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Definitional Complexity

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Definition of Definitional Complexity

Definitional complexity is a property of a term, such that the term has multiple definitions with very important differences, these different definitions are switched regularly without notice from the author, and this inconsistency is a crucial factor keeping the flaws in an argument from being recognized. The use of Definitional Complexity is a good example of tactical ambiguity.

Cases

Case #1: Irreducible Complexity

Irreducible complexity is something that is supposed to be a problem for Darwinian evolution. Behe and his followers argue that evolution cannot produce IC (sticklers will point out that the assertion is "wildly improbable" rather than "impossible," but this is a distinction without a difference).

However, they can't get the definition straight. Sometimes, IC is defined based on observational characters (the only universally applied character being "multiple parts required"), and the argument is made that Darwinian evolution cannot produce this structure. Using this observational definition leads to an at least potentially respectable argument (see IC for further discussion).

However, at other times IC is defined so that "unevolvable" or "wildly improbable" are effectively part of the definition. This renders the statement "the evolution of an IC system is impossible/improbable" a mere useless tautology, since there is then no way to tell if a system is IC without already knowing whether or not it is evolvable, and this is always exactly the point at issue. This tautological definition clearly confuses the discussion immensely, and should be dropped, but unfortunately it is (1) useful when a critic is showing how an IC system evolved (ready rebuttal for the ID-defender: "but that system isn't IC, by definition, since it evolved") and (2) this version of the definition is commonly used by Dembski, who says that irreducible complexity is a subset of specified complexity, and SC is most commonly explicitly defined tautologically.

Citation Quote Summary
Behe, Michael J. (1996). Darwin's black box : the biochemical challenge to evolution. New York, Free Press. Web Link Amazon. "By irreducibly complex I mean a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning." (p. 39, paragraph 3, sentence 2) Observational definition.
  • multiple parts required
  • well-matched
  • interacting
  • all parts necessary
Behe, Michael J. (1996). Darwin's black box : the biochemical challenge to evolution. New York, Free Press. Web Link Amazon. "An irreducibly complex system cannot be produced directly (that is, by continuously improving the initial function, which continues to work by the same mechanism) by slight, successive modifications of a precursor system, because any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional." (p. 39, paragraph 3, sentence 3, bold added) Tautological definition.
  • Nonfunctional precursors (The words "by definition nonfunctional" are often taken to mean that "nonfunctional precursors" is part of the definition, and therefore unevolvability is part of the definition)
Behe, Michael J. (1996). Darwin's black box : the biochemical challenge to evolution. New York, Free Press. Web Link Amazon. [Discussing the cilium] "In order to paddle, several components are required." (p. 65) Observational definition.
  • multiple parts required
  • In fairness, just before this quote Behe discusses the cilium and notes that a swimming system requires a motor, a paddle, and a connector (a mention of interaction, but not "well-matched").
Behe, Michael J. (1996). Darwin's black box : the biochemical challenge to evolution. New York, Free Press. Web Link Amazon. "Because the bacterial flagellum is necessarily composed of at least three parts -- a paddle, a rotor, and a motor -- it is irreducibly complex. Gradual evolution of the flagellum, like the cilium, therefore faces mammoth hurdles" (p. 72) Observational definition.
  • multiple parts required only
Behe, Michael J. (1996). Darwin's black box : the biochemical challenge to evolution. New York, Free Press. Web Link Amazon. "Because gated transport requires a minimum of three separate components to function, it is irreducibly complex" (p. 109) Observational definition.
  • multiple parts required only
Behe, Michael J. (1998). Molecular Machines: Experimental Support for the Design Inference. Cosmic Pursuit. Web Link. "By irreducible complexity I mean a single system which is composed of several interacting parts that contribute to the basic function, and where the removal of any one of the parts causes the system to effectively cease functioning. An irreducibly complex system cannot be produced directly by slight, successive modifications of a precursor system, since any precursor to an irreducibly complex system is by definition nonfunctional. [...] Because the mousetrap is necessarily composed of several parts, it is irreducibly complex. Thus, irreducibly complex systems exist. [...] What we see in the cilium, then, is not just profound complexity, but it is also irreducible complexity on the molecular scale. Recall that by "irreducible complexity" we mean an apparatus that requires several distinct components for the whole to work." Observational definition.
  • multiple parts required
  • interacting (minor; mentioned once)
  • all parts required in definition
Behe, Michael J. (1996). The Evolution of a Skeptic -- An Interview with Dr. Michael Behe, biochemist and author of recent best-seller, Darwin's Black Box. The Real Issue. Web Link. "Since that time, science has shown that the cell is an extremely complex system containing proteins and nucleic acids and all sorts of miniaturized machines. In my book I go through a number of these machines and argue that Darwinian natural selection cannot have produced them because they have a property called irreducible complexity; that is, they consist of a number of parts, all of which must be present for the machine to work. Irreducible complexity is like a mousetrap which has a number of parts, and all the parts must be present before it can work." Observational definition.
  • multiple parts required
  • all parts necessary
  • note tautology - IC's existence refutes evolution, and IC is defined as unevolvable.
Behe, Michael J. (2000). �In Defense of the Irreducibility of the Blood Clotting Cascade: Response to Russell Doolittle, Ken Miller and Keith Robison.� Accessed online: December 15, 2003. Web Link. "An irreducibly complex evolutionary pathway is one that contains one or more unselected steps (that is, one or more necessary-but-unselected mutations). The degree of irreducible complexity is the number of unselected steps in the pathway." (second-to-last paragraph) Tautological definition.
  • Evolvability is explicitly part of the definition
Dembski, William A. (2002). �Addicted to Caricatures: A Response to Brian Charlesworth.� Accessed online: July 18, 2004. Web Link. "Charlesworth invokes the eye as an example of an irreducibly complex system that could not have evolved. But the eye is not irreducibly complex -- components may be removed without vision being entirely destroyed." (second-to-last paragraph) Observational definition.
  • Multiple parts required

Case #2: Specified Complexity

Specified complexity is Dembski's contribution to ID. It is meant to include IC but also any other structures that are "complex" and "specified" (such as a paragraph or a gene). Dembski produces a massive amount of text to explain what he means by these terms, and why he thinks that specified complexity can't evolve (in the end, for biological structures he always relies on Behe's IC argument, rendering his entire body of work superfluous to Behe). However, Dembski defines and uses terms differently in different places. Primarily, Dembski can't decide if he prefers the observational or tautological definitions of specified complexity -- generally, he uses the observational definition in offense, and the tautological definition in defense.

Citation Quote Summary
Dembski, William A. (2003). �Gauging Intelligent Design�s Success.� Accessed online: December 15, 2003. Web Link. "An event exhibits specified complexity if it is contingent and therefore not necessary; if it is complex and therefore not readily repeatable by chance; and if it is specified in the sense of exhibiting an independently given pattern." (p. 4) Observational definition.
  • contingent
  • complex+
  • specified
+ Dembski sometimes defines "complexity" as something like "improbability under any natural stochastic process." This is rather different than arguing that complexity is unlikely to be repeated by a random chance process.
Dembski, William A. (2003). �Gauging Intelligent Design�s Success.� Accessed online: December 15, 2003. Web Link. "Specified complexity is the characteristic trademark or signature of intelligence. It is a reliable empirical marker of intelligence in the same way that fingerprints are a reliable empirical marker of a human being�s presence. Proponents of intelligent design argue that undirected natural causes cannot generate specified complexity. (My book No Free Lunch was devoted entirely to making that case.)" (p. 4) Observational definition.
  • Here, Dembski states that specified complexity is a "reliable empirical marker" of ID. This implies that one can identify SC based on criteria other than evolvability.
Dembski, William A. (2003). �Gauging Intelligent Design�s Success.� Accessed online: December 15, 2003. Web Link. "The probabilities I calculate [for the natural origin of the flagellum] -� and I try to be conservative �- are horrendous and render natural selection utterly implausible as a mechanism for generating the flagellum and structures like it. If I�m right and the probabilities really are horrendous, then the bacterial flagellum exhibits specified complexity." (p. 12) Tautological definition.
  • Dembski's if-then clearly states that "low probability of natural origin" is part of the definition of specified complexity.
Dembski, William A. (2003). �Gauging Intelligent Design�s Success.� Accessed online: December 15, 2003. Web Link. The point is whether nature (conceived as a closed system of blind, unbroken natural causes) can generate specified complexity in the sense of originating it when previously there was none." (p. 5, italics original) Observational definition.
  • Dembski implies that natural processes might (in principle) be able to generate specified complexity, giving no hint that "unevolvable" is part of the definition of specified complexity.
Dembski, William A. (2002). The Logical Underpinnings of Intelligent Design. Debating Design: From Darwin to DNA. Dembski, W. A. and Ruse, M., Eds. New York, Cambridge University Press. Web Link. "If something genuinely instantiates specified complexity, then it is inexplicable in terms of all material mechanism (not only those that are known but all of them). Indeed, to attribute specified complexity to something is to say that the specification to which it conforms corresponds to an event that is highly improbable with respect to all material mechanism that might give rise to the event." (p. 12) Tautological definition.
  • The words "genuinely instantiates" and "is to say [that the event] is highly improbable with respect to all material mechanism" clearly indicate that unevolvability is the key part of the definition of specified complexity

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