Dembski "displaces Darwinism" mathematically  or does he?
By Mark Perakh
Posted March 18, 2005
Introduction. In the beginning of March 2005 William
Dembski sent an email message to several critics of his output, including me.
Dembski wrote:
"Dear Critics,
Attached is a paper that fills in the details of chapter 4 of No Free Lunch,
which David Wolpert referred to as "written in jello." The key result
is a displacement theorem. Along the way I prove and (sic) measuretheoretic
variant of the No Free Lunch theorems."
Dembski
concluded his message as follows: "... I expect that Ken Miller's public remarks
about intelligent design being a 'total, dismal failure scientifically' will
become increasingly difficult to sustain.
This paper, and subsequent revisions, can be found on my
website www.designinference.com. I
welcome any constructive comments about it."
Dembski's
new paper (in PDF format) is found at http://www.designinference.com/documents/2005.03.Searching_Large_Spaces.pdf,
where its text has already undergone some modifications compared to its initial
version. Perhaps these modifications were prompted by critical comments that
appeared on the internet, in particular those made by a contributor to the ARN
website who signs his posts as RBH, as well as by Tom English and David Wolpert
(whose remarks appeared on a certain internet forum).
In his
essay at http://www.designinference.com/documents/2004.04.Backlash.htm)
Dembski wrote, "I'm not going to give away all my secrets, but one thing I
sometimes do is post on the web a chapter or section from a forthcoming book,
let the critics descend, and then revise it so that what appears in book form
preempts the critics' objections. An additional advantage with this approach is
that I can cite the website on which the objections appear, which typically
gives me the last word in the exchange. And even if the critics choose to
revise the objections on their website, books are far more permanent and
influential than webpages."
While
Dembski's frank admission of the tricks he resorts to in order to "win" the
cultural war may sound commendable, the tricks themselves are hardly in tune
with what normally is considered intellectual integrity. He should have added that making the
described revisions in his texts, he usually does not acknowledge the input
from critics.
While I make
a note of Dembski's invitation to offer "constructive comments about it," it
seems proper to point out that Dembski's earlier rendition of the topics
covered in his new paper have been extensively discussed and critiqued but he
has not deemed it necessary to respond to critique. In particular, in a chapter
which I authored in the anthology Why Intelligent Design Fails (editors
Matt Young and Taner Edis, Rutgers Univ. Press, 2004) I specifically addressed
Dembski's [mis]interpretation of the No Free Lunch theorems and his
"displacement problem" as it was rendered in chapter 4 of his No Free Lunch
book. Dembski's new paper in no way answers my critique of his earlier
output where he discussed the same notions in a less mathematical rendition. None of my earlier critical comments
regarding Dembski's misinterpretation and misuse of the NFL theorems and his
displacement problem (in its original presentation) is deflected by anything in
his new paper.
I'll try to
answer the question  does Dembski's new paper justify his assertion that "Ken
Miller's public remark about intelligent design being a 'total, dismal failure
scientifically' will become increasingly difficult to sustain"?
Not quite consistent. In
the same vein as my chapter in the anthology Why Intelligent Design Fails,
I'll discuss Dembski's new paper without delving into mathematical symbolism as
this essay is addressing a general audience rather than only mathematically
prepared readers.
Dembski
states in his new paper that it mathematically formalizes the ideas previously
outlined in a less rigorous form in chapter 4 of his book No Free Lunch
(in his words, his new paper "fills in the details of chapter 4 in No Free
Lunch").
This
statement seems to be, first, aimed at asserting the supposed consistency of
Dembski's discourse, and, second, at providing a sort of answer to the well
known characterization (by David Wolpert) of Dembski's treatment of the No Free
Lunch theorems as "written in jello" (www.talkreason.org/articles/jello.cfm).
Wolpert is
a cooriginator of the No Free Lunch theorems, hence his opinion of Dembski's
treatment of these theorems carried considerable weight. Some of Dembski's
admirers tried to play down the significance of Wolpert's critique by posting
letters to that effect on various internet fora. However, Dembski himself has maintained
a deafening silence, as if Wolpert's critique did not exist. It seems that the statement in his new paper
which points to the supposed consistency between chapter 4 in his 2002 book and
his new paper is a device designed to blunt the sharpness of Wolpert's
characterization.
However,
the comparison of Dembski's new paper with chapter 4 in his book shows that the
assertion of consistency is not quite true. In fact, Dembski's new paper introduces
certain substantial modifications of the basic concepts suggested in the "jello"
chapter in his earlier book. The displacement problem No 1 (as rendered in the No
Free Lunch book) and the displacement problem No 2 (as discussed in the new
paper) seem to be not quite the same problem (as I'll discuss below), although
Dembski's position is that the two displacement problems are identical.
Dembski's
new paper is heavily mathematical and is obviously designed to impress readers
with his mathematical sophistication. Dembski's colleagues (some of whom may
even not have a proper background to comprehend his mathematical ruminations) have
promptly acclaimed this new paper as "splendid" and allegedly "displacing" that
perfidious offshoot of materialistic philosophy, "Darwinism."
I believe
the delight of Dembski and his colleagues is premature.
Fallacious assumptions. First a very general observation. Dembski's delight is based on the
implicit assumption that fundamental concepts of biological science can be "proved"
or "disproved" mathematically. Dembski has adhered to similar notions previously, for example, suggesting in his book The Design Inference that representing certain notions in a mathematically
symbolic form somehow "proves" them. In my book Unintelligent Design
(chapter 1, pages 2628) I have demonstrated the fallacy of such a supposition,
using as an example Dembski's presentation of an argument for design in two
versions  once expressed in plain words, and once in a mathematically symbolic
form. As is evident from that juxtaposition of two renditions of the same
argument, using mathematical symbolism does not provide any additional insight
and, in Dembski's case, only served to embellish his discourse. In his recent
papers, including the paper I am discussing here, Dembski makes a further step
on the same road. Now his overall
approach seems to be implicitly based on the idea that a purely mathematical
discourse is capable of "displacing Darwinism."
Of course,
this is wishful thinking. "Mathematics
is a language," said the great American physicist Josiah Willard Gibbs. Indeed.
Mathematics is an extremely powerful tool. However, no mathematical theorem or
equation "proves" or "disproves" anything beyond the logical connection between
a premise and a conclusion. If a
premise is false, so is the conclusion, regardless of how sophisticated and
impeccably correct the applied mathematical apparatus is.
Since
Dembski's proclaimed goal is to prove "Darwinism" false, all of his
mathematical exercise is irrelevant as it in principle cannot achieve such a
goal. Evolutionary biology is an experimental science and "Darwinian"
mechanisms of evolution have been supported by an immense empirical material.
No mathematical theorems or equations can "displace" evolutionary biology. Its successes and failures can only stem
from empirical research and observations bolstered by proper theorizing, wherein
mathematics, however important and enlightening, is always only a tool.
Closely
connected to this fallacious approach to mathematics as allegedly capable of "disproving"
evolution, there is another serious (I would say fatal) drawback to Dembski's
approach. He seems to first implicitly define his goal (in this case to prove
that "Darwinian" mechanisms cannot explain evolution) and then apply what is an
analog of "reverse engineering" to find a premise from which his already chosen
conclusion can be mathematically derived.
The premise deliberately chosen to lead to a predetermined conclusion has
little chance to be true.
Dembski's premise. To
be more specific, let us see what Dembski's premise implies. Here there is
indeed a certain consistency between his earlier discourse in his No Free
Lunch book and his new paper. He considers biological evolution as the search
for a certain small target within a very large search space (which in his book
was referred to as the "phase space").
As I
pointed out in Why Intelligent Design Fails, in his No Free Lunch
book Dembski did not suggest a definition of a target. In his new paper this
lacuna has been filled. Now Dembski provides a definition of a target. Without
delving into Dembski's mathematical formalism, he defines target T as a
particular small region somewhere within the very large search space Q. He asserts next that finding the target
using a blind search is an endeavor whose success has a very small
probability. For the search to be
successful, it has to be "assisted," which means the search algorithm needs to
get information about the structure of the search space. For example, the
search algorithm may be assisted by feedback, letting the algorithm know
whether each step brings it closer to the target or pushes it farther from the
target. The source of such information
lies in a "higherorder" information space. In Dembski's No Free Lunch this
higherorder space was denoted J. From
that earlier discourse seemed to follow that space J contained (perhaps besides
some other things) all possible fitness functions. In his new paper the "higherorder" space is denoted M and seems
now to contain not the fitness functions but rather all possible "searches,"
that is all possible search algorithms.
This seems to be a substantial change of the entire concept of the
"displacement problem" which Dembski claims to be the main element of his
discourse. It seems to be at odds with
Dembski's claim asserting that his new paper is just "filling in details" in
his earlier rendition of his ideas, this time on a more rigorous level, so it
is no longer "written in jello."
In fact,
his new rendition is substantially different from the original version found in
his book.
Dembski's assisted searches and NFL regress. Let us
recall once again the problem Dembski discusses in his new paper. It is a
search for a small target within a large search space. Mathematically analyzing this problem,
Dembski concludes that only an "assisted search" has a reasonable chance of
success and such an "assisted search" is only possible if, first, a "search for
a search" is conducted in a higherorder informationresource space. The
latter, however, in turn requires information from an even higherorder space,
etc. Dembski calls this situation "No Free Lunch Regress." He maintains that
"stochastic processes" (and biological evolution belongs in this category) are
incapable of getting out of the regress in question, so for the search to be
successful, input from intelligence is necessary (which seems to be in fact his
a priori conviction, just not expressed explicitly).
Dembski's
claim that the "assistance" can only come from an intelligent source reflects
his antecedent belief but is not supported by any argument, either mathematical
or heuristic. A detailed discussion of this point is not necessary, however,
because, as I will show, Dembski's entire schema is irrelevant for reallife
searches.
Another comment
that immediately comes to mind is that if a search is assisted by information
from a higherorder space, the search algorithm that has acquired such information is not a "blackbox" algorithm
any more, so the No Free Lunch theorems, at least in the form they were proven
by Wolpert and Macready, are invalid for such algorithms. (WolpertMacready's
proof was valid for blackbox algorithms. A blackbox algorithm has no advance
knowledge of the fitness landscape and acquires such knowledge stepbystep,
extracting it from the fitness landscape in such a way that it accumulates
information about the already visited points in the landscape but still has no
knowledge of any points not yet visited; it possesses no knowledge of a target
either, if the search is targetdirected.)
Although this simple consideration
casts doubts on Dembski's entire discourse (unless he can prove that the
requirements for an algorithms to be of a "blackbox" variety can be
invalidated) it is of a secondary importance because the No Free Lunch theorems
are only about the average "performance" of search algorithms and are
irrelevant to the actual problem of a specific search algorithm facing a
specific fitness landscape. In that, Dembski's new paper is not an improvement
over his earlier discourse and fails to account for the irrelevance of the NFL
theorems for biological evolution.
Moreover,
regardless of the NFL theorems, Dembski's discourse seems to be, again, irrelevant
to reallife problems for a more universal reason. Here is why.
Do we need
to analyze all of Dembski's convoluted mathematics in order to see whether his
conclusion is substantiated? No. There are several reasons to ignore Dembski's
mathematical exercise but I will now point to only one such reason which, I
believe, is fully sufficient to reject Dembski's conclusion.
Is biological evolution a search for a target? Biological evolution has nothing to do
with the problem Dembski analyzes in his new paper  the problem of a search
for a small target in a large search space.
Let us
grant Dembski the assumptions and derivations he offered in his mathematical
exercise. They may be perfectly correct or partially defective, but either way
it will not affect our general conclusion.
Biological
evolution is not a search for a target in a search space. It knows of no
target. It is blind and its results are not predetermined, unlike the results
of a targeted search employed in certain artificially designed evolutionary
algorithms (such as in Dawkins's "weasel" algorithm).
Look
at Dembski's example of a "search" for a particular protein. He calculates that the probability of "finding" a particular protein which is 100
amino acids in length via a random search in a space of all possible proteins
of such a length, assuming uniform distribution of probabilities in this space,
is so small ( 10^{130} ) as to be practically hopeless. The arithmetic
here may be perfectly correct, but it has no relevance to real biological
evolution. Evolution does not search for a particular protein determined in
advance as a target. It conducts a variety of blind "searches," the number of
which is immense and some of them result in a spontaneous emergence of certain
biologically useful proteins, whose biological role was not foreseen. The
probabilities of such occurrences are irrelevant: because of the very large
number of such "searches," the overall likelihood of emergence of some useful
proteins is by many orders of magnitude larger than the number Dembski
calculates. Moreover, imposing upon
"random searches" a nonrandom factor  natural selection may serve as an
example of such a nonrandom factor  drastically accelerates the process.
There are other natural factors ignored in Dembski's schema which naturally
"assist" the "search," so it is "assisted" without input from intelligence and
without a need to search a "higherorder" space. Dembski's model of protein's
components randomly assembling all at once is very far from realistic
scenarios discussed in evolutionary biology.
Dembski
schema is utterly arbitrary insofar as it relates to a natural biological
process.
Therefore
all Dembski's theorems and equations, as well as his conclusions, have no
relevance to evolutionary biology.
Conclusion: is Dembski's mathematics relevant to
intelligent design? Are Dembski's
mathematical exercises relevant to intelligent design in general? I don't think
so. Indeed, let us assume that Dembski's thesis is valid for targeted genetic
algorithms like Dawkins's "weasel" algorithm. Even if this is true, it has no
relevance to the question of the validity of intelligent design. We know anyway
that such artificially designed algorithms receive input from an intelligent
agent  a human programmer who supplies "assistance" to the algorithm in the
way of a feedback: it tells the algorithm at every step of the search whether
it comes closer to the target, stays the same distance from it, or moves farther
from the target. The same may be true for many other artificially programmed
genetic algorithms.
However,
this in no way means that an analogous situation exists in the biosphere where
the search is not targetoriented and where therefore no input from an
"assisting" agent is required. In fact,
in biological evolution no "assistance" from a "higherorder" information space
is possible because the outcome of a search is not known in advance, so the "search"
(if we agree to apply this term, which is in fact a misnomer) is in all cases
spontaneous and undirected.
All this
has no relation to the No Free Lunch theorems, either those for fixed
landscapes or those for coevolution, which all are irrelevant to the actual
encounters of specific natural genetic algorithms with specific
fitness landscapes, either fixed, or coevolving in the course of the
search. Hence the question of whether
Dembski's mathematical exercise is formally correct or contains errors is
irrelevant to the question of intelligent design's validity. Even if artificial
genetic computer programs indeed require an input from intelligence (although
even some of such algorithms work without such an input) this is not a question
of concern if intelligent design is discussed. The latter's validity is
predicated upon whether or not intelligent input is required for natural
nontargeted searches.
Neither
Dembski nor anybody else has so far suggested any evidence that such input is
necessary for nontargeted searches. Dembski's new paper has not done anything
like that by a long shot. In my view
this paper is an exercise whose heavy mathematical embellishment serves no
other purpose than showing once more that Dembski, on the one hand, knows a lot
of mathematical symbols, and on the other hand has problems with overall
consistency and logic.
As the
matter now stands, Ken Miller's statement quoted by Dembski remains fully
valid. (Besides Miller, it is shared by most scientists who happened to come
across Dembski's numerous publications  a good example is perhaps the
anthology Why Intelligent Design Fails  which Dembski fails to even
mention, let alone to reply to).
Dembski's new mathematical exercise does nothing to make the statement
about the abject scientific futility of intelligent design any less true than
it has been until now.
