Now if, like me, you post things on the internet, you expect that if you get something wrong – or even just don't make something clear – then somebody will come along and tell you so, especially if the issue is a controversial one. One would have thought that higher standards would be observed if somebody is going into print – obviously with publication of papers, but as much so with books. Unless, that is, you are telling lots of people what they want to hear. I really can't think of any other way of explaining the fact that Dawkins fails to fairly represent Behe's work.
I want to react to just three sentences from this section.
The speedy resort to a dramatic proclamation of 'irreducible complexity' represents a failure of the imagination. (TGD p.154)This is, of course, correct to an extent. Indeed, Behe would agree with him – and there are no such speedy resorts to dramatic proclamations in Darwin's Black Box (DBB). Further, contrary to Dawkins' implication, no physiological structures, such as the eye or the weasel toad's elbow, are labelled as irreducibly complex by Behe. (No, Dawkins doesn't say that he does – he just spends a great deal of energy pointing out how such labelling would be wrong, giving the impression that this was what Behe had done.) Indeed, at the start of DBB, Behe specifically makes the point that he is not concerned with the gradual evolution of such structures. The concept of irreducible complexity is carefully defined (see below), related only to biochemical systems, and guardedly applied.
However, Dawkins' sentence is also misleading from a scientific point of view. An excess of imagination is not entirely a good thing for a scientist. Science is not simply story-telling – a story explaining how the multicellular organism got its immune system should not be a far-fetched “just-so” story. It has to be scientifically plausible. It is possible to write explanations of all sorts of complex observed phenomena, but more difficult to establish whether the descriptions provide a feasible or probable explanation. It seems to be considered an adequate scientific explanation if it is simply conceivable. In terms of the sort of biological structure that Dawkins is particularly interested in, it's worth reading this paper discussing different models for the evolution of the giraffe's neck. This post, however, is not the place to discuss such things. Suffice it to say that the speedy resort to a dramatic proclamation of 'scientifically explained' may represent in some cases a surfeit of imagination.
Without a word of justification, explanation or amplification, Behe simply proclaims the bacterial flagellar motor to be irreducibly complex. (TGD, p.158, emphasis in original)This is incorrect. Behe defines quite carefully what he means by irreducible complexity. The concept itself is not hard to understand, and it was the fact that I quickly understood it that resulted in my being convinced that DBB made a compelling case. A biochemical system, Behe explains, is irreducibly complex if it contains multiple components, the absence of more than one of which would result in loss of functionality of the system. The bacterial flagellum was considered by Behe to be irreducibly complex because he claimed that removal of, or damage to, any of a number of the constituent proteins, would impair the flagellar function. Why is this significant? Because the system evolved from a state where those components were not originally present. If more than one component is essential to the operation of the system, then there is no selective advantage to the addition of one of the components without the simultaneous addition of the other essential ones. The simultaneous, random addition of two components is too low probability to be considered realistically possible.
This is substantially different from Dawkins' conception of “50% of an eye being more useful than 49%”, although there is little to suggest that Dawkins particularly understands this. Dawkins seems to view biological systems as evolving from monolithic sequences of DNA. To illustrate this, consider a random sequence of say 1000 letters, which has to mutate using Dawkins' METHINKS program into an English text. His argument is that if 510 letters are correct (51%), this is more accurate than 500 (50%), and so the more accurate version would have a “selective advantage”.
Behe's model is different. He argues that a biochemical system is more like a sequence of 1000 letters that actually breaks into 10 groups of 100. For the system to work, not only does each group of 100 letters have to make sense separately, but also until all of the groups make sense, the whole system has no function, and can't therefore provide anything that offers a selective advantage.
The discussion relating to the flagellum has moved on substantially from here since DBB was published. I won't go into that here, although to an extent, it follows below. The point I want to make is that this statement of Dawkins is simply not true. Behe does provide justification, explanation and amplification. Dawkins might not have bothered to read or been able to understand all of DBB: that doesn't mean that the rest of it doesn't exist.
The key to demonstrating irreducible complexity is to show that none of the parts could have been useful on its own. (p.158)This relates to how the discussion about irreducible complexity has moved on since the publication of DBB, but this statement itself is also incorrect. The key to demonstrating irreducible complexity is to show that parts can't be removed without loss of functionality of the system – that is what irreducible complexity is. What Dawkins is talking about here is something different. A system may be irreducibly complex, but an evolutionary way around this can arguably be found if one or more of the required proteins is already present in a cell. If this is the case, it is possible to conceive of these proteins being co-opted to a new function. So whilst a biochemical pathway may irreducibly depend for its function on eight or twelve proteins, if proteins similar to those required are present in the organism already, then it is suggested that they could be relatively easily co-opted to their new role.
This does represent a hypothetical way forward, and to see what this might look like in the context of the bacterial flagellum, check out Nick Matzke's paper “Evolution in Brownian Space” – it goes some way further than Ken Miller's comments about the Type Three Secretory System that Dawkins refers to. However, just as Behe must be careful about labelling systems as irreducibly complex, I really think that the claims made for this means of getting around IC should be more guarded. To the best of my knowledge, there are few proteins that can definitively be said to have been co-opted to new roles. And an infinite regression can't be hypothesized – at some stage, new proteins have to be generated from scratch; new gene control mechanisms produced; new means of co-ordinating the function of groups of proteins to make biochemical systems need to be derived.
In short, Dawkins fails to go even as far as other researchers have in interacting with Behe in his book, and gives the impression either that he doesn't understand Behe's work, or that he is deliberately trying to misrepresent it to his readers.
Finally, all of this debate about irreducible complexity is, in a sense, yesterday's news. Behe's more recent book, “The Edge of Evolution”, suggests that undirected evolution is in any case able to achieve far less than the production of an irreducibly complex system. He has not backed away from irreducible complexity; he has strengthened his claim. As with DBB, most interaction with Behe's latest book – including Dawkins' own review of it in the New York Times – fails to get to grips with the issues it raises.