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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.”NFL, p. 148.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.”NFL, p. 289.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.”NFL, p. 289.

“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.”NFL, p. 15.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?”NFL, p. 15.

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.

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E. Coli at the No Free Lunchroom

Is the flagellum specified?

The Core of Dembski’s Case for ID
Why focus on the bacterial flagellum?
Getting Acquainted With the ID Vocabulary
Doing what comes naturally
Darwinism = evolution + maximal naturalism
The Darwinian mechanism
What does it mean to be “intelligently designed”?
The signs of design
E. coli and its Rotary Propulsion System: Dembski’s Flagship Case for Design
Is the flagellum complex? General considerations
Is the flagellum complex? Computing the crucial probability.
Bacterial Flagella and Dembski’s Case for Intelligent Design: Closing Arguments


Howard Van Till
Dr. Howard Van Till

See also:

Dembski: Intelligent Design Coming Clean...
Purpose and Design
Charles Darwin
Bacterial Flagellum
DNA Double-Helix
Books on Biology, Genetics and Theology