William A. Dembski
Conceptual Foundations of Science
Baylor University
November 22, 2004


Talk presented at the annual American Academy of Religion meeting,
San Antonio, November 22, 2004


According to evolutionist Francisco Ayala, Darwins greatest achievement was to
show that the organized complexity of living things could be brought about
without recourse to a designing intelligence. Given this view of Darwins
achievement, what evolutionary biology has come to mean by evolution is an
unintelligent or blind form of it. This was brought home to me two years ago at
a debate in which I participated. I was invited, along with my colleague and
friend Michael Behe, to debate Darwinists Kenneth Miller and Robert Pennock at
the American Museum of Natural History in Manhattan. The debate was initially
titled Blind Evolution or Intelligent Design? Yet, when the debate actually
took place on April 23, 2002, the program bulletin distributed at the event
quietly dropped the word blind and titled the debate simply Evolution or
Intelligent Design? The original title was more accurate. Intelligent design,
the view for which Behe and I were arguing, is opposed to blind evolution, not
to evolution simpliciter.

Why should anyone doubt blind evolution or, as it is now increasingly being
called, unintelligent evolution? At the heart of unintelligent evolution is
Darwins theory. It is no accident that in debates over biological evolution
Darwins name keeps coming up. Nor are repeated references to Darwin and
Darwinism simply out of respect for the history of the subject, as though
evolutionary biology needed constantly to be reminded of its founder. Darwin
looms larger than life in the study of biological origins because his theory
constitutes the very bedrock of evolutionary biology. Indeed, nothing in
evolutionary biology makes sense apart from Darwinism.

To see this, we need to understand Darwinisms role in contemporary evolutionary
theory. Darwinism is really two claims. The less crucial claim is that all
organisms trace their lineage back to a universal common ancestor. Thus you, the
fly buzzing around your head, and the bacteria perched on the fly all share the
same great-great-great grandparent. Alternatively, any two organisms are n-th
cousins k-times removed where n and k depend on the two organisms in question.
This claim is referred to as common descent or universal common ancestry.
Although evolutionary biology is committed to common descent, that is not its
central claim.

The central claim of evolutionary biology, rather, is that an unintelligent
physical process can account for the emergence of all biological complexity and
diversity. Filling in the details of that process remains a matter for debate
among evolutionary biologists. Yet it is an in-house debate, and one essentially
about details. In broad strokes, however, any unguided physical process capable
of producing biological complexity must have three components: (1) hereditary
transmission, (2) incidental change, and (3) natural selection.

Think of it this way: Start with some organism. It incurs some change. The
change is incidental in the sense that it doesnt anticipate future changes that
subsequent generations of organisms may experience (neo-Darwinism, for instance,
treats such changes as random mutations or errors in genetic material). Whats
more, incidental change is heritable and therefore can be transmitted to the
next generation. Whether it actually is transmitted to the next generation and
then preferentially preserved in subsequent generations, however, depends on
whether the change is in some sense beneficial to the organism. If so, then
natural selection will be likely to preserve organisms exhibiting that change.

This picture is perfectly general. As already noted, it can accommodate
neo-Darwinism. It can also accommodate Lamarckian evolution, whose incidental
changes occur as organisms, simply by putting to use existing structures,
enhance or modify the functionalities of those structures. It can accommodate
Lynn Marguliss idea of symbiogenetic evolution, whose incidental changes occur
as different types of organisms come together to form a new, hybrid organism.
Other forms of incidental change that it can accommodate include genetic drift,
lateral gene transfer, and the action of regulatory genes in development.

Evolutionary biologists debate the precise role and extent of hereditary
transmission and incidental change. The debate can even be quite sharp at times.
But evolutionary biology leaves unchallenged Darwinisms holy of holiesnatural
selection. Darwin himself was unclear about the mechanisms of hereditary
transmission and incidental change. But whatever form they took, Darwin was
convinced that natural selection was the key to harnessing them. The same is
true for contemporary evolutionary biologists. Thats why to this day we hear
repeated references to Darwins theory of natural selection but not to Darwins
theory of variation or Darwins theory of inheritance.

Apart from design or teleology, what can coordinate the incidental changes that
hereditary transmission passes from one generation to the next? To perform such
coordination, evolution requires a designer substitute. Darwins claim to fame
was to propose natural selection as a designer substitute. But natural selection
is no substitute for intelligent coordination. All natural selection does is
narrow the variability of incidental change by weeding out the less fit. Whats
more, it acts on the spur of the moment, based solely on what the environment at
present deems fit, and thus without any foresight of future possibilities. And
yet this unintelligent process, when coupled with another unintelligent process
(incidental change), is supposed to produce designs that exceed the capacities
of any designing intelligences in our experience.

Leaving aside small-scale evolutionary changes, like insects developing
insecticide resistance (which no one disputes anyway), where is the evidence
that natural selection can accomplish the intricacies of bioengineering that are
manifest throughout the living world (like producing insects in the first
place)? Where is the evidence that the sorts of incidental changes required for
large-scale evolution ever occur? The evidence simply isnt there. But dont
take my word for it. Three years ago, cell biologist Franklin Harold published a
book with Oxford University Press titled The Way of the Cell. In it he
explicitly repudiated intelligent design: We should reject, as a matter of
principle, the substitution of intelligent design for the dialogue of chance and
necessity. (Note that the dialogue between chance and necessity here refers to
the interplay of incidental change and natural selection, in other words,
unintelligent evolution.) And yet, Harold continued, But we must concede that
there are presently no detailed Darwinian accounts of the evolution of any
biochemical or cellular system, only a variety of wishful speculations.

James Shapiro, Stuart Kauffman, and Lynn Margulis have raised similar doubts.
But what are their alternatives? Certainly not intelligent design. Shapiro
places his hopes in what he calls natural genetic engineering; in other words,
organisms design themselves. But Shapiro has no account of how organisms of
sufficient complexity can arise in the first place to do their own genetic
engineering. As for Kauffman, he places his hopes in laws of self-organization
and complexity. Yet a decade after he published At Home in the Universe: The
Search for Laws of Self-Organization and Complexity (publication date 1995),
Kauffman is still searching for those laws. And as for Lynn Margulis, she places
her hopes in symbiogenesis, where the driving force behind evolution becomes
organisms coming together to hybridize and thereby increase biological
complexity. Though Margulis has argued effectively that symbiogenesis plays some
role in biological evolution, she is far from showing that it is the missing
key. In short, the proposals on the table for shoring up Darwinian theory with
still other blind material mechanisms are even more speculative than what they
are trying to shore up.

To appreciate whats at stake in raising criticisms and doubts about
unintelligent evolution, imagine what would happen to the germ theory of disease
if scientists never found any microorganisms or viruses that produced diseases.
Thats the problem with unintelligent evolution. To be sure, evolutionary
theorists have proposed mechanisms to explain small-scale changes in organisms
(like bacteria developing antibiotic resistance). What they have not shown,
however, is how such mechanisms can reasonably be extrapolated to explaining
large-scale changes in organisms (like bacteria developing the complex molecular
machines that Michael Behe discusses in his book Darwins Black Box). In place
of detailed, testable accounts of how a complex biological system could
realistically have emerged, evolutionary theory offers handwaving just-so
stories for how such systems might have emerged in some idealized conceptual
space far removed from biological reality.

This is bad enough, but the situation is even worse for evolutionary theory.
Its one thing, as I have been doing, to suggest that unintelligent evolution
has yet to be adequately substantiated. Proponents of unintelligent evolution
can then just claim that more effort and research funds will vindicate the
theory. But I want to press the critique further. In particular, I want to argue
that evolutionary theory, by being wedded exclusively to unintelligent material
forces, lacks the conceptual resources to explain biological complexity and
diversity.

One way to see this is by reflecting on a principle of scientific reasoning
described by John Stuart Mill, a contemporary of Darwins. In his System of
Logic, Mill put forward his well-known method of difference. According to the
method of difference, to explain a difference in effects, one must identify a
difference in causes. Put differently, common causes cannot explain differences
in effects. To see the validity of this principle, consider the following
difference in effects, namely, slowed reflexes versus ordinary reflexes, as well
as the following possible causes, namely, watching television, combing hair,
consuming alcohol, and eating candy. Watching television, combing hair, and
eating candy are equally compatible with slowed as well as ordinary reflexes.
Consuming alcohol, however, is not. Consuming alcohol is reliably correlated
with slowed reflexes. It is the difference that makes a difference here.

Now, consider the following difference in effects directly relevant to our
discussion, namely, increasing biological complexity in the history of life
versus stagnating or even dwindling biological complexity over that same history
. Evolutionary theory wants to say that what makes the difference in leading
life to ever greater levels of biological complexity is systems that reproduce
subject to the three factors described previously, namely, (1) hereditary
transmission, (2) incidental change, and (3) natural selection. The problem is,
however, that these three factors are not reliably correlated with increasing
complexity of replicacting systems. There are many examples of this. Brian
Goodwin, in How the Leopard Changed Its Spots, relates one notable instance:

In a classic experiment, [Sol] Spiegelman ... showed what happens to a molecular
replicating system in a test tube, without any cellular organization around it.
The replicating molecules (the nucleic acid templates) require an energy source,
building blocks (i.e., nucleotide bases), and an enzyme to help the
polymerization process that is involved in self-copying of the templates. Then
away it goes, making more copies of the specific nucleotide sequences that
define the initial templates. But the interesting result was that these initial
templates did not stay the same; they were not accurately copied. They got
shorter and shorter until they reached the minimal size compatible with the
sequence retaining self-copying properties. And as they got shorter, the copying
process went faster. So what happened with natural selection in a test tube: the
shorter templates that copied themselves faster became more numerous, while the
larger ones were gradually eliminated. This looks like Darwinian evolution in a
test tube. But the interesting result was that this evolution went one way:
toward greater simplicity. Actual evolution tends to go toward greater
complexity, species becoming more elaborate in their structure and behavior,
though the process can also go in reverse, toward simplicity. But DNA on its own
can go nowhere but toward greater simplicity. In order for the evolution of
complexity to occur, DNA has to be within a cellular context; the whole system
evolves as a reproducing unit.

But that raises the next question, which is how does evolution produce whole
systems capable of providing the right context for evolution to thrive and thus
bring about increasing complexity? Evolutionists have no answer here. But again,
dont take my word for it. According to Stuart Kauffman, one of the leading
self-organizational theorists, One of the deep puzzles is why the universe has
become complex. Why has the biosphere become complex? Why has the number of ways
of earning a living increased so dramatically? We have no theory about this
overwhelming feature of our universe. (www.iscid.org/stuartkauffman-chat.php)

Life over the course of natural history has become more complex. One of the
great appeals of evolutionary theory, when thinkers such as Darwin first
proposed it, was to underwrite a progressive, onward-and-upward,
complexity-increasing form of evolution. And yet, on closer examination, it
becomes evident that the theory lacks the conceptual resources to do so. To be
sure, the unguided material mechanisms to which evolutionary theory appeals play
a significant role in the history of life (natural selection certainly has
played a role in preserving species and adapting them to their environments).
But as Mills method of difference points up (especially when combined with
experiments like Sol Spiegelmans), these mechanisms, and any theory of
unintelligent evolution based exclusively on them, cannot be the whole story.
Simply put, evolutionary theory is incomplete. Moreover, the incompleteness here
is a gaping conceptual lacuna, and not merely a pocket of ignorance that
promises to be quickly remedied.

To appreciate the problem here, consider the following analogy. Imagine an
immense stadium with a million people. Each person is initially standing and
holds a coin. They now begin tossing their coins. Each person remains standing
so long as he or she tosses heads, but must sit down otherwise. On average, at
the end of twenty tosses one person will be left standing. The rationale here is
this: after the first toss, on average 500,000 people will be left standing;
after the second toss, on average half that number will be left standing, or
250,000; after the third toss, on average half that number will be left
standing, or 125,000; and so on. Twenty tosses, on average, leaves one person
standing.

Now, suppose after twenty tosses exactly one person is left standing. Do we turn
to that person and ask, Hey, whats your secret for coin tossing? Hardly. The
theory of coin tossing (probability theory) tells us that out of a million such
coin-tossers, one person will on average be left standing who has tossed twenty
heads in a row. So too, the theory of evolution tells us that, periodically,
nature will produce beneficial incidental changes that, rather than simply
disappearing into the dust of prehistory, will be passed on by the power of
natural selection. Through a long chain of such events, the cumulative effect of
natural selection and incidental change over several billion years is likely to
produce the degree of biological complexity and diversity we observe now. Just
as the theory of coin tossing does not justify attributing to the person who
tossed twenty heads in a row any special skill or wisdom at coin tossing, so too
the theory of evolution does not justify attributing to the evolutionary process
any special skill or wisdom at generating biological complexity and diversity.
In each case, the outcome is properly regarded as the expected or predictable
outcome of unintelligent material mechanisms and not as the creative achievement
of a designing intelligence.

But there is a crucial difference between these two cases. In the coin tossing
case, we have the observed outcome (twenty heads in a row) as well as a detailed
history and mechanistic theory to account for the outcome. In the history of
life, by contrast, we have only the observed outcome (the multiplicity of
complex life forms, both extant and fossilized) but neither a detailed history
nor a mechanistic theory that adequately accounts for this outcome. The key
point to note here is the presence of an adequate mechanistic theory in one
case, but its absence in the other. In the coin tossing case, give a million
people each a coin, let them start tossing, and after twenty tosses one person
will usually be left standing. By contrast, let some bacteria evolve within the
perimeters set by contemporary evolutionary theory, and theres no assurance
that any interesting biological structures will be produced. Lets nail this
down more concretely.

Consider how biologists propose to explain the emergence of the bacterial
flagellum, a molecular machine that has become the mascot of the intelligent
design movement. In public lectures, Harvard biologist Howard Berg calls the
bacterial flagellum the most efficient machine in the universe. The flagellum
is a nano-engineered bidirectional motor-driven propeller on the backs of
certain bacteria. It spins at tens of thousands of rpm, can change direction in
a quarter turn, and propels a bacterium through its watery environment.
According to evolutionary theory it had to emerge via some material mechanisms.
Fine, but how?

The usual story is that the flagellum is composed of parts that previously were
targeted for different uses and that natural selection then co-opted to form a
flagellum. This seems reasonable until we try to fill in the details. The only
well-documented examples that we have of successful co-option come from human
engineering. For instance, an electrical engineer might co-opt components from a
microwave oven, a radio, and a computer screen to form a working television. But
in that case, we have an intelligent agent who knows all about electrical
gadgets and about televisions in particular.

But natural selection doesnt know a thing about bacterial flagella. So how is
natural selection going to take extant protein parts and co-opt them to form a
flagellum? The problem is that natural selection can only select for preexisting
function. It can, for instance, select for larger finch beaks when the available
nuts are harder to open. Here the finch beak is already in place and natural
selection merely enhances its present functionality. Natural selection might
even adapt a preexisting structure to a new function; for example, it might
start with finch beaks adapted to opening nuts and end with beaks adapted to
eating insects.

But for co-option to result in a structure like the bacterial flagellum, we are
not talking about enhancing the function of an existing structure or reassigning
an existing structure to a different function, but reassigning multiple
structures previously targeted for different functions to a novel structure
exhibiting a novel function. Even the simplest bacterial flagellum requires
around forty proteins for its assembly and structure. All these proteins are
necessary in the sense that lacking any of them, a working flagellum does not
result.

The only way for natural selection to form such a structure by co-optation,
then, is for natural selection gradually to enfold existing protein parts into
evolving structures whose functions co-evolve with the structures. We might, for
instance, imagine a five-part mousetrap consisting of a platform, spring,
hammer, holding bar, and catch evolving as follows: It starts as a doorstop
(thus consisting merely of the platform), then evolves into a tie-clip (by
attaching the spring and hammer to the platform), and finally becomes a full
mousetrap (by also including the holding bar and catch).

Design critic Kenneth Miller finds such scenarios not only completely plausible
but also deeply relevant to biology (in fact, he regularly sports a modified
mousetrap cum tie-clip). Intelligent design proponents, by contrast, regard such
scenarios as rubbish. Heres why. First, in such scenarios the hand of human
design and intention meddles everywhere. Evolutionary biologists assure us that
eventually they will discover just how the evolutionary process can take the
right and needed steps without the meddling hand of design. All such assurances,
however, presuppose that intelligence is dispensable in explaining biological
complexity. Yet the only evidence we have of successful co-option comes from
engineering and confirms that intelligence is indispensable in explaining
complex structures like the mousetrap and, by implication, the flagellum.
Intelligence is known to have the causal power to produce such structures.
Unguided material mechanisms have never given any evidence of such causal power.


Indeed, the primary mechanism of evolutionary theory, namely, the interplay
between incidental change and natural selection, looks increasingly feeble in
this regard. The whole point of this Darwinian selection mechanism is to show
how one can traverse biological configuration space by taking sufficiently small
steps (or, as Darwin put it, numerous successive slight modifications). How
small? Small enough that they are reasonably probable. But what guarantee is
there that a sequence of baby-steps connects two points in configuration space?

Yet the problem goes deeper. For the Darwinian selection mechanism to connect
point A to point B in configuration space, it is not enough that there merely
exist a sequence of baby-steps connecting the two. In addition, each baby-step
needs in some sense to be successful. In biological terms, each step requires
an increase in fitness as measured in terms of survival and reproduction. (Note
that without a strict increase in fitness, we are talking about a neutral theory
of evolution in which searching biological configuration space devolves to a
random search. Random searches are fine for breaking out of local optima or, if
you will, ruts that natural selection has gotten the evolutionary process into,
but because biological configuration spaces are so huge, random searches play
only a minor, occasional role in evolution). Natural selection, after all, is
the primary motive force behind each baby-step, and selection only selects what
is advantageous to the organism. Thus, for the Darwinian mechanism to connect
two organisms, there must be a sequence of successful baby-steps connecting the
two.

Richard Dawkins compares the emergence of biological complexity to climbing a
mountainMount Improbable, as he calls it (see his book Climbing Mount
Improbable). He calls it Mount Improbable because if you had to get all the way
to the top in one fell swoop (that is, achieve a massive increase in biological
complexity all at once), it would be highly improbable. But Mount Improbable
does not have to be scaled in one leap. Evolutionary theory purports to show how
Mount Improbable can be scaled in small incremental steps. Thus, according to
Dawkins, Mount Improbable always has a gradual serpentine path leading to the
top that can be traversed in baby-steps. But such a claim requires verification.
It might be a fact about nature that Mount Improbable is sheer on all sides and
getting to the top from the bottom via baby-steps is effectively impossible. A
gap like that would reside in nature herself and not in our knowledge of nature
(it would not, in other words, constitute a god-of-the-gaps).

Consequently, it is not enough merely to presuppose that a fitness-increasing
sequence of baby steps connects two biological systemsit must be demonstrated.
For instance, it is not enough to point out that some genes for the bacterial
flagellum are the same as those for a type III secretory system (a type of pump)
and then handwave that one was co-opted from the other. Anybody can arrange
complex systems in series based on some criterion of similarity. But such series
do nothing to establish whether the end evolved in a Darwinian fashion from the
beginning unless each step in the series can be specified, the probability of
each step can be quantified, the probability at each step turns out to be
reasonably large, and each step constitutes an advantage to the organism (in
particular, viability of the whole organism must at all times be preserved).
Only then do we have a mechanistic explanation (acceptable to evolutionary
theory) of how one system arose from another. Only then can we legitimately say
that unintelligent evolution is confirmed.

So, what is the alternative to unintelligent evolution? My aim in this talk has
not been to proselytize for any alternative position. Unintelligent evolution
remains an unsupported, speculative hypothesis. Accuracy demands that it be
treated as such regardless of alternatives. Proponents of evolutionary theory
regularly compare their theory favorably to the established theories of the
physical sciences. Thus Ive seen evolutionists compare their theory favorably
to Einsteinian physics, claiming that it is just as well established as general
relativity. Yet how many physicists, to argue for the truth of Einsteinian
physics, will claim that general relativity is as well established as
evolutionary theory? Zero. Unintelligent evolution is nowhere near as well
confirmed as the established theories of physics and chemistry. Thankfully, it
is now increasingly getting the critical scrutiny it deserves.