The Evolution of a Protein Transport Machine: Fazale Rana on Irreducible Complexity

Last year marked the 20th anniversary of Darwin’s Black Box, Michael Behe’s groundbreaking work on intelligent design. This month, the documentary Revolutionary: Michael Behe and the Mystery of Molecular Machines was made available online. It’s remarkably well made and is certainly required viewing for anyone interested in this topic. Behe’s ideas have been knocking around for more than 20 years now, and much has changed in the time that has passed. Revolutionary presents Behe’s argument in an updated and fresh form. In light of this focus on Behe’s work on design, I thought it would be fitting to write an article on irreducible complexity.

For the past few months, biochemist and old-earth creationist Dr.Fazale Rana has been posting ‘Question of the Week’ videos on his Facebook page (the videos are also available on YouTube), where he discusses various science and faith questions. Rana primarily focuses on topics surrounding the biological origins debate. I have followed much of his work in the past, primarily because he comes at the design debate from a different perspective. Though he does accept intelligent design, he doesn’t always agree with the way most ID theorists advance their arguments. Interestingly, one of his primary disagreements is with Behe’s argument from irreducible complexity and in one of his more recent videos he discussed the question ‘Is irreducible complexity a good argument for design?’.(1)

In the video, Rana begins by helpfully laying out some basic definitions and talks about how Behe’s work influenced him in the past. He then goes into a discussion about some of the usual responses ID critics use against Behe’s argument (co-option etc.). I was half expecting Dr. Rana to stop there and come down on the side of the critics, but I was pleasantly surprised. Rana recognises that the co-option response (at least with respect to the Type Three Secretory System) is completely misguided, and, as Behe and others have to point out continuously, it doesn’t begin to appropriately tackle this nagging biological perplexity. However, Dr. Rana brings up another example. In talking about his past enthusiasm for the argument he notes:

But all that changed for me in 2009 when a team of researchers from Australia and the UK published a paper in the Proceedings of the National Academy of Sciences, where they were looking at the evolutionary origin of what’s called the TIM23 protein import machine. This is an irreducibly complex protein transporter that is embedded in the inner membrane of mitochondria, that plays a role in mitochondria biogenesis, transporting proteins from the cytoplasm of the cell into the lumen of the mitochondria.(2)

You can read the full paper that Rana is referring to here.

Rana goes into a little more detail on the irreducible complexity of the mitochondrial machine that is in question, claiming that we can show experimentally that if one protein is removed from this complex, it will cease to function. For him, by demonstrating a plausible co-option scenario for the Darwinian development of this system, this paper essentially disproved Behe’s argument from irreducible complexity, though he does qualify the conclusions of the paper:

This work could be interpreted from a design framework where you could just simply argue that the similarity between the TIM A and TIM B, and the proteins that are part of the TIM 23 complex, is essentially a reflection of the modular design of biochemical systems, where you have components that can be pieced together in a variety of different ways to produce a number of different types of functional systems. Or you could view them as part of an archetypal design that a creator used to build different types of machines.(3)

Despite this, he thinks that the paper shows that irreducible complexity is a claim that can no longer be made because the researchers demonstrated a plausible stepwise pathway. Though he recognises that they hadn’t fleshed out all the details, and that it doesn’t definitively prove that the system emerged in the way they argue, to him they did succeed in presenting a plausible pathway.

Concerns About the Paper

Before moving on to some of Rana’s other points , I want to take a look at his reservations about irreducible complexity. I happen to disagree with his conclusions here, sensibly tentative though they are. Though the paper is now quite old (published in 2009), I did read the paper at the time and the media hype surrounding it. Various science news outlets picked up on it (4), asserting with smug triumphalism, intelligent design’s ignominious demise (yet again).

The main thing I’d like to do in this article is to draw attention to the other side of the argument. As I quoted above, though Rana charitably notes that the results of the paper in question can, conceivably, be interpreted in a design framework, I felt he wasn’t doing justice to the way various ID proponents have responded to the paper. Shortly after the paper was published, there were several noteworthy comments from various ID proponents, which cast serious doubt over the success of the paper in question. Here I will breifly outline some of them.

The first response was from Behe himself, though unfortunately he was predictably refused a ‘letters to the editor’ response to the paper. He subsequently posted his thoughts at Evolution News. Behe essentially points out that ‘the claims made in the paper far surpassed the data, and distinctions between such basic ideas as “reducible” versus “irreducible” and “Darwinian” versus “non-Darwinian” were pretty much ignored.'(5) The first questions to consider is whether the system is irreducibly complex or reducibly complex. And whether anyone claimed the system is in fact irreducibly complex in the first place. The authors of the paper, Clements et al, clearly think they are demonstrating that a previously postulated irreducibly complex system, is actually reducible. Yay for Darwin. They write:

Molecular machines have been described as being of irreducible complexity. But could a single component of the machine function in the absence of the others to provide even inefficient protein transport? Although searches of genomes have not found a species of eukaryote in which the LivH/Tim 23 type channel is present in the absence of Tim44 and Tim14 subunits, equivalent studies on the TOM complex in the outer mitochondrial membrane have provided just such proof of principle.(6)

However, Behe responds:

The authors intend to show that Darwinian processes can account for a reducibly complex molecular machine. Yet, even if successful, that would not show that such processes could account for irreducibly complex machines, which Clements et al cite as the chief difficulty for Darwinism raised by intelligent design proponents like myself. Irreducibly complex molecular systems, such as the bacterial flagellum or intracellular transport system, plainly cannot sustain their primary function if a critical mechanical part is removed. (2-4) Like a mousetrap without a spring, they would be broken. Here the authors first postulate (they do not demonstrate) an amino acid transporter that fortuitously also transports proteins inefficiently. They subsequently attempt to show how the efficiency might be improved. A scenario for increasing the efficiency of a pre-existing, reducible function, however, says little about developing a novel, irreducible function.(7)

Clearly, contrary to the assertion of the authors, and by extension Dr Rana, Behe argues that the mitochondrial machine is not irreducibly complex. More importantly, as Casey Luskin points out in his response ‘No ID proponent has ever claimed that this particular system is irreducibly complex, making this a straw man attack.'(8) Of course, the system still could be one that meets the standard criteria of an IC system, even if Behe and others never focussed on it, showing that there are plausible Darwinian pathways to such systems. Rana claimed that it had been experimentally confirmed that if one part is removed, the system crashes, but he neglected to elaborate on the details. If we look at the paper itself, we find no detailed support of this claim. Behe mentions a few other points, which you can read in the response, but concludes that:

…if these are the best “refutations” that leading journals such as PNAS and Science can produce in more than a decade, then the concept of irreducible complexity is in very fine shape indeed.(9)

To my mind, Behe’s response was a little brief, yet he managed to cast a few serious doubts about the paper. Aside from Behe’s comments, a more thorough and devastating rebuttal came from Casey Luskin. As mentioned, Luskin argues that the paper is a straw man, due to the fact that ID theorists haven’t claimed this system is irreducibly complex (10). Even apart from that, there are more serious problems with the arguments in the paper. One of the main problems with it, is their flippant and vague understanding of the IC challenge. Luskin references the work of philosopher Angus Menuge, who sharpened the challenge by laying out several necessary steps that an argument against IC must make. They are reproduced below:

For a working flagellum to be built by exaptation, the five following conditions would all have to be met:

C1: Availability. Among the parts available for recruitment to form the flagellum, there would need to be ones capable of performing the highly specialized tasks of paddle, rotor, and motor, even though all of these items serve some other function or no function.

C2: Synchronization. The availability of these parts would have to be synchronized so that at some point, either individually or in combination, they are all available at the same time.

C3: Localization. The selected parts must all be made available at the same ‘construction site,’ perhaps not simultaneously but certainly at the time they are needed.

C4: Coordination. The parts must be coordinated in just the right way: even if all of the parts of a flagellum are available at the right time, it is clear that the majority of ways of assembling them will be non-functional or irrelevant.

C5: Interface compatibility. The parts must be mutually compatible, that is, ‘well-matched’ and capable of properly ‘interacting’: even if a paddle, rotor, and motor are put together in the right order, they also need to interface correctly. (11)

Like most critics of Behe’s argument, Clements et al, only attempt to address C1 and as one can clearly see, this barely even scratches the surface of the problem. Luskin goes into quite some detail on other problems with the paper, such as the suspiciously easy appeal to ‘preadaption’, often using teleological language. You can read Luskin’s full response here.

The final response I’ll point to is one by Brian Thomas at The Institute For Creation Research. Despite the fact that I disagree with his theological stance, in the article he makes some legitimate points. Thomas criticises the reasoning of the authors and their preadaptation hypothesis:

…the very label “preadaptation” counters the authors’ claims. The idea admits that not-yet-evolved “proto-machines” are not subject to Darwinian selection of adaptations. Preadaptation is observed nowhere; it is a devised assumption “in keeping with Darwinian evolution.” The fact that non-functioning “machine parts” are invisible to Darwinian selection is exactly what design theorists have observed.(12)

There were two other responses made to the paper which are worth reading. One was by Clive Hayden at Uncommon Descent here, and Cornelius Hunter at his blog here.

In my view, the responses to the paper I have outlined provide some strong counter arguments to the claims made in the paper, removing Fazale Rana’s reason for having doubts about irreducible complexity.

Is Irreducible Complexity a Negative Argument?

Coming back to Rana’s video, there were some other comments he made that I’ll briefly touch on. One of Rana’s criticisms of Behe’s argument is that it’s framed in purely negative terms, and so risks a kind of “god of the gaps” reasoning. He sees the standard design argument this way:

The way in which, I believe Michael Behe, framed the argument…is in negative terms. That is evolution cannot explain the emergence of irreducibly complex systems, therefore these systems must be the product of a designer.(13)

I was disappointed to hear this comment made by Rana because it’s one of the weakest objections and the most common misunderstanding about the formal structure of design theory. I’m not going to bother responding in great detail to this claim, since it has been thoroughly dealt with in other publications. A good response to the god of the gaps charge can be found here. In short, as atheist Bradley Monton argues:

…I maintain that Behe’s irreducible complexity argument is not a God-of-the-gaps argument at all. Behe is not saying that we don’t know (or can’t know) how irreducibly complex systems like the bacterial flagellum could plausibly arise naturalistically. Instead, Behe is giving positive reasons that the sequence of events that would have to happen for irreducibly complex systems like the bacterial flagellum to arise via an undesigned process is an improbable sequence, and hence the design hypothesis should be taken seriously.(14)

Behe himself points out that:

…irreducibly complex systems such as mousetraps and flagella serve both as negative arguments against gradualistic explanations like Darwin’s and as positive arguments for design. The negative argument is that such interactive systems resist explanation by the tiny steps that a Darwinian path would be expected to take [because direct routes are impossible and indirect routes unlikely]. The positive argument is that their parts appear arranged to serve a purpose, which is exactly how we detect design.(15)

Rana complains that Behe and others don’t appeal to the positive designed qualities of biological systems, such as the information bearing properties, optimisation, and analogs to designed objects by humans. I find this a bizarre claim to make coming from anyone who has done even a cursory reading of Behe’s work, because even back in 1996, Behe’s argument appealed to all the things Rana accuses it of lacking.

One further point to make about Rana’s ‘god of the gaps’ charge is that ID doesn’t necessarily posit a god. It posits intelligence. The most one could accuse ID of doing is arguing for an ‘intelligence of the gaps’. This is not a problem if those gaps are features that positively require an appeal to intelligence. Rana worries that by doing this, one is backing into a vulnerable position, where all it takes is for someone to demonstrate one plausible Darwinian pathway, and the argument lies in tatters. That may be the case for particular molecular systems, but on the other hand, all it takes for naturalistic accounts to be falsified, is one single demonstration of a true irreducibly complex system. Famously, Darwin himself recognised this.(16) Essentially, Rana makes a straw man argument against the standard challenge from irreducible complexity, alleging that it makes a purely negative claim against evolution, but ID proponents have been crystal clear about the positive aspect of their theory, and so I conclude that Rana’s concerns here are misplaced.


Rana goes on to argue very strongly for design and I agree with all his comments about the richness of the design hypothesis. It’s just that he believes he is making a different type of argument to Behe’s and the rest of the standard ID model, when in fact he is merely making the same claims as standard ID theory. I’ll end this article by saying that I genuinely appreciate Rana’s work and his powerful case for biological design, I just think his reasons for rejecting Behe’s irreducible complexity challenge and his problems with the formal structure of the argument are very weak.

The dispute over irreducible complexity continues. What I aimed to do in this article was to address some of Rana’s concerns, especially surrounding this particular 2009 paper. Much more work has and is being done (17), and Behe’s provocative ideas continue to be written about in the philosophical and scientific literature.(18) As I mentioned at the beginning of this article, to get a clear and contemporary presentation of Behe’s ideas, I highly recommend giving Revolutionary a watch.


  1. Reasons to Believe (2017) Question of the Week: Aug 21, 2017 Is irreducible complexity a good argument for design?. Available at:
  2. Ibid.
  3. Ibid.
  4. Websites such as Softpedia, Wiredand ID critic Jack Scanlan picked up on the publication.
  5. Michael Behe, Reducible Versus Irreducible Systems and Darwinian Versus Non-Darwinian Processes, Evolution News (2009), Available at:
  6. Clements A, et al. (2009) The reducible complexity of a mitochondrial molecular machine. Proc Natl Acad Sci USA doi/10.1073/pnas.0908264106.
  7. Behe, op cit.
  8. Casey Luskin, PNAS Authors Resort to Teleological Language in Failed Attempt to Explain Evolution of Irreducible Complexity, Evolution News (2009), Available at:
  9. Behe, op cit.
  10. In Luskin’s article Molecular Machines in the Cell, he lists various molecular systems, some of which have been argued by scientists to be irreducibly complex. However, Luskin puts TIM and TOM systems in the category of machines ‘that may be irreducibly complex, but have not been studied in enough detail yet by biochemists to make a conclusive argument.’
  11. Angus Menuge, Agents Under Fire: Materialism and the Rationality of Science, (Rowman & Littlefield, 2004), p.104-105.
  12. Brian Thomas, Preadaptation: A Blow to Irreducible Complexity?, Acts & Facts (2009), 38 (11): 15.
  13. Reasons to Believe, op cit.
  14. Bradley Monton, Seeking God in Science: An Atheist Defends Intelligent Design (Broadview Press, 2009), p.115.
  15. Michael Behe, Darwin’s Black Box: The Biochemical Challenge to Evolution (New York: Free Press (2006), p.263-264.
  16. Darwin 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.’ (Charles Darwin, Origin of Species, (1872), 6th edition, (New York University Press, 1988), p. 154.
  17. For some of the most up-to-date work on mitochondrial transport systems I recommend reading Origin and Evolutionary Alteration of the Mitochondrial Import System in Eukaryotic Lineages.
  18. Many critics believe ID to be a dead theory. However Behe’s ideas, 20 years on, are still being studied to this day: Digital Irreducible Complexity: A Survey of Irreducible Complexity in Computer Simulations, A New View of Irreducible Complexity, The Argument from Irreducible Complexity, Michael Behe’s Challenge — Past, Present, and Future.

Critic’s Corner: Elliott Sober

Elliott Sober is a highly respected professor of philosphy at University of Wisconsin-Madison. His main fields of interest are philosophy of science and philosophy of biology.

Sober has interacted quite a bit with ID theorists, and has published several interesting papers and books advancing his take on ID and evolution. To my mind he is a very thoughtful critic, whose responses to ID present quite a strong challenge. That being said, I think design advocates have also done a good job at replying to Sober’s criticisms. Sober’s output is pretty vast so in this post I have only link to his published works related to evolution and ID:

Books by Sober


(Sober’s papers directly related to ID can be found at the bottom of his page)

Selected Papers

Intelligent Design, Irreducible Complexity, and Minds-A Reply to John Beaudoin

Popper’s Shifting Appraisal of Evolutionary Theory-(with Mehmet Elgin


Lectures and Interviews

Youtube Playlist

(Podcast Episodes)

Think Atheist: Episode 43

Elliott Sober on Darwin’s Theory

Darwin or Design with Jason Rennie




William Dembski responds to Sober in:

-No Free Lunch: Why Specified Complexity Cannot Be Purchased Without Intelligence (Roman & Littlefield, 2002) in chapter 2: Another Way to Detect Design?

-The Design Revolution: Answering the Toughest Questions About Intelligent Design (Inter-Varsity Press, 2004) at various points.

Bradley Monton Responds to Sober on p.42-46 of Seeking God in Science: An Atheist Defends Intelligent Design (Broadview Press, 2009)

David Reuben Stone responds to Sober in The Loftus Delusion: Why Atheism Fails and Messianic Israelism Prevails (2010) in chapter one ‘Intelligent Design and Modus Tollens’.


(Papers & Articles)

A Critique of the Rejection of Intelligent Design as a Scientific Hypothesis by Elliott Sober from His Book Evidence and EvolutionJames LeMaster

Testability of Intelligent Design Argument in the Perspective of Quantitative Methodology-Chong Ho Yu

Firing Squads and Fine Tuning: Sober on the Design Argument-Jonathan Weisberg

Sober on Intelligent Design and the Intelligent Designer-John Beaudoin 

Another Way to Detect Design? A Preliminary Reply-William Dembski

Another Way to Detect Design? Lecture Notes-William Dembski

Elliott Sober’s Independent Evidence Requirement for Design– William Dembski

If Not Natural Selection?(A review of Steven Hecht Orzack and Elliott Sober, eds., Adaptationism and Optimality)William A. Dembski

Sober’s “Progenic Fallacy”-William Dembski

Elliott Sober, Alvin Plantinga and the Design Argument-Graham Veale & David Glass

A Critique of Elliott Sober’s Goals and Abilities Objection to the Design Argument-Daniel Lim

On the Logic of Evolution and the Vanity of Scientism-Thomas E. Elliott

Observation Selection Effects and the Fine-Tuning Argument for Cosmic Design
Jonathan Lipps

Epistemology, Miracles, and the God Who Speaks-Lydia McGrew

Historical Inquiry-Lydia McGrew

Testability, Likelihoods, and Design -Lydia McGrew

Elliot Sober: Just Don’t Call the Designer “God” (Part 1/Part 2)-Sean D. Pitman

Empiricism and Intelligent Design I: Three Empiricist Challenges-Sebastian Lutz

On Likelihoodism and Intelligent Design-Sebastian Lutz

On Elliott Sober’s Challenge for Biological Design Arguments-Troy Nunley

Fossils, Fishnets, Fine­tuning…and Flaws in Sober’s Defense of Common Ancestry-Troy Nunley

Fishnets, Firing Squads, and Fine-Tuning (Again): How Likelihood Arguments Undermine Elliot Sober’s Weak Anthropic Principles-Troy Nunley

Where the Design Argument Goes Wrong: Auxiliary Assumptions and UnificationMaarten Boudry & Bert Leuridan

Thomas Nagel vs. His Critics: Has Neo-Darwinian Evolution Failed, and Can Teleological Naturalism Take its Place?-Vincent Torley 

Sober and Irreducible Complexity-Dave S

Deconstructing Sober-Dave S

“No Designer Worth His Salt”? At the University of Chicago, Gregory Radick Critiques the Theology of Darwinism

Sober Analysis-Logan Gage

What is Wrong with Sober’s Attack on ID? (Part 1/Part 2/Part 3/Part 4)-Casey Luskin

Cornelius Hunter’s Blogposts on Sober

Getting Sober About Survival (Part 1/Part 2/Part 3)-Michael Sudduth

Probabilistic Modus Tollens and the Design Argument-Alan Rhoda

Nagel and his critics, Part III-Edward Feser

The “Achilles’ Heel” of the Design Argument?

Sober Continued

Sober, Arbuthnot and Fisher

Elliott Sober: Confusing Religion and Philosophy-Jeremy Pierce

Sober on ID being Inherently Supernatural-Bradley Monton

Quote of the Month: Cornelius Hunter on the Unfalsifiability of Evolution

This month’s quote is by ID proponent Cornelius Hunter. Hunter is the author at the blog Darwin’s God. I used this quote myself in my article ‘Jeffrey Koperski on Good and Bad Ways to Attack Intelligent design (Part 2): The ‘Good’ Ways’, and I have seen it used in ID literature quote often. This quote is taken from Arsenic-Based Biochemistry: Turning Poison Into Wine.

Being an evolutionist means there is no bad news. If new species appear abruptly in the fossil record, that just means evolution operates in spurts. If species then persist for eons with little modification, that just means evolution takes long breaks. If clever mechanisms are discovered in biology, that just means evolution is smarter than we imagined. If strikingly similar designs are found in distant species, that just means evolution repeats itself. If significant differences are found in allied species, that just means evolution sometimes introduces new designs rapidly. If no likely mechanism can be found for the large-scale change evolution requires, that just means evolution is mysterious. If adaptation responds to environmental signals, that just means evolution has more foresight than was thought. If major predictions of evolution are found to be false, that just means evolution is more complex than we thought.

I think that at face value, Hunter’s point is undeniably true. It seems that there is little that can be discovered that would overturn evolution. That’s not to say that evolution is entirely unfalsifiable, it just demonstrates that it’s extremely difficult to falsify. Perhaps one might respond by saying that the erratic data we often encounter is the result of many different factors and mechanisms that nature utilises. Nonetheless, this response seems very ad hoc and contrived to me.

I don’t think a theory necessarily need be falsifiable to be considered scientific or true. Some theories are more difficult to falsify than others (evolution being one of them). The way I see it, testability and verifiability are more essential. Having said that, a theory that is falsifiable and verifiable is stronger than one that is merely the latter. 

What do you think?