What’s wrong with intelligent design?

In a thought-provoking paper from the March issue of The Quarterly Review of Biology, Elliott Sober (University of Wisconsin) clearly discusses the problems with two standard criticisms of intelligent design: that it is unfalsifiable and that the many imperfect adaptations found in nature refute the hypothesis of intelligent design.

Biologists from Charles Darwin to Stephen Jay Gould have advanced this second type of argument. Stephen Jay Gould’s well-known example of a trait of this type is the panda’s thumb. If a truly intelligent designer were responsible for the panda, Gould argues, it would have provided a more useful tool than the stubby proto-thumb that pandas use to laboriously strip bamboo in order to eat it.

ID proponents have a ready reply to this objection. We do not know whether an intelligent designer intended for pandas to be able to efficiently strip bamboo. The “no designer worth his salt” argument assumes the designer would want pandas to have better eating implements, but the objection has no justification for this assumption. In addition, Sober points out, this criticism of ID also concedes that creationism is testable.

A second common criticism of ID is that it is untestable. To develop this point, scientists often turn to the philosopher Karl Popper’s idea of falsifiability. According to Popper, a scientific statement must allow the possibility of an observation that would disprove it. For example, the statement “all swans are white” is falsifiable, since observing even one swan that isn’t white would disprove it. Sober points out that this criterion entails that many ID statements are falsifiable; for example, the statement that an intelligent designer created the vertebrate eye entails that vertebrates have eyes, which is an observation.

This leads Sober to jettison the concept of falsifiability and to provide a different account of testability. “If ID is to be tested,” he says, “it must be tested against one or more competing hypotheses.” If the ID claim about the vertebrate eye is to be tested against the hypothesis that the vertebrate eye evolved by Darwinian processes, the question is whether there is an observation that can discriminate between the two. The observation that vertebrates have eyes cannot do this.

Sober also points out that criticism of a competing theory, such as evolution, is not in-and-of-itself a test of ID. Proponents of ID must construct a theory that makes its own predictions in order for the theory to be testable. To contend that evolutionary processes cannot produce “irreducibly complex” adaptations merely changes the subject, Sober argues.

“When scientific theories compete with each other, the usual pattern is that independently attested auxiliary propositions allow the theories to make predictions that disagree with each other,” Sober writes. “No such auxiliary propositions allow … ID to do this.” In developing this idea, Sober makes use of ideas that the French philosopher Pierre Duhem developed in connection with physical theories – theories usually do not, all by themselves, make testable predictions. Rather, they do so only when supplemented with auxiliary information. For example, the laws of optics do not, by themselves, predict when eclipses will occur; they do so when independently justified claims about the positions of the earth, moon, and sun are taken into account.

Similarly, ID claims make predictions when they are supplemented by auxiliary claims. The problem is that these auxiliary assumptions about the putative designer’s goals and abilities are not independently justified. Surprisingly, this is a point that several ID proponents concede.

From University of Chicago Press


  1. Dov Henis
    A Humanist Answers A Religious Pen-pal
    (Nov 11 – Dec 4, 2005 DH, in Brights and biologicalEvolution forums)

    Dear Pen-Pal,


    We live on a tiny speck of dust within an infinitely immense swirl.

    Life ( also a black hole? ) is a substantiation of a temporary containment of cosmic energy dilution. All forms of Earth life are thus temporary energy bubbles. We are not yet able to figure out the implications of this.

    Evolution did us a disservice, endowing us with “intelligence”, with the fruit of the Tree of Knowledge, causing us to perceive and explore and wonder.

    Some of us, like you, feel desperately lost without an ID (Inteligent Design) or without “everything being shaped by…something”. You need to subsist under some form of Providence. Your peace of mind and your reflective elation are founded on a feeling that your existence is purposed towards something vague of which it will somehow sometime become a part.

    Some of us, like me, regard our cosmic circumstances, all reality, and our meagre comprehension of them as an invitation to explore and chart the infinite aspects of the evolving universe. In pursuit of this we try to fashion ourselves in accordance with what we progressively learn about the universe and about life and about ourselves.

    This, in my opinion, is the difference between religious and science-based worldviews.

    (From http://blog.360.yahoo.com/blog-P81pQcU1dLBbHgtjQjxG_Q–?cq=1&p=185)

  2. I’m ashamed to live in a country that is still debating the theory of evolution. ID is not science and will crumble when asked to conform to the scientific method.

  3. The “no designer worth his salt” argument assumes the designer would want pandas to have better eating implements, but the objection has no justification for this assumption.

    In other words, no matter how flawed the design is, it was supposed to be that way. Congratulations, this is a claim that is not falsifiable and thus not scientific.

    for example, the statement that an intelligent designer created the vertebrate eye entails that vertebrates have eyes, which is an observation.

    The claim is that an intelligent designer was the one that designed that eye, and that is not falsifiable.

  4. I’m glad to see some signs that the scientific community and the media may finally be utilizing some of the important advances in philosophy of science since Popper’s ideas decades ago. Unfortunately, as it might be clear from one of the comments here, these distinctions may simply be too subtle to matter to most people or even many scientists.

    “Intelligent Design is Unfalsifiable!” does after all, sound much snappier than “Intelligent Design, although technically falsifiable, requires auxialiary hypotheses that cannot be independently attested to!”

    I suppose that’s fine when it comes to the Intelligent Design-Evolution Debate since it still delivers the right answer but may cause more trouble when some physicists start accusing other physicists (e.g. string theorists) of having unfalsifiable theories.


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