Shots Across The Bow

ID...More Debate

I'm moving this up from the comments for two reasons. One, I think it deserves more exposure and two, after writing this, I'm not going to feel like writing another post.

I get lazy sometimes.

A couple of days ago, I wrote a short article explaining exactly why Michael Behe's defense of Intelligent Design using irreducible complexity is hog wash.

In the comments, Rob Huddleston disagreed, claiming that Behe had thoroughly discredited the idea of Neo-Darwinian evolution as applied to biochemical systems, and therefore had good reason to claim intelligent design was in action. I disagreed, and laid out th arguments in a response.

Rob then claimed that nobody has been able to refute Mr. Behe, and questioned the origin of the universe, a quite different subject.

OK, enough review.

Let's take this one step at a time.
1)Refutation of Michael Behe. First off, let me point out that my argument effectively refutes Behe. Rob chooses not to respond to my argument, instead linking to a quote from Chuck Colson, claiming that nobody had successfully refuted Behe. Unfortunately for Rob, Mr. Colson did not provide any evidence for his assertions, just a bald statement. I can do better than that.

A quick google search found several pages worth of valid challenges to Behe's irreducible complexity model. One of the best and most accessible to the layman is this one, which explores the concept of redundant complexity in far more detail than I did. This one delves deeper into the clotting mechanism, explaining potential pathways for its evolution. It's a bit more technical but the determined reader should be able to follow the gist of the argument. For a very long, thorough, and devastating critique of Behe by a fellow biochemist, go here. And finally for a list of links of challenges to Behe's hypothesis, go here.

So much for Mr. Colson's comment.

Now, regarding Darwinism vs ID, Rob wants to know where the earth came from.

It's irrelevant to the discussion. We're talking about how life evolved on earth, not how the earth came to be. If you want to talk about the origin of the universe, that's cool, but don't ask an evolutionary biologist; he won't have the faintest clue because the two processes are unrelated. It's important in a debate to stay on track, and cosmology is certainly beyond the scope of a discussion of evolution.

Now then, let's get to the basic structure of the debate. Behe's argument can be reduced to the following set of statements:

1. There exist certain biochemical systems that exhibit irreducible complexity defined as follows:
   

   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.

   
   
2. An irreducibly complex system cannot have evolved by the gradual addition of new parts since by definition, lack of any one part would result in a non-functional system.
   
3. Since biochemical systems are the basis for all life as we know it, they must be subject to the same evolutionary processes and restrictions in order for evolution to be valid.
   
4. Since by definition irreducibly complex systems cannot have evolved through the gradual addition of components, Darwinian evolution cannot explain how biochemical systems arose.
   
5. Since evolution cannot explain biochemical systems, then they must have been designed.

Now then, for Behe's argument to be true, each of the above statments and the relationships between them must be true, or like one of Behe's irreducibly complex systems, the argument fails. So let's deal with each step one at a time.

1. By following the links I gave above the reader will discover that many systems Behe claims are irreducibly complex are in fact reducible, albeit with an attendent loss in efficiency. The system may function without the component, or a homologue may replace the missing component. As an example, one of Behe's examples is the blood clotting process. He claims that los of any one component will cause the entire process to fail completely. If this were a true statement, no hemophiliac would survive their first shot.

   So what does this mean for his argument? If irreducibly complex systems are actually reducible, then they might have possibly evolved, removing Behe's impediment to evolution, removing the need for ID. However, since we don't know every biochemical system on the planet, let's say for the sake of argument that there are irreducibly complex biochemical systems that fit Behe's definition.

2. At least three separate, observed, mechanisms are proposed for the evolution of irreducibly complex systems, those three being (A)redundant complexity, (B)improvements becoming necessities due to other changes, and (C)duplication and divergence.
   
   1. I've discussed redundant complexity before, where more chemicals are around than are absolutely necessary, but they support the process as more efficient systems gradually develop. Once the more efficient system is developed, the former system atrophies.
      
   2. H. Allen Orr describes this one, using the development of the lung as an example. In short, the first critters developed lungs not as necessities, but as an advantage. However later evolutionary adaptations: legs, arms, hands, etc. that made living on land easier made lungs a necessity. A similar process occurs in the cell.
      
   3. Gene duplication occurs regularly in the cell, resulting in an extra gene, one that can mutate without deleterious effect on the organism. Should that mutation prove advantageous, it will be selected and passed on, leading to divergence. That divergence, as noted in the previous example, could make the advantage necessary.
   
   In short, this statement is simply not true. It is very possible for systems that are defined as irreducibly complex could have developed gradually, through Darwinian evolution.

   But let's press on.
   

3. This statement in not necessarily true. In fact, it would be very surprising if it were true because throughout nature, when you change scale, the balance of operating forces change, meaning the rules also change. Newtonian physics works very well until your velocity achieves a significant fraction of c, at which point it breaks down completely. It is a reasonable approximation of the truth, but only within certain limits. Similarly, when you get into sub atomic physics, and quantum mechanics in particular, the physical "laws" that govern our mundane existence appear to go out for a bite of lunch, and all hell breaks loose.

   In short, the assumption that the same forces that control macro-evolution may not be the same forces that control micro or cellular evolution. This statmeent is not fact, but an as yet untested hypothesis.
   

4. This statment is a conditional, and since the first part of the statement is untrue, then so is the second. Since Darwinian evolution can explain irreducible complexity, then it can explain biochemical systems.
   
5. This final statement is a complete logical fallacy. Not only is it a conditional whose premise is false, even if the premise were true, the conclusion is invalid. Disproof of one theory does not constitute proof of another.

So, for those of you keping score at home, the final tally is one "maybe", and four "no"s.

Behe's argument does not stand up under scrutiny.

Posted by Rich at August 6, 2005 1:10 AM | TrackBack