Saturday, September 03, 2005

More on Intelligent Design, part I

It would seem that my off-site essay link to Jon Carroll's essay on the topic of Intelligent Design (henceforth ID", in which he argues that it has no place in a scientific course of study, particularly in the context of a public school's science classes, has generated a rather unusual amount of traffic. In addition to the posted comments, I got a fair share of email.

Much of the communication that I received was a dull iteration of the sort's of arguments that have been used in attempts to defend Creationism (or to attack Darwinism) ever since the publication of The Origin of Species. Few people actually addressed the issue of the theory of ID, which more or less what I expected given that it is my belief that most proponents of ID aren't really interested in it except in as much as it provides a back door for standard Creationism. One person, whom I shall not name, asked what I thought was a more pertinent and intelligent question — she wanted to know what, exactly, ID wasn't science.

[Science] is observation, formulation of an hypothesis, using that hypothesis to make predictions (ie, that there are as yet other undiscovered systems which can't be accounted for under existing evolutionary theory), etc. I know it's a gussied up "goddidit", but I can't see how that precludes it from being science, even if it's wrong.
I think that this is a fair question and I think that it deserves an answer. In addressing it I want to be clear that I am, specifically, addressing the Behe version of the ID argument. It is necessary to specify this since there are quite a lot of variations of ID with some being more overtly theological than others. The version supported by William Dembski, for instance, explicitly conjectures not only a hypothetical designer but, in fact, that the supposed designer is none other than the Christian God. Since science does not address anything outside of the natural world, any theory that appeals to the supernatural is not, by definition, science. Other ID variants are less explicit in their endorsement of supernatural agencies; however, it would be impossible for me to address every variant of the theory. The Behe version is the most famous and, I believe, the one that comes the closest to approaching scientific standards, therefore, I will be limited my discussion of the subject to it.

I want to also make it clear that what is being proposed for the schools is not the Behe version of the theory. I think that it is important that we not lose sight of this. The question of whether ID could be considered scientific is distinct from the question of whether it should be taught in public classrooms. Unfortunately, in the current political climate, one cannot really address the question of the scientific metrics ID without addressing that other question, although I will address the question of its scientific merits before returning the secondary issue of its appropriateness for students.

I think that we must first clearly define what Behe's hypothesis is. In Darwin's Black Book Behe raised the following conjecture: certain systems in the biological world can not be accounted for via evolutionary processes; it is, therefore, rational to conclude that those features are the product of an external intelligence. He proposed that the distinguishing feature of these systems was a property called irreducible complexity (henceforth IC and ICS for irreducible complexity and irreducibly complex system). An ICS is a system that is composed in such a way that one cannot remove any component of the system without breaking it.

The typical analogy of an ICS is a mousetrap. Behe, himself, uses this example in his book. He says that a spring-loaded mousetrap is an ICS because one can not remove, for instance, catch. Behe claims that the same sort of irreducibility is found in certain natural systems such as the flagella of the E. coli bacteria.

Before I go any further, I want to contrast ID with an early 19th century argument for the existence of God known as "Paley's Watchmaker". This was an argument put forth by the philosopher William Paley (although variants go back at least as far as the roman philosopher Cicero). A typical version of the watchmaker argument asks us to imagine that we are walking along a trail when we come across a watch (imagine an old-fashioned pocket watch with lots of intricate gears). As we examine the watch we are impressed by its complexity. That same complexity tells us that the watch isn't something that just happened to form by natural processes; it was constructed. The fact that it was constructed implies the existence of a constructor, i.e. a watchmaker. Paley argues that the fact that the complexity of the watch implies a designer must also imply that the complexity of nature requires one as well.

Paley's argument has a great deal of intuitive appeal. Indeed, among the people impressed by it was none other than Charles Darwin, who believed, as a young man, that the argument did, in fact, demonstrate the existence of a god (if not, indeed, God himself). The argument is, however, fundamentally flawed. The particular flaw is a type that philosophers often call begging the question. A question is begged when the answer provided is circular. In this case, Paley uses the complex nature of the watch to argue that it is an artifact, which is to say the creation of artifice — which is to say that it is not a product of nature. However, he then uses the artificial complexity of the watch to argue that biological objects must also be products of artifice. In other words the aspect of the watch that he's contrasting with the natural world is being used to draw a conclusion about the natural world.

A more reasonable conclusion is that our observation that natural structures exhibit complexity means that the mere complexity of the watch is not, in and of itself, sufficient for us to draw the conclusion that the watch has a watchmaker. There are other factors that lead us to the rational conclusion that it had a maker, not least being the fact that we have experience with watches and with biological systems and that we know that the creation of one (by construction) is not like the creation of the other (by germination and growth). The conclusion that Paley reaches is not justified by the observation.

Paley's watchmaker had a lot of pull beyond its logical merits simply because no one had any alternative idea of how biological complexity could, ultimately, be accounted for. Ultimately it was Darwin — older, wiser, and with the benefit of his observations in the Galapagos — who showed how that very thing could happen without requiring us to suppose an intelligent agency (Richard Dawkins has referred to the agency of natural selection as a blind watchmaker in a jab at Paley's original argument). Darwin did more than simply offering an explanatory framework that allowed us to see past Paley, he demonstrated the danger of reaching a conclusion based solely on the lack of a compelling alternative.

Although Behe's designer has much in common with Paley's watchmaker (indeed, it is a philosophical descendant), Behe's arguments are more subtle and don't suffer from the specific logical flaw that Paley fell prey to. Behe isn't drawing a direct comparison between artificial and natural system; rather, he is making a comparison between one type of natural system and another.

Both detractors and supporters of ID often fail to realize that Behe does not deny the existence of natural selection. In point of fact, Behe believes that the majority of structures in the natural world, including the existence of ecosystems with diverse species, can and must be accounted for my conventional Darwinism. It is not even entirely clear that Behe is a creationist since he doesn't offer any opinion about the origin of life. Behe's proposed designer is deliberately left vague as are the mechanisms whereby it (or they) implemented the designs that Behe believes require an intelligent agent to account for. Behe's designer could well be aliens who visited the earth back in the pre-Cambrian and who performed acts of genetic engineering on the local microfauna. Indeed, if the theory is to have any scientific merit, it must limit its speculations to the natural world.

Religious critics of science believe that the fact that science doesn't allow for supernatural speculations means that science is, at its heart, anti-theistic. This is an error. Science is, basically, an epistemological philosophy about the natural world. Science only addresses questions about the natural world by design. At the point where science entertains non-natural explanations it finds itself in the situation illustrated by a semi-famous Sydney Harris cartoon where two scientists are pondering a chalkboard full of equations. In the middle of the equations in the phrase "and then a miracle occurs". While it may be easier to suppose the existence of miracles, once we have done so, we have abandoned science for metaphysics.

Behe, to his credit, does not claim that irreducible structures are miraculous. He only claims that they are the product of intelligence. The intuitive implication is, of course, that there is something miraculous, indeed divine, going on, and I strongly suspect that Behe is being disingenuous when he coyly claims that people are jumping to conclusions, but a theory can not be dismissed simply because it implies something that's non-scientific, no matter how strong that implication may be.

A stronger criticism is that Behe is drawing a conclusion from an absence of evidence. Even if we grant the claim that current Darwinian theory can not account for an E. coli flagellum, are we required to conclude that the explanation must be an external intelligence? Before we evaluate this criticism, I think that it would be a good idea to consider a case where an observational absence led to a legitimate scientific conclusion.

A neutrino is a kind of massless (or near-masslesss, perhaps) particle that has nearly no interactions with other particles. A typical neutrino could pass through several light-years worth of solid lead before it was stopped. They have been described as being as close as it is possible to get to nothing while, never the less, still being something.

Neutrinos were originally postulated by Wolfgang Pauli to account for some missing energy and angular momentum during a processes known as beta decay. Neutrinos were not being observed during this type of decay. Indeed, because of their extremely non-interactive nature, it would take another quarter of a century before experimental evidence for the existence of neutrinos was produced. In the meanwhile, physicists contended themselves with a hypothesis whose sole rationale was to account for a discrepancy in the data.

So, how is this different from ID and IC? Well, for a start, physicists didn't just pull the neutrino out of their asses (although that would be a neat trick!). The basis for conjecturing the neutrino were two of the conservation laws: the conservation of mass and the conservation of angular momentum. It is not an exaggeration to say that these laws form an important part of the foundation of modern physics. They are philosophically important to physics since the idea of conservation provides a basis from which we can make speculations involving an invariant physical reality. If any of these laws did not hold, not only would we need to radically reevaluate our understanding of physics, we'd have to reevaluate our basis for deriving models of physical law in the first place.

Beyond the epistemological question, the laws of conservation have a firm grounding in experiment. Literal centuries of effort have found nothing which would lead us to suppose that the conservations do not hold. The most radical change to theory was provided by Einstein who showed that the conservation of mass and the conservation of energy were, in fact, both aspects of a single conservation law which allowed for mass and energy to change form from one state to the other (which is what allows the Sun to burn and nuclear bombs to go boom).

Faced with a single observation that seemed to show a violation of two conservations, Pauli decided that, given they overall success and importance, it was much more likely that something else was going on. The simplest supposition was that there was an unobserved particle. Such a weakly interacting particle would be a bit weird, but certainly not outlandish. His intuitions were validated by the eventual detection of neutrinos, which is now done on a regular and ongoing basis.

Many counter-intuitive theories follow a similar course. Astronomers are positive that there is dark matter in the universe because, otherwise, their observations of such things as galactic rotations simply don't make sense. These hypotheses are arrived at out of necessity and are based upon the application of known law (e.g., the Newtonian laws of gravity) in order to be arrived at.

How then is this different from ID?

I will take that up in next week's continuation of this essay (assuming, of course, that work concerns don't delay it).

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