The Explanatory Filter: What About Evolving Laws?

Lars posted recently about a National Geographic article on a group of lizards showing signs of extremely rapid evolution. In his post he mentioned something entitled the Explanatory Filter, linking to an article by William Dembski entitled “The Explanatory Filter: A three-part filter for understanding how to separate and identify cause from intelligent design.”

I was somewhat surprised that I had never heard of the explanatory filter before.  As I understand it, the filter asks three questions:

1. Does a law explain it?
2. Does chance explain it?
3. Does design explain it?

The ideas is simple; given any event, you run it through those three questions.  First you check for laws that can explain the occurrence of the event.  If there is none, you examine the statistical probability of the event occurring.  If it would be statistically improbable, then you ask whether or not design could explain it.  If it can, then you attribute the event to design.

The simplicity of the argument is appealing.  There is, however, a large problem with the filter: it doesn’t take into account the evolution of scientific laws.  Science is based on the scientific method.  This is often given as a set of steps:

1. Define the question
2. Gather information through observation
3. Form a hypothesis
4. Perform experiment and collect data
5. Analyze data
6. Interpret data and draw conclusions; form a new hypothesis if necessary

The key thing to note here is that if the information gathered from the experiment fails to support the hypothesis, then a new hypothesis must be formed.  Thus you perform steps three to six until the data supports the conclusions.

The explanatory filter seems to ignore this ability to form a new scientific law; it skips directly to attributing ideas to design.  To see how this could be a problem, let us apply the filter to an age old problem: the movement of the planets through the heavens.

Millennia ago, as humans learned to chart the heavens, they noted that there were certain stars that seemed to move through the others.  Various theories emerged over time, including the idea that the planets moved in circles around the earth.  The problem was that sometimes the planets would wander out of where the circular orbits should take them.  No natural law could explain why this should happen.  According to the explanatory filter, if the chances of them drifting far afield were too low, then the wandering of the planets should be attributed to design. (Indeed, some design-like ideas emerged, such as the concept that the planets were gods wandering in their chariots through the heavens.)

This is not where the story stops, of course.  Instead, numerous astronomers and mathematicians came up with increasingly complex theories involving dozens of rotating spheres to explain the drift.  In the end, Johannes Kepler brought it all together and proposed the idea of elliptical orbits.  Suddenly everything was explained and the need for design was removed.

The example is overly simplistic, of course, and an extremely condensed version of history.  Still, it serves to illustrate the point that science is designed to evolve new sets of laws to explain things naturally.  (Note that this says nothing about the concept of ultimate design.  That is, scientific theory can never speak to the existence of God.  This is because, as Kyle pointed out, scientific theory cannot ever look to the supernatural.)

In the end, it seems as if the explanatory filter is simply a means of giving scientific justification to “the God of the gaps.”  Still, I’ll be the first to admit that I have only dabbled in this.  I would be interested in hearing what others, especially those who support the filter, have to say.