a posteriori argument for the existence of God based on apparent design and purpose in the universe. The argument is based on an interpretation of teleology wherein purpose and intelligent design appear to exist in nature beyond the scope of any such human...
for God (the argument from design or from complexity). This states that because certain things in nature are very complicated, they must have been designed. William Paley
William Paley
William Paley was a British Christian apologist, philosopher, and utilitarian. He is best known for his exposition of the teleological argument for the existence of God in his work Natural Theology, which made use of the watchmaker analogy .-Life:Paley was Born in Peterborough, England, and was...
famously argued, in his 1802 watchmaker analogy
Watchmaker analogy
The watchmaker analogy, or watchmaker argument, is a teleological argument for the existence of God. By way of an analogy, the argument states that design implies a designer...
, that complexity in nature implies a God for the same reason that the existence of a watch implies the existence of a watchmaker. This argument has a long history, and can be traced back at least as far as Cicero
Cicero
Marcus Tullius Cicero , was a Roman philosopher, statesman, lawyer, political theorist, and Roman constitutionalist. He came from a wealthy municipal family of the equestrian order, and is widely considered one of Rome's greatest orators and prose stylists.He introduced the Romans to the chief...
's De Natura Deorum
De Natura Deorum
De Natura Deorum is a philosophical dialogue by Roman orator Cicero written in 45 BC. It is laid out in three "books", each of which discuss the theology of different Roman and Greek philosophers...
ii.34.
Up to the 18th century
GalenGalen
Aelius Galenus or Claudius Galenus , better known as Galen of Pergamon , was a prominent Roman physician, surgeon and philosopher...
(1st and 2nd centuries AD) wrote about the large number of parts of the body and their relationships, which observation was cited as evidence for creation. The idea that specifically the interdependence between parts would have implications for the origins of living things was raised by writers starting with Pierre Gassendi
Pierre Gassendi
Pierre Gassendi was a French philosopher, priest, scientist, astronomer, and mathematician. With a church position in south-east France, he also spent much time in Paris, where he was a leader of a group of free-thinking intellectuals. He was also an active observational scientist, publishing the...
in the mid 17th century and John Wilkins
John Wilkins
John Wilkins FRS was an English clergyman, natural philosopher and author, as well as a founder of the Invisible College and one of the founders of the Royal Society, and Bishop of Chester from 1668 until his death....
, who wrote (citing Galen), "Now to imagine, that all these things, according to their several kinds, could be brought into this regular frame and order, to which such an infinite number of Intentions are required, without the contrivance of some wise Agent, must needs be irrational in the highest degree." In the late 17th century, Thomas Burnet
Thomas Burnet
Thomas Burnet , theologian and writer on cosmogony.-Life:He was born at Croft near Darlington in 1635. After studying at Northallerton Grammar School under Thomas Smelt, he went to Clare Hall, Cambridge in 1651. There he was a pupil of John Tillotson...
referred to "a multitude of pieces aptly joyn’d" to argue against the eternity
Eternity
While in the popular mind, eternity often simply means existence for a limitless amount of time, many have used it to refer to a timeless existence altogether outside time. By contrast, infinite temporal existence is then called sempiternity. Something eternal exists outside time; by contrast,...
of life. In the early 18th century, Nicolas Malebranche
Nicolas Malebranche
Nicolas Malebranche ; was a French Oratorian and rationalist philosopher. In his works, he sought to synthesize the thought of St. Augustine and Descartes, in order to demonstrate the active role of God in every aspect of the world...
wrote "An organized body contains an infinity of parts that mutually depend upon one another in relation to particular ends, all of which must be actually formed in order to work as a whole," arguing in favor of preformation, rather than epigenesis
Epigenesis (biology)
In biology, epigenesis has at least two distinct meanings:* the unfolding development in an organism, and in particular the development of a plant or animal from an egg or spore through a sequence of steps in which cells differentiate and organs form;...
, of the individual; and a similar argument about the origins of the individual was made by other 18th century students of natural history.
In his 1790 book, The Critique of Judgment, Kant
KANT
KANT is a computer algebra system for mathematicians interested in algebraic number theory, performing sophisticated computations in algebraic number fields, in global function fields, and in local fields. KASH is the associated command line interface...
is said to argue that "we cannot conceive how a whole that comes into being only gradually from its parts can nevertheless be the cause of the properties of those parts"
19th century
As we transition to the 19th century, we find references which relate to evolution.Chapter XV of Paley's Natural Theology discusses at length what he called "relations" of parts of living things as an indication of their design.
Georges Cuvier
Georges Cuvier
Georges Chrétien Léopold Dagobert Cuvier or Jean Léopold Nicolas Frédéric Cuvier , known as Georges Cuvier, was a French naturalist and zoologist...
applied his principle of the correlation of parts to describe an animal from fragmentary remains. For Cuvier, this was related to another principle of his, the conditions of existence, which excluded the possibility of transmutation of species
Transmutation of species
Transmutation of species was a term used by Jean Baptiste Lamarck in 1809 for his theory that described the altering of one species into another, and the term is often used to describe 19th century evolutionary ideas that preceded Charles Darwin's theory of natural selection...
.
While he did not originate the term, Charles Darwin identified the argument as a possible way to falsify a prediction of the theory of evolution at the outset. In The Origin of Species, he wrote, "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. But I can find out no such case." Darwin's theory of evolution challenges the teleological argument by postulating an alternative explanation to that of an intelligent designer—namely, evolution by natural selection. By showing how simple unintelligent forces can ratchet up designs of extraordinary complexity without invoking outside design, Darwin showed that an intelligent designer was not the necessary conclusion to draw from complexity in nature. The argument from irreducible complexity attempts to demonstrate that certain biological features cannot be purely the product of Darwinian evolution.
In the late 19th century, in a dispute between supporters of the adequacy of natural selection
Natural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....
and those who held for inheritance of acquired characters
Inheritance of acquired characters
The inheritance of acquired characteristics is a hypothesis that physiological changes acquired over the life of an organism may be transmitted to offspring...
, one of the arguments made repeatedly by Herbert Spencer
Herbert Spencer
Herbert Spencer was an English philosopher, biologist, sociologist, and prominent classical liberal political theorist of the Victorian era....
, and followed by others, depended on what Spencer referred to as co-adaptation of co-operative parts, as in: "We come now to Professor Weismann
August Weismann
Friedrich Leopold August Weismann was a German evolutionary biologist. Ernst Mayr ranked him the second most notable evolutionary theorist of the 19th century, after Charles Darwin...
's endeavour to disprove my second thesis — that it is impossible to explain by natural selection alone the co-adaptation of co-operative parts. It is thirty years since this was set forth in "The Principles of Biology." In §166, I instanced the enormous horns of the extinct Irish elk
Irish Elk
The Irish Elk or Giant Deer , was a species of Megaloceros and one of the largest deer that ever lived. Its range extended across Eurasia, from Ireland to east of Lake Baikal, during the Late Pleistocene. The latest known remains of the species have been carbon dated to about 7,700 years ago...
, and contended that in this and in kindred cases, where for the efficient use of some one enlarged part many other parts have to be simultaneously enlarged, it is out of the question to suppose that they can have all spontaneously varied in the required proportions." The history of this concept in the dispute has been characterized: "An older and more religious tradition of idealist thinkers were committed to the explanation of complex adaptive contrivances by intelligent design. ... Another line of thinkers, unified by the recurrent publications of Herbert Spencer, also saw coadaptation as a composed, irreducible whole, but sought to explain it by the inheritance of acquired characteristics."
20th century
Hermann MullerHermann Joseph Muller
Hermann Joseph Muller was an American geneticist, educator, and Nobel laureate best known for his work on the physiological and genetic effects of radiation as well as his outspoken political beliefs...
, in the early 20th century, discussed a concept similar to irreducible complexity. However, far from seeing this as a problem for evolution, he described the "interlocking" of biological features as a consequence to be expected of evolution, which would lead to irreversibility of some evolutionary changes. He wrote, "Being thus finally woven, as it were, into the most intimate fabric of the organism, the once novel character can no longer be withdrawn with impunity, and may have become vitally necessary."
In 1974, Young Earth Creationist Henry M. Morris
Henry M. Morris
Henry Madison Morris was an American young earth creationist and Christian apologist. He was one of the founders of the Creation Research Society and the Institute for Creation Research...
introduced a similar concept in his book Scientific Creationism in which he wrote; "This issue can actually be attacked quantitatively, using simple principles of mathematical probability. The problem is simply whether a complex system, in which many components function unitedly together, and in which each component is uniquely necessary to the efficient functioning of the whole, could ever arise by random processes."
A book-length study of a concept similar to irreducible complexity, explained by gradual, step-wise, non-teleological evolution, was published in 1975 by Thomas H. Frazzetta. "A complex adaptation is one constructed of several components that must blend together operationally to make the adaptation "work". It is analogous to a machine whose performance depends upon careful cooperation among its parts. In the case of the machine, no single part can greatly be altered without changing the performance of the entire machine." The machine that he chose as an analog is the Peaucellier machine, and one biological system given extended description was the jaw apparatus of a python. The conclusion of this investigation, rather than that evolution of a complex adaptation was impossible, "awed by the adaptations of living things, to be stunned by their complexity and suitability", was "to accept the inescapable but not humiliating fact that much of mankind can be seen in a tree or a lizard."
In 1981, Ariel Roth, in defense of the creation science position in the trial McLean v. Arkansas
McLean v. Arkansas
McLean v. Arkansas Board of Education, 529 F. Supp. 1255, 1258-1264 , was a 1981 legal case in Arkansas.A lawsuit was filed in the United States District Court for the Eastern District of Arkansas by various parents, religious groups and organizations, biologists, and others who argued that the...
, said of "complex integrated structures" that "This system would not be functional until all the parts were there ... How did these parts survive during evolution ...?"
In 1985 Cairns-Smith
Graham Cairns-Smith
Alexander Graham Cairns-Smith is an organic chemist and molecular biologist at the University of Glasgow, most famous for his controversial 1985 book, Seven Clues to the Origin of Life...
wrote of "interlocking", "How can a complex collaboration between components evolve in small steps?" and used the analogy of the scaffolding called centering
Centring
Centring , or centering , is the structure upon which the stones of arches or vault are laid during construction. Once the arch is complete, it supports itself, but until the keystone is inserted, it has no strength and needs the centring to keep the voussoirs in their correct relative...
used to build an arch then removed afterwards: "Surely there was 'scaffolding'. Before the multitudinous components of present biochemistry could come to lean together they had to lean on something else." However, neither Muller or Cairns-Smith claimed that their ideas were evidence of something supernatural.
An essay in support of creationism
Creationism
Creationism is the religious beliefthat humanity, life, the Earth, and the universe are the creation of a supernatural being, most often referring to the Abrahamic god. As science developed from the 18th century onwards, various views developed which aimed to reconcile science with the Genesis...
published in 1994 referred to bacterial flagella as showing "multiple, integrated components", where "nothing about them works unless every one of their complexly fashioned and integrated components are in place" and asked the reader to "imagine the effects of natural selection on those organisms that fortuitously evolved the flagella ... without the concommitant control mechanisms".
An early concept of irreducibly complex systems comes from Ludwig von Bertalanffy
Ludwig von Bertalanffy
Karl Ludwig von Bertalanffy was an Austrian-born biologist known as one of the founders of general systems theory . GST is an interdisciplinary practice that describes systems with interacting components, applicable to biology, cybernetics, and other fields...
, a 20th-century Austrian biologist. He believed that complex systems must be examined as complete, irreducible
Irreducible (philosophy)
The principle of Irreducibility, in philosophy, has the sense that a complete account of an entity will not be possible at lower levels of explanation and which has novel properties beyond prediction and explanation...
systems in order to fully understand how they work. He extended his work on biological complexity into a general theory of systems in a book titled General Systems Theory
Systems theory
Systems theory is the transdisciplinary study of systems in general, with the goal of elucidating principles that can be applied to all types of systems at all nesting levels in all fields of research...
.
After James Watson
James D. Watson
James Dewey Watson is an American molecular biologist, geneticist, and zoologist, best known as one of the co-discoverers of the structure of DNA in 1953 with Francis Crick...
and Francis Crick
Francis Crick
Francis Harry Compton Crick OM FRS was an English molecular biologist, biophysicist, and neuroscientist, and most noted for being one of two co-discoverers of the structure of the DNA molecule in 1953, together with James D. Watson...
published the structure of DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
in the early 1950s, General Systems Theory lost many of its adherents in the physical and biological sciences. However, Systems theory remained popular in the social sciences long after its demise in the physical and biological sciences.
Origins
Michael Behe
Michael J. Behe is an American biochemist, author, and intelligent design advocate. He currently serves as professor of biochemistry at Lehigh University in Pennsylvania and as a senior fellow of the Discovery Institute's Center for Science and Culture...
developed his ideas on the concept around 1992, in the early days of the 'wedge movement
Wedge strategy
The wedge strategy is a political and social action plan authored by the Discovery Institute, the hub of the intelligent design movement. The strategy was put forth in a Discovery Institute manifesto known as the Wedge Document, which describes a broad social, political, and academic agenda whose...
', and first presented his ideas about "irreducible complexity" in June 1993 when the "Johnson-Behe cadre of scholars" met at Pajaro Dunes in California. He set out his ideas in the second edition of Of Pandas and People
Of Pandas and People
Of Pandas and People: The Central Question of Biological Origins is a controversial 1989 school-level textbook written by Percival Davis and Dean H. Kenyon and published by the Texas-based Foundation for Thought and Ethics...
published in 1993, extensively revising Chapter 6 Biochemical Similarities with new sections on the complex mechanism of blood clotting and on the origin of proteins.
He first used the term "irreducible complexity" in his 1996 book Darwin's Black Box
Darwin's Black Box
Darwin's Black Box: The Biochemical Challenge to Evolution is a book written by Michael J. Behe and published by Free Press in which he presents his notion of irreducible complexity and claims that its presence in many biochemical systems indicates therefore that they must be the result of...
, to refer to certain complex biochemical cellular
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
systems. He posits that evolutionary mechanisms cannot explain the development of such "irreducibly complex" systems. Notably, Behe credits philosopher William Paley
William Paley
William Paley was a British Christian apologist, philosopher, and utilitarian. He is best known for his exposition of the teleological argument for the existence of God in his work Natural Theology, which made use of the watchmaker analogy .-Life:Paley was Born in Peterborough, England, and was...
for the original concept, not von Bertalanffy, and suggests that his application of the concept to biological systems is entirely original.
Intelligent design advocates argue that irreducibly complex systems must have been deliberately engineered by some form of intelligence
Intelligent designer
An intelligent designer, also referred to as an intelligent agent, is the hypothetical willed and self-aware entity that the intelligent design movement argues had some role in the origin and/or development of life...
.
In 2001, Michael Behe
Michael Behe
Michael J. Behe is an American biochemist, author, and intelligent design advocate. He currently serves as professor of biochemistry at Lehigh University in Pennsylvania and as a senior fellow of the Discovery Institute's Center for Science and Culture...
wrote: "[T]here is an asymmetry between my current definition of irreducible complexity and the task facing natural selection. I hope to repair this defect in future work." Behe specifically explained that the "current definition puts the focus on removing a part from an already functioning system", but the "difficult task facing Darwinian evolution, however, would not be to remove parts from sophisticated pre-existing systems; it would be to bring together components to make a new system in the first place". In the 2005 Kitzmiller v. Dover Area School District trial
Kitzmiller v. Dover Area School District
Tammy Kitzmiller, et al. v. Dover Area School District, et al. was the first direct challenge brought in the United States federal courts testing a public school district policy that required the teaching of intelligent design...
, Behe testified under oath that he "did not judge [the asymmetry] serious enough to [have revised the book] yet."
Behe additionally testified that the presence of irreducible complexity in organisms would not rule out the involvement of evolutionary mechanisms in the development of organic life. He further testified that he knew of no earlier "peer reviewed articles in scientific journals discussing the intelligent design of the blood clotting cascade," but that there were "probably a large number of peer reviewed articles in science journals that demonstrate that the blood clotting system is indeed a purposeful arrangement of parts of great complexity and sophistication." (The judge ruled that "intelligent design is not science and is essentially religious in nature".)
According to the theory of evolution, genetic variations occur without specific design or intent. The environment "selects" the variants that have the highest fitness, which are then passed on to the next generation of organisms. Change occurs by the gradual operation of natural forces over time, perhaps slowly, perhaps more quickly (see punctuated equilibrium
Punctuated equilibrium
Punctuated equilibrium is a theory in evolutionary biology which proposes that most species will exhibit little net evolutionary change for most of their geological history, remaining in an extended state called stasis...
). This process is able to adapt
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
complex structures from simpler beginnings, or convert complex structures from one function to another (see spandrel
Spandrel (biology)
In evolutionary biology, a Spandrel is a phenotypic characteristic that is a byproduct of the evolution of some other characteristic, rather than a direct product of adaptive selection.-Origin of Term:...
). Most intelligent design advocates accept that evolution occurs through mutation and natural selection at the "micro level
Microevolution
Microevolution is the changes in allele frequencies that occur over time within a population. This change is due to four different processes: mutation, selection , gene flow, and genetic drift....
", such as changing the relative frequency of various beak lengths in finches, but assert that it cannot account for irreducible complexity, because none of the parts of an irreducible system would be functional or advantageous until the entire system is in place.
The mousetrap example
In his 2008 book Only A Theory
Only a Theory
Only A Theory: Evolution and the Battle for America's Soul is a 2008 book by the American cell biologist and Roman Catholic Kenneth R. Miller. In the book, Miller examines the battle between evolution and intelligent design , and explores the implications of science in America...
, biologist Kenneth R. Miller
Kenneth R. Miller
Kenneth Raymond Miller is a biology professor at Brown University. Miller, who is Roman Catholic, is particularly known for his opposition to creationism, including the intelligent design movement...
challenges Behe's claim that the mousetrap is irreducibly complex. Miller observes that various subsets of the five components can be devised to form cooperative units, ones that have different functions from the mousetrap and so, in biological terms, could form functional spandrels
Spandrel (biology)
In evolutionary biology, a Spandrel is a phenotypic characteristic that is a byproduct of the evolution of some other characteristic, rather than a direct product of adaptive selection.-Origin of Term:...
before being adapted to the new function of catching mice. In an example taken from his high school experience, Miller recalls that one of his classmates
...struck upon the brilliant idea of using an old, broken mousetrap as a spitball catapult, and it worked brilliantly....It had worked perfectly as something other than a mousetrap....my rowdy friend had pulled a couple of parts --probably the hold-down bar and catch-- off the trap to make it easier to conceal and more effective as a catapult...[leaving] the base, the spring, and the hammer. Not much of a mousetrap, but a helluva spitball launcher....I realized why [Behe's] mousetrap analogy had bothered me. It was wrong. The mousetrap is not irreducibly complex after all.
Other systems identified by Miller that include mousetrap components include the following:
- use the spitball launcher as a tie clip (same three-part system with different function)
- remove the spring from the spitball launcher/tie clip to create a two-part key chain (base + hammer)
- glue the spitball launcher/tie clip to a sheet of wood to create a clipboard (launcher + glue + wood)
- remove the hold-down bar for use as a toothpick (single element system)
Behe has responded, "What Miller actually means is that if you take away some components and then go on to, say, twist a couple of metal pieces in just the right way and add a few staples in the correct positions, you can construct a new kind of working trap, which may superficially resemble the starting trap. That, however, is intelligent design. Neither Miller nor anyone else has shown that the mousetrap I pictured in my book can be constructed by a series of small changes, one at a time, as Darwinian evolution would have to do."
Consequences of irreducible complexity
Behe's original examples of irreducibly complex mechanisms included the bacterial flagellumFlagellum
A flagellum is a tail-like projection that protrudes from the cell body of certain prokaryotic and eukaryotic cells, and plays the dual role of locomotion and sense organ, being sensitive to chemicals and temperatures outside the cell. There are some notable differences between prokaryotic and...
of E. coli, the blood clotting cascade, cilia, and the adaptive immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
.
Behe argues that organs and biological features which are irreducibly complex cannot be wholly explained by current models of evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
. In explicating his definition of "irreducible complexity" he notes that:
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.
Irreducible complexity is not an argument that evolution does not occur, but rather an argument that it is "incomplete". In the last chapter of Darwin's Black Box
Darwin's Black Box
Darwin's Black Box: The Biochemical Challenge to Evolution is a book written by Michael J. Behe and published by Free Press in which he presents his notion of irreducible complexity and claims that its presence in many biochemical systems indicates therefore that they must be the result of...
, Behe goes on to explain his view that irreducible complexity is evidence for intelligent design
Intelligent design
Intelligent design is the proposition that "certain features of the universe and of living things are best explained by an intelligent cause, not an undirected process such as natural selection." It is a form of creationism and a contemporary adaptation of the traditional teleological argument for...
. Mainstream critics, however, argue that irreducible complexity, as defined by Behe, can be generated by known evolutionary mechanisms. Behe's claim that no scientific literature adequately modeled the origins of biochemical systems through evolutionary mechanisms has been challenged by TalkOrigins
TalkOrigins Archive
The TalkOrigins Archive is a website that presents mainstream science perspectives on the antievolution claims of young-earth, old-earth, and "intelligent design" creationists...
. The judge in the Dover trial wrote "By defining irreducible complexity in the way that he has, Professor Behe attempts to exclude the phenomenon of exaptation
Exaptation
Exaptation, cooption, and preadaptation are related terms referring to shifts in the function of a trait during evolution. For example, a trait can evolve because it served one particular function, but subsequently it may come to serve another. Exaptations are common in both anatomy and behaviour...
by definitional fiat, ignoring as he does so abundant evidence which refutes his argument. Notably, the NAS
United States National Academy of Sciences
The National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...
has rejected Professor Behe’s claim for irreducible complexity..."
Stated examples
Behe and others have suggested a number of biological features that they believe may be irreducibly complex.Blood clotting cascade
The blood clotting or coagulationCoagulation
Coagulation is a complex process by which blood forms clots. It is an important part of hemostasis, the cessation of blood loss from a damaged vessel, wherein a damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop bleeding and begin repair of the damaged vessel...
cascade in vertebrates is a complex biological pathway which is given as an example of apparent irreducible complexity.
The irreducible complexity argument assumes that the necessary parts of a system have always been necessary, and therefore could not have been added sequentially. However, in evolution, something which is at first merely advantageous can later become necessary. Natural selection
Natural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....
can lead to complex biochemical systems being built up from simpler systems, or to existing functional systems being recombined as a new system with a different function. For example, one of the clotting factors that Behe listed as a part of the clotting cascade was later found to be absent in whales, demonstrating that it is not essential for a clotting system. Many purportedly irreducible structures can be found in other organisms as much simpler systems that utilize fewer parts. These systems, in turn, may have had even simpler precursors that are now extinct. Behe has responded to critics of his clotting cascade arguments by suggesting that homology
Homology (biology)
Homology forms the basis of organization for comparative biology. In 1843, Richard Owen defined homology as "the same organ in different animals under every variety of form and function". Organs as different as a bat's wing, a seal's flipper, a cat's paw and a human hand have a common underlying...
is evidence for evolution, but not for natural selection.
The "improbability argument" also misrepresents natural selection. It is correct to say that a set of simultaneous mutations that form a complex protein structure is so unlikely as to be unfeasible, but that is not what Darwin advocated. His explanation is based on small accumulated changes that take place without a final goal. Each step must be advantageous in its own right, although biologists may not yet understand the reason behind all of them—for example, jawless fish accomplish blood clotting with just six proteins instead of the full 10.
Eye
The eyeEye
Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...
is a famous example of a supposedly irreducibly complex structure, due to its many elaborate and interlocking parts, seemingly all dependent upon one another. It is frequently cited by intelligent design and creationism advocates as an example of irreducible complexity. Behe used the "development of the eye problem" as evidence for intelligent design in Darwin's Black Box. Although Behe acknowledged that the evolution of the larger anatomical features of the eye have been well-explained, he claimed that the complexity of the minute biochemical reactions required at a molecular level for light sensitivity still defies explanation. Creationist Jonathan Sarfati
Jonathan Sarfati
Jonathan D. Sarfati is a former New Zealand national chess champion and creationist author with a PhD in chemistry. Sarfati works for Creation Ministries International , formerly part of Answers in Genesis , a non-profit Christian Apologetics ministry specialising in Young-Earth creationism...
has described the eye as evolutionary biologists' "greatest challenge as an example of superb 'irreducible complexity' in God's creation", specifically pointing to the supposed "vast complexity" required for transparency.
In an often misquoted passage from On the Origin of Species, Charles Darwin
Charles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...
appears to acknowledge the eye's development as a difficulty for his theory. However, the quote in context shows that Darwin actually had a very good understanding of the evolution of the eye. He notes that "to suppose that the eye ... could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree". Yet this observation was merely a rhetorical device
Procatalepsis
Procatalepsis, also called prebuttal, is a figure of speech in which the speaker raises an objection to his own argument and then immediately answers it...
for Darwin. He goes on to explain that if gradual evolution of the eye could be shown to be possible, "the difficulty of believing that a perfect and complex eye could be formed by natural selection ... can hardly be considered real". He then proceeded to roughly map out a likely course for evolution using examples of gradually more complex eyes of various species.
Evolution of the eye
The evolution of the eye has been a subject of significant study, as a distinctive example of a homologous organ present in a wide variety of taxa. Certain components of the eye, such as the visual pigments, appear to have a common ancestry – that is, they evolved once, before the animals radiated...
has become much better understood. Although learning about the construction of ancient eyes through fossil evidence is problematic due to the soft tissues leaving no imprint or remains, genetic and comparative anatomical evidence has increasingly supported the idea of a common ancestry for all eyes.
Current evidence does suggest possible evolutionary lineages for the origins of the anatomical features of the eye. One likely chain of development is that the eyes originated as simple patches of photoreceptor cells that could detect the presence or absence of light, but not its direction. When, via random mutation across the population, the photosensitive cells happened to have developed on a small depression, it endowed the organism with a better sense of the light's source. This small change gave the organism an advantage over those without the mutation. This genetic trait would then be "selected for" as those with the trait would have an increased chance of survival, and therefore progeny, over those without the trait. Individuals with deeper depressions would be able to discern changes in light over a wider field than those individuals with shallower depressions. As ever deeper depressions were advantageous to the organism, gradually, this depression would become a pit into which light would strike certain cells depending on its angle. The organism slowly gained increasingly precise visual information. And again, this gradual process continued as individuals having a slightly shrunken aperture
Aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are,...
of the eye had an advantage over those without the mutation as an aperture increases how collimated the light is at any one specific group of photoreceptors. As this trait developed, the eye became effectively a pinhole camera
Pinhole camera
A pinhole camera is a simple camera without a lens and with a single small aperture – effectively a light-proof box with a small hole in one side. Light from a scene passes through this single point and projects an inverted image on the opposite side of the box...
which allowed the organism to dimly make out shapes—the nautilus
Nautilus
Nautilus is the common name of marine creatures of cephalopod family Nautilidae, the sole extant family of the superfamily Nautilaceae and of its smaller but near equal suborder, Nautilina. It comprises six living species in two genera, the type of which is the genus Nautilus...
is a modern example of an animal with such an eye. Finally, via this same selection process, a protective layer of transparent cells over the aperture was differentiated into a crude lens
Lens (anatomy)
The crystalline lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. The lens, by changing shape, functions to change the focal distance of the eye so that it can focus on objects at various distances, thus allowing a...
, and the interior of the eye was filled with humours to assist in focusing images. In this way, eyes are recognized by modern biologists as actually a relatively unambiguous and simple structure to evolve, and many of the major developments of the eye's evolution are believed to have taken place over only a few million years, during the Cambrian explosion
Cambrian explosion
The Cambrian explosion or Cambrian radiation was the relatively rapid appearance, around , of most major phyla, as demonstrated in the fossil record, accompanied by major diversification of other organisms, including animals, phytoplankton, and calcimicrobes...
.
Behe maintains that the complexity of light sensitivity at the molecular level and the minute biochemical reactions required for those first "simple patches of photoreceptor[s]" still defies explanation. Other intelligent design proponents have pointed to the difficulty of the entire visual system evolving rather than the eye alone.
Flagella
Scientists regard this argument as having been disproved in the light of research dating back to 1996 as well as more recent findings. They point out that the basal body of the flagella has been found to be similar to the Type III secretion system
Type three secretion system
Type three secretion system is a protein appendage found in several Gram-negative bacteria....
(TTSS), a needle-like structure that pathogenic germs such as Salmonella
Salmonella
Salmonella is a genus of rod-shaped, Gram-negative, non-spore-forming, predominantly motile enterobacteria with diameters around 0.7 to 1.5 µm, lengths from 2 to 5 µm, and flagella which grade in all directions . They are chemoorganotrophs, obtaining their energy from oxidation and reduction...
and Yersinia pestis
Yersinia pestis
Yersinia pestis is a Gram-negative rod-shaped bacterium. It is a facultative anaerobe that can infect humans and other animals....
use to inject toxin
Toxin
A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...
s into living eucaryote cells. The needle's base has ten elements in common with the flagellum, but it is missing forty of the proteins that make a flagellum work. Thus, this system negates the claim that taking away any of the flagellum's parts would render it useless. On this basis, Kenneth Miller
Kenneth R. Miller
Kenneth Raymond Miller is a biology professor at Brown University. Miller, who is Roman Catholic, is particularly known for his opposition to creationism, including the intelligent design movement...
notes that, "The parts of this supposedly irreducibly complex system actually have functions of their own."
Response of the scientific community
Like intelligent design, the concept it seeks to support, irreducible complexity has failed to gain any notable acceptance within the scientific communityScientific community
The scientific community consists of the total body of scientists, its relationships and interactions. It is normally divided into "sub-communities" each working on a particular field within science. Objectivity is expected to be achieved by the scientific method...
. One science writer called it a "full-blown intellectual surrender strategy."
Reducibility of "irreducible" systems
Potentially viable evolutionary pathways have been proposed for allegedly irreducibly complex systems such as blood clotting, the immune system and the flagellum, which were the three examples Behe used. Even his example of a mousetrap was shown to be reducible by John H. McDonald. If irreducible complexity is an insurmountable obstacle to evolution, it should not be possible to conceive of such pathways.Niall Shanks and Karl H. Joplin, both of East Tennessee State University
East Tennessee State University
East Tennessee State University is an accredited American university located in Johnson City, Tennessee. It is part of the Tennessee Board of Regents system of colleges and universities, the nation's sixth largest system of public education, and is the fourth largest university in the state...
, have shown that systems satisfying Behe's characterization of irreducible biochemical complexity can arise naturally and spontaneously as the result of self-organizing chemical processes. They also assert that what evolved biochemical and molecular systems actually exhibit is "redundant complexity"—a kind of complexity that is the product of an evolved biochemical process. They claim that Behe overestimated the significance of irreducible complexity because of his simple, linear view of biochemical reactions, resulting in his taking snapshots of selective features of biological systems, structures and processes, while ignoring the redundant complexity of the context in which those features are naturally embedded. They also criticized his over-reliance of overly simplistic metaphors, such as his mousetrap. In addition, research published in the peer-reviewed journal Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
has shown that computer simulations of evolution demonstrate that it is possible for irreducible complexity to evolve naturally.
It is illustrative to compare a mousetrap with a cat, in this context. Both normally function so as to control the mouse population. The cat has many parts that can be removed leaving it still functional; for example, its tail can be bobbed, or it can lose an ear in a fight. Comparing the cat and the mousetrap, then, one sees that the mousetrap (which is not alive) offers better evidence, in terms of irreducible complexity, for intelligent design than the cat. Even looking at the mousetrap analogy, several critics have described ways in which the parts of the mousetrap could have independent uses or could develop in stages, demonstrating that it is not irreducibly complex.
Moreover, even cases where removing a certain component in an organic system will cause the system to fail do not demonstrate that the system couldn't have been formed in a step-by-step, evolutionary process. By analogy, stone arches are irreducibly complex—if you remove any stone the arch will collapse—yet we build them easily enough, one stone at a time, by building over centering
Centring
Centring , or centering , is the structure upon which the stones of arches or vault are laid during construction. Once the arch is complete, it supports itself, but until the keystone is inserted, it has no strength and needs the centring to keep the voussoirs in their correct relative...
that is removed afterward. Similarly, naturally occurring arches
Natural arch
A natural arch or natural bridge is a natural geological formation where a rock arch forms, with an opening underneath. Most natural arches form as a narrow ridge, walled by cliffs, become narrower from erosion, with a softer rock stratum under the cliff-forming stratum gradually eroding out until...
of stone are formed by weathering away bits of stone from a large concretion that has formed previously.
Evolution can act to simplify as well as to complicate. This raises the possibility that seemingly irreducibly complex biological features may have been achieved with a period of increasing complexity, followed by a period of simplification.
In April 2006 a team led by Joe Thornton, assistant professor of biology at the University of Oregon's Center for Ecology and Evolutionary Biology, using techniques for resurrecting ancient genes, scientists for the first time reconstructed the evolution of an apparently irreducibly complex molecular system. The research was published in the April 7 issue of Science.
It may be that irreducible complexity does not actually exist in nature, and that the examples given by Behe and others are not in fact irreducibly complex, but can be explained in terms of simpler precursors. There has also been a theory that challenges irreducible complexity called facilitated variation
Facilitated variation
Facilitated variation is a new theory that has been presented by Marc W. Kirschner, a professor and chair at the Department of Systems Biology, Harvard Medical School, and John C. Gerhart, a professor at the Graduate School, University of California, Berkeley....
. The theory has been presented in 2005 by Marc W. Kirschner, a professor and chair of Department of Systems Biology at Harvard Medical School
Harvard Medical School
Harvard Medical School is the graduate medical school of Harvard University. It is located in the Longwood Medical Area of the Mission Hill neighborhood of Boston, Massachusetts....
, and John C. Gerhart, a professor in Molecular and Cell Biology, University of California, Berkeley
University of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...
. In their theory, they describe how certain mutation and changes can cause apparent irreducible complexity. Thus, seemingly irreducibly complex structures are merely "very complex", or they are simply misunderstood or misrepresented.
Gradual adaptation to new functions
The precursors of complex systems, when they are not useful in themselves, may be useful to perform other, unrelated functions. Evolutionary biologists argue that evolution often works in this kind of blind, haphazard manner in which the function of an early form is not necessarily the same as the function of the later form. The term used for this process is "exaptation". The mammalian middle earEvolution of mammalian auditory ossicles
The evolution of mammalian auditory ossicles is one of the most well-documented and important evolutionary events, demonstrating both numerous transitional forms as well as an excellent example of exaptation, the re-purposing of existing structures during evolution.In reptiles, the eardrum is...
(derived from a jawbone) and the panda
Giant Panda
The giant panda, or panda is a bear native to central-western and south western China. It is easily recognized by its large, distinctive black patches around the eyes, over the ears, and across its round body. Though it belongs to the order Carnivora, the panda's diet is 99% bamboo...
's thumb (derived from a wrist bone spur) are considered classic examples. A 2006 article in Nature demonstrates intermediate states leading toward the development of the ear in a Devonian
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
fish (about 360 million years ago). Furthermore, recent research shows that viruses play a heretofore unexpectedly great role in evolution by mixing and matching genes from various hosts.
Arguments for irreducibility often assume that things started out the same way they ended up—as we see them now. However, that may not necessarily be the case. In the Dover trial an expert witness for the plaintiffs, Ken Miller, demonstrated this possibility using Behe's mousetrap analogy. By removing several parts, Miller made the object unusable as a mousetrap, but he pointed out that it was now a perfectly functional, if unstylish, tie clip.
Falsifiability and experimental evidence
Some critics, such as Jerry CoyneJerry Coyne
-Online articles:* , The New Republic* , The New Republic* , The New Republic* ", The New Republic * -Online articles:* , The New Republic* , The New Republic* , The New Republic* ", The New Republic (Review of Michael Behe's The Edge of Evolution)* -Online articles:* , The New Republic* , The...
(professor of evolutionary biology at the University of Chicago
University of Chicago
The University of Chicago is a private research university in Chicago, Illinois, USA. It was founded by the American Baptist Education Society with a donation from oil magnate and philanthropist John D. Rockefeller and incorporated in 1890...
) and Eugenie Scott
Eugenie Scott
Eugenie Carol Scott is an American physical anthropologist who has been the executive director of the National Center for Science Education since 1987...
(a physical anthropologist
Physical anthropology
Biological anthropology is that branch of anthropology that studies the physical development of the human species. It plays an important part in paleoanthropology and in forensic anthropology...
and executive director of the National Center for Science Education
National Center for Science Education
The National Center for Science Education is a non-profit organization based in Oakland, California affiliated with the American Association for the Advancement of Science. It is the United States' leading anti-creationist organization, and defends the teaching of evolutionary biology and opposes...
) have argued that the concept of irreducible complexity, and more generally, the theory of intelligent design
Intelligent design
Intelligent design is the proposition that "certain features of the universe and of living things are best explained by an intelligent cause, not an undirected process such as natural selection." It is a form of creationism and a contemporary adaptation of the traditional teleological argument for...
is not falsifiable, and therefore, not scientific.
Behe argues that the theory that irreducibly complex systems could not have been evolved can be falsified by an experiment where such systems are evolved. For example, he posits taking bacteria with no flagellum and imposing a selective pressure for mobility. If, after a few thousand generations, the bacteria evolved the bacterial flagellum, then Behe believes that this would refute his theory.
Other critics take a different approach, pointing to experimental evidence that they believe falsifies the argument for Intelligent Design from irreducible complexity. For example, Kenneth Miller
Kenneth R. Miller
Kenneth Raymond Miller is a biology professor at Brown University. Miller, who is Roman Catholic, is particularly known for his opposition to creationism, including the intelligent design movement...
cites the lab work of Barry G. Hall on E. coli, which he asserts is evidence that "Behe is wrong."
Other evidence that irreducible complexity is not a problem for evolution comes from the field of computer science
Computer science
Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...
, where computer analogues of the processes of evolution are routinely used to automatically design complex solutions to problems. The results of such Genetic Algorithms are frequently irreducibly complex since the process, like evolution, both removes non-essential components over time as well as adding new components. The removal of unused components with no essential function, like the natural process where rock underneath a natural arch
Natural arch
A natural arch or natural bridge is a natural geological formation where a rock arch forms, with an opening underneath. Most natural arches form as a narrow ridge, walled by cliffs, become narrower from erosion, with a softer rock stratum under the cliff-forming stratum gradually eroding out until...
is removed, can produce irreducibly complex structures without requiring the intervention of a designer. Researchers applying these algorithms are automatically producing human competitive designs—but no human designer is required.
Argument from ignorance
Intelligent design proponents attribute to an intelligent designer those biological structures they believe are irreducibly complex and whereof they say a natural explanation is insufficient to account for them. However, critics view irreducible complexity as a special case of the "complexity indicates design" claim, and thus see it as an argument from ignoranceArgument from ignorance
Argument from ignorance, also known as argumentum ad ignorantiam or "appeal to ignorance" , is a fallacy in informal logic. It asserts that a proposition is true because it has not yet been proven false, it is "generally accepted"...
and God of the gaps
God of the gaps
God of the gaps is a type of theological fallacy in which gaps in scientific knowledge are taken to be evidence or proof of God's existence. The term was invented by Christian theologians not to discredit theism but rather to discourage reliance on teleological arguments for God's existence.-...
argument.
Eugenie Scott
Eugenie Scott
Eugenie Carol Scott is an American physical anthropologist who has been the executive director of the National Center for Science Education since 1987...
, along with Glenn Branch
Glenn Branch
Glenn Branch is the Deputy Director of the National Center for Science Education and a prominent critic of creationism and its offshoot, intelligent design...
and other critics, has argued that many points raised by intelligent design proponents are arguments from ignorance. Behe has been accused of using an "argument by lack of imagination", and Behe himself acknowledges that a failure of current science to explain how an "irreducibly complex" organism did or could evolve does not automatically prove the impossibility of such an evolution.
Irreducible complexity is at its core an argument against evolution. If truly irreducible systems are found, the argument goes, then intelligent design
Intelligent design
Intelligent design is the proposition that "certain features of the universe and of living things are best explained by an intelligent cause, not an undirected process such as natural selection." It is a form of creationism and a contemporary adaptation of the traditional teleological argument for...
must be the correct explanation for their existence. However, this conclusion is based on the assumption that current evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
ary theory and intelligent design are the only two valid models to explain life, a false dilemma
False dilemma
A false dilemma is a type of logical fallacy that involves a situation in which only two alternatives are considered, when in fact there are additional options...
.
Irreducible complexity in the Dover trial
While testifying at the Kitzmiller v. Dover Area School District trialKitzmiller v. Dover Area School District
Tammy Kitzmiller, et al. v. Dover Area School District, et al. was the first direct challenge brought in the United States federal courts testing a public school district policy that required the teaching of intelligent design...
Behe conceded that there are no peer-reviewed papers supporting his claims that complex molecular systems, like the bacterial flagellum, the blood-clotting cascade, and the immune system, were intelligently designed nor are there any peer-reviewed articles supporting his argument that certain complex molecular structures are "irreducibly complex."
In the final ruling of Kitzmiller v. Dover Area School District, Judge Jones specifically singled out Behe and irreducible complexity:
- "Professor Behe admitted in "Reply to My Critics" that there was a defect in his view of irreducible complexity because, while it purports to be a challenge to natural selection, it does not actually address "the task facing natural selection." and that "Professor Behe wrote that he hoped to "repair this defect in future work..." (Page 73)
- "As expert testimony revealed, the qualification on what is meant by "irreducible complexity" renders it meaningless as a criticism of evolution. (3:40 (Miller)). In fact, the theory of evolution proffers exaptation as a well-recognized, well-documented explanation for how systems with multiple parts could have evolved through natural means." (Page 74)
- "By defining irreducible complexity in the way that he has, Professor Behe attempts to exclude the phenomenon of exaptation by definitional fiat, ignoring as he does so abundant evidence which refutes his argument. Notably, the NASUnited States National Academy of SciencesThe National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...
has rejected Professor Behe’s claim for irreducible complexity..." (Page 75) - "As irreducible complexity is only a negative argument against evolution, it is refutable and accordingly testable, unlike ID [Intelligent Design], by showing that there are intermediate structures with selectable functions that could have evolved into the allegedly irreducibly complex systems. (2:15-16 (Miller)). Importantly, however, the fact that the negative argument of irreducible complexity is testable does not make testable the argument for ID. (2:15 (Miller); 5:39 (Pennock)). Professor Behe has applied the concept of irreducible complexity to only a few select systems: (1) the bacterial flagellum; (2) the blood-clotting cascade; and (3) the immune system. Contrary to Professor Behe’s assertions with respect to these few biochemical systems among the myriad existing in nature, however, Dr. Miller presented evidence, based upon peer-reviewed studies, that they are not in fact irreducibly complex." (Page 76)
- "...on cross-examination, Professor Behe was questioned concerning his 1996 claim that science would never find an evolutionary explanation for the immune system. He was presented with fifty-eight peer-reviewed publications, nine books, and several immunology textbook chapters about the evolution of the immune system; however, he simply insisted that this was still not sufficient evidence of evolution, and that it was not "good enough." (23:19 (Behe))." (Page 78)
- "We therefore find that Professor Behe’s claim for irreducible complexity has been refuted in peer-reviewed research papers and has been rejected by the scientific community at large. (17:45-46 (Padian); 3:99 (Miller)). Additionally, even if irreducible complexity had not been rejected, it still does not support ID as it is merely a test for evolution, not design. (2:15, 2:35-40 (Miller); 28:63-66 (Fuller)). We will now consider the purportedly “positive argument” for design encompassed in the phrase used numerous times by Professors Behe and Minnich throughout their expert testimony, which is the “purposeful arrangement of parts.” Professor Behe summarized the argument as follows: We infer design when we see parts that appear to be arranged for a purpose. The strength of the inference is quantitative; the more parts that are arranged, the more intricately they interact, the stronger is our confidence in design. The appearance of design in aspects of biology is overwhelming. Since nothing other than an intelligent cause has been demonstrated to be able to yield such a strong appearance of design, Darwinian claims notwithstanding, the conclusion that the design seen in life is real design is rationally justified. (18:90-91, 18:109-10 (Behe); 37:50 (Minnich)). As previously indicated, this argument is merely a restatement of the Reverend William PaleyWilliam PaleyWilliam Paley was a British Christian apologist, philosopher, and utilitarian. He is best known for his exposition of the teleological argument for the existence of God in his work Natural Theology, which made use of the watchmaker analogy .-Life:Paley was Born in Peterborough, England, and was...
’s argument applied at the cell level. Minnich, Behe, and Paley reach the same conclusion, that complex organisms must have been designed using the same reasoning, except that Professors Behe and Minnich refuse to identify the designer, whereas Paley inferred from the presence of design that it was God. (1:6- 7 (Miller); 38:44, 57 (Minnich)). Expert testimony revealed that this inductive argument is not scientific and as admitted by Professor Behe, can never be ruled out. (2:40 (Miller); 22:101 (Behe); 3:99 (Miller))." (Pages 79–80)
Additional references
- Behe, Michael (1996). Darwin's Black BoxDarwin's Black BoxDarwin's Black Box: The Biochemical Challenge to Evolution is a book written by Michael J. Behe and published by Free Press in which he presents his notion of irreducible complexity and claims that its presence in many biochemical systems indicates therefore that they must be the result of...
. New York: The Free Press. ISBN 0-684-83493-6 - Sunderland, Luther D. (March 1976). Miraculous Design in Woodpeckers. Creation Research Society Quarterly.
- Testing Darwin Discover Magazine Vol. 26 No. 02 | February 2005
External links
Supportive- Michael J. Behe home page
- About Irreducible Complexity Discovery InstituteDiscovery InstituteThe Discovery Institute is a non-profit public policy think tank based in Seattle, Washington, best known for its advocacy of intelligent design...
- How to Explain Irreducible Complexity -- A Lab Manual Discovery InstituteDiscovery InstituteThe Discovery Institute is a non-profit public policy think tank based in Seattle, Washington, best known for its advocacy of intelligent design...
- Institute for Creation Research (pdf)
- Irreducible Complexity Revisited (pdf)
- Behe's Reply to his Critics (pdf)
Critical
- Behe, Biochemistry, and the Invisible Hand
- Facilitated Variation
- Darwin vs. Intelligent Design (again), by H. Allen Orr (review of Darwin's Black Box)
- Talk.origins archive (see talk.originsTalk.originstalk.origins is a moderated Usenet discussion forum concerning the origins of life, and evolution...
) - TalkDesign.org (sister site to talk.origins archive on intelligent designIntelligent designIntelligent design is the proposition that "certain features of the universe and of living things are best explained by an intelligent cause, not an undirected process such as natural selection." It is a form of creationism and a contemporary adaptation of the traditional teleological argument for...
) - Professor Kenneth R. Miller's textbook website
- "The Flagellum Unspun: The Collapse of "Irreducible Complexity" by Professor Miller
- A rigorous mathematical analysis of the concept of irreducible complexity by Mishkin Berteig.
- PDF. 139 page in-depth analysis of Intelligent Design, Irreducible Complexity, and the book "Of Pandas and People" by a judge and based on expert testimony
- Devolution: Why intelligent design isn't (The New YorkerThe New YorkerThe New Yorker is an American magazine of reportage, commentary, criticism, essays, fiction, satire, cartoons and poetry published by Condé Nast...
) - Unlocking cell secrets bolsters evolutionists (Chicago TribuneChicago TribuneThe Chicago Tribune is a major daily newspaper based in Chicago, Illinois, and the flagship publication of the Tribune Company. Formerly self-styled as the "World's Greatest Newspaper" , it remains the most read daily newspaper of the Chicago metropolitan area and the Great Lakes region and is...
) - Does irreducible complexity imply Intelligent Design? by Mark Perakh
- Evolution of the Eye (Video) Zoologist Dan-Erik Nilsson demonstrates eye evolution through intermediate stages with working model. (PBSPublic Broadcasting ServiceThe Public Broadcasting Service is an American non-profit public broadcasting television network with 354 member TV stations in the United States which hold collective ownership. Its headquarters is in Arlington, Virginia....
) - Himma, Kenneth Einar. Design Arguments for the Existence of God. Internet Encyclopedia of Philosophy: 2. Contemporary Versions of the Design Argument, a. The Argument from Irreducible Biochemical Complexity