From: Josh Bembenek (jbembe@hotmail.com)
Date: Fri Aug 01 2003 - 10:17:35 EDT
Glenn-
Your endless diatribe is quite intolerable at this point to me. Rather than
continue arguing each point of a misconstrued discussion of ID's hypothesis,
I'll simply cut and paste an article from Dembski. Perhaps a second reading
will encourage you to rethink your position, and Dembski's own words can
correct the errors you attribute to him for any innocent bystanders
corrupted by your impossible strawmen.
William A. Dembski
Member
Member # 7
posted 29. August 2002 21:26
What Sort of Property is Specified Complexity?
By William A. Dembski
NOTE: The following essay is a chapter for a book I'm writing. As usual, I
hammer away at the bacterial flagellum. Critics of mine may wonder when I'm
going to let it go. I'll let go once my critics admit that it represents an
insoluble problem on naturalistic terms. Also, I say in this essay that
there is no evidence for an indirect Darwinian pathway to the bacterial
flagellum. Sorry, but the type III secretory system doesn't cut it. In fact,
Milt Saier's work at UCSD suggests that the type III secretory system, if
anything, evolved from the flagellum. But even if it could be shown that the
type III system predated the flagellum, it would at best represent one
possible step in the indirect Darwinian evolution of the bacterial
flagellum. To claim otherwise is like saying we can travel by foot from Los
Angeles to Tokyo because we've discovered the Hawaiian Islands. Evolutionary
biology needs to do better than that. At any rate, the aim of this essay is
not to rehash the flagellum, but to come to terms with what sort of property
specified complexity is. I hope this essay stimulates discussion on that
question.
Specified complexity is a property that things can possess or fail to
possess. Yet in what sense is specified complexity a property? Properties
come in different varieties. There are objective properties that obtain
irrespective of who attributes them. Water is such a property. There are
also subjective properties that depend crucially on who attributes them.
Beauty is such a property. To be sure, beauty may not be entirely in the eye
of the beholder (there may be objective aspects to it). But beauty cannot
make do without the eye of some beholder.
The distinction between objective and subjective properties has a long
tradition in philosophy. With Descartes, that distinction became important
also in science. Descartes made this distinction in terms of primary and
secondary qualities. For Descartes material objects had one primary quality,
namely, extension. The other properties of matter, its color or texture for
instance, were secondary qualities and simply described the effect that
matter, due to the various ways it was configured or extended, had on us as
perceivers. Descartes's distinction of primary and secondary qualities has
required some updating in light of modern physics. Color, for instance, is
nowadays treated as the wave length of electromagnetic radiation and
regarded as a primary quality (though the subjective experience of color is
still regarded as a secondary quality). Even so, the idea that some
properties are primary or objective and others are secondary or subjective
remains with us, especially in the sciences.
The worry, then, is that specified complexity may be entirely a subjective
property, with no way of grasping nature at its ontological joints and thus
no way of providing science with a valid tool for inquiry. This worry,
though misplaced, needs to be addressed. The first thing we need to see is
that the objective-subjective distinction is not as neat and dichotomous as
we might at first think. Consider the following three properties: X is
water, X is married, and X is beautiful (the "X" here denotes a place-holder
to which the properties apply). X is water, as already noted, is objective.
Anybody around the world can take a sample of some item in question, subject
it to a chemical test, and determine whether its composition is that of
water (i.e., H2O). On the other hand, X is beautiful seems thoroughly
subjective. Even if objective standards of beauty reside in the mind of God
or in a Platonic heaven, in practice people differ drastically in their
assessments of beauty. Indeed, no single object is universally admired as
beautiful. If specified complexity is subjective in the same way that beauty
is, then specified complexity cannot be a useful property for science.
But what about X is married? It certainly is an objective fact about the
world whether you or I are married. And yet there is an irreducibly
subjective element to this property as well: Unlike water, which is simply
part of nature and does not depend for its existence on human subjects,
marriage is a social institution that depends intimately for its existence
on human subjects. Whereas water is purely objective and beauty purely
subjective, marriage is at once objective and subjective. This confluence of
objectivity and subjectivity for social realities like money, marriage, and
mortgages is the topic of John Searle's The Construction of Social Reality.
Social realities are objective in the sense that they command
intersubjective agreement and express facts (rather than mere opinions)
about the social world we inhabit. But they exist within a social matrix,
which in turn presupposes subjects and therefore entails subjectivity.
Searle therefore supplements the objective-subjective distinction with an
ontological-epistemic distinction. Accordingly, water is ontologically
objective -- it depends on the ontological state of nature and is
irrespective of humans or other subjects. Alternatively, beauty is
epistemically subjective -- it depends on the epistemic state of humans or
other subjects, and its assessment is free to vary from subject to subject.
Properties reflecting social realities like money, marriage, and mortgages,
on the other hand, are ontologically subjective but epistemically objective.
Thus marriage is ontologically subjective in that it depends on the social
conventions of human subjects. At the same time, marriage is epistemically
objective -- any dispute about somebody being married can be objectively
settled on the basis of those social conventions.
How do Searle's categories apply to specified complexity? They apply in two
parts, corresponding to the two parts that make up specified complexity.
Specified complexity involves a specification, which is a pattern that is
conditionally independent of some observed outcome. Specified complexity
also involves a measure of complexity, which calculates the improbability of
the event associated with that pattern. Think of an arrow landing in a
target. The target is an independently given pattern and therefore a
specification. But the target also represents an event, namely, the arrow
landing in the target, and that event has a certain probability.
Specifications, by being conditionally independent of the outcomes they
describe, are, within Searle's scheme, epistemically objective. Moreover,
once a specification is given and the event it represents is identified, the
probability of that outcome is ontologically objective. Consider, for
instance, a quantum mechanical experiment in which polarized light is sent
through a polaroid filter whose angel of polarization is at forty-five
degrees with that of the light. Imagine that the light is sent through the
filter photon by photon. According to quantum mechanics, the probability of
any photon getting through the filter is 50 percent and each photon's
probability of getting through is probabilistically independent of the
others. This quantum mechanical experiment therefore models the flipping of
a fair coin (heads = photon passes through the filter; tails = photon
doesn't pass through the filter), though without the possibility of any
underlying determinism undermining the randomness (assuming quantum
mechanics delivers true randomness).
Suppose now that we represent a photon passing through the filter with a "1"
and a photon not passing through the filter with a "0." Consider the
specification 11011101111101111111..., namely, the sequence of prime numbers
in unary notation (successive 1s separated by a 0 represent each number in
sequence). For definiteness let's consider the prime numbers between 2 and
101. This representation of prime numbers is ontologically subjective in the
sense that it depend on human subjects who know about arithmetic (and
specifically about prime numbers and unary notation). It is also
epistemically objective inasmuch as arithmetic is a universal aspect of
rationality. Moreover, once this specification of primes is in place, the
precise probability of a sequence of photons passing through the filter and
matching it is ontologically objective. Indeed, that probability will depend
solely on the inherent physical properties of photons and polaroid filters.
Specified complexity therefore is at once epistemically objective (on the
specification side) and ontologically objective (on the complexity side once
a specification is in hand).
Specified complexity therefore avoids the charge of epistemic subjectivity,
which, if true, would relegate specified complexity to the whim, taste, or
opinion of subjects. Yet specified complexity does not merely avoid this
charge. More positively, it also displays certain positive virtues of
objectivity: specifications are epistemically objective and measures of
complexity based on those specifications are ontologically objective. Is
this enough to justify specified complexity as a legitimate tool for
science? To answer this question, let's consider what could go awry with
specified complexity to prevent it from functioning as a legitimate tool
within science.
Specifications are not the problem. True, specifications, though
epistemically objective are not ontologically objective. The failure of
specifications to be ontologically objective, however, does not prevent them
from playing a legitimate role in the natural sciences. In biology,
specifications are independently given functional patterns that describe the
goal-directed behavior of biological systems. A bacterial flagellum, for
instance, is an outboard rotary motor on the backs of certain bacteria for
propelling them through their watery environments. This functional
description is epistemically objective but on any naturalistic construal of
science must be regarded as ontologically subjective (if nature, as
naturalism requires, is a closed nexus of undirected natural causes, then
nature knows nothing about such functional descriptions). And yet biology as
a science would be impossible without such functional descriptions.
Functional language is indispensable to biology, and specifications are one
way to clarify and make precise that language.
Any problem justifying specified complexity's legitimacy within science
therefore resides elsewhere. Indeed, the problem resides with complexity.
Although complexity becomes ontologically objective once a specification is
in place, our assessment of complexity is just that -- our assessment. And
the problem with assessments is that they can be wrong. Specifications are
under our control. We formulate specifications on the basis of background
knowledge. The complexity denoted by specified complexity, on the other
hand, resides in nature. This form of complexity is a measure of
probability, and these probabilities depend on the way nature is
constituted. There is an objective fact of the matter what these
probabilities are. But our grasp of these probabilities can be less than
adequate. The problem, then, with specified complexity legitimately entering
science is bridging complexity as it exists in nature with our assessments
of that complexity. Alternatively, the problem is not with specified
complexity being a valid property for science but with our ability to
justify any particular attribution of specified complexity to particular
objects or events in nature.
To illustrate what's at stake, consider an analogy from mathematics. There
exist numbers whose decimal expansions are such that every single digit
between 0 and 9 has relative frequency exactly 10 percent as the decimal
expansion becomes arbitrarily large (or, as mathematicians would say, "in
the limit" each single digit has exactly a 10 percent occurrence). The
simplest such number is perhaps .01234567890123456789... where "0123456789"
just keeps repeating over and over again. Let's call such numbers regular
(mathematicians typically prefer a stronger notion of regularity called
normality, which characterizes the limiting behavior of all finite strings
of digits and not merely that of single digits; for the purposes of this
example, however, regularity suffices). The property X is regular therefore
applies to this number. Regularity is clearly a legitimate mathematical
property -- it is perfectly well-defined and numbers either are regular or
fail to be regular.
But suppose next we want to determine whether the number pi is regular (pi
equals the ratio of the circumference of a circle to its diameter). Pi has a
nonrepeating decimal expansion. Over the years mathematicians and computer
scientists have teamed up to compute as many digits of pi as mathematical
methods and computer technology permit. The current record stands at
206,158,430,000 decimal digits of pi and is due to the Japanese researchers
Yasumasa Kanada and Daisuke Takahashi (the currently standard 40 gigabyte
harddrive is too small to store this many decimal digits). Each of the
single digits between 0 and 9 has relative frequency roughly 10 percent
among these 200 billion decimal digits of pi. Is pi therefore regular?
Just as there is a physical fact of the matter whether an object or event in
nature exhibits specified complexity, so there is a mathematical fact of the
matter whether pi is regular. Pi either is regular or fails to be regular.
Nonetheless, the determination whether pi is regular is another matter. With
the number .01234567890123456789..., its regularity is evident by
inspection. But the decimal digits of pi are nonrepeating, and to date there
is no theoretical justification of its regularity. The closest thing to a
justification is to point out that for the standard probability measure on
the unit interval (i.e., Lebesgue measure), all numbers except for a set of
probability zero are regular. The presumption, then, is that pi is likely to
be regular. The problem here, however, is that the numbers we deal with in
practice are rational numbers and most of these are not regular. Thus most
of the numbers we deal with in practice belong to that set of probability
zero. What's more, a simple set theoretic argument shows that among
irrational numbers like pi, there are as many nonregular ones as regular
ones (both subsets have cardinality of the continuum). There is thus no
reason to think that pi was sampled according to Lebesgue probability
measure and therefore likely to fall among the regular irrational numbers
(the nonregular irrational numbers having probability zero with respect to
Lebesgue measure). As a consequence, we have no basis in mathematical
experience or theory for being confident that pi is regular.
Even the discovery that the single digits of pi have approximately the right
relative frequencies for pi's first 200 billion decimal digits provides no
basis for confidence that pi is regular. However regular the decimal
expansion of pi looks in some initial segment, it could go haywire
thereafter, possibly even excluding certain single-digits entirely after a
certain point. On the other hand, however nonregular the decimal expansion
of pi looks in some initial segment, the relative frequencies of the single
digits between 0 and 9 could eventually settle down into the required 10
percent and pi itself could be regular (any initial segment thereby getting
swamped by the infinite decimal expansion that lies beyond it). Thus, to be
confident that pi is regular, mathematicians need a strict mathematical
proof showing that each single digit between 0 and 9 has a limiting relative
frequency of exactly 10 percent.
Now critics of intelligent design demand this same high level of
justification (i.e., mathematical proof) before they accept specified
complexity as a legitimate tool for science. Yet a requirement for strict
proof, though legitimate in mathematics, is entirely wrong-headed in the
natural sciences. The natural sciences make empirically based claims, and
such claims are always falsifiable. Errors in measurement, incomplete
knowledge, and the problem of induction cast a shadow over all scientific
claims. To be sure, the shadow of falsifiability doesn't incapacitate
science. But it does make the claims of science (unlike those of
mathematics) tentative, and it also means that we need to pay special
attention to how scientific claims are justified. The key question for this
discussion, therefore, is how to justify ascribing specified complexity to
natural structures.
To see what's at stake, consider further the analogy between the regularity
of numbers and the specified complexity of natural structures. We need to be
clear where that analogy holds and where it breaks down. The analogy holds
insofar as both specified complexity and regularity make definite claims
about some fact of the matter. In the case of regularity, it is a
mathematical fact of the matter -- the decimal expansions of numbers either
exemplify or fail to exemplify regularity. In the case of specified
complexity, it is a physical fact of the matter -- a biological system, for
instance, either exemplifies or fails to exemplify specified complexity.
This last point is worth stressing. Attributing specified complexity is
never a meaningless assertion. On the assumption that no design or teleology
was involved in the production of some event, that event has a certain
probability and therefore an associated measure of complexity. Whether that
level of complexity is high enough to qualify the event as exemplifying
specified complexity depends on the physical conditions surrounding the
event. In any case, there is a definite fact of the matter whether specified
complexity obtains.
Any problem with ascribing specified complexity to that event therefore
resides not in its coherence as a meaningful concept -- specified complexity
is well-defined. If there is a problem, it resides in what philosophers call
its assertibility. Assertibility refers to our justification for asserting
the claims we make. A claim is assertible if we are justified asserting it.
With the regularity of pi, it is possible that pi is regular. Thus in
asserting that pi is regular, we might be making a true statement. But
without a mathematical proof of pi's regularity, we have no justification
for asserting that pi is regular. The regularity of pi is, at least for now,
unassertible. But what about the specified complexity of various biological
systems? Are there any biological systems whose specified complexity is
assertible?
Critics of intelligent design argue that no attribution of specified
complexity to any natural system can ever be assertible. The argument runs
as follows. It starts by noting that if some natural system exemplifies
specified complexity, then that system must be vastly improbable with
respect to all purely natural mechanisms that could be operating to produce
it. But that means calculating a probability for each such mechanism. This,
so the argument runs, is an impossible task. At best science could show that
a given natural system is vastly improbable with respect to known mechanisms
operating in known ways and for which the probability can be estimated. But
that omits (1) known mechanisms operating in known ways for which the
probability cannot be estimated, (2) known mechanisms operating in unknown
ways, and (3) unknown mechanisms.
Thus, even if it is true that some natural system exemplifies specified
complexity, we could never legitimately assert its specified complexity,
much less know it. Accordingly, to assert the specified complexity of any
natural system constitutes an argument from ignorance. This line of
reasoning against specified complexity is much like the standard agnostic
line against theism -- we can't prove that atheism (cf. the total absence of
specified complexity from nature) holds, but we can show that theism (cf.
the specified complexity of certain natural systems) cannot be justified and
is therefore unassertible. This is how skeptics argue that there is no (and
indeed can be no) evidence for God or design.
A little reflection, however, makes clear that this attempt by skeptics to
undo specified complexity cannot be justified on the basis of scientific
practice. Indeed, the skeptic imposes requirements so stringent that they
are absent from every other aspect of science. If standards of scientific
justification are set too high, no interesting scientific work will ever get
done. Science therefore balances its standards of justification with the
requirement for self-correction in light of further evidence. The
possibility of self-correction in light of further evidence is absent in
mathematics and accounts for mathematics' need for the highest level of
justification, namely, strict logico-deductive proof. But science does not
work that way. Science must work with available evidence and on that basis
(and that basis alone) formulate the best explanation of the phenomenon in
question.
Take, for instance, the bacterial flagellum. Despite the thousands of
research articles on it, no mechanistic account of its origin exists.
Consequently, there is no evidence against its being complex and specified.
It is therefore a live possibility that it is complex and specified. But is
it fair to assert that it is complex and specified, in other words, to
assert that it exhibits specified complexity? The bacterial flagellum is
irreducibly complex, meaning that all its components are indispensable for
its function as a motility structure. What's more, it is minimally complex,
meaning that any structure performing the bacterial flagellum's function as
a bidirectional outboard rotary motor cannot make do without certain basic
components.
Consequently, no direct Darwinian pathway exists that incrementally adds
these basic components and therewith evolves a bacterial flagellum. Rather,
an indirect Darwinian pathway is required, in which precursor systems
performing different functions evolve by changing functions and components
over time (Darwinists refer to this as coevolution and co-optation).
Plausible as this sounds (to the Darwinist), there is no evidence for it.
What's more, evidence from engineering strongly suggests that tightly
integrated systems like the bacterial flagellum are not formed by trial and
error tinkering in which form and function coevolve. Rather, such systems
are formed by a unifying conception that combines disparate components into
a functional whole -- in other words, by design.
Does the bacterial flagellum exhibit specified complexity? Is such a claim
assertible? Certainly the bacterial flagellum is specified. One way to see
this is to note that humans developed outboard rotary motors well before
they figured out that the flagellum was such a machine. 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 all the more clear that
the system satisfies independent functional requirements and therefore is
specified. At any rate, no biologist I know questions whether the functional
systems that arise in biology are specified. At issue always is whether the
Darwinian mechanism, by employing natural selection, can overcome the vast
improbabilities that at first blush seem to arise with such systems, thereby
breaking a vast improbability into a sequence of more manageable
probabilities.
To illustrate what's at stake in breaking vast improbabilities into more
manageable probabilities, suppose a hundred pennies are tossed. What is the
probability of getting all one hundred pennies to exhibit heads? The
probability depends on the chance process by which the pennies are tossed.
If, for instance, the chance process operates by tossing all the pennies
simultaneously and does not stop until all the pennies simultaneously
exhibit heads, it will require on average about a thousand billion billion
billion such simultaneous tosses for all the pennies to exhibit heads. If,
on the other hand, the chance process tosses only those pennies that have
not yet exhibited heads, then after about eight tosses, on average, all the
pennies will exhibit heads. Darwinists tacitly assume that all instances of
biological complexity are like the second case, in which a seemingly vast
improbability can be broken into a sequence of reasonably probable events by
gradually improving on an existing function (in the case of our pennies,
improved function would correspond to exhibiting more heads).
Irreducible and minimal complexity challenge the Darwinian assumption that
vast improbabilities can always be broken into manageable probabilities.
What evidence there is suggests that such instances of biological complexity
must be attained simultaneously (as when the pennies are tossed
simultaneously) and that gradual Darwinian improvement offers no help in
overcoming their improbability. Thus, when we analyze structures like the
bacterial flagellum probabilistically on the basis of known material
mechanisms operating in known ways, we find that they are highly improbable
and therefore complex in the sense required by specified complexity.
Is it therefore fair to assert that the bacterial flagellum exhibits
specified complexity? Design theorists say yes. Evolutionary biologists say
no. As far as the evolutionary biologists are concerned, design theorists
have failed to take into account indirect Darwinian pathways by which the
bacterial flagellum might have evolved through a series of intermediate
systems that changed function and structure over time in ways that we do not
yet understand. But is it that we do not yet understand the indirect
Darwinian evolution of the bacterial flagellum or that it never happened
that way in the first place? At this point there is simply no evidence for
such a indirect Darwinian evolutionary pathways to account for biological
systems that display irreducible and minimal complexity.
Is this, then, where the debate ends, with evolutionary biologists chiding
design theorists for not working hard enough to discover those (unknown)
indirect Darwinian pathways that lead to the emergence of irreducibly and
minimally complex biological structures like the bacterial flagellum?
Alternatively, does it end with design theorists chiding evolutionary
biologists for deluding themselves that such indirect Darwinian pathways
exist when all the available evidence suggests that they do not. Although
this may seem like an impasse, it really isn't. Like compulsive gamblers who
are constantly hoping that some big score will cancel their debts,
evolutionary biologists live on promissory notes that show no sign of being
redeemable. Science must form its conclusions on the basis of available
evidence, not on the possibility of future evidence. If evolutionary
biologists can discover or construct detailed, testable, indirect Darwinian
pathways that account for the emergence of irreducibly and minimally complex
biological systems like the bacterial flagellum, then more power to them --
intelligent design will quickly pass into oblivion. But until that happens,
evolutionary biologists who claim that natural selection accounts for the
emergence of the bacterial flagellum are worthy of no more credence than
compulsive gamblers who are forever promising to settle their accounts.
There is further reason to be skeptical of evolutionary biology and side
with intelligent design. In the case of the bacterial flagellum, what keeps
evolutionary biology afloat is the possibility of indirect Darwinian
pathways that might account for it. Practically speaking, this means that
even though no slight modification of a bacterial flagellum can continue to
serve as a motility structure, a slight modification could serve some other
function. But there is now mounting evidence of biological systems for which
any slight modification does not merely destroy the system's existing
function but also destroys the possibility of any function of the system
whatsoever (cf. Xxx Yyy's work on individual enzymes). For such systems,
neither direct nor indirect Darwinian pathways could account for them. In
this case we would be dealing with an in-principle argument showing not
merely that no known material mechanism is capable of accounting for the
system but also that any unknown material mechanism is incapable of
accounting for it as well. The argument here turns on an argument from
contingency and degrees of freedom outlined in the previous chapter.
Is the claim that the bacterial flagellum exhibits specified complexity
assertible? You bet! Science works on the basis of available evidence, not
on the promise or possibility of future evidence. Our best evidence points
to the specified complexity (and therefore design) of the bacterial
flagellum. It is therefore incumbent on the scientific community to admit,
at least provisionally, that the bacterial flagellum could be the product of
design. Might there be biological examples for which the claim that they
exhibit specified complexity is even more assertible? Yes there might.
Assertibility comes in degrees, corresponding to the strength of evidence
that justifies a claim. For the bacterial flagellum it is logically
impossible to rule out the infinity of possible indirect Darwinian pathways
that might give rise to it (though any such proposed route to the bacterial
flagellum is at this point a mere conceptual possibility). Yet for other
systems, like certain enzymes, there can be strong grounds for ruling out
such indirect Darwinian pathways as well.
The evidence for intelligent design in biology is therefore destined to grow
ever stronger. There's only one way evolutionary biology could defeat
intelligent design, and that is by in fact solving the problem that it
claimed all along to have solved but in fact never did, namely, to account
for the emergence of multi-part tightly integrated complex biological
systems (many of which display irreducible and minimal complexity) apart
from teleology or design. To claim that the Darwinian mechanism solves this
problem is false. The Darwinian mechanism is not itself a solution but
rather describes a reference class of candidate solutions that purport to
solve this problem. But none of the candidates examined to date indicates
the slightest capacity to account for the emergence of multi-part tightly
integrated complex biological systems. That's why molecular biologist James
Shapiro, who is not a design theorist, writes, "There are no detailed
Darwinian accounts for the evolution of any fundamental biochemical or
cellular system, only a variety of wishful speculations." (Quoted from his
1996 book review of Darwin's Black Box that appeared in The National
Review.)
In summary, specified complexity is a well-defined property that applies
meaningfully to events and objects in nature. Specified complexity is an
objective property -- specifications are epistemically objective and
complexity is ontologically objective. Any concern over specified
complexity's legitimacy within science rests not with its coherence or
objectivity, but with its assertibility, namely, with whether and the degree
to which ascribing specified complexity to some natural object or event is
justified. Any blanket attempt to render specified complexity unassertible
gives an unfair advantage to naturalism, ensuring that design cannot be
discovered even if it is present in nature. What's more, science can proceed
only on available evidence, not on the promise or possibility of future
evidence. As a consequence, ascriptions of specified complexity to natural
objects and events, and to biological systems in particular, can be
assertible. And indeed, there are actual biological systems for which
ascribing specified complexity -- and therefore design -- is eminently
assertible.
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