Specified complexity

From EvoWiki

Introduction

"Specified complexity" is the favored weapon of William Dembski. Specified complexity is defined and used in at least two completely different ways:

1. Specified complexity is defined by certain criteria identifiable in biological systems and then used to argue that natural evolutionary processes are wildly unlikely to be able to produce these systems.
2. Specified complexity is defined as "unevolvable" and then certain biological systems are asserted to exhibit this property.

(1) is a potentially valid argument but suffers from the same problems as the irreducible complexity argument. (2) is essentially the tautology "systems that are wildly unlikely to evolve are wildly unlikely to evolve," which proves nothing about whether or not a particular systems really are wildly unlikely to evolve. See Definitional Complexity for more exploration of this bit of confusion.

Observational definition

One of Dembski's versions of specified complexity, which approximates the "popular" understanding and usage of the term (outside the ID debate, and at a popular level inside the ID debate), is:

"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)

(Dembski, William A. (2003). ?Gauging Intelligent Design?s Success.? Accessed online: December 15, 2003. Web Link.)

Tautological definition

However, Dembski is just plain inconsistent in his usage of his key term. When he gets at all technical, it turns out that Dembski defines specified complexity not just as something that fits a specific independent pattern that is complex, but that what Dembski really means by "complex" is "highly improbable with respect to all material mechanism":

"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)

(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.)

Obviously, if specified complexity is defined this way, then evolution cannot produce specified complexity, by definition. But this does not stop Dembski from using specified complexity as if it were defined observationally in numerous locations, e.g.:

"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)

(Dembski, William A. (2003). ?Gauging Intelligent Design?s Success.? Accessed online: December 15, 2003. Web Link.)

That's not the point at all, if specified complexity is defined beforehand as something which natural process cannot produce. This kind of confusion has been pointed out to Dembski many times and yet he persists in promulgating it. This is thus an excellent example of Definitional Complexity.