Defending Science by Defining It

As part of that fact-based approach, Jones emphasizes, science goes out of its way to avoid a search for "meaning" or "purpose."

By contrast, intelligent design's views on how the world got to be the way it is offer no testable facts, choosing instead to rely on authoritative statements. Adherents posit, for example, that animals were abruptly created (many in the same form in which they exist today) by a supernatural designer.

The court found that intelligent-design documents are quite open about the movement's goal of changing "the ground rules" of science to accommodate much more than natural phenomena -- a broadening so great, one witness for intelligent design testified, that science would embrace even astrology.

"Science cannot be defined differently for Dover students than it is defined in the scientific community," Jones writes.

The judge also cites several ways in which he says proponents of intelligent design failed to think logically, each example offering a take-home lesson that could prove useful to people trying to rebut challenges to evolutionary theory.

First, Jones writes, people would be well advised to remember that an argument against one thing cannot necessarily be interpreted as an argument for something else. For example, the fact that the fossil record is incomplete is not evidence that human beings must have been created in their current form.

The world, in other words, is not a zero-sum, dichotomous one in which a vote against one candidate equals a vote for another.

"Just because scientists cannot explain today how biological systems evolved does not mean that they cannot, and will not, be able to explain them tomorrow," the judge says.

Another logical failing cited by the court concerns one of intelligent design's central arguments: "irreducible complexity."

That argument states that some biological systems -- such as the bacterial flagellum, a whiplike appendage that offers some microbes a means of propelling themselves -- are made of components that, individually, do not have any purpose. Because there would be no evolutionary advantage for those individual parts, they must have arisen all at once -- and expressly for the purpose of serving in that complex organ.

But Jones notes that just because a complex organ cannot work today with one component removed, that does not mean the component did not evolve independently to serve a different purpose and later took on a new role when combined with other parts. The judge notes multiple examples involving the immune system, the blood clotting system, and even the bacterial flagellum itself, in which this appears to have been the case.

Irreducible complexity is in many ways a theological argument -- and a rather old one. A theologian testified at the trial that Thomas Aquinas argued in the 13th century that wherever there is complex design, there must be a designer, and that because nature is complex, it must also have a designer.

While many of the scientists who defended intelligent design in the Pennsylvania trial stopped short of saying that the idea requires belief in God, the defense's chief expert, biochemist Michael J. Behe of Lehigh University, noted that intelligent design's plausibility depends on the extent to which a person believes in God.

"As no evidence in the record indicates that any other scientific proposition's validity rests on belief in God . . . Professor Behe's assertion constitutes substantial evidence that in his view . . . ID is a religious and not a scientific proposition," Jones notes in his opinion.