Is intelligent design a legitimate scientific movement?


The “intelligent design” movement was formed in the mid-1990s by a group of scholars whose objective was to present a significantly more tenable alternative to evolution than that promoted by young-earth creationists such as Henry Morris and John Whitcomb. The principal figures of the intelligent design movement, notably Michael Behe, William Dembski, Phillip Johnson and Jonathan Wells, have respectable academic credentials and generally accept the overall scientific account and timeline of the creation. However, they still insist that many features of life on earth are too complex to be explained by natural evolution. They acknowledge limited variations within basic “kinds,” but insist that the individual kinds were separately formed or designed by an intelligent entity, utilizing means that may not be subject to human investigation.

The Discovery Institute, near Seattle, Washington, has provided much of the funding and central direction for the intelligent design movement’s activities. In spite of legal setbacks (see Court cases for details), the intelligent design movement continues to press forward in various U.S. states, including (as of June 2014) Louisiana, Missouri, Oklahoma, South Carolina, Texas and Wyoming.

What exactly is “intelligent design”?

So what exactly is the “intelligent design” movement? On one hand, intelligent design is a refreshing improvement over young-earth creationism, provided one focuses on the writings of its most prominent spokespersons, such as Michael Behe, a microbiologist at Lehigh University. In his 2007 book The Edge of Evolution [Behe2007], Behe acknowledges that life has been on earth for several billion years [pg. 19], that fish have been around for millions of years [pg. 16], and that “perhaps a trillion” creatures have preceded humans on the planet in the past ten million years [pg. 60]. In general he sees “little question that all species on earth descended from a common ancestor” [dust jacket]. This stance certainly places Behe in a much more scientifically tenable position than the young-earth creationist school.

But given Behe’s approach, one might ask, “What is the point of intelligent design?” If essentially all of the principal assertions of evolutionary theory are granted from the start (e.g., evolution over many millions of years, common ancestry of species, etc.), and the only question is whether the creation exhibits “design” in some sense, or whether mutation and natural selection are sufficient by themselves to explain evolution, then from the public’s perspective, there seems little to be gained from intelligent design, scientifically or theologically. Indeed, Behe’s comments have drawn sharp criticism from some in the evangelical creationist community [Lyons2008].

Intelligent design and creationism

Although intelligent design writers and their proponents take pains to distinguish themselves from traditional creationists, there is clear evidence that the intelligent design movement is also rooted in fundamentalism and biblical inerrancy. The intelligent design textbook Of Pandas and People is a lightly edited version of an earlier creationist textbook, where, among other things, the word “creation” has been replaced with “intelligent design” [Kitzmiller2005]. The Discovery Institute’s Center for Science and Culture, is devoted “to defeat scientific materialism and its destructive moral, cultural, and political legacies” and “to replace materialistic explanations with the theistic understanding that nature and human beings are created by God.” And although there are exceptions, most intelligent design writers agree with creationist writers that modern evolutionary theory is irreconcilable with Christian religion.

Intelligent design and scientific evidence

One key weakness of intelligent design, as it currently stands, is that these writers have not yet produced a solid body of quantitative, falsifiable scientific hypotheses that can be tested and scrutinized by the scientific community. For example, exactly what do the intelligent design writers mean by “design”? By contrast, creationists have at least produced a number of testable hypotheses, such as their assertions that the earth was created in roughly 4000 BCE, and that all fossil layers were deposited during a global flood in roughly 2500 BCE (which hypotheses have been soundly refuted by scientific evidence). Instead, intelligent design writers have mostly focused their efforts on identifying weaknesses in the established evolutionary theory.

Nonetheless, many are convinced that intelligent design writers have identified substantive technical issues that draw into question certain aspects of evolutionary theory. Since these issues are very frequently raised in these discussions, here is a brief summary of the some issues raised by the intelligent design writers and the consensus response of the scientific world:

  1. Irreducibly complex systems. Michael Behe has argued that certain biological systems, such as bacterial flagella, blood clotting machinery, and the immune system, are “irreducibly complex”: they consist of multiple subsystems, the removal of any one of which would render the system nonfunctional. He argues that such systems must have been designed by an intelligent entity, because none of the components could have evolved in the absence of the others. Scientists counter that systems labeled as “irreducibly complex” by Behe can arise by natural evolution — individual parts may arise separately, each useful in different context, and then later be combined into a larger system. This is discussed in more detail at Complexity.
  2. Probability. Creationists and intelligent design writers have argued that the probability of a biomolecule such as human alpha globin, which is a sequence of 141 amino acids, forming at random from scratch is so remote that it could not be expected to have occurred even once in the history of the universe. Such calculations are often flawed. But more importantly, this type of probability-based arguments suffers from the fatal fallacy of presuming that a structure such as alpha globin arises by a single all-or-nothing event (which, after all, is the creationist theory, not the scientific theory, of their origin). Instead, available evidence suggests that alpha globin and other proteins arose as the end product of a long sequence of intermediate steps, each of which was biologically useful in an earlier context. This is discussed in more detail at Probability.
  3. Information theory. William Dembski has invoked probability and information theory (the mathematical theory of information content) in arguments against Darwinism. But knowledgeable researchers who have examined Dembski’s works in detail are not convinced that he has identified any such weaknesses in evolutionary theory. This is discussed in more detail at Probability.
  4. Biological novelty. A key premise of intelligent design theory is that whereas minor changes may occur within an established kind, “random” or “undirected” evolution can never produce anything fundamentally new [Dembski1999, pg. 113]. Biologists counter with examples such as a 1974 experiment, wherein a gene in the bacterium E. coli that is responsible for metabolizing lactose was removed. Within 24 hours the bacteria had re-evolved a capability to utilize lactose, by means of a similar but distinct three-part biochemical pathway [Miller1999, pg. 145-147]. An even more remarkable case is Richard Lenski’s multi-decade experiment, in which one colony of E. coli bacteria, after 33,000 generations, suddenly developed the ability to utilize citrate, by means of a combination of two mutations [Pennisi2013]. Perhaps the best-known examples, however, are the recent evolution of new strains of tuberculosis that are resistant to all known anti-TB drugs, and drug-resistant strains of HIV that in many cases evolve within the body of a single patient [Coyne2009, pg. 130-131]. This is discussed in more detail at Novelty.

The intelligent design community’s notion of design presents severe problems, technical and theological, not only in light of the many troublesome features of nature, such as pain, disease and violence, but also from the undeniable fact that millions of species that once roamed the earth have become extinct. For example, paleontologists have identified 22 distinct species of elephants that arose and became extinct during the past six million years. Why did it take so many tries to “design” modern elephants? [Miller1999, pg. 97].

For that matter, numerous features of the human body present difficulties for the “design” hypotheses. Many persons suffer from back ailments, due to a skeletal design that is clearly adapted from four-footed ancestors [Miller1999, pg. 101]. Almost all mammals generate their own vitamin C, but while we have the same biochemical machinery, it doesn’t work because mutations have inactivated a key final step [Fairbanks2007, pg. 53-54; Miller2008, pg. 97-98]. Numerous other examples could be mentioned, but the conclusion is the same — at the least, design must be viewed in high-level terms, not in low-level mechanics. This is discussed in more detail at Design.

Do intelligent design writers publish in peer-reviewed scientific publications?

Intelligent design writers have published their arguments dissenting from conventional evolutionary science in books and in online articles, but, as far as anyone can determine, not in any recognized peer-reviewed scientific journal. For additional details, see Peer review. This lack of peer-reviewed publications presents a severe obstacle to intelligent design being taken seriously in the scientific world. After all, if intelligent design writers (individually or collectively) believe that any of their technical issues have significant merit on purely scientific grounds, why do they not compose them into well-researched and well-analyzed articles and submit these articles to recognized peer-reviewed scientific journals?

Criticism of intelligent design from the religious community

The intelligent design movement has even drawn criticism from religious writers. For example, Stephen M. Barr, a University of Delaware physicist and columnist for the inter-denominational publication First Things, recently summarized the impact of intelligent design in these terms [Barr2010a]:

It is time to take stock: What has the intelligent design movement achieved? As science, nothing. The goal of science is to increase our understanding of the natural world, and there is not a single phenomenon that we understand better today or are likely to understand better in the future through the efforts of ID theorists. If we are to look for ID achievements, then, it must be in the realm of natural theology. And there, I think, the movement must be judged not only a failure, but a debacle.


The intelligent design movement, like creationist movement that preceded it, was founded out of deeply felt concerns that modern science in general, and evolutionary theory in particular, are a direct affront to the Bible and Judeo-Christian religion. Many of its adherents are deeply religious people and practice their religion in daily life. Their general notion that a supreme Being oversaw or governed the creation is one that many scientists, religious and not-so-religious, can accept. Certainly the majority of intelligent design writers are much more scientifically reasonable than creationist writers.

But this raises the question of what is the point of intelligent design, from the public’s perspective. Indeed, this writer suspects that the public’s enthusiasm for intelligent design would wane considerably if it were more widely known that the leading intelligent design scientist (Behe), for instance, fully accepts the notions that the earth and its fossil layers are many millions of years old, and that individual species are related by common descent in a family tree. In other words, if the main tenets of modern evolutionary theory are granted from the start, then there seems little to be gained by pursuing intelligent design.

But even with regards to the specific technical issues addressed by the intelligent design movement, the consensus of the vast majority of scientists who have examined these matters is that the intelligent design assertions are refuted by well-known evidence, or else are not genuinely substantive. Most of these issues were settled long ago in the scientific literature. At the very least, the intelligent design community certainly has not delivered a “knock-out” blow to evolutionary theory as they have hoped.

One overriding difficulty with both the creationist and intelligent design movements is that invoking a Creator or Designer whenever one encounters a difficult question is a “thinking stopper.” Such an approach places numerous grand questions of our existence off-limits to human investigation, buried in the inscrutable mind of a mysterious supreme Being: “Why was the earth (or the universe in general) designed the way it was?” “How did the design and creative processes proceed?” “What physical laws were employed?” “Why those particular laws?” “What prompted the creation?” “Have other earths or universes been designed or created?” “Where are they?” Surely there is a more fruitful avenue for finding a harmony between science and religion than just saying “God created and/or designed it that way” and then deeming it either unnecessary or inappropriate to inquire further.

For these reasons, neither creationism nor intelligent design can be recommended for those seeking rational harmony between science and religion. Other approaches, which acknowledge basic scientific precepts, and do not attempt to “combat” the world of science, are recommended instead.

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