IC Counterarguments
Two of the more sophisticated arguments against Michael Behe’s irreducible complexity (IC) are as follows:
Equivocation — Behe is equivocating between two different meanings of IC, a purely theoretical one that doesn’t care about the evidence, and an empirical one that says existing adaptations were not created by evolution. Behe equivocates by carrying the inescapable truth of the first meaning over to the other one.
God-of-the-gaps (a.k.a. “argument from ignorance”) — Behe is committing a god-of-the-gaps fallacy by presuming that anything evolutionists can’t explain today won’t be explainable tomorrow. He’s simply attributing gaps in our current scientific knowledge to miracles of God. Science doesn’t work that way.
Both of these charges have been addressed well in many pro-ID books and websites, but I want to bring the exact logic into focus in a short blog entry, which is something I don’t think I’ve found elsewhere. Hopefully people who have time to read mainly short articles on their iPhone will appreciate.
The equivocation charge accuses Behe of arguing in the following form:
IC =def A. certain theoretical characterics of a system
IC =def B. certain biochemical systems in the real world
Since we know that A is unevolvable, then B must also be unevolvable, because we we have defined IC to mean both A and B.
That’s the classic fallacy of equivocation. But Behe’s IC argument is actually of this form:
1. IC =def such-and-such characteristics of a mechanical system
2. If a biochemical system has the characteristics IC, then it cannot plausibly have evolved via natural mutation-selection evolution.
3. We observe that many existing biochemical systems do have the characteristics IC.
4. Therefore, those existing biochemical systems cannot plausibly have evolved via natural mutation-selection evolution.
Behe’s argument is not an equivocation. It employs just one definition of IC (statement 1), and the only part of the argument that is inescapably true, sans evidence, is statement 2 — but that statement hinges on the contingency, “If a biochemical system has the characteristics IC.” When moving to the empirics in step 3, the evidence must satisfy that contingency to make the argument work, so inescapable truth is not being equivocated from the definition to the evidence. Many biochemical adaptations (e.g. antibiotic resistance) do not satisfy the contingency, and are thus perfectly plausible by naturalistic evolution. But many other adaptations do satisfy the contingency, and no plausible evolutionary explanations exist for those adaptations.
Which brings us to god-of-the-gaps. This charge (also called argument-from-ignorance) accuses Behe’s argument of being of the following form:
Mutation-selection evolution has explained many biological features.
But it hasn’t explained others.
Therefore those others must not be amenable to explanation by mutation-selection evolution, and another cause (presumably design) is inferred.
Yes, that’s the god-of-the-gaps, argument-from-ignorance fallacy, perfectly illustrated. But Behe isn’t advancing it — his missing-explanations point is actually of this form:
1. IC =def such-and-such characteristics of a biological system, the presence of which can be ascertained independently of any knowledge of whether mutation-selection evolution has plausibly explained the system
2. Mutation-selection evolution has explained many biological features.
3. But it hasn’t explained others.
4. All of the biological features that mutation-selection has explained, can be observed to not have the characterics IC.
5. All of the biological features which can be observed to have the characteristics IC, have not been explained by mutation-selection evolution.
6. Therefore biological features that can be observed to have the characteristics IC are not amenable to explanation by mutation-selection evolution, and another cause (presumably design) is inferred.
Instead of a god-of-the-gaps fallacy, Behe’s argument is just the standard scientific inference that a consistent pattern in the currently available evidence will most likely remain consistent as future evidence is gathered, and that the pattern demands (of the scientifically curious) some explanation for its existence.
Update 2008.12.25 — “explained, do” changed to “explained, can be observed to”
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