Monday, January 28, 2008

The Intelligent Design Contention: Part4

Casey Luskin
In this web article Casey Luskin, Intelligent Design apologist, responds with a comprehensive rebuttal of America’s National Academy of Science’s negative assessment of ID. The article exploits the self-criticizing quotes of evolutionary theorists who candidly admit weaknesses and gaps in the theory in relation to a variety of outstanding problems: the inconsistencies in trying to build phylogenetic trees, the poor state of abiogenesis, problems in relating evolution to the fossil record, and the patchy evidence of hominid evolution. For me these problems are not unexpected given the nature of beast – evolution is one of those big historical theories dealing with a complex ontological category. My own gut feeling is that evolutionary theory, given what it is trying achieve, does a good job of achieving it – that of linking a diversity of observations into one theoretical framework. It will, of course, never be so sure footed as say celestial mechanics, or atomic theory, simply because it deals with such epistemologically intractable objects as deep time and, it hardly needs be said, the most complex objects we know of – living things. It is unfair, as does Luskin in his article, to make comparison with the much simpler objects that physics studies. Evolution is certainly not less well founded than some of the other epistemologically tricky things I believe in like, for example, historical narratives, middle of the road socialism, the constitutional monarchy, or theism. I take evolution and evolutionists seriously. It’s one thing to criticize evolution, but it’s quite another to attempt to advance an alternative theory that is as successful.

But I also take Luskin and his fellow ID proponents seriously and especially that key concept of ID, irreducible complexity. In this series of blogs I will be using my blog as a kind of sounding board to help develop my abstract ideas in relation to this key ID notion. In ID theory, if theory it is, the whole edifice of intelligent design stands or falls by the notion of irreducible complexity. Hence it is this concept that I want to focus my efforts on here.

In his article Luskin addresses the NAS treatment of irreducible complexity. He answers the sort of criticism of irreducible complexity that we find in the video of Ken Miller which I posted in my last entry on this subject:

Dembski …. recognizes that Darwinists wrongly characterizes irreducible complexity as focusing on the non-functionality of sub-parts. Conversely, pro-ID biochemist Michael Behe, who popularized the term “irreducible complexity,” properly tests it by assessing the plausibility of the entire functional system to assemble in a step-wise fashion, even if sub-parts can have functions outside of the final system. The “leap” required by going from one functional sub-part to the entire functional system is indicative of the degree of irreducible complexity in a system. Contrary to the NAS’s assertions, Behe never argued that irreducible complexity mandates that sub-parts can have no function outside of the final system.

Luskin also quotes Michael Behe the “Galileo” of ID who explains why the existence of the Type Three Secretory System, as a precursor of the E. Coli flagellum proves little:

At best the Type Three Secretory System represents one possible step in the indirect Darwinian evolution of the bacterial flagellum. But that still wouldn’t constitute a solution to the evolution of the bacterial flagellum. What’s needed is a complete evolutionary path and not merely a possible oasis along the way. To claim otherwise is like saying we can travel by foot from Los Angeles to Tokyo because we’ve discovered the Hawaiian Islands. Evolutionary biology needs to do better than that.

Our ignorance of the structure of morphospace is cutting both ways here: Behe is claiming that absence of evidence of possible evolutionary routes in morphospace is evidence of absence. On the other hand evolutionists claim that absence of evidence of these evolutionary paths is not evidence of absence. Of course, neither party has provided killer evidence either way. So who has the edge here? The claims of ID theorists and evolutionists are, logically speaking, in complementary opposition rather than symmetrical opposition. It is surely an irony that of the two sides ID, in an elementary Popperian sense, is ostensively making the more easily refutable claims: ID is stating a quasi-universal, namely that evolutionary paths to the working structures like the flagellum of E. coli don’t exist – all we need to do is find one route and the proposition is ‘falsified’. Evolutionists, on the hand are making an existential statement; they are claiming that the routes do exist: such statements can’t be falsified, but they can be ‘verified’ by just one case - if they find that one case their claim is ‘proved’. But both sides have their work cut out; the sheer size and complexity of morphospace makes it a little more difficult to investigate than the Pacific! Moreover, the ontological complexities of what is basically a historical subject will no doubt scupper any claims of either absolute falsification or verification and at best only evidence tipping the balance in one direction or the other is likely to be found.

However, having said that the existence of “islands” such as the TTSS do start to weaken the ID case: the ‘irreducible complexity’ of the flagellum structure is thus less irreducible than we were lead to believe; the TTSS sets a precedent that starts to erode blanket claims that evolutionary paths don’t exist. If Behe is so demanding as to require evolutionists to map out a full path, then it is only fair that evolutionists are as equally demanding and require ID theorists to show that such paths don’t exist. So given that neither party can easily provide a suite of evidence that comprehensively proves their case, we have to plump for partial evidence weighing the case in either direction. Thus, in this weaker sense the TTSS is evidence in favor of evolution, whatever Behe says.

Since the ID theorists have come up with no absolute proof that evolutionary routes to their ‘irreducibly complex’ structures don’t exist, they are forced to sit with a passive uneasiness hoping that such paths don’t pop out of the scientific woodwork. There is a marked difference in the strategic positions of the opposing sides: ID theorists are in passive defense, hoping that evolutionary paths through morphospace will not be found. Evolutionist, on the other hand have the initiative – they can imaginatively and proactively search for solutions – and who knows, they may yet come up with the goods. Frankly from a strategic point of view I would rather be an evolutionist.

One final question that Luskin addresses is this: Is ID science? Luskin says, Yes, of course it is! True, the notion of irreducible complexity as a bare idea is an intelligible notion that can be investigated empirically and logically, although as it deals with the structure of that complex beast we call morphospace, scientists have their work cut out. However, it is when ID theorists jump from irreducible complexity to the operation of intelligence, that the waters start to muddy. When we discover an archeological object that looks like an artifact the working assumption is that it is human intelligence has been at work. We can test this assumption in relation to the known traits of human beings. But ID does not identify the source of the artifaction and in spite of using the scientific sounding term ‘Intelligent Design’, that intelligence is a wild card: it is a naked intelligence of unknown powers and motives. This throws into sharp relief such questions as: What is the nature of intelligence? How does intelligence achieve what it does? Why is intelligence needed to create certain structures? It is these sorts of questions I hope to probe and make some progress with in this series of posts.


Anonymous said...

"If Behe is so demanding as to require evolutionists to map out a full path, then it is only fair that evolutionists are as equally demanding and require ID theorists to show that such paths don’t exist."

How is the demand to prove a universal negative, which is logically impossible, a reasonable expectation? That is a clever rhetorical trick that Darwin himself used, but why isn't the burden of proof on those making the historical and factual claim that some complex system like a bacterial flagellum not only could have, but actually did evolve in a step-wise, gradual fashion?


Timothy V Reeves said...

Is that you Celal? Thanks for your stimulating comment.

Well, I’ve only got myself to blame! I shouldn’t have used such a value-laden term as ‘fair’ in favour of one side of the debate! I didn’t really want to get involved in a quasi-moral debate about who should have the burden of proof and who doesn’t, but it looks as though I have! Thinking about the logical categories here: certainly given the seemingly analytically insurmountable task of exhaustively searching morphospace to prove the absence of possible evolutionary paths to the flagellum structure, then you are right, the demand that ID theorist prove these paths don’t exist is at least practically impossible if not logically impossible. This point does reveal that the ID community have given themselves a rather difficult task: In ascribing ‘irreducible complexity’ to this or that biological structure, they are imputing a property that they have little chance of proving outright. OK, given the analytical/logical barrier here, I can give ID theorists some leeway and accept a weaker criterion for trying to identify IR (but what is this weaker criterion?) But then shouldn’t I also be giving evolutionists a little leeway? After all evolutionists may also be faced with a difficult problem, an epistemological problem. Even if they have the imagination to tentatively propose possible evolutionary routes to the structure in question, the empirical evidence for this path being traversed in actuality may well be lost in the mists of time; therefore the demand that they produce empirical evidence for the full path is as impossible to fulfill as the demand that ID theorists show that such paths don’t exist. How does some one who is trying to be fair choose between these two parties and make a fair judgment? Who is making the most extraordinary claims requiring the most extraordinary proof? In fact how does one evaluate what is ‘extraordinary’?