IS INTELLIGENT DESIGN TESTABLE?
A RESPONSE TO EUGENIE SCOTT
William A. Dembski
<William_Dembski@baylor.edu>
1. Eugenie Scott is a physical anthropologist who as director of the
National Center for Science Education travels the United States warning
audiences about the threat of creationism and unmasking its various guises.
Intelligent design, according to her, is currently the most sinister of these
guises. Scott has developed a standard shtick, which includes not only some
well-worn arguments against creationism and some newer arguments against
intelligent design (which she refers to as "neocreationism") but also
some comedic elements, like the Monty Python wink-wink-nudge-nudge routine,
which
she uses when she wants to make clear to her audiences that the designer of
intelligent design is really none other than the "Big G" of the
Christian faith.
2. Recently (January 18, 2001) Scott presented a lecture at U.C. Berkeley
sponsored by the department of integrative biology and titled "Icons of
Creationism: The New Anti-Evolutionism and Science" (http://ib.berkeley.edu/seminars/index.html).
The title alludes to Jonathan Wells's recent book _Icons of Evolution_,
which critiques the various standard evidences used in textbooks to support
Darwinian evolution. Scott presumably means to turn the tables and show that
intelligent design is similarly open to criticism.
3. Scott's key criticism against intelligent design, both in her talk the
other day and since the early nineties, has been that intelligent design is
untestable. For instance, in an exchange with Stephen Meyer back in 1994 in Insight
magazine, Scott remarked that until design theorists develop a "theo-meter"
(this neologism is hers) to test for design, they are treading water in a sea of
retarded scientific aspirations. In her talk the other day at U.C. Berkeley she
claimed
that intelligent design does not propose any "testable model."
4. The testability objection to intelligent design can be interpreted in
two ways. One is to claim that intelligent design is in principle untestable.
This seems to have been Scott's line in the early nineties. Certainly it is a
hallmark of science that any of its claims be subject to revision or refutation
on the basis of new evidence or further theoretical insight. If this is what one
means by testability, then design is certainly testable. Indeed, it was in this
sense that Darwin tested William Paley's account of design and found it wanting.
It simply won't wash to say that design isn't testable and then in the same
breath say that Darwin tested design and refuted it.
5 . The other way to interpret the testability objection is to claim that
intelligent design may in principle be testable, but that no tests have been
proposed to date. This seems to be Scott's line currently. Indeed, if the
testability objection is to bear any weight, its force must reside in the
absence of concrete proposals for testing intelligent design. Are such proposals
indeed lacking? Rather than looking solely at the testability of intelligent
design, I want also to consider the testability of Darwinism. By comparing the
testability of the two theories, it will become evident that even the more
charitable interpretation of Scott's testability objection does not hold up.
6. In relation to science testability is a very broad notion. It certainly
includes Karl Popper's notion of falsifiability, but it is
hardly coextensive with it and can apply even if falsifiability does not obtain.
Testability as well covers confirmation, predicability, and explanatory power.
At the heart of testability is the idea that our scientific theories must make
contact with and be sensitive to what's happening in nature. What's happening in
nature must be able to affect our scientific theories not only in form and
content but also in the degree of credence we attach to or withhold from them.
For a theory to be immune to evidence from nature is a sure sign that we're not
dealing with a scientific theory.
7. What then are we to make of the testability of both intelligent design
and Darwinism taken not in a generic abstract sense but concretely? What are the
specific tests for intelligent design? What are the specific tests for
Darwinism? And how do the two theories compare in terms of testability? To
answer these questions, let's run through several aspects of testability,
beginning with falsifiability.
FALSIFIABILITY:
7.
Is intelligent design falsifiable? Is Darwinism falsifiable? Yes to the first
question, no to the second. Intelligent design is eminently falsifiable.
Specified complexity in general and irreducible complexity in biology are within
the theory of intelligent design the key markers of intelligent agency. If it
could be shown that biological systems like the bacterial flagellum that are
wonderfully complex, elegant, and integrated could have been formed by a gradual
Darwinian process (which by definition is non-telic), then intelligent design
would be falsified on the general grounds that one doesn't invoke intelligent
causes when purely natural causes will do. In that case Occam's razor finishes
off intelligent design quite nicely.
8. On the other hand, falsifying Darwinism seems effectively impossible.
To do so one must show that no conceivable Darwinian pathway could have led to a
given biological structure. What's more, Darwinists are apt to retreat into the
murk of historical contingency to shore up their theory. For instance, Allen Orr
in his critique of Behe's work shortly after Darwin's Black Box appeared
remarked, "We have no guarantee that we can reconstruct the history of a
biochemical
pathway." What he conceded with one hand, however, he was quick to retract
with the other. He added, "But even if we can't, its irreducible complexity
cannot count against its gradual evolution."
9. The fact is that for complex systems like the bacterial flagellum no
biologist has or is anywhere close to reconstructing its history in Darwinian
terms. Is Darwinian theory therefore falsified? Hardly. I have yet to witness
one committed Darwinist concede that any feature of nature might even in
principle provide countervailing evidence to Darwinism. In place of such a
concession one is instead always treated to an admission of ignorance. Thus it's
not that Darwinism has been falsified or disconfirmed, but that we simply don't
know enough about the biological system in question and its historical context
to determine how the Darwinian mechanism might have produced it.
10 For instance, to neutralize the challenge that the irreducible
complexity of the bacterial flagellum raises against Darwinism, Ken Miller
employs the following argument from ignorance. Like the rest of the biological
community, Miller doesn't know how the bacterial flagellum originated. The
biological community's ignorance about the flagellum, however, doesn't end with
its origin but extends to its very functioning. For instance, according to David
DeRosier, "The mechanism of the flagellar motor remains a mystery."
Miller takes this admission of ignorance by DeRosier and uses it to advantage.
In
Finding Darwin's God he writes: "Before [Darwinian] evolution is
excoriated for failing to explain the evolution of the flagellum, I'd request
that the scientific community at least be allowed to figure out how its various
parts work." But in the article by DeRosier that Miller cites, Miller
conveniently omits the following quote: "More so than other motors, the
flagellum resembles a machine designed by a human."
11. So apparently we know enough about the bacterial flagellum to know
that it is designed or at least design-like. Indeed, we know what most of its
individual parts do. Moreover, we know that the flagellum is irreducibly
complex. Far from being a weakness of irreducible complexity as Miller suggests,
it is a strength of the concept that one can determine whether a system is
irreducibly complex without knowing the precise role that each part in the
system plays (one need only knock out individual parts and see if function is
preserved; knowing what exactly the individual parts do is not necessary).
Miller's appeal to ignorance obscures just how much we know about the flagellum,
how compelling the case is for its design, and how unfalsifiable Darwinism is
when Darwinists proclaim that the Darwinian selection mechanism can account for
it despite the absence of any identifiable biochemical pathway.
CONFIRMATION:
12.
What about positive evidence for intelligent design and Darwinism? From the
design theorist's perspective, the positive
evidence for Darwinism is confined to small-scale evolutionary changes like
insects developing insecticide resistance. This is not to deny large-scale
evolutionary changes, but it is to deny that the Darwinian mechanism can account
for them. Evidence like that for insecticide resistance confirms the Darwinian
selection mechanism for small-scale changes, but hardly warrants the grand
extrapolation that Darwinists want. It is a huge leap going from insects
developing
insecticide resistance via the Darwinian mechanism of natural selection and
random variation to the very emergence of insects in the first place by that
same mechanism.
13. Darwinists invariably try too minimize the extrapolation from
small-scale to large-scale evolution, arguing that it is a failure of
imagination on the part of critics to appreciate the wonder-working power of the
Darwinian mechanism. From the design theorist's perspective, however, this is
not a case of failed imagination but of the emperor's new clothes. Yes, there is
positive evidence for Darwinism, but the strength and relevance of that evidence
on behalf of large-scale evolution is very much under dispute, if not within the
Darwinian community then certainly outside of it.
14. What about the positive evidence for intelligent design? It seems that
here we may be getting to the heart of Eugenie Scott's concerns. I submit that
there is indeed positive evidence for intelligent design. To see this, let's
consider an example that I recycle endlessly in my writings (if only because its
force seems continually lost on Darwinists). Consider the movie Contact
that appeared summer of 1997, based on the novel by Carl Sagan. In the movie
radio astronomers determine that they have established contact with an
extraterrestrial intelligence after they receive a long sequence of prime
numbers, represented as a sequence of bits.
15. Although in the actual SETI program (Search for Extraterrestrial
Intelligence) radio astronomers look not for something as flamboyant as
prime numbers but something much more plebeian, namely, a narrow bandwidth of
transmissions (as occur with human radio transmissions), the point nonetheless
remains that SETI researchers would legitimately count a sequence of prime
numbers (and less flamboyantly though just as assuredly a narrow bandwidth
transmission) as positive evidence of extraterrestrial intelligence. No such
conclusive signal has yet been observed, but I can assure you that if it were to
be observed, Eugenie Scott would not be complaining about SETI not having
proposed any "testable models." Instead she would rejoice that the
model had been tested and decisively confirmed.
16. Now what's significant about a sequence of prime numbers from outer
space is that they exhibit specified complexity -- there has to be a long
sequence (hence complexity) and it needs to display an independently given
pattern (hence specificity). But what if specified complexity is also exhibited
in actual biological systems? In fact it is -- notably in the bacterial
flagellum. Internet mavens have been pestering me for actual calculations of
complexity involved in such systems. I address this in my forthcoming book (No
Free Lunch), but such calculations are out there in the literature (cf. the
work of Hubert Yockey, Robert Sauer, Peter Rüst, Paul Erbrich, Siegfried
Scherer, and most recently Douglas Axe -- I'm not enlisting these individuals as
design advocates but merely pointing out that methods for determining specified
complexity are already part of biology).
17. Even so, it appears that Eugenie Scott would not be entirely happy
admitting that intelligent design is positively confirmed once some clear-cut
instances of specified complexity are discovered in biological systems. Why not?
As she put it in her U.C. Berkeley lecture, design theorists "never tell
you what happened." Well, neither do SETI researchers. If a SETI researcher
discovers a radio transmission of prime numbers from outer space, the inference
to an extraterrestrial intelligence is clear, but the researcher doesn't know
"what happened" in the sense of knowing any details about the
radio transmitter or for that matter the extraterrestrial that transmitted the
radio transmission.
18. Ah, but we have experience with radio transmitters. At least with
extraterrestrial intelligences we can guess what might have happened. But we
don't have any experience with unembodied designers, and that's clearly what
we're dealing with when it comes to design in biology. Actually, if an
unembodied designer is responsible for biological complexity, then we do have
quite a bit of experience with such a designer through the designed objects (not
least ourselves) that confront us all the time. On the other hand, it is true
that we possess very little insight at this time into how such a designer acted
to bring about the complex biological systems that have emerged over the course
of natural history.
19. Darwinists take this present lack of insight into the workings of an
unembodied designer not as remediable ignorance on our part and not as evidence
that the designer's capacities far outstrip ours, but as proof that there is no
unembodied designer (at least none relevant to biology). By the same token, if
an extraterrestrial intelligence communicated via radio signals with earth and
solved computational problems that exceeded anything an ordinary or quantum
computer could ever solve, we would have to conclude that we weren't really
dealing with an intelligence because we have no experience of
super-mathematicians that can solve such problems. My own view is that with
respect to biological design humans are in the same position as William James's
dog studying James while James was reading a book in his library. Our
incomprehension over biological design is the incomprehension of a dog trying to
understand its master's actions. Interestingly, the biological community
regularly sings the praises of natural selection and the wonders it has wrought
while admitting that it has no comprehension of how those wonders were wrought.
Natural selection, we are assured, is cleverer than we are or can ever hope to
be. Darwinists have merely swapped one form of awe for another. They've not
eliminated it.
20. It is no objection at all that we don't at this time know how an
unembodied designer produced a biological system that exhibits specified
complexity. We know that specified complexity is reliably correlated with the
effects of intelligence. The only reason to insist on looking for non-telic
explanations to explain the complex specified structures in biology is because
of prior commitment to naturalism that perforce excludes unembodied designers.
It is illegitimate, scientifically and rationally, to claim on a priori grounds
that such entities do not exist, or if they do exist that they can have no
conceivable relevance to what happens in the world. Do such entities exist? Can
they have empirical consequences? Are they relevant to what happens in the
world? Such questions cannot be prejudged except on metaphysical grounds. To
prejudge these questions the way Eugenie Scott does is therefore to make certain
metaphysical commitments about what there is and what has the capacity to
influence events in the world. Such commitments are utterly gratuitous to the
practice of science. Specified complexity confirms design regardless whether the
designer responsible for it is embodied or unembodied.
PREDICTABILITY:
21.
Another aspect of testability is predictability. A good scientific theory, we
are told, is one that predicts things. If it predicts things that don't happen,
then it is tested and found wanting. If it predicts things that do happen, then
it is tested and
regarded as successful. If it doesn't predict things, however, what then? Often
with theories that try to account for features of natural history, prediction
gets generalized to include retrodiction, in which a theory also specifies what
the past should look like. Darwinism is said to apply retrodictively to the
fossil record and predictively in experiments that place an organism under
selection pressures and attempt to induce some adaptive change. But in fact
Darwinism does not retrodict the fossil record. Natural selection and random
variation applied to single-celled organisms offers no insight at all into
whether we can expect multi-celled organisms, much less whether evolution will
produce the various body-plans of which natural history has left us a record. At
best one can say that there is consilience, i.e., that the broad sweep of
evolutionary history as displayed in the fossil record is consistent with
Darwinian evolution. Design theorists strongly dispute this as
well (pointing especially to the Cambrian explosion). But detailed retrodiction
and detailed prediction are not virtues of Darwin's heory. Organisms placed
under selection pressures either adapt or go extinct. Except in the simplest
cases where there is, say, some point mutation that reliably confers antibiotic
resistance on a bacterium, Darwin's theory has no way of predicting just what
sorts of adaptive changes will occur. "Adapt or go extinct" is not a
prediction of Darwin's theory but an axiom that can be reasoned out
independently.
22. Challenging me in American Outlook biologist Alex Duncan
remarked:
"A scientific theory makes predictions about the world around us, and enables us to ask and answer meaningful questions. For example, we might pose the question 'why do polar bears have fur, while penguins have feathers, given the similar nature of their environments?' Evolution provides an answer to this question. The only answer creationism (or intelligent design) provides is 'because God made them that way.'"
23.
Actually, evolution, whether Darwinian or otherwise, makes no predictions about
there being bears or birds at all or for that matter bears having fur and birds
having feathers. Once bears or birds are on the scene, they need to adapt to
their environment or die. Intelligent design can accommodate plenty of
evolutionary change and allows for natural selection to act as a conservative
force to keep organisms adapted to their environments. Contrary to Duncan's
remark, intelligent design does not push off all explanation to the inscrutable
will of God. On the other hand, intelligent design utterly rejects natural
selection as a creative force capable of bringing about the specified complexity
we see in organisms.
24. It's evident, then, that Darwin's theory has virtually no predictive
power. Insofar as it offers predictions, they are either extremely general,
concerning the broad sweep of natural history and in that respect quite
questionable (Why else would Stephen Jay Gould and Niles Eldredge need to
introduce punctuated equilibria if the fossil record were such an overwhelming
vindication of Darwinism?); and when the predictions are not extremely general
they are extremely specific
and picayune, dealing with small-scale adaptive changes. Newton was able to
predict the path that a planet traces out. Darwin's disciples can neither
predict nor retrodict the pathways that organisms trace out in the course of
natural history.
25. But what about the predictive power of intelligent design? To require
prediction fundamentally misconstrues design. To require prediction of design is
to put design in the same boat as natural laws, locating their explanatory power
in an extrapolation from past experience. This is to commit a category mistake.
To be sure, designers, like natural laws, can behave predictably (designers
often institute policies that end up being rigidly obeyed). Yet unlike natural
laws, which are universal and uniform, designers are also innovators.
Innovation, the emergence to true novelty, eschews predictability.
Designers are inventors. We cannot predict what an inventor would do short of
becoming that inventor. Intelligent design offers a radically different
problematic for science than a mechanistic science wedded solely to undirected
natural causes. Yes, intelligent design concedes predictability. But this
represents no concession to Darwinism, for which the minimal predictive power
that it has can readily be assimilated to a design-theoretic framework.
EXPLANATORY POWER:
26.
According to Darwin the great advantage of his theory over William Paley's
theory of design was that Darwin's theory
managed to account for a wide diversity of biological facts that Paley's theory
could not. Darwin's theory was thus thought to have greater explanatory power
than Paley's , and this relative advantage could be viewed as a test of the two
theories. Underlying explanatory power is a view of explanation known as
inference to the best explanation in which a "best explanation" always
presupposes at least two competing explanations and attempts to determine which
comes out
on top. Design theorists see advances in the biological and information sciences
as putting design back in the saddle and
enabling it to outperform Darwinism, thus making design currently the best
explanation biological complexity. Darwinists of course see the matter quite
differently.
27. What I want to focus on here, however, is not the testing of Darwinism
and design against the broad body of biological data, but the related question
of which theory can accommodate the greater range of biological possibilities.
Think of it this way: Are there things that might occur in biology for which a
design-theoretic framework could give a better, more accurate account than a
purely Darwinian and therefore non-teleological framework? The answer is yes.
28. First off, let's be clear that design can accommodate all the results
of Darwinism. Intelligent design does not repudiate the Darwinian mechanism. It
merely assigns it a lower status than Darwinism does. The Darwinian mechanism
does operate in nature and insofar as it does, design can live with its
deliverances. Even if the Darwinian mechanism could be shown to do all the
design work for which design theorists want to invoke design (say for the
bacterial flagellum), a design-theoretic framework would not destroy any valid
findings of science. To be sure, design would then become superfluous, but it
would not become contradictory or self-refuting.
29. The same cannot be said for Darwinism and the naturalism it embodies
as a framework for science. Suppose I were a super-genius molecular biologist,
and I invented some hitherto unknown molecular machine, far more complicated and
marvelous than the bacterial flagellum. Suppose further I inserted this machine
into a bacterium, set this genetically modified organism free, allowed it to
reproduce in the wild, and destroyed all evidence of my having created the
molecular
machine. Suppose, for instance, the machine is a stinger that injects other
bacteria and explodes them by rapidly pumping them up with some gas (I'm not
familiar with any such molecular machine in the wild), thereby allowing the
bacteria endowed with my invention to consume their unfortunate prey.
30. Now let's ask the question, If a Darwinist came upon this bacterium
with the novel molecular machine in the wild, would that machine be attributed
to design or to natural selection? When I presented this example to David Sloan
Wilson at a conference at MIT two years ago, he shrugged it off and remarked
that natural selection created us and so by extension also created my novel
molecular machine. But of course this argument won't wash since the issue is
whether natural selection could indeed create us. What's more, if Darwinists
came upon my invention of a novel molecular machine inserted into a bacterium
that allows it to feed on other bacteria, they wouldn't look to design but would
reflexively turn to natural selection. But, if we go with the story, I designed
the bacterial stinger and natural selection had nothing to do with it. Moreover,
intelligent design would confirm the stinger's design whereas Darwinism never
could. It follows that a design-theoretic framework could account for biological
facts that would forever remain invisible within a Darwinian framework. It seems
to me that this possibility constitutes a joint test of Darwinism and
intelligent design that strongly
supports intelligent design -- if not as the truth then certainly as a live
possible theoretical option that must not be precluded for a priori
philosophical reasons like naturalism.
CONCLUSION
31.
In conclusion, there is no merit to Eugenie Scott's claim that intelligent
design is untestable or hasn't put forward any "testable models."
Intelligent design's claims about specified and irreducible complexity are in
close contact with the data of biology and open to refutation as well as
confirmation. What's more, as a framework for doing science intelligent design
is more robust and sensitive to the possibilities that nature might actually
throw our way than Darwinism, which must view everything through the lens of
chance and necessity and take a reductive approach to all signs of teleology in
nature.
32. But isn't intelligent design just a stone's throw from fundamentalist
Christianity and rabid creationism? Even if a theory of intelligent design
should ultimately prove successful and supersede Darwinism, it would not follow
that the designer posited by this theory would have to be the Christian God or
for that matter be real in some ontological sense. One can be an anti-realist
about science and simply regard the designer as a regulative principle -- a
conceptually useful device for making sense out of certain facts of biology --
without assigning the designer any weight in reality. Wittgenstein, for
instance, regarded the theories of Copernicus and Darwin not as true but as
"fertile new points of view."
33. Ultimately, the main question that confronts scientists working on a
theory of intelligent design is whether design provides powerful new insights
and fruitful avenues of research. The metaphysics underlying such a theory, and
in particular the ontological status of the designer, can then be taken up by
philosophy and theology. Indeed, one's metaphysics ought to be a matter of
indifference to one's scientific theorizing about design. The fact that it is
not for design theorists, whose primary task is to explore the fruitfulness of
design for science. Yes, we've got our work cut out for us. But instead of
facilitating that work, Scott and her National Center for Science Education are
far more interested in exiling that work to oblivion. Fortunately, design
theorists have suffered exile for so long at the hands of Darwinists that we've
learned to operate effectively even in oblivion.
William Dembski
1-25-01
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