Intelligent design theory fails tests, no new knowledge

Letter to the Editor

To the Editor:

The "Breeze Reader's View" by Andrew Chudy in the Oct. 23 issue of The Breeze offered a defense of Intelligent Design theory — a theory intended to provide an explanation of the fact that biological entities are often surprisingly complex and well suited to their environments or their functions.

The basic idea is easy to understand — there are biological organisms and systems in nature that are so complex and finely tuned to their surroundings or to the functions they perform that they could not have evolved by natural selection . The only reasonable alternative is that they were designed by an intelligent being — specifically, God.

This is not a new argument. Charles Darwin discusses it, writing in "The Origin of Species" that to think that something as complex as an eye could have evolved by natural selection "seems, I freely confess, absurd in the highest possible degree." Modern versions of the argument rely on fancier examples, like the bacterial flagellum or the proteins involved in blood-clotting, but the idea is the same.

Clearly, ID purports to be a legitimate scientific theory and a rival to orthodox Darwinian natural selection. We, therefore, must evaluate it by accepted scientific standards. How does it stand up?

Let's start with the biological facts that are to be explained. ID focuses on traits that seem to be tailored for their functions or environments, but examples of such traits are quite rare in nature. Far more common are traits that only are adapted adequately to their purposes, or that have no purpose at all.

A famous example is the panda's "thumb," which is used awkwardly to strip bamboo — the animal's only food. Others are the human spine, which is not well adapted to walking upright, or the teeth that whale embryos develop, but lose before birth.

This is hardly what we would expect to find if every animal was designed by an all-knowing, all-powerful engineer. On the other hand, it is exactly what we would expect if all living things evolved from a common ancestor and if traits are retained even if they are merely adequate for their purposes.

A defender of ID might explain such imperfect traits by saying that only some traits or organisms have been designed, or that the designer is less-than-perfectly competent. That kind of suggestion, however, only highlights another problem for the theory. Any scientific theory makes testable predictions only when joined with specific supplemental hypotheses. If we choose the supplemental hypotheses carefully, we can use the basic idea of ID — that there is an intelligent designer — to deduce any biological fact whatsoever.

The problem is that these supplemental hypotheses are not testable. So, a defender of ID might explain why some traits are well suited to their purposes and others are not by saying that the designer designed a trait carefully only if it was especially important to him, and that he doesn't think whale teeth — for example — are important. But, this sort of explanation relies on untestable assumptions about the designer, and theories that rely on untestable assumptions are not accepted in science, precisely because they are untestable.

Testability in general is a problem for ID. A serious, testable scientific theory is expected to make new, verifiable predictions. ID, however, makes no such predictions.

To speak even more generally, a fundamental problem of that theory is its lack of content. ID claims to give us explanations, but for 1,000 years the theory has had nothing to tell us about any particular phenomenon except, "It's like that because that's how God made it."

The contrast between ID and Darwinian biology hardly could be greater. In only 150 years, that theory has improved our understanding of many details of the origin of life, the variety and similarity of organisms, the evolution of sex, the development of individual organisms and so on.

ID relies for much of its appeal on misunderstandings of biology and the nature of science. One misunderstanding is the idea that, when confronted with an intricately adapted phenomenon, we have to choose between thinking it came about randomly, and thinking it was designed.

In fact, natural selection is not random in the relevant sense. The appearance of variations within a population or species might be random, but the selection that is made among those variations definitely is not random. Traits are selected if they increase an organism's fitness or survivability.

Another misunderstanding concerns the unfinished nature of science. Some people argue that, if today's biology cannot explain everything, then it is completely wrong and should be rejected, perhaps in favor of ID, which can give the appearance of explaining everything.

But this is mistaken. It is no criticism of a science to point out that it cannot explain everything — even in physics and math there are unanswered problems. The right question is not "What hasn't Darwinism explained?" but rather "What has it explained?" If that theory already has a significant record of explanatory success, then that is reason to think it will be able to make progress with the unanswered problems.

As it happens, Darwinism has a great number of impressive accomplishments to its credit. The same cannot be said of ID.

Eric Wolf
department of philosophy
James Madison University.