By Peter Coghlan
WITH the intelligent design debate in the Harrisburg District Court of Pennsylvania now reaching its climax, it is important to be clear about what intelligent design involves and what can reasonably be said for and against it.
As Michael Gawenda points out in his article "Crusade for the classroom" (The Age, 19/11), the most significant proponent of ID is the American biochemist Michael Behe. Behe claims that there are some biological systems, such as the flagellum that propels mobile bacteria, which are "irreducibly complex". The flagellum, Behe argues, is an integrated whole: its component parts have no function outside the mechanism and the mechanism cannot function without each of its component parts.
This means that the flagellum could not have evolved through small modifications to its parts over time, as the Darwinian process of natural selection implies, because its parts have no biological use apart from the mechanism they compose. The flagellum is irreducibly complex.
How, then, was it formed? Behe recognises there could be some other natural process, such as the self-organisation various phenomena from crystals to flocking birds seem to display, that would account for systems such as the flagellum. But the self-organising phenomena we have observed do not combine complex form with function in the way the flagellum does. Thus the most reasonable explanation is that the flagellum was designed by some intelligent agent. This is what Behe calls "design beyond the laws of nature".
Behe himself does not say who this intelligent agent is — that, he thinks, goes beyond his competence as a scientist. But it is not surprising that Behe's readers have identified a being that has power over nature with the traditional Judeo-Christian God.
The critics of intelligent design, such as the Australian scientists and science teachers who recently supported an open letter on the subject, accuse people such as Behe of "making a leap of faith to supernatural intervention". This, they say, is not science but a "theological or philosophical notion". In their view, intelligent design is in the same category as "astrology, spoon bending, flat-earth cosmology or alien abductions".
But this response overlooks several crucial distinctions. Behe's claim that there are some biological systems that cannot be explained by any unintelligent natural process is clearly one that is open to scientific refutation and many scientists have engaged with him on those terms. I can see no reason this debate cannot be raised in senior biology classes in schools.
The claim that the best explanation of complex systems is the action of a supernatural intelligence is, however, just as clearly a philosophical rather than a scientific claim. Behe himself sometimes confuses this issue when he speaks of "pursuing" the "hypothesis of intelligent design" and when he likens his work to that of forensic scientists, archaeologists and cryptologists who distinguish between the products of blind nature and the products of intelligent design.
But the hypothesis of a supernatural designer is not one that can be pursued through the normal methods of experimental science. And the work of these other branches of science depends on our ordinary familiarity with the way the natural world behaves compared with the way human beings behave. We do not have the same familiarity with the behaviour of a supernatural designer.
Yet Behe's critics, too, sometimes confuse the scientific and the philosophical. Richard Dawkins and Jerry Coyne ( The Sunday Age', 11/9) argue that the hypothesis of a supernatural designer is "statistically improbable" because such a being would have to be far more complex than the systems it creates. Derek Denton ( The Age, 17/11) argues that there is "obvious evidence against" the hypothesis because no supernatural intelligence would design sinuses like ours that do not drain properly or eyes like ours with their "blind spot".
Both these arguments make philosophical claims about the nature of God that are at least debatable. A mind that designs complex systems need not itself be complex — it may be simple because it is supremely clear and logical. And such a mind might allow imperfections in its creations so intelligent beings such as ourselves can learn to overcome them.
These are not questions for the school science class but for the philosophy class. Behe is no literal-minded creationist and his position cannot be summarily dismissed as an irrational "leap of faith".
Yet the deepest issue in the ID debate does involve the relationship between faith and reason. All design arguments, including Behe's, draw our attention to the order we find in nature. David Hume famously thought that this order needs no explanation precisely because it is natural. The processes of nature just are regular and intelligible — that is how the world is. Religious believers are struck with wonder at this fact and believe it cries out for explanation. The debate between these views will go on long after the present intelligent design controversy has passed into history.