Introduction
E. Coli at the No Free Lunchroom: Bacterial Flagella
and Dembski’s Case for Intelligent Design
Howard J. Van
Till
Professor of
Physics and Astronomy Emeritus
Calvin CollegeR,
Grand Rapids, MI 49546
18 November, 2002
The Intelligent Design movement argues that
it can point to specific biological systems that exhibit what ID’s chief
theorist William A. Dembski calls “specified complexity.” Furthermore, Dembski
claims to have demonstrated that natural causation is unable to generate this
specified complexity and that the assembling of these biological systems must,
therefore, have required the aid of a non-natural action called “intelligent
design.” In his book, No Free Lunch, Dembski presents the bacterial flagellum
as the premier example of a biological system that, because he judges it to be
both complex and specified, must have been actualized by the form-conferring
action of an unembodied intelligent agent. However, a critical examination of
Dembski’s case reveals that, 1) it is built on unorthodox and inconsistently
applied definitions of both “complex” and “specified,” 2) it employs a concept
of the flagellum’s assembly that is radically out of touch with contemporary
genetics and cell biology, and 3) it fails to demonstrate that
the flagellum is either “complex” or “specified” in the manner required to make
his case. If the case for Intelligent Design is dependent on the bacterial
flagellum, then ID is a failure.
The Core of Dembski’s Case
for ID
In his latest book, No Free
Lunch, William A. Dembski argues at length (as he has done in
several other works) that there are natural objects in the world that a) can be
unambiguously identified as objects that could not be the outcome of unguided natural processes alone, and b) must therefore be
the products of intelligent design.[1]
How would we recognize these remarkable
objects? They exhibit, says Dembski, the empirically detectable quality he
calls specified complexity. And why is it that
these objects must be the products of intelligent design? Because, claims
Dembski, unguided natural processes are inherently incapable of generating
specified complexity. Intelligence alone could do that.
In the cultural context of the
creation-evolution debate, a predominantly North American phenomenon, the
natural objects of greatest interest here are biological systems. Dembski’s
favored example is the bacterial flagellum, a quite remarkable molecular
machine that functions as a propeller for some bacteria, such as E. coli. This
rotary propulsion system also played a prominent role in Michael Behe’s book, Darwin’s Black Box, as an example of a biotic system that
exhibits the quality he called irreducible complexity.
Dembski considers irreducible complexity - after he
carefully redefines and qualifies the meaning of Behe’s term - to be a special
form of his more broadly defined specified
complexity.
Now, if there are biological systems
that - because they exhibit specified complexity - could not
have been actualized by natural processes alone, then, argues Dembski, some
unembodied intelligent agent must have done something to bring about this
naturally impossible outcome. A non-natural action called intelligent
design must have made possible what nature, unguided by any
interactive intelligence, was wholly incapable of doing. That is Dembski’s core
claim - the claim on which the intelligent design movement either stands or
falls. Hence the subtitle of his book: Why Specified Complexity
Cannot Be Purchased Without Intelligence.
Why focus on the bacterial flagellum?
The natural sciences concern themselves with
a vast diversity of physical, chemical and biological processes that transform
some system of interest from an initial state (i) to a final state (f).
Evolutionary biology, for example, deals at length with the processes by which
organisms, employing their own functional and transformational capabilities and
interacting with both their physical and ecological environments, change in the
course of time. Substantial progress has been made in the scientific effort to
become acquainted with the numerous processes relevant to evolutionary
transformations, but even more remains to be discovered and comprehended.
The vast majority of Dembski’s argumentation
in No Free Lunch focuses the reader’s
attention on his particular concept of the way in which these transformational
processes might be limited and constrained by the logical and mathematical
requirements of information theory. In Dembski’s judgment, the scientific
community has been lax in its dealing with these limitations and constraints,
especially as they apply to the Darwinian mechanism for evolution. By presuming
that all of the transformations of interest to evolutionary biology can be
accomplished by purely natural processes, the scientific community has failed,
in Dembski’s judgment, to give due consideration to the limitations of natural
causation and the consequent necessity for supplemental action by a non-natural
intelligent agent.
Sometimes, however, Dembski’s purely
theoretical argumentation regarding these issues seems abstruse and esoteric,
far removed from the real life things to which scientific theories are supposed
to apply. Concrete illustrations then become essential. In my experience, the
key to understanding the character or quality of Dembski’s abstract theories is
to see how he applies them to specific biological systems. That’s where the
case of the bacterial flagellum comes into play.
In Dembski’s
judgment, a straightforward application of his “design-theoretic reasoning” will
clearly demonstrate the need for designer action. “Design-theoretic
explanations are concerned with determining whether some particular event,
object, or structure exhibits clear marks of intelligence and can thus be
legitimately ascribed to design.”[2]
Focusing on the arena of biotic evolution, Dembski believes that he is now in a
position to demonstrate convincingly that “transforming a biological system
that does not exhibit an instance of specified complexity (say a bacterium
without a flagellum) into one that does (say a bacterium with a flagellum)
cannot be accomplished by purely natural means but also requires intelligence.”[3]
This is the specific claim that we will examine later in this paper.[4]
Getting Acquainted With the ID Vocabulary
Before we proceed with our analysis of
Dembski’s case regarding the bacterial flagellum, however, we need to invest a
substantial effort to become familiar with the fundamental goals and vocabulary
of the ID movement. Knowing the broad goals of the movement will help us to
understand some elements of its rhetorical strategy. Knowing the vocabulary of
the movement is essential because of the strategic manner in which familiar
words are often assigned specialized or unusual meanings in ID literature.
The many faces of naturalism
In large part, the ID movement is a reaction
to its leaders’ perception that the worldview of naturalism
has effectively dominated the worlds of higher education and professional
science, and that it is now providing the religious framework for the pre-college
public educational system as well. The ID movement is
committed to the defeat of naturalism. But naturalism comes in many
different versions that must, I believe, be carefully distinguished from one
another. I find the following distinctions to be essential.
-
I use the term maximal
naturalism (or ontological
naturalism) to denote the comprehensive worldview built on the premise that
Nature is all there is - there is no other form of being, no God or gods - and that
there is no ultimate purpose in its existence, character, or historical
development.[5]
This point of view could also be identified by such labels as materialism (the material/physical world is all there is) or
atheism (there is no transcendent God as
envisioned by any of the theistic religions).
-
I use the term minimal
naturalism (it could also be called metaphysical
naturalism, but that name has additional connotations) to denote the family of
worldviews that reject the idea of supernatural
action by any deity. All actions (processes and events) in the universe are
presumed to fall entirely in the category of natural
actions - actions performed by members of the natural world in ways that are
wholly consistent with their own character and capabilities. Although the
existence of God, or gods, or purpose is neither affirmed nor denied by minimal
naturalism, the idea that any divine being would act supernaturally - that
is, coercively overpowering or superceding the natural actions of members of
the universe, thereby interrupting the flow of natural phenomena - is rejected.
(Intelligent Design advocate Phillip Johnson frequently uses the term scientific naturalism, which appears to be minimal
naturalism, as here defined, substantially modified by adding the assertions
that natural actions are purposeless and that science provides the only reliable pathway to knowledge. Given these additions,
Johnson’s label, scientific naturalism, comes very
close to what we are calling maximal
naturalism.)
-
The term methodological
naturalism is often employed to denote the idea that the natural
sciences have the competence to investigate natural actions alone and must
remain agnostic with regard to any form of
divine action.
-
Naturalistic theism
builds its worldview on the premise that there is a God who acts purposefully
and effectively in the world, but this divine action is always persuasive and
never coercive. In contrast to the several forms of supernaturalistic
theism, naturalistic theism rejects coercive supernatural intervention as
something that would violate the essential natures of God, the world, and the
God-world relationship.
The ID movement, we noted, is committed to
the defeat of “naturalism.” But toward which form of naturalism does it aim its
rhetorical guns? There may be some variation in the ID literature, but the
consensus seems to be that it doesn’t really matter very much. In the judgment
of most ID proponents, the distinctions outlined above are effectively
meaningless because all of these versions of naturalism agree on the key proposition
to which the ID movement takes exception - that there is no way to detect divine
action empirically. The distinctions noted above are judged by ID spokespersons
to be hollow rhetorical distinctions without
an empirically discernable difference.
Among the chief claims of the ID movement is
that design is empirically detectable. In
Dembski’s words, “Design is detectable; we do in fact detect it; we have
reliable methods for detecting it.... As I have argued throughout this book,
design is common, rational, and objectifiable.”[6]
That being the claim, then each and every one of the forms of naturalism listed
above - because they uniformly reject the empirical detectability of divine
action - is the target for defeat. To the ID movement, to be a God who is not empirically
detectable is to a dispensable God. Any God whose actions are not empirically
detectable would be of no value in defeating naturalism. Naturalism would
always be able to say, in effect, “A God who can never do anything that makes a
difference, and of whom we can have no reliable knowledge, is of no importance
to us.”[7]
The God envisioned by the chief proponents of ID, on the other hand, is a God
who makes an empirically detectable difference.
Doing what comes naturally
The ID movement has labored vigorously to
formulate a way to determine how things came to be actualized
(assembled, arranged, organized, constructed) in the course of time. In
contrast to theology’s concern - in its doctrine of
creation - for how any universe came to have its being (its existence and/or its
particular character) in the first place, the ID movement is concerned with
portions of the universe’s formational history.
In Dembski’s words, “Design is fundamentally
concerned with arrangements of pre-existing stuff that signify intelligence.”[8]
When looking at some natural object
(any object not crafted by human or animal action, usually some organism or
part of an organism), the question for ID advocates is, Could this object have
been actualized by means of natural processes (or
natural causes) alone?[9]
Purely natural processes are those that can
be fully accounted for by the actions and interactions of the material
substances of which the object and its environment are composed. These are the
processes that the natural sciences are equipped to describe in terms of the empirically known mechanisms by which atoms, molecules,
cells and organisms act, interact, organize or transform themselves. These are
often designated in ID literature as unguided natural processes
to distinguish them from other processes in which some agent (like ID’s
intelligent designer) intentionally participates (or “guides” them) to bring
about an outcome distinctly different from what would otherwise have happened
naturally.
In ID literature all natural processes or
causes are presumed to fall into one of three causal categories: 1) chance, 2)
necessity, or 3) the joint action of chance and necessity. Natural objects or
events that are the outcome of pure chance are
products of wholly random
phenomena (a fair coin-flipping exercise, for example) with no patterning
influences at work, and can best be described in purely statistical terms.
Natural objects or events that are the products of necessity
are the outcome of deterministic natural laws
in which contingency and chance play no effective roles (as in the
orbital motion of planets, for example). Most natural objects, however, are the
outcome of the joint action of both chance and necessity,
with randomness, contingency and deterministic laws each playing some significant
role.
For the purposes of his “design-theoretic”
analysis, Dembski prefers to treat all three categories at once under the
rubric of stochastic processes, a concept that
allows for variable contributions of both chance and necessity - from pure randomness
to full determinism, and all variations between - in one mathematically
convenient formalism. Although the unwary reader might easily be confused,
Dembski usually designates this full spectrum of causal possibilities by the
label “chance.” Throughout most of No Free Lunch,
the terms “chance hypothesis” and “chance explanation” do not refer to chance (random events
or processes) alone, but must be taken to mean “all
hypotheses, postulates and theories concerning the natural causation of
events.” The comprehensiveness and inclusiveness of these terms must
be understood in order to see the extremity of Dembski’s
numerous claims in No Free Lunch.
Darwinism = evolution + maximal naturalism
Proponents of ID are not in full agreement in
their evaluation of the basic vision of biological evolution.
Some ID advocates are willing to accept a limited amount of variation and
selection but nonetheless balk at the idea that all life forms are related by common ancestry. Evolution limited to small changes (often
called microevolution) is often tolerated, as it is even among many young-earth
creationists, but the idea of uninterrupted genealogical continuity (or
macroevolution) among all life forms over billions of years of earth-history is
rejected. Phillip Johnson, for instance, sees the common ancestry thesis as the
foundation of Darwinism - the view of life’s
formational history that he vigorously rejects.
When we posit that the discontinuous groups
of the living world were united in the remote past in the bodies of common ancestors, we are implying a great deal about the process by
which the ancestors took on new shapes and developed new organs. ...There may be
arguments about the details, but all the basic elements of Darwinism are
implied in the concept of ancestral descent.[10]
There are other ID advocates, however, who
express a willingness to accept the common ancestry thesis as a real
possibility, but insist that the changes that took place over time required
more than natural processes alone. Michael Behe, for instance, says
I find the idea of common descent (that all organisms share a common
ancestor) fairly convincing, and have no particular reason to doubt it.
...Although Darwin’s
mechanism - natural selection working on variation - might explain many things,
however, I do not believe it explains molecular life.[11]
And Dembski
comments that
...intelligent design is not a form of anti-evolutionism. [On the
contrary, intelligent design is] fully compatible with large-scale evolution
over the course of natural history, all the way up to what biologists refer to
as “common descent.”[12]
But - and this is the place where an ID-based curriculum will differ from
how biological evolution is currently taught - intelligent design is not willing
to accept common descent as a consequence of the Darwinian mechanism. The
Darwinian mechanism claims the power to transform a single organism (known as
the last common ancestor) into the full diversity of life that we see both
around us and in the fossil record. If intelligent design is correct, then the
Darwinian mechanism of natural selection and random variation lacks that power.[13]
What all advocates of ID do seem to be agreed
on is their judgment that Darwinism is
impossible because the Darwinian mechanism is
inadequate to accomplish the large-scale transformations envisioned by nearly
every professional biologist today. But a reader of ID literature must pay
careful attention to the varied operative meanings that these key terms convey.
At minimum, Darwinism denotes the concepts of
large-scale biological evolution and common descent as consequences of unguided
natural processes. But there is usually far more meaning packed into the term
as it is employed rhetorically in ID literature. “Darwinism” is commonly
employed to characterize biological evolution as a way of accounting for the
formational history of life that is both “thoroughly naturalistic”
and “nonteleological.” But which form of naturalism does “thoroughly
naturalistic” entail? If only minimal or methodological naturalism, then a number of theistic
worldviews could accommodate it. But if the term Darwinism is presumed to
entail maximal naturalism (or scientific naturalism, as Johnson uses the term), then
Darwinism effectively becomes a member of the family of atheistic worldviews.
This is, I believe, the rhetorical impact most commonly intended in the
literature of the ID movement, especially when the reader is offered the binary
choice - either Darwinism or
design.
Similar concerns must be raised when
Darwinism is referred to as a “nonteleological” theory - a concept that excludes
reference to goals, purposes or intentions. If this exclusion refers only to
individual events or to low level natural processes in isolation from the
larger context, that would be consistent with minimal naturalism and open to
various forms of theism. But if the characterization of “nonteleological”
entails the rejection of purpose or intention at all
levels of consideration, then “Darwinism” is once again functioning effectively
as a substitute label for “maximal naturalism.”[14]
The Darwinian mechanism
The term “Darwinian mechanism” refers, of
course, to the menu of relevant natural processes
that are presumed by the vast majority of biologists to make biological
evolution and common descent possible. Here the key question is, In the
judgment of ID advocates, what are the “relevant” natural processes that belong
on this list? At minimum, the Darwinian mechanism menu includes genetic variation and natural selection. As
Dembski’s expresses it, “The Darwinian mechanism consists of random variation,
which provides the raw material for Darwinian evolution, and natural selection,
which sifts that material.”[15]
But there may be many more categories of
natural processes that have contributed to the success of biological evolution over
life’s formational history. Would ID proponents place all of these in the
category of Darwinian mechanism? Evidently not. For instance, in their
evaluation of the proposition that certain “irreducibly complex” biological
structures like bacterial flagella were formed by this mechanism, both Behe and
Dembski limit their evaluation to gradual
processes only, processes that bring about only minuscule functional
improvements (sometimes narrowly constrained to a single function) from
generation to generation. According to Behe, for instance, “The key question is
this: How could complex biochemical systems be gradually produced?”[16]
And in Behe’s book, Darwin’s Black Box,
the index listing for “Darwinian evolution” includes the parenthetical
clarification “(gradualism).”
In No Free Lunch,
Dembski tells us that “The problem, then, is to coordinate the gradual
Darwinian evolution of an organism with the emergence of an irreducibly complex
system that the organism now houses but did not always possess.”[17]
And what about various transformational processes or events that fall outside
of a strict gradualism? It seems that they are to be set aside as natural
processes that are not relevant to ID’s evaluation of the Darwinian mechanism.
“Ideas like coordinated macromutations, lateral gene transfer, set-aside cells,
and punctuated saltational events are thoroughly non-Darwinian.”[18]
But the real question, it seems to me, is this: Whether or not these and other
such events are considered to fall within the bounds of a strict gradualist
definition of the “Darwinian mechanism,” are they relevant to the
formational history of life on earth? The historical development of novel biotic structures is no
respecter of the labels that we might choose to pin on the various factors
contributing to their actualization.
Another restriction on the menu of relevant natural processes considered by Dembski as
legitimate contributors to the Darwinian mechanism arises from his requirement
that scientific explanations regarding evolutionary processes must be causally specific. In Dembski’s words, “Causal specificity
means specifying a [natural] cause sufficient to account for the effect in
question.”[19]
“Lack of causal specificity leaves one without the means to judge whether a
transformation can or cannot be effected.”[20]
Full causal specificity is, of course, the
goal of all scientific explanations, but it is often very difficult to achieve,
especially in the reconstruction of life’s formational history. That’s just a
fact of life in evolutionary biology, as well as in many other areas of
science. What, then, should biology do? Abandon its search for natural causes?
Open the door to hypotheses regarding non-natural causation? Posit the
possibility of occasional form-conferring interventions by an unembodied
intelligent agent? Yes, says Dembski. In effect, that is the ID proposal. After
noting that science - “when biased by naturalism” - tends to restrict its search
for explanations to purely natural causes, Dembski argues: “But in the absence
of causal specificity, there is no reason to let naturalism place such
restrictions on our scientific reasoning.”[21]
I suppose that one could grant the
possibility that this last point is technically correct, but one could equally
well argue that there are good
reasons - scientific, philosophical, and theological - why most of us do find positing the sufficiency of natural causes to be
warranted. Regardless of that, however, Dembski
introduces a serious problem into his analysis when he takes full causal
specificity to be a requirement for natural causes to be relevant contributions
to the Darwinian mechanism. Many scientific hypotheses regarding the manner in
which various transformational processes may have contributed to the
actualization of some new biotic structure might fall short of full
causal specificity - even though they may be highly plausible
applications of mechanisms that are at least partially understood. When that is
the case, the ID approach tends to denigrate them as nothing more than “just-so
stories” and to remove them from further consideration.[22]
If these scientific hypotheses do not exhibit sufficient causal specificity to
allow the computation of a numerical probability for success, then they are
likely to be dismissed from ID’s consideration. Only those mechanisms that are
now fully understood, it seems, can be
placed on the menu of relevant natural processes contributing to the Darwinian
mechanism.
What is the net effect of this requirement
that only causally specific explanations count as relevant scientific accounts of how certain biotic
structures got actualized? I believe it throws the door wide open to false
positive claims regarding the need for non-natural explanations. No doubt there
are now numerous biotic structures for which science is unable to formulate
causally specific (detailed and complete) accounts of their actualization. In
the absence of full causal specificity (a quality, incidentally, that ID
demands of scientific explanations but not of its own explanations) the ID
movement does indeed have opportunity to posit its non-natural, intelligent
design explanations as logically permitted alternatives. However, each time a
new causally specific scientific explanation for one of these biotic structures
is developed, the ID explanation for its actualization immediately becomes
superfluous.[23]
ID’s insistence that its claims can be refuted only by causally specific
scientific accounts stands as an open invitation to false positive claims
regarding the need for its appeal to non-natural causes.
What does it mean to be “intelligently designed”?
Stated as succinctly as possible, the core
scientific claim of the ID movement is, in effect: “We have firm empirical
evidence that some biotic system X could not possibly have been actualized (at
least not for the very first time) by purely natural processes; therefore X
must have been intelligently designed.” In order
to evaluate that claim, two questions must be asked: (1) On what evidence and
reasoning do ID advocates base their claim that X could not have been
actualized by natural processes alone? (2) What does it mean to say that X was
intelligently designed? Question (1) will be dealt with in our analysis of
Dembski’s claim that the bacterial flagellum (a specific example of an X) could
not have formed naturally. Question (2) will now be the focus of our attention.
What do ID advocates actually mean when they
say “X was intelligently designed”? Presuming that intelligent design is some
form of action, what kind of action? And,
action by what sort of agent?
We speak often today of things that have been
designed. Cars are designed; clothing is designed; buildings are designed.
Suppose, then, we were to walk into the headquarters of a major automobile
manufacturer and ask to observe the process of cars being designed. What kind
of activity would we be shown? Would we be taken to the assembly line to see
cars being put together by human hands and mechanical robots? No, we would be
taken to the “design center” where we would see people working with their minds
(augmented, of course, by computers and various means of modeling what their
minds conceive) to conceptualize new cars of various styles to achieve the
intentions of the manufacturer in the marketplace. In other words, to say that
a car was designed is to say that a car was thoughtfully conceptualized to
accomplish some well-defined purpose. In contemporary parlance, the action of design is performed by a mind, intentionally
conceptualizing something for the accomplishment of a purpose.
This mind-like
action of designing is clearly distinguishable
from the hand-like action of actualizing
(assembling, arranging, constructing) what had first been designed. On a tour
of an automobile manufacturing facility, for instance, we would have no
difficulty in distinguishing the mental work done at the design center from the
manual work done on the assembly line.
But in the history of thought about how
living things got to be the way they now are, the word “design” as the name of
an action has often had a different meaning. Two centuries ago William Paley,
for instance, spoke eloquently of things like the eye as having been designed,
much like he would say that a pocket-watch was designed. Clearly the several
parts of a watch work efficiently and harmoniously to accomplish the task of
keeping and displaying the time. Looking at a watch, we would say without
hesitation that such a timepiece had been designed by a watchmaker. Without
doubt, the watchmaker had used his mind to conceptualize the workings of the
watch for the purpose of keeping and displaying the time.
But mind-action alone does not produce a
working watch. The watch must also be actualized by
hand-action. As an artisan, the watchmaker must not only conceptualize the
configuration of gears and dials that comprise a watch; he must also form the various parts and assemble
them into an actual working mechanism. In the context of eighteenth century
natural theology, to say that something had been designed was to say that it
had been both purposefully conceptualized
(by mind-like action) and skillfully crafted (formed and/or assembled by hand-like action). This
traditional meaning of design action was based on the artisan metaphor. One
person, the artisan, performed two actions - mindfully conceptualizing
some artifact and manually crafting what
had first been planned.
What does it now
mean to be “intelligently designed”? Given ID’s almost exclusive emphasis on
the question of how things came to be structured as they now are, and given
ID’s repeated emphasis on the presumed inadequacy of natural processes to
actualize these structures, it is clear that the primary meaning of “X was
intelligently designed” is that “X was actualized by the form-conferring action
of some non-natural agent called an intelligent designer.”
As an action, intelligent design entails both the mind-action of
conceptualization and the hand-like action of constructing or assembling some
functional structure, with a very strong
emphasis on “design” as the means of actualization. Adding the
adjective “intelligent” sometimes functions (1) to call attention to the idea
that design is an action of an intelligent (choice making) agent, with no claim
made regarding the “optimality of design,” and sometimes (2) to ensure “that
the design we are talking about is not merely apparent but also actual.”[24]
What sort of agents are capable of performing
the proposed action of intelligent design? First, of course, they must be intelligent, which in this context means capable of making intentional choices. Human agents are
certainly intelligent in this sense, but one could speak also of choice-making
by some animals as well. However, as noted above, the intelligent agents of
which ID speaks must also be able to effect what was
first chosen, or to actualize what
was first conceptualized.
When considering embodied
intelligent agents, such as humans or animals, we have no difficulty
envisioning how the dual action of conceptualizing and actualizing might be
carried out. Paley’s artisan-watchmaker could both conceive of an appropriate
mechanical clockwork and then proceed to form the various parts and to assemble
them into a functional watch. However, when ID advocates speak of biotic
systems in nature as the products of intelligent design action they are
proposing action by an agent of an entirely different sort - an umembodied intelligent agent who can both purposefully
conceptualize something and actualize that conception in some material/physical
structure. For the moment, suppose we set aside the matter of how an unembodied
intelligent agent might engage in the mind-like action of conceptualizing
something, say a bacterial flagellum. Philosophers and theologians have long
presumed it reasonable to posit and reflect on such mind-like action.
The more difficult problem, it seems to me,
arises when ID advocates posit an unembodied intelligent agent acting in such a
way as to effect or modify some physical/material structure. How, for instance,
might an unembodied intelligent agent act on a bacterium with no flagellum to
actualize a flagellum where none had been before? How does intelligence
(now meaning the action of an unembodied, choice-making agent) accomplish that?
Does the unembodied agent somehow force the
various atomic and molecular components into their proper configuration? How
does a non-physical agent exert physical forces?
Dembski freely
admits that he cannot offer any causally specific model for this action, but he
also argues that this should not be seen as a shortcoming of the ID proposal.
After all, “Intelligent design is not a mechanistic theory.”[25]
Yes, but earlier Dembski had suggested that a more substantial proposal
regarding a model for designer action might be forthcoming. “A design inference
therefore does not avoid the problem of how a designing intelligence might have
produced an object, It simply makes it a separate problem.”[26]
It seems, however, that this particular “separate problem” has been permanently
placed in the “solution impossible” file. Dembski’s disclaimer that modeling
intelligent design action is both unnecessary and at the same time a “separate
problem” seems a bit thin and facile.
But Dembski makes
another disclaimer that seems even more difficult to maintain or defend: to posit intelligent design action is not the same as positing a
miracle. In his effort to “get around the usual charge of miracles,”
as Dembski aptly puts it, he defines a miracle in a way designed (in the sense
of mindfully intended)
to avoid the problem. “Miracles typically connote a violation or suspension or
overriding of natural laws.”[27]
That is, where a natural cause was set to make X happen, Y happened instead. A
miracle is a form of “counterfactual substitution.”
According to Dembski, however, intelligent
design action does not necessarily
entail a suspension or overriding of natural laws.
When humans, for instance, act as [embodied] intelligent agents, there
is no reason to think that any natural law is broken. Likewise, should an
unembodied designer act to bring about a bacterial flagellum, there is no
reason prima facie to suppose that this designer did not act consistently with
natural laws. It is, for instance, a logical possibility that the design in the
bacterial flagellum was front-loaded into the universe at the Big Bang and
subsequently expressed itself in the course of natural history as a miniature
outboard motor on the back of E. coli.[28]
What does Dembski
here mean by “the design of the bacterial flagellum” that may have been
“front-loaded into the universe at the Big Bang”? In the larger context of
Dembski’s argument, I am led to conclude that “design,” used as a noun in this
instance, here denotes both a plan and a provision - a plan for actualizing the
flagellum and a provision of all of the initial conditions and formational
capabilities needed to ensure that the plan would be carried out in detail.
Front-loading a universe for the actualization of some biotic structure appears
to be comparable to providing a computer with both a specific program and all
of the computational capabilities needed to ensure that some particular result
would be generated.
Elsewhere in No Free
Lunch, however, Dembski makes it abundantly clear that he is no
friend of this “front-loading” hypothesis. Dembski’s Intelligent Designer is
one who interacts with the universe in the course of time. The design action posited to
actualize the bacterial flagellum, as we shall see, is an action that occurs
long after the Big Bang. Furthermore, since Dembski argues vigorously that the
assembling of E. coli’s flagellum could not have come about naturally, the
question is, How could the Intelligent Designer bring about a naturally impossible outcome by interacting with a bacterium
in the course of time without either a suspension or overriding of natural
laws?[29]
Natural laws (which entail the probabilities for various outcomes) would have
led to the outcome, no flagellum. Instead, a flagellum appeared as the outcome
of the Intelligent Designer’s action. Is that is not a miracle, what is? How
can this be anything other than a supernatural intervention?
Dembski does
attempt an answer to this question. “The physical world consists of physical
stuff, and for a designer to influence the arrangement of physical stuff seems
to requirethat the designer intervene in, meddle
with, or in some way coerce this physical stuff.”[30]
... “But what if the designer is not in the business of moving particles but of
imparting information? In that case nature moves its own particles, but an
intelligence nonetheless guides the arrangement.”[31]
In response to concerns that I have often raised about the character of design
as an action, Dembski says, “Van Till asks whether the design that design
theorists claim to find in natural systems is strictly mind-like ... or also
hand-like.... But Van Till has omitted a
third option, namely, that design can also be word-like (i.e., imparting
information to a receptive medium).”[32]
So, as we try to picture an unembodied intelligent designer adding a flagellum
to E. coli, we must envision the bacterial cell as a “receptive medium” to
which the designer, in word-like fashion, imparts
information concerning the process of assembling a rotary propulsion
system. Might we find it difficult to understand how this designer-speech works
without entailing a suspension or overriding of natural processes? Yes, of
course we would, but difficulty in understanding is not unusual in science,
suggests Dembski. “We do not understand how
quantum mechanics works, but we know that it
works. So too, we may not understand how
an unembodied designer imparts specified complexity into the world, but we can know that such a designer imparts specified complexity into
the world.”[33]
I must confess that I do not have such knowledge, but let us move on to
evaluate Dembski’s claim that he does.
The signs of design
How would we come to know that something was
intelligently designed? It’s very straightforward, says Dembski.
There does in fact exist a rigorous criterion for discriminating
intelligently caused from unintelligently caused objects. ... I call it the complexity-specification criterion. When intelligent agents
act, they leave behind a characteristic trademark or signature - what I define as
specified complexity. The complexity-specification criterion detects design by
identifying this trademark of designed objects.[34]
Whenever we infer design we must establish three things: contingency, complexity, and
specification.[35]
An object/event is said to be contingent if, while it is fully consistent with natural
laws, it is not wholly determined by them and represents only one outcome among
several possible outcomes of natural processes. Complexity
is related inversely to probability. Highly complex objects have a low
probability of being actualized naturally. Dembski looks for objects whose
probability of actualization by natural means is less than what he calls the
“universal probability bound,” which has the value 10–150. For some
event/object to be specified it
must exhibit a distinctive pattern that is detachable from
the particular event/object itself. A detachable pattern might, for instance,
correspond to some independently derivable sequence of numbers or letters that
has no necessary connection to the object/event being subjected to the
complexity-specification criterion. For example, if SETI researchers received a
radio signal representing the first 100 prime numbers they would be justified
in concluding that the signal exhibited a detachable pattern that had no
necessary relationship to the electromagnetic waves that carried it.
In Dembski’s language, if some event/object is contingent (not the outcome of any deterministic natural
law), and sufficiently complex (its probability of
natural actualization is less than 10–150), and specified,
then it exhibits specified complexity. The central
argument of No Free Lunch is that objects/events
that exhibit specified complexity cannot be actualized by natural
processes alone and must, therefore, be the outcome of intelligent design, in the sense consistent with the way in
which all of the key terms have been defined above.
Establishing the contingency of some
event/object is ordinarily a rather simple matter. Establishing complexity and
specification, however, is difficult (perhaps impossible), as our case study of
the bacterial flagellum will illustrate.
E. coli and its Rotary Propulsion System: Dembski’s Flagship Case for Design
Escherichia coli is a species of bacteria
commonly found in the human intestinal tract and has been used extensively for
studies of molecular genetics. Its single, rod-shaped, prokaryotic cell is
surrounded by a rigid but porous cell wall. Immediately inside the cell wall is
the plasma membrane, which effectively functions as the barrier between the
interior of the cell and its external environment. The nucleoid within the cell
contains the cell’s circular DNA molecule, which houses E. coli’s
genetic information.
The genome of E. coli - the instructional
information residing in the genetically relevant portion of its DNA - consists of
about 4.7 million base pairs, representing approximately 4000 genes. These
genes specify the particular character of the numerous RNA and protein
molecules that carry out the multitude of diverse tasks that enable the cell to
act and interact as it does. The formation, structure and functions of the cell
and its component parts are expressions of the information coded in the base
pair sequences that comprise the E. coli genome.
Protruding outward from the E. coli cell wall
is a hair-like filament made of the protein flagellin. The base of the filament
is attached via a bent “hook” structure to a miniature rotary drive mechanism
embedded in the plasma membrane and constructed from several types of protein
molecules. This configuration of motor, hook and filament constitutes the
flagellum system. The energy for the flagellum’s rotary motion is derived from
a proton gradient across the bacterial membrane.
A cutaway sketch of the flagellum, complete
with its rotary motor system, appears prominently on the front cover of
Dembski’s book, No Free Lunch. Dembski uses the
bacterial flagellum as the principal example of what he considers to be an intelligently designed biotic
structure.
The flagellum is an acid-powered rotary motor with a whip-like tail
whose rotating motion enables a bacterium to navigate through its watery
environment. Behe shows that the intricate machinery of this molecular
motor - including a rotor, a stator, O-rings, bushings, and a drive
shaft - requires the coordinated interactions of about thirty proteins and
another twenty or so proteins to assist in their assembly.[36]
On a Darwinian view, a bacterium with a flagellum evolved via the
Darwinian selection mechanism from a bacterium without a flagellum. For this
mechanism to produce the flagellum, chance modifications have to generate the
various proteins that constitute the flagellum and then selection must preserve
them, gather them to the right location in the bacterium, and then properly
assemble them.[37]
With regard to a particular biochemical system like the bacterial
flagellum, intelligent design asserts that “No undirected natural process could
produce this system”[38]
In the eyes of design theorists like Behe and
Dembski, the bacterial flagellum presents the Darwinian
mechanism with an insurmountable problem. Employing some of the ID
vocabulary that we have already examined, the nature of the problem as they see
it can be stated as follows:
-
The bacterial flagellum displays specified complexity.
-
Specified complexity in biotic systems
cannot be generated by the Darwinian mechanism,
which relies on chance.
-
Therefore the bacterial flagellum must
have been intelligently designed - that is, it could
have been actualized only with the assistance of form-conferring interventions
by an unembodied intelligent agent.
Each of these three statements could, I
believe, be successfully contested, but it should be clear that if the first of
these fails, then Dembski’s whole system of design inferences built on the
premise that specified complexity is demonstrably present
but naturally impossible also fails. Therefore, let us examine
statement 1) more closely.
To say that the bacterial flagellum exhibits
specified complexity requires the demonstration that the flagellum is both complex and specified,
where the meaning of each of these two terms must be taken from Dembski’s
development of the complexity-specification criterion. We shall deal with each
of these two requirements individually, beginning with complexity.
Is the flagellum complex? General considerations
Recall that, according to Dembski, to say
that any biotic system X (such as the bacterial flagellum) is complex is to say that the probability of its actualization
(its coming to be assembled or constructed as a distinct biotic structure) must
be less than the “universal probability bound,” a = 10–150;
or, to say it more concisely, X is complex if P(X) < a.[39] Note that
this makes the “complexity” of X a property, not of X itself, but of the means
by which it came to be actualized. This unorthodox employment of the word complexity is an essential element in Dembski’s case for
intelligent design.
Dembski’s criterion
for complexity is quite easy to state, but that does not mean that it is
equally easy to apply. The principal difficulty arises when we examine
precisely what has to be taken into account when P(X), the probability that X
will be actualized, is computed (or estimated). Two considerations lead me to
the same conclusion regarding what factors the computation P(X) must take into
account.
First, Dembski calls attention to the
importance of computing P(X) in the context of all available “probabilistic
resources that describe the number of relevant ways an event might occur.”[40]
“The important question therefore is not What is the probability of the event
in question? but rather What does its probability become after all the relevant
probabilistic resources have been factored in?”[41]
In the context of applying the complexity-specification criterion, the relevant
probability is the probability that X came to be actualized as the outcome of
unguided natural processes, whether these are a) pure chance phenomena, b)
regularities described by deterministic natural laws, or c) the joint action of
chance and regularity. For the sake of convenience, let us use the notation
P(X|N) to denote the probability that X will be actualized by the joint action
of all relevant natural processes, N. (Remember that this “N” is what Dembski
most often, but not always, means by the term,
“chance hypothesis.”) The complexity requirement can now be stated more clearly
as: X is complex if P(X|N) < a.
Second, when Dembski develops his
mathematical system for dealing with the role of natural processes in
generating complex specified information (equivalent to specified complexity)
he argues that “stochastic processes (representing nondeterministic natural
laws and therefore the combination of chance and necessity) ... constitute the
most general mathematical formalism” for dealing with both chance and necessity
at the same time. “Natural causes are properly represented by nondeterministic
functions (stochastic processes).”[42]
For the moment I need not agree at all with the way in which Dembski argues his
case that “natural causes are incapable of generating complex specified
information.” (In fact, I will later argue that natural causes can have the
effect of making the generation of specified complexity wholly unnecessary.)
The important consideration for the moment is simply to note that in
determining the complexity of some X, all relevant natural
causes - what Dembski often calls the “chance
hypothesis,” or the joint action of both chance and necessity - must
be taken into account. In Dembski’s system, testing for the presence of
specified complexity must be done in the context of assessing the potential
contributions of all relevant natural causes to the actualization of the object
in question.
By either route, we come to the same
conclusion: To determine if X is complex (using
Dembski’s meaning of the term rather than common usage) we need to compute the
value of P(X|N), the probability that X could be actualized by the joint action
of all relevant natural processes - all pure chance
opportunities, all regularities
described by deterministic laws, all contingent histories influenced by evolutionary
algorithms, and the like. If this P(X|N) < a, then Dembski
counts X as exhibiting sufficient complexity to proceed with the question
regarding its specification.
But there is, of course, an obvious epistemic
difficulty here. In no case do we know with certainty all
relevant natural ways in which some biotic system may have historically come to
be actualized. If “N” represents all relevant
natural causes, both known and unknown, and if we use a lower case “n” to
designate only those natural causes that are known
to be relevant, then it is clear that the best we can do is calculate P(X|n),
which is most likely to be considerably less than P(X|N).
In some cases this limitation of knowledge
might be inconsequential. If we know enough to make the calculated value of
P(X|n) > a, then the question of complexity can be settled (X is not
complex) without an exhaustive knowledge of all relevant natural processes. But
what if our knowledge is inadequate to do the probability calculations? What
if, for instance, we were able to propose one or more plausibility arguments
regarding the kinds of natural processes that are likely to contribute to
P(X|N), but were not yet able to translate these arguments into numerical
values for probability?
Dembski does seem
to recognize this as a problem when he remarks, “Now it can happen that we may
not know enough to determine all the relevant chance hypotheses [which here, as
noted above, means all relevant natural
processes (hvt)]. Alternatively, we might think we know the relevant
chance hypotheses, but later discover that we missed a crucial one. In the one
case a design inference could not even get going; in the other, it would be
mistaken.”[43]
In principle, this epistemic problem should introduce a considerable degree of
modesty in all assessments of probability values related to the question of the
complexity of any particular biotic system. Complexity - in the unorthodox sense
that Dembski wishes to use this term in his complexity-specification
criterion - is an elusive quality. Our ability to determine the presence or
absence of it is severely hampered by our limited state of knowledge regarding
the specific way in which natural causes have contributed to the formation of
biotic structures.
One thing we can say, however, is that the
more we learn about the self-organizational and transformational feats that can
be accomplished by biotic systems, the less likely it will be that the
conditions for complexity - as Dembski employs
this term in relation to specified complexity - will
be satisfied by any biotic system.[44]
For example, in reference to the power of evolutionary algorithms - natural
processes that effectively search for increasingly better performance at some
task - Dembski acknowledges that “An evolutionary algorithm acts as a probability amplifier. ... But a probability amplifier is also
a complexity diminisher.”[45]
This is true not only for evolutionary algorithms, but for any natural cause
that functions to explore the “possibility space” of useful biotic systems and
to submit novel variations to the test of viability.
On numerous occasions Dembski asserts, in
effect, that “natural causes cannot generate specified complexity.” Given the
definition of specified complexity, however, such statements are, at best, only
trivially true. They are nothing more than tautological statements. The
principal requirement for exhibiting specified complexity is the requirement
that some structure/system cannot be (or is highly unlikely to be) actualized
by natural causes. The question is, however, Are there any actual objects that
demonstrate this quality? If there are no biotic systems that actually have
this Dembski-defined quality of specified complexity,
then there would be no need to “generate” it in the first place.
The subtitle of No Free
Lunch is Why Specified Complexity
Cannot Be Purchased Without Intelligence. Why not? Because “cannot
be purchased without intelligence” is effectively included in the definition of
specified complexity! Demonstrating that some object actually exhibits
specified complexity depends upon the prior demonstration that natural causes
are effectively unable (because of improbability barriers) to actualize that
object. The trivial truth of ID’s fundamental proposition lies in carefully
crafted definitions.
In the absence of a full knowledge of the
universe’s formational capabilities, computed values for P(X|n) might give the appearance of complexity where there is no actual complexity. The appearance of complexity in the
absence of actual complexity constitutes a false positive indication of the
need for non-natural action. In the light of later discoveries of previously
unknown natural formational or transformational processes, this apparent
complexity would simply vanish like ground fog vaporized in the warmth of
sunlight.
And if no biotic systems have this quality of
complexity, and thus no specified complexity, then Dembski’s prohibitions
regarding their natural formation are inconsequential. All of the biotic
systems relevant to biotic evolution are free to form as naturally as biologists
have long proposed. No free lunch available? No problem; no lunch needed.
But what about the bacterial flagellum in
particular? Dembski is quite confident that he has demonstrated that it is more
than sufficiently complex (difficult to assemble naturally) to satisfy the
complexity portion of the complexity-specification criterion. How did he do the
computation, and what is the standing of his conclusion?
Is the flagellum complex? Computing the crucial
probability.
Following Behe, Dembski describes the bacterial
flagellum as an “irreducibly complex system that is unattainable by the
Darwinian mechanism.”[46]
He then seeks “to show how irreducible complexity is a special case of
specified complexity, and ... to sketch how one calculates the relevant
probabilities to eliminate chance and infer design for such systems.
Determining whether an irreducibly complex system exhibits specified complexity
involves two things: showing that the system is specified and computing its
probability.... Specification is never a problem.”[47]
We will deal with that glib remark about specification shortly, but our
immediate concern is with Dembski’s attempt to compute P(flag|N), the
probability that E. coli’s flagellum was actualized by the joint action of all
relevant natural processes.
Curiously, Dembski not only rejects any
proposal consistent with the gradualism that ID presumes to be an essential
feature of the Darwinian mechanism, he also effectively ignores the fundamental
role that genes play in providing the instructions for the development of
cellular structures. Instead, Dembski simply asserts that the probability in
question must be computed by treating the bacterial flagellum as a
chance-assembled discrete combinatorial object. A
discrete combinatorial object (dco) is an object that is composed of particular
kinds of building blocks that must first be gathered into one location and then
configured in a particular arrangement to form the complete object. According
to Dembski, the probability that such an object would form naturally is the
product of three distinct probability factors. P(dco) = P(orig) x P(local) x
P(config) where
P(orig) = the origination probability = the probability that the requisite
building blocks for the structure in question will originate, by chance,
P(local) = the localization
probability = the chance probability of localizing these building
blocks in one place once they become available, and
P(config) = the configuration probability = the chance probability of
configuring the building blocks into the particular structure once they are
localized.
Dembski repeatedly
refers to these probability factors as probabilities that some process
(origination, localization, or configuration) will successfully occur “by
chance.” Remembering that in ID literature the term “by chance” can mean either
“by pure chance” or “by all relevant natural processes,” how can we tell which
meaning is here intended? In context, and given Dembski’s repeated references
to these same phenomena as being wholly “random” in character, it would appear
that the “pure chance” meaning is the primary meaning here intended. Dembski’s
method of computation affirms that interpretation.
So, then, we are asked to imagine a bacterial
flagellum arising from the pure chance gathering of approximately 50 of the
right kinds of proteins (and in the correct proportions) at some spot in the
vicinity of the cell wall and plasma membrane of E. coli and then, again by
chance, happening to configure themselves into a functioning rotary propulsion
system for this bacterial cell.
Not surprisingly, Dembski’s computations and
estimations of the three probability factors lead him firmly to the expected
conclusion: Considered as a discrete combinatorial
object that must self-assemble from the chance localization of the requisite,
chance-assembled molecular components, the probability of a flagellum
assembling itself and attaching itself to the cell membrane of E. coli is
exceedingly small in comparison to the universal probability bound. By
Dembski’s measure, it is demonstrable beyond any shadow of doubt that bacterial
flagella cannot self-assemble as discrete combinatorial objects.
Note carefully, however, what Dembski has
actually done with his probability computation. By his own definition of
complexity, the probability value he needs is P(flag|N), the probability that
the flagellum could form by the joint action of all relevant
natural means. However, given the epistemic limitation we noted
earlier, the best he could possibly do would be to compute P(flag|n), the
probability that the flagellum could form by the joint action of known natural means. But this is not
what he actually computed. What Dembski computed instead is P(flag|dco), the
probability that the flagellum could form by pure chance
alone as a discrete combinatorial
object.
But, of course, no biologist
has ever taken the bacterial flagellum to be a discrete combinatorial object
that self-assembled in the manner described by Dembski.Dembski has not defeated any actual biological
proposition. He has slain nothing more than an imaginary dragon - a fictitious
adversary that Dembski himself has fabricated from a stack of rhetorical straw.
E. coli bacteria possess flagella, not
because flagella self-assemble and self-attach to the cell membrane, but
because the genome of E. coli came to include in its genetic library - the
instruction manual that enables the cell to perform a vast number of functional
and formational operations - the coded instructions for growing the flagellar
propulsion system. That being the case, the question that Dembski
needed to deal with was not, Could the flagellum self-assemble as a discrete
combinatorial object? but rather, Could that portion of the E. coli genome that
codes for the production of a flagellum have come about by natural means?
Stating the question in this manner, however,
places Dembski in a difficult and awkward position.
The awkward element is simply that he failed to deal with this fundamental
question in any substantive way. By focusing his energies on an attempt to
compute the mathematical probability that a bacterial flagellum would
self-assemble from a highly improbable environment of specialized proteins, Dembski effectively chose to ignore the role of genetics in
the formation of biotic systems. That is an astounding choice. But there may be
reasons for taking that questionable option. Choosing to deal realistically
with the role of genetics would have presented Demski
with a formidable menu of strategic difficulties.
The question on the table remains, Could that
portion of the E. coli genome that codes for the production of a flagellum have
come about by natural means? To answer affirmatively would be to say that the
bacterial flagellum was not intelligently designed - that it needed no
supplemental, non-natural action to actualize it. The ID movement would then
have to abandon the bacterial flagellum as its flagship example of an
intelligently designed biotic structure.
To answer negatively, on the other hand,
would introduce an equally awkward difficulty. To single out the flagellar portion of the E. coli genome as the only subset
of base-pair sequences that required non-natural action to configure them
correctly forces that portion into a special category relative to the rest of
the genome. Why would the flagellar portion need
supplemental non-natural action if the rest of the genome did not? Would that
not seem odd? Indeed it would, and Dembski knows it.[48]
We must grant, then, that Dembski
expects some non-flagellar portions of the E. coli
genome to be equally in need of non-natural configurational
action. There is, however, a
certain irony here in Dembski’s reasoning. In effect,
he is presuming that if designer action (form-conferring intervention by an
unidentified and unembodied choice-making agent) is
required for configuring what I might call “the flagellar
2%” of the E. coli genome, then a person may reasonably infer that similar
designer action was required for forming some portions of the other 98%. Dembski does not offer one iota of supportive empirical
evidence for this conjecture. He does not provide even a hint regarding what
other structural components of E. coli might need that supplemental designer
action. As it stands, Dembski’s position is based on
nothing more than a grand extrapolation from one purported “instance” of
designer action. How does Dembski justify this sort
of unconstrained extrapolation in the face of his claim that the ID perspective
is based solidly on scientific
evidence and his injunction that, “Science must form its
conclusions on the basis of available evidence, not on the possibility or
promise of future evidence”?
Interestingly, the E. coli genome does
contain genes for the formation of structures remarkably similar to portions of
the flagellum system. Bacteria like E. coli possess systems for the secretion
of certain proteins from the cytoplasm in the cell interior to the
extracellular space beyond, often directly into host cells. Several structures
are known to accomplish this secretion function. Of special relevance here is
the type III secretion apparatus, composed of about 20 proteins, most of which
are homologous to the to components of the flagellar biosynthesis apparatus.[49]
To put it as simply as possible, the type III secretion apparatus and the
“motor apparatus” of the bacterial flagellum employ similar building blocks and
share numerous structural features. Thus, the genetic coding for one of these
structures is going to be closely related to the genetic coding for the other.
The question now becomes, What is that
relationship? Were these coding sequences independently configured by an
intelligent designer? If so, where is Dembski’s
“design-theoretic” analysis of the secretion apparatus? If not, how could the
coding for the secretion apparatus arise naturally if the coding for the structurally
similar flagellum required non-natural configurational
action?
We must remember, however, that Dembski did not actually argue for designer action
(actualizing particular molecular structures) to configure the genetic codes for either the secretion apparatus or the
flagellum His argumentation was instead focused solely on the probability that
the flagellum itself could be actualized by
the joint action of all natural processes (the “chance hypothesis”). Well,
then, suppose that the flagellum really was assembled for the first time by the
form-conferring action of an unembodied intelligent designer independently of
genomic instructions. Since instructions for the development of flagella are
now part of the E. coli genome, are we to believe that the designer added those
instructions to the genome as a separate act? Are there two independent
form-conferring acts here - one for the first flagellum and another for the
genomic instructions to produce all subsequent flagella?
Presumably, Dembski
could argue that a single designer-action would be sufficient - infusing the E.
coli genome with the genetic information
needed to effect the construction of the flagellum. But then the entirety of Dembski’s argument and computation based on treating the
flagellum as a chance-assembled discrete combinatorial object would become
irrelevant to the question of complexity. Dembski would have to deal openly
with the genome and the relationship of its coding for the flagellum with its
coding for structurally similar systems like the type III secretion apparatus.
In fact, he would have to scrap his original calculation regarding the
flagellum as a dco and develop an entirely new genetic approach to computing
the probability that the flagellum was formed naturally.
Are the flagella of the E. coli bacteria
complex? Dembski thinks so, but his strategy of treating the flagellum as a
discrete combinatorial object is far off the mark of demonstrating this. The
probability value that he claims to have computed has no biological relevance
to the question of how flagella of E. coli bacteria were first actualized.
Is the flagellum specified?
If the complexity of
the bacterial flagellum - where complexity is defined by Dembski’s own unorthodox
criterion - has not been successfully demonstrated, then the matter of its specification could, perhaps, be set aside as no longer
relevant. Nonetheless, let us look at Dembski’s development of
this portion of his argument for the specified complexity of the flagellum
In several places in No Free Lunch,
Dembski goes to considerable lengths to state the requirements that
specification and detachability must satisfy in the careful language of logic,
set theory and the like. The index of the book cites more than 40 pages dealing
with the topics of “specification” and “detachability,” plus approximately 100
page-citations for closely related topics such as “specifiability,”
“specificational resources,” “biological specificity,” and “specified
complexity.”
However, when it comes time for Dembski to
support his conviction that the bacterial flagellum is specified, the procedure
becomes considerably more casual, almost facile. Speaking on the specification
of biological systems in general, Dembski simply asserts that, “Biological
specification always refers to function. An organism is a functional system
comprising many functional subsystems. In virtue of their function, these
systems embody patterns that are objectively given and can be identified
independently of the systems that embody them. Hence these systems are
specified in the sense required by the complexity-specification criterion.”[50]
In these four brief sentences the foundation of Dembski’s entire strategy for
certifying the specification of biotic systems is laid.
Addressing the particular question regarding
whether the bacterial flagellum is specified, Dembski confidently declares
that, “Specification is never a problem. The irreducibly complex systems we
consider, particularly in biology, always satisfy independently given
functional requirements.... For instance, in the case of the bacterial flagellum,
humans developed outboard rotary motors well before they figured out that the
flagellum was such a machine.”[51]
The flagellum functions like an outboard rotary motor. The rotary outboard
motor pattern represents a functional requirement independent of biological
systems. Therefore, concludes Dembski, the flagellum is specified.
This use of a human contrivance like the
outboard motor as the independent, detachable pattern that certifies the
flagellum as being specified bears further scrutiny. Following the quotation
above, Dembski continues: “This is not to say that for the biological function
of a system to constitute a specification humans must have independently
invented a system that performs the same function. Nevertheless, independent
invention makes the detachability of a pattern from an event or object all the
more stark. At any rate, no biologist I know questions whether the functional
systems that arise in biology are specified.”[52]
“Specified” in the same technical sense
defined by Dembski? Specified by exhibiting an object/event-independent
pattern? Not necessarily. We need to look closely at the way in which Dembski
first introduced the concepts of specification and detachability. “For a
pattern to count as a specification, the important thing is ... whether in a
certain well-defined sense it is independent of
the event it describes. Drawing a target around an arrow already embedded in a
wall is not independent of the arrow’s trajectory.”[53]
Patterns that satisfy this condition of independence are designated as detachable. To determine if some particular pattern is
detachable, the following question must be answered affirmatively, says
Dembski: “Given an event whose design is in question and a pattern describing
it, would we be able to explicitly identify or exhibit that pattern if we had
no knowledge of which event occurred?”[54]
To illustrate this test, Dembski uses the
“event” of coin-flipping and looks at numerical patterns that might be
generated by the sequence of heads and tails transcribed into strings of 0’s
and 1’s. If a string corresponding to the first 100 digits written in binary
form appeared, we would be warranted in believing that the sequence did indeed
conform to a detachable pattern. That numerical pattern
could easily be identified independently of the event
of coin flipping that generated it.
However, to move from Dembski’s pattern
illustrations involving sequences of numbers or alphabetical letters (as in a
sentence of words) to biological systems requires, I believe, far more than a
hand-waving reference to biological functions playing the role of detachable
patterns. On what basis can Dembski assert, for instance, that “Biological
specification always refers to function”? Is this any different from “drawing a
target (representing some particular biological function) around an arrow
already embedded in a wall (representing a functioning organism)”? What is the
specific function of the flagellum that warrants being counted as a detachable specification
pattern? Its function as a means of locomotion? Apparently not. If that were
the case, would we not find ID books filled with claims that all animals
equipped with any means of locomotion were intelligently designed?
So, then, do only rotary
motor systems count as biological propulsion systems exhibiting a detachable
pattern in their function? On what basis would other propulsion systems be
disqualified? How narrowly does Dembski define biological function? And where
does he develop a system for determining that some functions count toward
specification and others do not? If it really is the case that, as Dembski
states, “Biological specification always refers to function,” wouldn’t all biological functions then count as detachable patterns
exhibited by biological systems?
Apparently not. Although the E. coli cell is
a system rich with interacting structures and subsystems, each with an
important biological function, only the rotary propulsion function is cited as
being specified. On what basis is the function of the flagellum singled out as
the only bacterial function that is sufficiently spectacular to serve as
illustrative of a purported need for cinfigurational
assistance by an unidentified and unembodied
designer?
However, perhaps there is another approach
that deserves investigation. In our reflections on the question, Is the
flagellum complex? we argued that the focus of attention should be shifted from
the flagellum structure itself to the portion of the E. coli genome that coded
for its development. If that is correct, as it must be, then our search for a
detachable pattern should be directed toward the base pair sequence in E.
coli’s circular DNA molecule. Surely there is an identifiable pattern there
that characterizes the genetic coding for the flagellum, right? Right, indeed.
But the crucial question is, Is that pattern detachable
from the event under consideration, E. coli develops
a flagellum?
The answer to this question is a resounding,
No. The pattern in the base-pair sequence associated with this
flagellum-actualization event is unique to that event and to that event alone.
The pattern and the event are not independent, but stand in a one-to-one
relationship. This pattern is the epitome of non-detachability. The base pair
sequence pattern is like a blueprint for the flagellum. But the pattern itself
would never be recognized unless it were first provided the appropriate
environmental context and allowed to express itself in the formation of a flagellar appendage to a bacterial cell. The base-pair
sequence pattern in question is not detachable, and the flagellum is not
specified in the particular sense required by Dembski’s
complexity-specification criterion.
Bacterial Flagella and Dembski’s
Case for Intelligent Design: Closing Arguments
Earlier in this critique we outlined
Dembski’s case for the proposition - bacterial flagella are
intelligently designed - as follows:
-
The bacterial flagellum displays specified complexity.
-
Specified complexity in biotic systems
cannot be generated by the Darwinian mechanism,
which relies on chance.
-
Therefore the bacterial flagellum must
have been intelligently designed - that is, it could
have been actualized only with the assistance of form-conferring interventions
by an unembodied intelligent agent.
We then focused our attention on the first of
these statements and asked, Does the bacterial flagellum exhibit “specified
complexity” as it is defined by Dembski? In order to
do that it would have to be a) sufficiently complex, and b) specified.
Is the bacterial flagellum sufficiently
complex? Using Dembski’s own criterion, only if the probability of its being
actualized by the joint action of all natural causes is less than the universal
probability bound. Dembski attempted to demonstrate this to be true by treating
the bacterial flagellum as if it were a discrete combinatorial object
actualized by the pure chance gathering of 50 of the right kinds of proteins
(and in the correct proportions) at some spot in the vicinity of the cell wall
and plasma membrane of E. coli and then, again by chance, happening to
configure themselves into a functioning rotary propulsion system for this
bacterial cell. The only natural formational process that Dembski
considered in his probability computation was self-assembly by pure
happenstance.
We reject that argument as being a totally
unrealistic caricature of how the flagellum is actualized and an approach that
totally ignores the role of the bacterial genome in coding for all of the
structures and functions that contribute to the nature of E. coli. E. coli
bacteria possess flagella, not because flagella self-assemble and self-attach
to the cell membrane, but because the genome of E. coli came to include in its
genetic library the coded instructions for growing the flagellar
propulsion system. Dembski’s case for the complexity (as he defines it) of the bacterial flagellum
fails.
Is the bacterial flagellum specified? Using
Dembski’s own criterion, only if it exhibits a pattern that is
detachable - wholly independent of the event that produced it. Appearing to set
aside his laboriously crafted formalism regarding the specification and
detachability requirements, Dembski simply asserts that in the case of biological systems specification always refers to function,
and declares that biological functions are inherently detachable from the
particular biological systems that instantiate them.
We reject that argument for a number of
reasons. First, the general principle that biological function counts for
specification was never established by Dembski. Second, his application of this
principle appears to be entirely ad hoc. Dembski provides no systematic means
for concluding that the function of the flagellum should count as a detachable
specification while other equally remarkable biological functions of E. coli go
unmentioned. If none of the other biological functions of the bacterium count
as sufficiently remarkable to serve as a detachable specification, then neither
should the function of the flagellum. Dembski’s case for the specification (as he defines it) of the flagellum fails.
Finally, there is the broad question
concerning Dembski’s rhetorical use of key terms like complexity
and specification. On the question of
specification, for instance, Dembski asserts that, “no biologist I know
questions whether the functional systems that arise in biology are specified.”[55]
The question is, however, Is Dembski using the term “specified” in the same way
as the biologists he has in mind? The answer, I believe, is, No. Dembski treats
the presence of biological function as if it constituted a detachable pattern
independent of the organism under scrutiny. For Dembski, biological function is
one of the qualities of a complex organism that only intelligent intervention
could produce. For biology, on the other hand, biological function plays nearly
the opposite role. Biological function is the very capacity of an organism that
gives it the ability to respond to its environment in the manner described by a
rich menu of dynamically changing fitness functions, a responsive phenomenon
that lies at the heart of evolutionary dynamics.
A similar concern about Dembski’s use of key
terms arises in regard to the meaning of “complexity.” After quoting a number
of prominent biologists regarding the scientific challenge of accounting for
the information now resident in complex biological systems, Dembski asks, “But
what sort of information are they talking about?”[56]
He soon answers his question in a way that appears to place their concern
squarely in his own design-theoretic court. “I submit that what they have in
mind is specified complexity, or what equivalently we have been calling ...
complex specified information. Certainly the complexity of biological
information is not at issue.”[57]
But of course this bold assertion could be true only if Dembski is using the
term “complexity” in the same way as the persons he quoted, which seems not to
be the case. As we saw in our general considerations on complexity, the
“complexity” that Dembski computes is a property, not of some biotic system
itself, but of the means by which it becomes actualized. That is why, for
instance, he treated the bacterial flagellum as if it were a chance-assembled
discrete combinatorial object and judged its complexity on the basis of the
probability of its coming to be actualized by nothing more than pure accident.
Most biologists, on the other hand, use the term “complexity” as the name of
something quite different - a structural or functional quality of the biotic
system itself.
But “specification” and “complexity” are not
the only terms that Dembski, like other leaders of the ID movement, employs
rhetorically with unorthodox meanings. Recall, for instance, that to be
“intelligently designed” is, in effect, to be assembled
with the aid of form-conferring (or information-infusing) action performed by
an unnamed and unembodied choice-making agent. Recall also that when
this unembodied intelligent agent brings about a
naturally impossible outcome, it is not a “miracle.” And recall that
“chance hypothesis” most often means all hypotheses, postulates
and theories concerning the natural causation of events. The case
for ID relies on a web of words that have been assigned extraordinarily unusual
meanings.
Given this character trait of ID literature,
including such works as Dembski’s No Free Lunch,
would it not be appropriate to suggest that Dembski pause to reflect on his own
admonition regarding the need to use words appropriately, consistently, and
with precision to avoid the charge of equivocation? Says Dembski,
“The fallacy of equivocation is the fallacy of speaking out of both sides of
your mouth. It is the deliberate confusing of two senses of a term, using the
sense that’s convenient to one’s agenda.”[58]
On this point Dembski
and I agree. Ironically, however, I find Dembski’s
rhetoric to be riddled with the very equivocation that he condemns.