By Carl Lee
One branch of arguments for the existence of God is that of Teleological Arguments, which posit that only the existence of an Intelligent Designer can explain certain features of the natural world. This essay examines a particular argument under this category – the biological version of the teleological argument (BTA) advanced by biochemist Michael J. Behe. Behe’s argument fails on the basis that its claims are not well-substantiated with empirical evidence and instead border on being mere hypotheses. I will first explain Behe’s BTA and define key terms, such as irreducible complexity, and evaluate the examples he raises to support them. In the second section, I provide two objections to Behe’s argument supported by the work of other academics, more notably Russell F. Doolittle and Kenneth R. Miller. Thereafter, in the third section, I attempt at offering a response to both objections on Behe’s behalf. In the fourth section, I conclude that his version of the argument on Intelligent Design does not succeed nor support the Abrahamic God’s existence.
Behe argues that the origin of life can only be explained by an Intelligent Designer on the basis that certain molecular systems appear to be intentionally designed. Their complexities cannot be explained by any other theory, such as Darwin’s theory of evolution. To explicate his position further, let us examine his argument, which is as follows:
1. Irreducible complexity exists in living biological systems.
2. The fact that irreducible complexity in living biological systems exists is extremely improbable, if an Intelligent Designer did not create life.
3. The fact that irreducible complexity exists in living biological systems is probable, if there were an Intelligent Designer that created life.
4. Therefore, probably, irreducibly complex biological systems were created by an Intelligent Designer.
According to Behe, a system of irreducible complexity (IC) is “composed of several well-matched, 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”. It cannot be reduced to something simpler because its mechanism is such that requires its complexity of parts to function.
Behe raises two molecular examples, the cilium and bacterial flagellum, to support the idea of IC. I will focus on the latter example. A flagellum (plural: flagella) is a cellular organelle that acts as a propeller to move the cell forward through a liquid medium. Behe takes extra care in explaining the several components that constitute a flagellum, such as flagellin, hook protein, drive shaft, and the rotary motor… and suddenly concludes that because “the flagellum requires a number of parts to work, it is IC, and its origin presents quite a stumbling block to Darwinian theory.”
We must realise that whenever Behe determines that a mechanism is IC, he is making his case towards the existence of an intelligent designer, as we see in his second and third premises. His argument rests heavily on the concept of IC, but I am sceptical as to whether it is sound. In order to understand why Behe devotes the idea of IC to an intelligent designer, we must first understand what he is contesting – that is, Darwin’s naturalistic account of evolution by natural selection.
“Evolution” refers to descent with modification and that organisms change over time.And “natural selection” refers to a process whereby living organisms that possess more beneficial traits – ones that can aid in their survival – generate more offspring than those that do not.Darwin posited that all of life has the same origin and came from one common ancestor. We see diversity of living beings now only because its descendants had undergone (and continue to undergo) slight variations which accumulate, causing the eventual divergence into different species – plants, animals, humans – according to their different survival needs in the environment they live in. This phenomenon of variation is what we now know as genetic mutations that occur in an organism’s genetic code. Due to these mutations, organisms look and function differently from their very first original ancestor. Additionally, their adeptness to cope with environmental adversities increases their chances to survive as well.
Behe does not believe that Darwin’s theory can explain IC and is often found to challenge Darwin’s stance, “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.” In Behe’s view, IC biological systems are “resistant to being produced in the gradual, step-by-step manner that Darwin envisioned”, and therefore takes IC as a notion capable of refuting Darwin’s natural selection entirely. He thinks that examples such as the flagellum support his theory of IC because their complicated structures could not have arisen by degrees, nor evolved from something simpler. More importantly, Behe argues that if we remove one of its components, ie. drive shaft, the flagellum would cease to function completely.
I disagree with Behe’s postulation of an IC system. His claim is not only an aggressive one against Darwinian evolution, but also one against molecular biology. According to Angus Menuge, a so-called IC biological system that loses one of its components might not end up ceasing to function at all. We shall examine this in terms of Behe’s example of the flagellum. In an article by Kenneth R. Miller, he argues that Behe’s concept of IC is false, showing that the flagellum may have evolved from simpler structures to what it is today. No doubt the loss of one or more of its component parts results in the flagellum being unable to act as a propeller, but it will still be able to perform another function. For example, a flagellum without the proteins required for its motility would be reduced to a Type Three Secretion System (thence referred to as TTSS).
The basal protein structure of the TTSS is homologous to that of the flagellum and its function, as its name suggests, is to secrete bacterial toxins into the cell(s) which the bacteria has attached to. Its structure looks and functions like an injection syringe, and the toxins injected by the TTSS are so harmful that it may lead to the organism with the infected cells to be plagued with illness. Depending on the strain of bacteria, the toxins released by TTSS may even lead to the organism’s death.
More importantly, the structural similarities show that the flagellum is an evolved structure of the TTSS. In fact, research shows that both had evolved from a common ancestor. Put simply, a flagellum, originally a TTSS, had accumulated gradual genetic mutations for it to develop into a flagellum. With this example, Miller asserts that “the existence of the TTSS in a wide variety of bacteria demonstrates that a small portion of the ‘irreducibly complex’ flagellum can indeed carry out an important biological function”. Thus Behe’s main supporting example of the flagellum cannot be considered an IC as it still has an important function when some of its constituent parts are removed. Contrarily, Darwin’s theory is able to explain this gradual change and might further explain why certain bacteria cells have these flagellar structures (perhaps their environment requires their motility, but that is another study altogether).
In explaining the improbability of IC in the flagellum, I have posited that complex structures may have arisen through gradual, intermittent changes to their genetic codes. In this section, I will further argue against Behe’s second premise on the basis that his argument fails to be empirically supported and even denies advancing biochemical research. First, however, let us examine the example he uses to support this premise.
Behe writes that “the blood clotting cascade (BCC) is an example of an IC system” because “in the clotting cascade, one component acts on another, which acts on the next, and so forth… [and] if a component is removed, the pathway is either immediately turned on or permanently turned off”. In another of his works, he argues that for IC to develop gradually it “would have to arise as an integrated unit, in one fell swoop, for natural selection to have anything to act on.” He then concludes that the BCC is an IC that can only be explained by an Intelligent Designer.
But prevailing scientific research shows otherwise. An American biochemist, Russell F. Doolittle (whose work centres on the evolution of proteins), was also aware of Behe’s book Darwin’s Black Box, and had offered a response in 1997 by citing an important research paper by Bugge et al. which showed that when plasminogen-lacking mice and fibrinogen-lacking mice bred, they produced mice which were without any complications associated with the lack of the above two proteins. Both fibrinogen and plasminogen are important proteins in the BCC, and their absence should have served as supporting evidence to Behe’s claim that removing one or more components results in the BCC to fail. But Doolittle had asserted that the progeny of the mice lacking in fibrinogen and plasminogen were normal based on the results of the Bugge’s research. He wrote, “Contrary to claims about irreducible complexity, the entire ensemble of proteins is not needed. Music and harmony can arise from a smaller orchestra.” This throws Behe’s IC into question once again as it shows that the BCC can still work without needing all its proteins. It will not cease functioning.
Furthermore, it is not true that the BCC arose “in one fell swoop”. Doolittle, in a more recent paper, shows through various experiments conducted on different species that the BCC is much more sophisticated in mammals than other species such as fish, whose BCCs are more primitive. He hypothesizes that this is due to different environmental factors and biological needs, causing certain gene factors to mutate and diverge from the original “template” as part of a biological response to cope. If this is true, as his research suggests it is, then the BCC would be further evidence to support the reliability of the Darwinian account of gradual evolution, and a stumbling block to Behe’s argument for intelligent design.
With respect to the first objection, Behe argues that removing parts of the flagellum would no longer enable it to properly work as a flagellum, and that Miller “was equivocating, switching the focus from the function of the system to act as a rotary propulsion machine to the ability of a subset of the system to transport proteins across a membrane”. He reasserts that removing a part of the flagellum’s molecular structure, although enables it to take on another function, will cause it to no longer propel.
Strangely, this reasoning is exactly what I am supporting. I am trying to prove that a so-called IC system can still work even though it loses some of its components. Miller was not fallaciously equivocating. He was merely examining the structure of the flagella according to Behe’s definition of IC, where “ removal of any one of the parts causes the system to effectively cease functioning”, but not IC as a property that results in only the loss of a specific function, such as the flagellum’s ability to propel through liquid medium.More strangely, Behe rebuts —“taking away the parts of the flagellum certainly destroys the ability of the system to act as a rotary propulsion machine, as I have argued.”. But this is not quite congruent to the definition of IC which he had argued for in 1996’s Darwin’s Black Box. It seems as if Behe is compounding a specificity to his definition which was not originally there in order to protect his stance. This is a problem especially since his entire argument rests on the concept of IC. If the definition is unclear, then his argument is insufficient in proving the existence of an Intelligent Designer.
For the sake of argument let us adopt a charitable view and assume that there is indeed an IC system. But what could Behe deny about the objection regarding the second premise?
Many things, apparently. First, he attacks Doolittle’s interpretation of Bugge et al.’s results, saying that “Doolittle misread the paper.” He goes on to identify the symptoms of the plasminogen and fibrinogen-lacking progeny, such as that of haemorrhage and death in pregnancy, and concludes that “the double-knockout mice do not merely have a less sophisticated but still functional clotting system. They have no functional clotting system at all.” Behe may be right about the problems encountered by the double-knockout mice, but he conveniently omits research results which show that the double-knockout mice have a higher chance of survival and a lower risk of morbidity than the single-knockout mice. In fact, “the survival characteristics of Plg-/- and Fib-/- mice were comparable with those of Fib-/- and control (normal) mice, with only 2 (9%) of the cohort of 23 mice becoming terminally ill within a 320 day observation period”. Now even if we grant that the BCC is an IC, how can Behe explain the loss of two important proteins having a less disastrous effect than the loss of one?
Both Doolittle and Bugge were not saying that the results show a complete eradication of problems associated with an incomplete BCC. Rather, they were trying to show that the offspring of organisms with incomplete BCCs are able to cope better than their parents even though they have incomplete BCCs themselves. Perhaps, given more time, the double-knockout mice will produce progeny with even more sophisticated BCCs than their own. More importantly, the results show that taking away plasminogen and fibrinogen does not make the BCC an IC, because they might only be beneficial, and not necessary, to an organism’s survival. If the BCC were truly an IC according to Behe’s (original) definition, then the double-knockout mice should not have a higher survival rate at all. They should not even have survived.
Furthermore, Behe thinks that the BCC could have arisen in “one fell swoop”. But Doolittle has shown that it is a product of step-by-step evolution and not the creation of an Intelligent Designer. In stark contrast, all Behe has done is to deny the empirical results obtained from the work of other scientific researchers, eventually concluding that an Intelligent Designer must exist to explain the source of IC. But he has not scientifically proven the existence of an Intelligent Designer with a similar rigor undertaken by his fellow biochemists who have managed to refute the term IC. My views are aligned with that of Philip Kitcher, who argues that Behe’s argument is not justified because he has not provided sufficient empirical evidence for an IC or an Intelligent Designer. Behe therefore does not provide a satisfactory answer against Doolittle’s research results that corroborate with Darwinian evolution.
Behe had set out to “break down” Darwinian theory, but his own theories of IC and Intelligent Design have not established a firm foothold for his argument, which has unravelled into an incoherence matched by his responses to other prevailing scientific research work. Not only does Behe fails to prove the existence of an Intelligent Designer in his BTA, but he also fails in trying to make scientific research consistent with his own argument. He has not succeeded in proving the existence of an Intelligent Designer, and thus nor the existence of the Abrahamic God.
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