Sunday morning, I had the opportunity to hear Massimo Pigliucci debut a new lecture debunking the latest form of Creationism, Intelligent Design. The lecture was sponsored by the Rationalists of East Tennessee and was held at The Candy Factory.
In short, Intelligent Design theory states that living things (or in some versions, parts of living things) are so complex, and so specific to their function, that they could not have arisen by random mutation, and therefore must have been designed. Pr. Pigliucci, a few quibbles aside that I'll get to shortly, did a good job of demonstrating the flaws of such an approach.
Pr. Pigliucci took issue with Demski's Explanatory Filter, which through elimination, tries to prove that some systems must have been designed. As Pr. P pointed out, the filter is incomplete, leaving out a range of alternative explanations for the system. With his filter, Dembski makes the same mistake as does Michael Behe, inferring a result that is not justified by the evidence. Simply pointing out flaws in current evolutionary models does not automatically indicate that the system was designed, only that there are gaps in our knowledge.
Pr. Pigliucci did make a few questionable assertions during the lecture. At one point, he stated that every number he had seen assigned to the probability of evolution was bunk. He spelled out his justification, by saying that 1) we don't have a strong theoretical basis for assigning the probabilities, and 2) we don't have enough data to generate the probabilities. I tend to disagree with him on the first statement, since I can come up with an algorithm for a rough estimate myself. Through observation, we can come up with an estimate of the current rate of genetic mutation. Using our knowledge of global conditions throughout earth's existence, we can develop a rough range of how the rate of genetic change varies over time. Next, we'd determine what proportion of genetic changes are beneficial, and therefore likely to be selected. Combining the three gives us the expected rate of beneficial genetic changes. All that remains is to compare the time predicted for a change to the time recorded in the fossil record for the change to see how probable it was that evolutionary forces were behind the change.
This would be a very rough estimate at first, but the model could be refined as more information is obtained. After all, as Pr. Pigliucci said during the Q and A portion of the lecture, science doesn't always hit the true answer, especially not on the first swing. Often, it's a matter of picking the closest answer that fits the most data, to get an approximation of the true answer.
In another portion of the lecture, Pr. Pigliucci stated that design theory implies a "perfect" design by a "perfect" designer. His humorous example was that if the universe were designed, zebras would have automatic rifles, to defend themselves from the lions. He went on to say that obviously, zebras couldn't have guns, as there was no evolutionary pathway for that kind of development. Approaching that argument from the design side, perhaps the "perfect" designer wanted a predator/prey relationship between the two animals, thus both animals are "perfectly" suited to their roles. On the more serious scientific side, obviously the evolutionary pathway did exist, and was taken by primates as they developed the intelligence and capability for handling tools. I would suggest that, given enough time, zebra's reversing their evolutionary course and moving towards a tool handling path is no more or less unlikely than the evolutionary reversal of aquatic mammals, who developed arms and legs from fins, then reversed course on their return to the sea.
However, as I mentioned above, these are just quibbles, and do nothing to take away from Pr. Pigliucci's main point, that Intelligent Design, as proposed by Dembski, is not valid science. But before closing, I must address the atmosphere surrounding this lecture.
Pr. Pigliucci did a good job keeping his antipathy towards religion under wraps; it only surfaced in a couple of quick side comments that obviously were not part of the formal lecture. It rapidly became apparent during the Q and A portion that his audience had no such restraint. "Misguided" was perhaps the kindest term used to describe those who have a religious faith, while one fellow bluntly asked if all creation scientists were liars. That type of emotional bias provides nothing constructive.
Going back to the lecture, Pr. Pigliucci demonstrated that Dembski's filter did have a real world application, as long as additional information is available, and as long as a "designer" is assumed. Since creationists make that assumption, the filter would be valid in their frame of reference. No lying or deception required. Science, on the other hand, makes no assumptions about the existence of a deity, positive or negative; it does not deny God, rather it ignores Him.
The Rationalists at this meeting fall into a trap similar to the one that trips up Dembski and Behe, trying to reach a conclusion that isn't justified by the data. Proof of evolution does not disprove the existence of God, despite fundamentalists' fears. Rationalists need to remember that just because a rational explanation exists, that doesn't automatically make it correct. At one point, it was rational to believe that the earth was the center of the universe. It wasn't just religious doctrine; it made sense. The earth was steady beneath our feet; it was the heavens that whirled above us. What seems rational today may be revealed as wildly irrational by new information tomorrow, and our current beliefs may seem as quaint as the Ptolemaic view of the universe.
Additionally, there are aspects of our existence that do not yield themselves to rational explanations.
Try coming up with a rational explanation for Beethoven's 9th some time.
Posted by Rich at November 6, 2003 2:20 PM | TrackBack