Talk:Definitional Complexity

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tautology

"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."

I'm not happy with this being called tautological. "any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional" is a restatement of the can't-remove-parts definition as long as you take 'nonfunctional' to mean 'not functioning in the current sense'. Allowing for this (surprise!) sloppy use of language, if he had said 'additions to' instead of 'modifications of', he would have just been making an obvious deduction from the can't-remove-parts definition.

However, using 'modifications of' he has arrived at a more useful statement for his cause (as it includes substitution and reduction), but now it is a serious logical error: of course you can make a chair by whittling away bits of a treestump.

So, I think he is NOT using a second tautological definition of IC here, but is rather taking his can't-remove-parts concept and using shoddy logic and convenient sloppiness in meaning to 'deduce' that anything which is can't-remove-parts IC is logically unevolvable.

I'm not about to modify the article because I think it needs a big restructure and I'm a complete newbie

Ignore Distinctions

I think that more consideration to his point is required. The man himself has stated that a chair is not irreducibly complex that a tree stump can suffice just as well as the finished product and so can conceivably evolve to a three legged stool. He clarifies the IC definition in an essay as follows;

“To determine whether a system is irreducibly complex therefore employs two approaches: (1) An empirical analysis of the system that by removing parts (individually and in groups) and then by rearranging and adapting remaining parts determines whether basic function can be recovered among those remaining parts. (2) A conceptual analysis of the system, and specifically of those parts whose removal renders the basic function unrecoverable, to demonstrate that no system with (substantially) fewer parts exhibits the basic function.�?

This is not just a “cant-remove-parts�? argument that applies to anything as with the case of the chair. The argument is that is very specific parts (or groups of parts) are removed the system cases to exist. Like is you take the spark plugs out of your boat’s two stroke, the motor as a useful system now cesses to function and has no use. This is distinct from the chair analogy.

Isn't this irrelevant?

Behe wants to go backwards from the system to its immediate evolutionary predecessors. The first steps he can think of are:

• Drop one part, or
• Rearrange the parts.

He finds that the results are not viable. But the point is that he misses the possibility

• Add one part.

So the claim "this system cannot evolve because there are no possible immediate evolutionary predecessors" reduces to "this system cannot evolve because I can't think of any possible immediate evolutionary predecessors", and is unmasked as an argument from ignorance. This is true independently of whether Behe thinks of the possibility "rearrange the parts" or not. --tk (t) 12:38, 19 Jan 2006 (GMT)