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Does Irreducible Complexity Imply Intelligent Design?

Michael Behe’s “irreducible complexity,” according to “design theorists,” implies Intelligent Design of biological systems. In fact, such a conclusion lacks a logical foundation. Irreducible complexity can even more reasonably be construed as an argument against Intelligent Design.

MARK PERAKH

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Michael Behe is a university professor of biochemistry. Although he has to his credit a number of papers published in professional journals on biochemistry, he is much better known as the author of the popular book Darwin’s Black Box (Behe 1996). Widely reviewed, both exorbitantly acclaimed and sharply critiqued, this book introduced the concept of “irreducible complexity” (IC) of protein systems in biological cells. IC, according to Behe, is a common feature of very complex protein “machines” performing vital functions in bio cells. A protein assembly which is IC, according to Behe, can only properly function if all of its constituent proteins are present; if even a single component of such a system is missing, the system becomes nonoperational. If a system is IC, concludes Behe, this indicates it cannot be a result of “blind” evolution but more reasonably has to be attributed to “design.”

Michael Behe’s concept of irreducible complexity (IC) (Behe 1996) has been critically discussed by experts in biology. The attitude of many professional biologists to Behe’s IC concept has found its most uncompromising expression in Kenneth Miller’s words: “. . . the notion of irreducible complexity is nonsense” (1999, p.150).

While critical analysis of IC by professional biologists seems to be sufficient to dismiss Behe’s alleged great discovery in biology, there is another aspect to IC which, to my mind, makes the very notion of “IC implies Intelligent Design (ID)” implausible.

A concept that’s identical in all but name to irreducible complexity was around for a long time before Behe. It was applied to the problems with the evolution of various anatomical structures, such as the mammalian eye (recall the many-times-answered question, “What good is half an eye?”) or snakes’ apparatus for venom injection (Marcell 1976).

An even more relevant and practically identical concept, “interlocking complexity,” had been already discussed from the standpoint of genetics nearly eighty years earlier (Muller 1918, 1939). Even the application of the concept of IC to the molecular assemblies within a biological cell (which is Behe’s playing field) was put into circulation some ten years before Behe (Cairns-Smith 1985). Unlike Behe and his supporters, these predecessors did not claim that irreducible complexity constituted a great discovery or implied Intelligent Design, so this prior version would hardly invoke Miller’s categorical rejection quoted above.

The critical discussion of Behe’s idea has mainly concentrated on three specific aspects of IC:

1. The very definition of IC has been a subject of much discussion. For example, Behe’s colleague, William Dembski (viewed by the ID advocates as their leading logician), admitted that Behe’s idea of IC was “neither exactly correct nor wrong” (Dembski 2002, 280).
   
2. The question of whether molecular systems offered by Behe as examples of IC are indeed IC has likewise been subject to critique. A number of biologists pointed out that systems such as bacterial cilia or blood-clotting cascades which, according to Behe, exemplify IC, are in fact reducible without losing their “basic function.” (See, for example, Miller 1999.)
   
3. Behe asserts that IC systems, exemplified by the protein assemblies in biological cells, cannot have evolved via a direct “Darwinian” path because such a path necessarily goes through a sequence of intermediate stages at which the system performs the same “basic” function. Since any system comprising fewer parts than the IC system in question is, by definition of IC, dysfunctional, it could not be an evolutionary precursor of an IC system, or so says Behe. Regarding the evolution of an IC system via an indirect evolutionary path, Behe admits that such a process is possible but, in his opinion, so highly improbable that it cannot be considered a feasible option.

The last point has been disputed by professional biologists. They suggest detailed scenarios showing how, for example, a bacterial flagellum could have evolved from evolutionary precursors with a sufficiently high likelihood (Matzke 2003, Ussery 2004, Musgrave 2004). The consensus of the vast majority of professional biologists seems to favor the views of Behe’s opponents. Except for vague protestations, wherein Behe and his supporters demand from their opponents highly detailed proofs of the factual occurrence of indirect evolutionary paths leading to IC systems, Behe seems to be unable to offer substantive counterarguments.

Even if the IC concept is valid, and even if many biological systems are indeed IC, this in itself does not logically lead to the design inference. I contend that IC in itself can more reasonably be construed as an argument against the design inference.

In an essay titled “Irreducible Contradiction” posted on the Internet in 1999 (Perakh 1999), I suggested critical comments to Behe’s Darwin’s Black Box. In the nearly six years since that essay appeared, Michael Behe has never uttered a word acknowledging the existence of my critical remarks. Nor has William Dembski, who has actively promoted Behe’s concept of irreducible complexity, ever mentioned those comments. Neither did anybody else from the Intelligent Design camp.

Recently, Dembski posted an article titled “Irreducible Complexity Revisited” (Dembski 2005) that has initiated some discussion (RBH 2005, Perakh 2005). And an op-ed article by Behe appeared recently in The New York Times, wherein Behe repeats the same much-critiqued notions without having changed his position or having accounted for a single point suggested by his critics. I think, therefore, it is worthwhile to revisit certain points that seem to need clarification regarding the IC concept and its alleged logical segueing into ID.

I’ll not discuss here Dembski’s recent modifications of the IC definition (addressed in Perakh 2005 and RBH 2005). Instead, I will refer to Behe’s original definition of IC, which, although suffering from certain deficiencies (as admitted by Dembski [2002]), does essentially reflect his principal idea.

The essence of Behe’s original IC concept is as follows:

A system is irreducibly complex if:

a)It consists of several parts.

b)The parts are “well-matched.” (Behe offered no definition of the notion of being “well-matched.”)

c)It performs a certain “basic” function (for example, it clots blood). d)It ceases to function if even a single part is missing.

Having discussed several examples of protein “machines” in biological cells that, according to Behe, are IC, Behe then asserts that the existence of IC systems in biological cells points to them being designed rather than having emerged as a result of evolution. I intend to show that Behe’s assertion contradicts logic.

Note that Behe’s concept of IC comprises two components: one is complexity and the other is irreducibility.

Behe expends a great deal of effort demonstrating how staggeringly complex the protein systems in a cell are. It is evident that for Behe, the complexity in question is part of his idea, which points to design as the alternative to evolution. According to Behe, biological systems must have been designed because they (A) are very complex and (B) cannot function unless all of their parts are present.

Regarding A, note that Behe has not provided a definition of complexity. Several such definitions have been suggested, though, by Dembski—whose various definitions of complexity are often incompatible with each other. There is among them a definition repeated by Dembski many times, which is in tune with Behe’s point A. According to that definition, complexity is equivalent to small probability (Dembski 1998). For example, Dembski asserts in his book that “probability measures are disguised complexity measures” (114). Variations of this assertion are scattered over Dembski’s books. In this view, the more complex a system, the less probable its spontaneous emergence as a result of chance. According to Behe and Dembski, the more complex a system, the more likely it was designed—this is the essence of point A in Behe’s concept.

Point B (irreducibility) in Behe’s concept asserts that an IC system loses its function if even a single part is missing. According to Behe, protein “machines” in a cell meet both requirements for being IC—they are very complex and they are irreducible. What if this assertion is true? Does it lead logically to the design inference? Behe’s answer is yes. However, I submit that that answer is illogical, and here is why (starting with complexity):

Contrary to Dembski’s persistent assertions, complexity is certainly not just disguised improbability. Examples to the contrary abound. Imagine a pile of stones. Each stone has some irregular shape that resulted from a series of chance events. Among these irregularly shaped stones, we find a perfectly rectangular brick. It has a simple shape that can be described by a simple equation containing only three numbers—width, length, and height. On the other hand, each of the irregularly shaped stones can be described only by a more complex program containing many numbers. However, the probability of a rectangular brick being produced as a result of chance is low; the brick can reasonably (with a high probability) be assumed to be a product of design. For irregularly shaped stones, the opposite is true—the probability of their having been created by chance is larger than the probability of their having been created by design. Here, the relationship between probability and complexity is the opposite of the one prescribed by Dembski’s definition (but compatible with the definition of Kolmogorov complexity [see the box to the right and, for example, Chaitin 2003]).

In the case of the stones and the brick, simplicity rather than complexity is a marker of design. This shows not only that Dembski’s definition of complexity fails for certain situations but also that, generally, a more reasonable statement is that simplicity points to design while complexity as such points to chance (more about this in Perakh 2004). If this is so, then the first part of Behe’s IC concept—complexity—is more reasonably construed as an indication of “blind” evolution rather than of design.

Turning to the second part of Behe’s IC—irreducibility—recall that Behe’s idea is that the loss of a single part of a protein “machine” makes it nonoperational. Therefore, says Behe, such a “machine” could not have evolved via a “Darwinian” evolutionary process, which requires the existence of functional precursors.

The simple fact is, though, that if an IC system has been designed, it is a case of bad design. If the loss of a single part destroys the system’s function, such a system is unreliable, and therefore, if it is designed, the designer is inept. When engineers design machines, bridges, skyscrapers, TV sets, or artificial kidneys, they always try to envision what can go wrong with their design and how to ensure that small defects do not result in a failure of their products: they build in certain redundancies so that in case some part of the construction fails, its function will not be completely lost but rather taken over by certain self-compensatory features.

IC systems, by definition, are highly vulnerable to accidental damage. Therefore, if IC systems are designed, they are poorly designed.

It must be stressed that in this case, we go beyond the problem of suboptimal design. When we deal with just suboptimal design, the ID advocates use various arguments that supposedly justify the reasons for a design being not optimal. For example, one such argument is that we simply don’t know anything about the designer’s reasons to behave as he does; hence, our notion is just an argument from ignorance. Perhaps what looks like suboptimal design from a limited human standpoint has good reasons, that are beyond our comprehension, to be as it is. Such an argument usually, albeit not always explicitly, presumes that suboptimality is a “side effect” rather than a deliberate goal of the designer.

Whether such arguments are convincing depends on the mindset of the person who hears them. For this discourse, however, such arguments are not really relevant. Indeed, Behe’s concept contains, as a crucial part, the assumption that the irreducibility of a biological system is a marker of design. Such an assumption obviously does not refer to a designer who has failed to provide an optimal solution or compromised in his design for some unknown reason. It is no longer about some “side effect” that the designer has simply failed to correct or has kept for unknown reasons that are extraneous to the design’s purpose.

Behe assumes that the very feature that makes the design bad indicates that the system has been designed. In other words, Behe’s concept entails that suboptimality not be viewed as just an unfortunate oversight by the designer nor as something that, albeit seemingly detrimental to the designed entity, has some reasons known only to the designer but unfathomable to us. No, in Behe’s conception, the very suboptimality is suggested as a marker of design: an IC system by definition is easily destroyed by damaging just a single part, so a system’s being IC means that its vulnerability is its ineliminable feature. Behe’s idea implies that the system is irreducibly complex (and hence suboptimal) because such was the goal of the designer. “The system is suboptimal, therefore, it is a product of design”—that is what Behe’s concept entails.

ID advocates are welcome to accuse me of offering a caricature of their idea, but it cannot be helped when an idea’s essence sounds like a parody; the idea that “IC implies ID” can most succinctly be rendered by a maxim: stupid, therefore designed.

If this is a satisfying logic, I don’t know what a lack of logic is.

Remember also that Behe’s design inference is based not on some positive evidence but rather on a negative assertion: IC systems could not have evolved via a “Darwinian” path. Since such a path is impossible, concludes Behe, the only remaining option is design.

This is an argument of the either-or type. I will not discuss here whether or not there are indeed only two mutually exclusive options. My point is different: if Behe infers design only because the direct evolutionary path, in his view, is impossible and an indirect evolutionary path is improbable, then to be consistent, he should use the same probabilistic criteria for judging whether or not it is reasonable to assume that the feature that makes design bad is a marker of design. How probable is it that the putative designer deliberately designs his products to be irreducibly complex if that means the product will be unreliable?

Dembski asserts that ID does not imply a smart designer (Dembski 2001). The designer can even be stupid, says Dembski. However, from many other utterances of ID advocates, including Dembski, it is clear that all such statements are just a smoke screen and, in fact, they believe that their “designer” is the God of the Bible. (See, for example, Dembski 1999, part 3, or Johnson 2000.) This designer is supposed to be omnipotent and omni-benevolent.

In fact, ID advocates want to have their cake and to eat it too. On the one hand, they concede that the putative designer may be stupid—this they say when trying to explain suboptimality of design. On the other hand, they speak about Christian values, cultural war, the Logos of John’s gospel, and the imminent triumph of ID over “materialistic” science. (Dembski 1999, part 3; Johnson 2000). It is not by accident that the leading young-Earth creationist, Henry Morris, who is more consistent in his frank biblical literalism, referred to Dembski’s contortions regarding the nature of the designer as “nonsense” (Morris 2005).

How probable is it that the very features that make a design bad are markers of design (as follows from Behe’s discourse)? It is hardly less improbable than the evolution of protein assemblies via indirect “Darwinian” paths.

If Behe infers design just because evolution of protein assemblies via indirect “Darwinian” paths looks improbable to him, design inference also has to be excluded because of the improbability of the putative designer’s deliberately incorporating in the protein assemblies the very features (like IC) that make the design bad.

The above discourse is, to my mind, sufficient to reject the design inference based on the notion that IC implies ID as logically untenable.

Kolmogorov Complexity This concept is part of the Algorithmic Theory of Information / Probability / Complexity (ATP) whose main creators were were Ray Solomonoff, Andrei Kolmogorov, and Gregory Chaitin. Complex systems are represented in ATP as strings of binary numbers. If the structure of such a string incorporates certain regularity, i.e., it is not fully random, it can be encoded by a computer program containing an instruction of how to generate the string in question, which program is shorter than the string itself. The Kolmogorov complexity of a system is a quantity that equals the size of the shortest program that encodes the system in question if the latter is represented by a string of digits. The longer the minimal possible “encoding” program for a system, the larger is the Kolmogorov complexity of that system. The more random a system, the larger its Kolmogorov complexity.

References

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Cairns-Smith, A.G. 1985. Seven Clues to the Origin of Life: A Scientific Detective Story. Cambridge: Cambridge University Press.

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Dembski, William A. 1998. The Design Inference. Cambridge: Cambridge University Press.

———. 1999. Intelligent Design. Downers Grove, Illinois: InterVarsity Press.

———. 2001. What Intelligent Design is not. In William A. Dembski and James M. Kushiner, eds. Signs of Intelligence: Understanding Intelligent Design. Grand Rapids, Michigan: Brazos Press.

———. 2002. No Free Lunch: Why Specified Complexity Cannot Be Purchased without Intelligence. Lanham, Maryland: Rowman & Littlefield.

———. 2005. Irreducible complexity revisited. Available at www.iscid.org Accessed on February 1, 2005.

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———. 1939. Reversibility in evolution considered from the standpoint of genetics. Biological Reviews of the Cambridge Philosophical Society. 14: 261–280.

Musgrave, Ian. 2004. Evolution of the bacterial flagellum. In Matt Young and Taner Edis, eds. Why Intelligent Design Fails: A Scientific Critique of the New Creationism. New Brunswick, New Jersey: Rutgers University Press.

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———. 2001a. Razumniy zamysel ili slepaya sluchainost? (Intelligent Design or blind chance?). Kontinent 107, 338–362.

———. 2001b. Razumniy zamysel ili slepaya sluchainost? Vremya Iskat 5, 30–50.

———. 2004. Unintelligent Design. Amherst, New York: Prometheus Books.

———. 2005. IC’s irreducible inconsistency revisited. In Talk Reason. Accessed on February 17, 2005.

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———. 2004. Darwin’s transparent box: The biochemical evidence for evolution. In Matt Young and Taner Edis, eds. Why Intelligent Design Fails: A Scientific Critique of the New Creationism. New Brunswick, New Jersey: Rutgers University Press.

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