By: Michael J. Behe
Discovery Institute
July 31, 2000


I. Is Intelligent Design Falsifiable?

Some reviewers of Darwins Black Box (Behe 1996) have raised philosophical
objections to intelligent design. I will discuss several of these over the next
few sections, beginning with the question of falsifiability. To decide whether,
or by what evidence, it is falsifiable, one first has to be sure what is meant
by intelligent design. By that phrase someone might mean that the laws of
nature themselves are designed to produce life and the complex systems that
undergird it. In fact, something like that position has been taken by the
physicist Paul Davies and the geneticist Michael Denton in their recent books,
respectively, The Fifth Miracle: The Search for the Origin and Meaning of Life
(Davies 1999) and Natures Destiny: How the Laws of Biology Reveal Purpose in
the Universe. (Denton 1998) That stance also seems to pass muster with the
National Academy of Sciences:

Many religious persons, including many scientists, hold that God created the
universe and the various processes driving physical and biological evolution and
that these processes then resulted in the creation of galaxies, our solar
system, and life on Earth. This belief, which sometimes is termed theistic
evolution, is not in disagreement with scientific explanations of evolution.
Indeed, it reflects the remarkable and inspiring character of the physical
universe revealed by [science]. (National Academy of Sciences 1999, 7)

In such a view even if we observe new complex systems being produced by
selection pressure in the wild or in the laboratory, design would not be
falsified because it is considered to be built into natural laws. Without
commenting on the merits of the position, let me just say that that is not the
meaning I assign to the phrase. By intelligent design I mean to imply design
beyond the laws of nature. That is, taking the laws of nature as given, are
their other reasons for concluding that life and its component systems have been
intentionally arranged? In my book, and in this essay, whenever I refer to
intelligent design (ID) I mean this stronger sense of design-beyond-laws.
Virtually all academic critics of my book have taken the phrase in the strong
sense I meant it.

In the strong sense ID is no longer approved by the National Academy, for a
specific reason: [I]ntelligent design . . . [is] not science because [it is]
not testable by the methods of science. (National Academy of Sciences 1999, 25)
In his review of Darwins Black Box for Nature, Jerry Coyne, professor of
evolutionary biology at the University of Chicago, explains why he also thinks
intelligent design is unfalsifiable.

If one accepts Behes idea that both evolution and creation can operate
together, and that the Designers goals are unfathomable, then one confronts an
airtight theory that cant be proved wrong. I can imagine evidence that would
falsify evolution (a hominid fossil in the Precambrian would do nicely), but
none that could falsify Behes composite theory. Even if, after immense effort,
we are able to understand the evolution of a complex biochemical pathway, Behe
could simply claim that evidence for design resides in the other unexplained
pathways. Because we will never explain everything, there will always be
evidence for design. This regressive ad hoc creationism may seem clever, but it
is certainly not science. (Coyne 1996)

Coynes conclusion that design is unfalsifiable, however, seems to be at odds
with the arguments of other reviewers of my book. Clearly, Russell Doolittle
(Doolittle 1997), Kenneth Miller (Miller 1999), and others have advanced
scientific arguments aimed at falsifying ID. (See my articles on blood clotting
and the acid test on this web site.) If the results with knock-out mice (Bugge
et al. 1996) had been as Doolittle first thought, or if Barry Halls work (Hall
1999) had indeed shown what Miller implied, then they correctly believed my
claims about irreducible complexity would have suffered quite a blow. And since
my claim for intelligent design requires that no unintelligent process be
sufficient to produce such irreducibly complex systems, then the plausibility of
ID would suffer enormously. Other scientists, including those on the National
Academy of Sciences Steering Committee on Science and Creationism, in
commenting on my book have also pointed to physical evidence (such as the
similar structures of hemoglobin and myoglobin) which they think shows that
irreducibly complex biochemical systems can be produced by natural selection:
However, structures and processes that are claimed to be irreducibly complex
typically are not on closer inspection. (National Academy of Sciences 1999, p.
22)

Now, one cant have it both ways. One cant say both that ID is unfalsifiable
(or untestable) and that there is evidence against it. Either it is
unfalsifiable and floats serenely beyond experimental reproach, or it can be
criticized on the basis of our observations and is therefore testable. The fact
that critical reviewers advance scientific arguments against ID (whether
successfully or not) shows that intelligent design is indeed falsifiable.

In fact, my argument for intelligent design is open to direct experimental
rebuttal. Here is a thought experiment that makes the point clear. In Darwins
Black Box (Behe 1996) I claimed that the bacterial flagellum was irreducibly
complex and so required deliberate intelligent design. The flip side of this
claim is that the flagellum cant be produced by natural selection acting on
random mutation, or any other unintelligent process. To falsify such a claim, a
scientist could go into the laboratory, place a bacterial species lacking a
flagellum under some selective pressure (for mobility, say), grow it for ten
thousand generations, and see if a flagellum--or any equally complex system--was
produced. If that happened, my claims would be neatly disproven.(1)

How about Professor Coynes concern that, if one system were shown to be the
result of natural selection, proponents of ID could just claim that some other
system was designed? I think the objection has little force. If natural
selection were shown to be capable of producing a system of a certain degree of
complexity, then the assumption would be that it could produce any other system
of an equal or lesser degree of complexity. If Coyne demonstrated that the
flagellum (which requires approximately forty gene products) could be produced
by selection, I would be rather foolish to then assert that the blood clotting
system (which consists of about twenty proteins) required intelligent design.

Lets turn the tables and ask, how could one falsify the claim that, say, the
bacterial flagellum was produced by Darwinian processes? (Professor Coynes
remarks about a Precambrian fossil hominid are irrelevant since I dispute the
mechanism of natural selection, not common descent. I would no more expect to
find a fossil hominid out of sequence than he would.) If a scientist went into
the laboratory and grew a flagellum-less bacterial species under selective
pressure for many generations and nothing much happened, would Darwinists be
convinced that natural selection is incapable of producing a flagellum? I doubt
it. It could always be claimed that the selective pressure wasnt the right one,
or that we started with the wrong bacterial species, and so on. Even if the
experiment were repeated many times under different conditions and always gave a
negative result, I suspect many Darwinists would not conclude that the claim of
its Darwinian evolution was falsified. Of complex biochemical systems Coyne
himself writes we may forever be unable to envisage the first proto-pathways.
It is not valid, however, to assume that, because one man cannot imagine such
pathways, they could not have existed. (Coyne 1996) If a person accepts
Darwinian paths which are not only unseen, but which we may be forever unable to
envisage, then it is effectively impossible to make him think he is wrong.

Kenneth Miller announced an acid test for the ability of natural selection to
produce irreducible complexity. He then decided that the test was passed, and
unhesitatingly proclaimed intelligent design falsified (Behe is wrong; Miller
1999, 147). But if, as it certainly seems to me, E. coli actually fails the
lactose-system acid test, would Miller consider Darwinism to be falsified?
Almost certainly not. He would surely say that the experiment started with the
wrong bacterial species, used the wrong selective pressure, and so on. So it
turns out that his acid test was not a test of Darwinism; it tested only
intelligent design. The same one-way testing was employed by Russell Doolittle.
He pointed to the results of Bugge et al. (1996) to argue against intelligent
design. But when the results turned out to be the opposite of what he had
originally thought, Professor Doolittle did not abandon Darwinism.

It seems then, perhaps counterintuitively to some, that intelligent design is
quite susceptible to falsification, at least on the points under discussion.
Darwinism, on the other hand, seems quite impervious to falsification. The
reason for that can be seen when we examine the basic claims of the two ideas
with regard to a particular biochemical system like, say, the bacterial
flagellum. The claim of intelligent design is that No unintelligent process
could produce this system. The claim of Darwinism is that Some unintelligent
process (involving natural selection and random mutation) could produce this
system. To falsify the first claim, one need only show that at least one
unintelligent process could produce the system. To falsify the second claim, one
would have to show the system could not have been formed by any of a potentially
infinite number of possible unintelligent processes, which is effectively
impossible to do.

I think Professor Coyne and the National Academy of Sciences have it exactly
backwards. A strong point of intelligent design is its vulnerability to
falsification. (Indeed, some of my religious critics dislike intelligent design
theory precisely because they worry that it will be falsified, and thus theology
will appear to suffer another blow from science. See, for example, (Flietstra
1998).) A weak point of Darwinian theory is its resistance to falsification.
What experimental evidence could possibly be found that would falsify the
contention that complex molecular machines evolved by a Darwinian mechanism?

II. What Is Irreducible Complexity and What Does It Signify?

Some reviewers have criticized the concept of irreducible complexity. In Boston
Review University of Rochester evolutionary biologist H. Allen Orr agrees that
many biological systems are irreducibly complex, but argues that Darwinian
evolution can, at least in theory, directly account for them. However, as I will
show, his argument depends on changing the definition of irreducible complexity,
which obscures the difficulty.

In his review Orr initially seems to clearly understand what I meant by
irreducible complexity (quoted earlier). Of the example I used in Darwins
Black Box he writes: A mousetrap has a clear function (crushing mice) and is
made of several parts (a platform, a spring, a bar that does the crushing). If
any of these parts is removed, the trap doesnt work. Hence its irreducibly
complex. (Orr 1996) So far, so good. Nonetheless, later in the review he seems
to lose hold of the concept:

An irreducibly complex system can be built gradually by adding parts that, while
initially just advantageous, become--because of later changes--essential. The
logic is very simple. Some part (A) initially does some job (and not very well,
perhaps). Another part (B) later gets added because it helps A. This new part
isnt essential, it merely improves things. But later on, A (or something else)
may change in such a way that B now becomes indispensable. This process
continues as further parts get folded into the system. And at the end of the
day, many parts may all be required. (Orr 1996)

Now, how can we square this paragraph with his initial agreement that if any
part of a mousetrap is removed, it doesnt work? Thinking of the mousetrap
example, what would correspond to Some part (A) that initially does some
job? In fact, the whole point of the mousetrap example was to show that there
is no part (A) that will initially do the job. There is no part (B) that
helps gradually improve part (A). A gradual addition of parts is not possible
for the mousetrap example (or at least it is very far from obvious that it is
possible). Orr later gives a biological example of what he has in mind.

The transformation of air bladders into lungs that allowed animals to breathe
atmospheric oxygen was initially just advantageous: such beasts could explore
open niches--like dry land--that were unavailable to their lung-less peers. But
as evolution built on this adaptation (modifying limbs for walking, for
instance), we grew thoroughly terrestrial and lungs, consequently, are no longer
luxuries--they are essential. The punch-line is, I think, obvious: although this
process is thoroughly Darwinian, we are often left with a system that is
irreducibly complex. (Orr 1996)

In Orrs example, however, what is the irreducibly complex system? Is it the
swim bladder? The lung? The whole organism? What is the function of the system?
Is it swimming, breathing, living, or something else? If we assume he
meant that the irreducibly system is, say, the lung, can the lung be considered
a single system, as my definition requires (Behe 1996, p. 39)? What are the
parts of the lung without which it will stop working, like a mousetrap without a
spring? What is part (A) and what is part (B)? None of these things is clear
at all--certainly not as clear as the parts and function of a mousetrap.

Let me preface my remaining remarks on this subject by acknowledging that it is
often notoriously difficult to rigorously define a concept, as exemplified by
the problems encountered in trying to define science, life, or species.
Furthermore, I am no philosopher; my end purpose is not to come up with a string
of words that completely defines the phrase irreducible complexity. Rather, my
purpose is to focus attention on a class of biochemical systems that pose a
particular challenge to Darwinian evolution. The examples I gave in my book--a
mousetrap, cilium, clotting cascade, and so on--clearly show the necessity for
some systems of having a number of discrete parts working together on a single
function. The examples, I think, better get across the concept of irreducible
complexity than does the definition I offered (Behe 1996, 39), although I think
the definition I gave does an adequate job.

With those comments in mind, it can be seen that Orr simply switched concepts in
mid-review, as shown by his conflicting remarks quoted above. He jumped from my
idea of irreducible complexity to a hazy concept that can perhaps be paraphrased
as, if you remove this part, the organism will eventually die. Im happy to
agree for purposes of discussion that a class of biological phenomena exists
which are required for life and which can be changed gradually by natural
selection, perhaps even including the swim bladder/lungs Orr mentions (although
it is not nearly so obvious as he assumes it to be). Its just that they are not
the same types of things as, nor do they somehow obviate the problem of,
irreducibly complex systems like mousetraps and cilia. If they were, then Orr
could have explained them away as easily as he does swim bladders and lungs.
(After all, lung tissue contains cilia plus many, many other components; Orr
should thus find it easier to explain cilia alone, rather than
cilia-plus-other-components.) Implicitly changing the definition of irreducible
complexity, as Orr did, does not tell us how the blood clotting cascade or the
bacterial flagellum could have been produced. On the contrary, it distracts our
attention from those features of the systems that make them recalcitrant to
Darwinian explanation.

Other scientific reviewers have made arguments similar to Orrs which depend on
implied definitions of irreducible complexity different from what I used.
Writing in the Wall Street Journal Paul Gross compares biochemical systems to
cities, where features can be added over time. (Gross 1996) But the analogy is
poorly chosen because no city completely stops working when a part is removed,
as does a mousetrap or cilium. In Boston Review Douglas Futuyma writes:

In mammals, successive duplications of the beta gene gave rise to the gamma and
epsilon chains, which characterize the hemoglobin of the fetus and early embryo
respectively, and enhance uptake of oxygen from the mother. Thus a succession of
gene duplications, widely spaced through evolutionary time, has led to the
irreducibly complex system of respiratory proteins in mammals. (Futuyma 1997)

But the several hemoglobins that Futuyma calls the irreducibly complex system
of respiratory proteins in fact do not constitute an irreducibly complex system
in my sense of the term. They do not interact with each other, as do the parts
of a mousetrap or clotting cascade. They go their separate ways, and for the
most part arent even present at the same time in the organism. Like Allen Orr,
Futuyma implicitly switches the meaning of irreducibly complex. Unfortunately,
that does not solve the problem I pointed out, but only obscures it. (As an
aside, it is difficult to understand what Futuyma intends by the quotation marks
around the phrase irreducibly complex. He cant be quoting me; I never used the
term in connection with hemoglobin--quite the opposite. He may intend them to be
taken as scare quotes, to warn the reader to take the phrase with a grain of
salt. But since he is the one who decided to use the term in conjunction with
hemoglobins and then to argue against it, the effect is that of setting up a
straw man.)

A different question about irreducible complexity is asked by David Ussery on
his web site. He notes that, whereas a bacterial flagellum in E. coli requires
about 40 different proteins, in H. pylori only 33 are required. Since fewer
proteins are required, how can the flagellum be irreducibly complex? Two
responses can be made. First, some systems may have parts that are necessary for
a function, plus other parts that, while useful, are not absolutely required.
Although one can remove the radio from a car and the car will still work, one
cant remove the battery or some other parts and have a working car. Ussery
himself seems to recognize this when he writes I would readily admit that there
is STILL the problem of the evolution of the minimal flagellum, (Ussery 1999)
but he hopes gene duplication will explain that. Second, one must be careful not
to identify one protein with one part of a biochemical machine. For example,
genes coding for two proteins in one organism may be joined into a single gene
in another. A single protein in one organism may be doing the jobs of several
polypeptides in another. Or two proteins may combine to do one job (an example
is the α- and β-subunits of tubulin, which together make microtubules, a part
of the eukaryotic cilium).

In his review Ussery mistakenly attributes to me the belief that 240 separate
proteins are required for the bacterial flagellum. The confusion apparently
arose because at the end of a chapter on the eukaryotic cilium and bacterial
flagellum, I stated that a typical cilium contains over two hundred different
kinds of proteins. In the next paragraph I wrote, The bacterial flagellum, in
addition to the proteins already discussed, requires about forty other proteins
for function. (Behe 1996, p. 72) Although I meant in addition to the flagellar
proteins I had discussed a few pages earlier in the chapter, Ussery interpreted
the statement to include the several hundred ciliary proteins as well.
Ordinarily I would simply overlook such a mistaken attribution, since it should
be obvious to informed readers that I wouldnt be lumping the proteins of cilia
and flagella together--after all, they are completely different structures that
occur in separate kinds of organisms. In his review in Biology and Philosophy,
however, Bruce Weber writes Behe cannot imagine how anything short of the full
240 components of the flagellum could propel a bacterium. But only 33 proteins
are needed to produce a functional flagellum for Helicobacter pylori. (Weber
1999) And Weber then cites Usserys web site as his source. Since Usserys
misreading of my book seems to be spreading, and since naive readers might be
more impressed by a drop from 240 to 33 than by a change from 40 to 33, I have
to state for the record that I did not mean the bacterial flagellum requires the
proteins of the eukaryotic cilium!

Several reviewers have questioned whether irreducible complexity is necessarily
a hallmark of intelligent design. James Shapiro, who has worked on adaptive
mutations, writes in the Boston Review (Shapiro 1997) of some developments in
contemporary life science that suggest shortcomings in orthodox evolutionary
theory while arguing for a growing convergence between biology and information
science which offers the potential for scientific investigation of possible
intelligent cellular action in evolution. Thus Shapiro appears to think that
irreducibly complex biochemical structures might be explained in a non-Darwinian
fashion without invoking intelligence beyond the cells themselves. In Biology
and Philosophy Bruce Weber (1999) writes that the work of Stuart Kauffman and
others on self-organizing phenomena disrupts the dichotomy Behe has set up of
selection or design. Most explicitly, Shanks and Joplin argue in Philosophy of
Science that self-organizing phenomena such as the Belousov-Zhabotinsky reaction
demonstrate that irreducible complexity is not necessarily a pointer to
intelligent design. (Shanks and Joplin 1999) I have responded to Shanks and
Joplins argument in a separate paper. (Behe 2000) Briefly, complexity is a
quantitative feature; systems can be more or less complex. Although it produces
some complexity, the self-organizing behavior so far observed in the physical
world has not produced complexity and specificity comparable to irreducibly
complex biochemical systems. There is currently little reason to think that
self-organizing behavior can explain biochemical systems such as the bacterial
flagellum or blood clotting cascade.

The underlying point of all these criticisms that needs to be addressed, I
think, is that it is possible future work might show irreducible complexity to
be explainable by some unintelligent process (although not necessarily a
Darwinian one). And on that point I agree the critics are entirely correct. I
acknowledge that I cannot rule out the possibility future work might explain
irreducibly complex biochemical systems without the need to invoke intelligent
design, as I stated in Darwins Black Box. (Behe 1996, 203-204) I agree I cannot
prove that studies of self-organization will not eventually show it to be
capable of much more than we know now. Nor can I definitively say that Professor
Shapiros ideas about self-designing cells might not eventually prove true, or
that currently unknown theories might prevail. But the inability to guarantee
the future course of science is common to everyone, not just those who are
supportive of intelligent design. For example, no one can warrant that the
shortcomings of self-organization will not be exacerbated by future research,
rather than overcome, or that even more difficulties for natural selection will
not become apparent.

I agree with the commonsense point that no one can predict the future of
science. I strongly disagree with the contention that, because we cant
guarantee the success of intelligent design theory, it can be dismissed, or
should not be pursued. If science operated in such a manner, no theory would
ever be investigated, because no theory is guaranteed success forever. Indeed,
if one ignores a hypothesis because it may one day be demonstrated to be
incorrect, then one paradoxically takes unfalsifiability to be a necessary trait
of a scientific theory. Although philosophers of science have debated whether
falsifiability is a requirement of a scientific theory, no one to my knowledge
has argued that unfalsifiability is a necessary mark.

Because no one can see the future, science has to navigate by the data it has in
hand. Currently there is only one phenomenon that has demonstrated the ability
to produce irreducible complexity, and that is the action of an intelligent
agent. It seems to me that that alone justifies pursuing a hypothesis of
intelligent design in biochemistry. In his recent book Tower of Babel: The
Evidence against the New Creationism, however, philosopher of science Robert
Pennock argues that science should avoid a theory of intelligent design because
it must of necessity embrace methodological naturalism. (Pennock 1999) I have
responded to Pennock elsewhere. (Behe 1999) Briefly, science should follow the
data wherever it appears to lead, without preconditions. Further, the question
of the identity of the designer remains open (see below) -- just as the cause of
the Big Bang has been open for decades. Thus, science can pursue theories with
extra-scientific implications (such as the Big Bang(2) or intelligent design) as
far as it can, using its own proper methods.

III. Can We--May We--Detect Design in the Cell?

Several reviewers have argued against the legitimacy of reasoning to a
conclusion of intelligent design based on biochemical evidence. In the same
review discussed above Allen Orr raises an intriguing question of how we
apprehend design. He writes:

We know that there are people who make things like mousetraps. (Im not being
facetious here--Im utterly serious.) When choosing between the design and
Darwinian hypotheses, we find design plausible for mousetraps only because we
have independent knowledge that there are creatures called humans who construct
all variety of mechanical contraptions; if we didnt, the existence of
mousetraps would pose a legitimate scientific problem. (Orr 1997)

So, Orr says, we know mousetraps are designed because we have seen them being
designed by humans, but we have not seen irreducibly complex biochemical systems
being designed, so we cant conclude they were.

Although he makes an interesting point, I think his reasoning is incorrect.
Consider the SETI project (Search for Extraterrestrial Intelligence), in which
scientists scan space for radio waves that might have been sent by aliens. Those
scientists believe that they can distinguish a designed radio wave (one carrying
a message) from the background radio noise of space. However, we have never
observed space aliens sending radio messages; we have never observed aliens at
all. Nonetheless, SETI workers, funded for years by the federal government, are
confident that they can detect intelligently-designed phenomena, even if they
dont know who produced them.

The relevance to intelligent design in biochemistry is plain. Design is evident
in the designed system itself, rather than in pre-knowledge of who the designer
is. Even if the designer is an entity quite unlike ourselves, we can still reach
a conclusion of design if the designed system has distinguishing traits (such as
irreducible complexity) that we know require intelligent arrangement. (One
formal analysis of how we come to a conclusion of design is presented by William
Dembski in his recent monograph, The Design Inference (Dembski 1998).)

We can probe Orrs reasoning further by asking how we know that something was
intelligently designed even if it indeed resulted from human activity. After
all, humans engage in all sorts of activities which we would not ascribe to
intelligence. For example, in walking through the woods a person might crush
plants by his footsteps, accidentally break tree branches and so on. Why do we
not ascribe those marks to purposeful activity? On the other hand, when we see a
small snare (made of sticks and vines) in the woods, obviously designed to catch
a rabbit, why do we unhesitatingly conclude the parts of the snare were
purposely arranged by an intelligent agent? Why do we apprehend purpose in the
snare but not in the tracks? As Thomas Reid argued in response to the skepticism
of David Hume, intelligence is apprehended only by its effects; we cannot
directly observe intelligence. (Dembski 1999) We know humans are intelligent by
their outward actions. And we discriminate intelligent from non-intelligent
human actions by external evidence. Intelligence, human or not, is evident only
in its effects.

Michael Ruse in Boston Review raises another objection, saying that scientists
qua scientists simply cant appeal to design.

Design is not something you add to science as an equal--miracles or molecules,
take your pick. Design is an interpretation which makes some kind of overall
metaphysical or theological sense of experience. (Ruse 1997)

Contrary to Ruses argument, however, many scientists already appeal to design.
I mentioned the SETI program above; clearly those scientists think they can
detect design (and nonhuman design at that.) Forensic scientists routinely make
decisions of whether a death was designed (murder) or an accident.
Archaeologists decide whether a stone is a designed artifact or just a chance
shape. Cryptologists try to distinguish a coded message from random noise. It
seems unlikely that any of those scientists view their work as trying to make
metaphysical or theological sense of experience. They are doing ordinary
science.

Ruse probably meant that scientists cant specifically appeal to God or the
supernatural. Evolutionary biologist Douglas Futuyma echoes Ruses sentiment
with rousing rhetoric:

When scientists invoke miracles, they cease to practice science . . . . Behe,
claiming a miracle in every molecule, would urge us to admit the defeat of
reason, to despair of understanding, to rest content in ignorance. Even as
biology daily grows in knowledge and insight, Behe counsels us to just give up.
(Futuyma 1997)

In speaking of miracles--relying for rhetorical effect on that words
pejorative connotations when used in a scientific context--Ruse and Futuyma are
ascribing to me a position I was scrupulous in my book to avoid. Although I
acknowledged that most people (including myself) will attribute the design to
God--based in part on other, non-scientific judgments they have made--I did not
claim that the biochemical evidence leads ineluctably to a conclusion about who
the designer is. In fact, I directly said that, from a scientific point of view,
the question remains open. (Behe 1996, 245-250) In doing so I was not being coy,
but only limiting my claims to what I think the evidence will support. To
illustrate, Francis Crick has famously suggested that life on earth may have
been deliberately seeded by space aliens (Crick and Orgel 1973). If Crick said
he thought that the clotting cascade was designed by aliens, I could not point
to a biochemical feature of that system to show he was wrong. The biochemical
evidence strongly indicates design, but does not show who the designer was.

I should add that, even if one does think the designer is God, subscribing to a
theory of intelligent design does not necessarily commit one to miracles. At
least no more than thinking that the laws of nature were designed by God--a
view, as weve seen, condoned by the National Academy of Sciences (National
Academy of Sciences 1999). In either case one could hold that the information
for the subsequent unfolding of life was present at the very start of the
universe, with no subsequent intervention required from outside of nature. In
one case, the information is present just in general laws. In the other case, in
addition to general laws, information is present in other factors too. The
difference might boil down simply to the question of whether there was more or
less explicit design information present at the beginning--hardly a point of
principle.

While were on the subject of God, another point should be made: A number of
prominent scientists, some of whom fault me for suggesting design, have
themselves argued for atheistic conclusions based on biological data. For
example, Professor Futuyma has written: Some shrink from the conclusion that
the human species was not designed, has no purpose, and is the product of mere
mechanical mechanisms--but this seems to be the message of evolution. (Futuyma
1982) And Russell Doolittle remarks concerning the blood clotting cascade: . .
. no Creator would have designed such a circuitous and contrived system.
(Doolittle 1997) It is rather disingenuous, however, for those who use
biological data to argue that life shows no evidence of design, to complain when
others use biological evidence to argue the opposing view.

IV. Giving Up in Ignorance

Some scientific reviewers have dismissed the conclusion of design as an
argument from ignorance, or a God of the gaps argument. This can take
several forms. One form of the objection is presented by University of London
evolutionary biologist Andrew Pomiankowski, who writes:

Most biochemists have only a meagre understanding of, or interest in, evolution.
As Behe points out, for the thousand-plus scholarly articles on the biochemistry
of cilia, he could find only a handful that seriously addressed evolution. This
indifference is universal. (Pomiankowski 1996)

So, Pomiankowski argues, we do not have answers because nobody has looked, and
biochemists havent looked because they have little interest in the subject.

Although initially plausible, this interpretation suffers from the fact that
there is demonstrable interest in evolution among molecular bioscientists. (One
doesnt have to officially call oneself a biochemist to address such problems.
Molecular biologists, geneticists, immunologists, embryologists-- investigators
in all of these disciplines are in a position to work on them.) The authors of
the large number of books and papers listed on John Catalanos and David
Usserys web sites are clearly interested in evolution (see my discussion of the
evolutionary literature on this web site), as are the authors of numerous other
studies that involve sequence comparisons. Since many papers are published in
the general area of molecular evolution, we have to ask why there are so few in
the particular area of the Darwinian evolution of irreducibly complex systems.
Pomiankowski proposes it is because the problem is so difficult (Pomiankowski
1996); I suggest it is difficult because irreducibly complex systems fit poorly
within a gradualistic theory such as Darwinism.

A less reasonable form, I think, of the ignorance accusation is presented by
Neil Blackstone. An evolutionary biologist at Northern Illinois University,
Blackstone levels a formal charge at me of an error in logic--the argumentum ad
ignorantium, as his review is titled (Blackstone 1997). He even cites a
philosophy textbook by Irving Copi to give the charge authority. Those who chop
logic to rule out a hypothesis, however, should make sure they are on very firm
logical ground. Blackstone is not.

Copi defines the fallacy as follows: The argumentum ad ignorantium is committed
whenever it is argued that a proposition is true simply on the basis that it has
not been proved false, or that it is false because it has not been proved true.
(Copi 1953) But I certainly did not argue that the Darwinian evolution of
biochemical complexity is false simply on the basis that it has not been
proved true. Nor did I say that intelligent design is true simply on the basis
that it has not been proved false. To lay the groundwork for a proposal of
intelligent design I did argue extensively that the blood clotting cascade and
other systems have not been explained by Darwinism. That, of course, was
necessary because many people have the impression that Darwinian theory has
already given a satisfactory account for virtually all aspects of life. My first
task was to show the readership that that impression is not correct.

But my argument did not stop there. I spent many pages throughout the book
showing that there is a structural reason--irreducible complexity--for thinking
that Darwinian explanations are unlikely to succeed. Furthermore, I argued that
irreducible complexity is a hallmark of intelligent design, took several
chapters to explicate how we apprehend design, showed why some biochemical
systems meet the criteria, and addressed objections to the design argument.
Truncating my case for intelligent design and then saying I commit the fallacy
of argumentum ad ignorantium is not, in my opinion, fair play.

Lets explore the intricacies of formal logic a little further. Although
Blackstone didnt mention it, Copi has more to say on the argument from
ignorance.

A qualification should be made at this point. In some circumstances it can be
safely assumed that if a certain event had occurred, evidence of it could be
discovered by qualified investigators. In such circumstances it is perfectly
reasonable to take the absence of proof of its occurrence as positive proof of
its non-occurrence. (Copi 1953)

Although I did not limit my argument to the lack of evidence for the Darwinian
evolution of irreducibly complex biochemical systems, when qualified
investigators (such as, say, those investigating blood clotting) come up empty,
it is perfectly reasonable to weigh that against Darwinism. (By itself, of
course, it is not positive evidence for design.) Although lack of progress is
not proof of the failure of Darwinism, it certainly is a significant factor to
consider.

In a milder variation of the argument from ignorance complaint, other
scientific reviewers have objected that an appeal to intelligent design is
tantamount to giving up. For example, in the Forward Emory University
evolutionary biologist Marc Lipsitch remarks:

[Behe] correctly suggests that a complete theory of evolution would include an
account of how the intricate chemical systems inside our bodies arose (or might
have arisen) from inanimate molecules, one step at a time. Mr. Behes question
is a fair one, but instead of suggesting a series of experiments that could
address the question, he throws up his hands. (Lipsitch 1996)

Unfortunately, the point is made with circular logic: it depends on the
presupposition that life is not designed, which is the point at issue. If life
is not designed then, yes, a theory of intelligent design is ultimately a blind
alley (if not quite giving up). However, if aspects of life are indeed
designed, then the search for the putative unintelligent mechanisms that built
them is the blind alley. But how do we decide ahead of time which is correct?

We cant decide the correct answer ahead of time. Science can only follow the
data where they lead, as they become available.

References

Behe, M. J. (1996). Darwin's black box: the biochemical challenge to evolution.
(The Free Press: New York.)

Behe, Michael J. The God of Science: The case for intelligent design. The Weekly
Standard, 35-37. 6-7-1999.

Behe, Michael J. (2000). Self-organization and irreducibly complex systems: A
reply to Shanks and Joplin. Philosophy of Science 67, 155-162.

Blackstone, N. W. (1997). Argumentum ad ignoratium. Quarterly Review of Biology
72, 445-447.

Bugge, T. H., Kombrinck, K. W., Flick, M. J., Daugherty, C. C., Danton, M. J.,
and Degen, J. L. (1996). Loss of fibrinogen rescues mice from the pleiotropic
effects of plasminogen deficiency. Cell 87, 709-719.

Copi, I. M. (1953). Introduction to logic. (Macmillan: New York.)

Coyne, J. A. (1996). God in the details. Nature 383, 227-228.

Crick, Francis and Orgel, L. E. (1973). Directed panspermia. Icarus 19, 341-346.

Davies, P. C. W. (1999). The Fifth Miracle: The Search for the Origin and
Meaning of Life. (Simon & Schuster: New York.)

Dembski, W. A. (1998). The design inference: eliminating chance through small
probabilities. (Cambridge University Press: Cambridge.)

Dembski, W. A. (1999). Intelligent design: the bridge between science and
theology. (Intervarsity Press: Dowbers Grove, Illinois.)

Denton, M. J. (1998). Nature's Destiny: How the Laws of Biology Reveal Purpose
in the Universe. (Free Press: New York.)

Doolittle, R. F. A delicate balance. Boston Review [Feb/March], 28-29. 1997.

Flietstra, R. A response to Michael Behe. Books & Culture [Sept/Oct], 37-38.
1998.

Futuyma, D. J. (1982). Science on Trial. (Pantheon Books: New York.)

Futuyma, D. J. Miracles and molecules. Boston Review [Feb/March], 29-30. 1997.

Gross, P. R. The dissent of man. Wall Street Journal, A12. 7-30-1996. New York.

Hall, B. G. (1999). Experimental evolution of Ebg enzyme provides clues about
the evolution of catalysis and to evolutionary potential. FEMS Microbiology
Letters 174, 1-8.

Lipsitch, M. Fighting an evolutionary war. Forward 9. 10-25-1996.

Maddox, John (1989). Down with the Big Bang. Nature 340, 425.

Miller, K. R. (1999). Finding Darwin's God: a scientist's search for common
ground between God and evolution. (Cliff Street Books: New York.)

National Academy of Sciences (1999). Science and creationism: a view from the
National Academy of Sciences. (National Academy Press: Washington, DC.)

Orr, H. A. Darwin v. intelligent design (again). Boston Review [Dec/Jan], 28-31.
1996.

Orr, H. A. H. Allen Orr responds. Boston Review [Feb/March], 35-36. 1997.

Pennock, R. (1999). Tower of Babel: The evidence against the new creationism.
(MIT Press: Cambridge, Massachusetts.)

Pomiankowski, A. The God of the tiny gaps. New Scientist. 9-14-1996.

Ruse, M. Enough speculation. Boston Review [Feb/March], 31-32. 1997.

Shanks, Niall and Joplin, Karl H. (1999). Redundant complexity: A critical
analysis of intelligent design in biochemistry. Philosophy of Science 66,
268-282.

Shapiro, J. A. A third way. Boston Review [Feb/March], 32-33. 1997.

Ussery, David (1999). A biochemist's response to "The Biochemical Challenge to
Evolution". Bios70, 40-45.

Weber, Bruce (1999). Irreducible complexity and the problem of biochemical
emergence. Biology & Philosophy14, 593-605.

EndNotes

(1) Kenneth Miller leads readers of Finding Darwins God into thinking such a
process would be very easy. He writes, If microevolution can redesign one gene
in fewer than two hundred generations (which in this case took only thirteen
days!), what principles of biochemistry or molecular biology would prevent it
from redesigning dozens or hundreds of genes over a few weeks or months to
produce a distinctly new species? There are no such principles of course...
(Miller 1999, 108) Well, then, why doesnt he just take an appropriate bacterial
species, knock out the genes for its flagellum, place the bacterium under
selective pressure (for mobility, say), and experimentally produce a
flagellum--or any equally complex system--in the laboratory? (A flagellum, after
all, has only 30-40 genes, not the hundreds Miller claims would be easy for
natural selection to rapidly redesign.) If he did that, my claims would be
utterly falsified. But he wont even try it because he is grossly exaggerating
the prospects of success.

(2) That the Big Bang theory has extra-scientific implications can be seen in
the reaction of those who do not welcome the implications. For example, in a
1989 editorial in Nature with the intriguing title Down with the Big Bang,
John Maddox wrote Creationists and those of similar persuasions seeking support
for their theories have ample justification in the doctrine of the Big Bang.
That, they might say, is when (and how) the Universe was created. (Maddox 1989)