Many evolutionists long regarded it as counterproductive to engage in public discussions and debates about Intelligent Design (ID). Doing so, they worried, would give ID publicity and respect that it did not deserve. Plus, it was a waste of time. But this reticence turned out to be a bad public-relations strategy. It made evolutionary scientists seem arrogant and evasive, and it allowed ID claims to go, all too often, unanswered.
Increasingly, though, the evolution side has shown a willingness to grapple with, rather than ignore, ID. One reason for this may be the spurring to action by the documentary Flock of Dodos, which makes fun of evolutionists as tongue-tied and out-of-touch even while arguing that they are right. One critic described the film as "engaging" and "hilarious." (Disclosure: I was that critic. My review is here.)
Two new books provide valuable defenses of evolution and dissections of ID. In Intelligent Thought: Science versus the Intelligent Design Movement, edited by John Brockman, a variety of scientists and scholars address diverse aspects of evolution and ID. In Why Darwin Matters: The Case Against Intelligent Design, Michael Shermer, publisher of Skeptic magazine and columnist for Scientific American, presents a wide-ranging argument. (Disclosure: As a freelancer at Scientific American, I have fact-checked some of Shermer's columns -- which makes me kind of a "skeptic's skeptic.")
In Intelligent Thought's opening essay, University of Chicago biologist Jerry A. Coyne contrasts evolutionary theory's explanatory power with that of ID. Evolution, he notes, explains the fossil record's distinct patterns, with older, deeper layers of rock containing only simple invertebrates, and newer layers revealing the successive appearance of fish, amphibians, reptiles and mammals. Evolution explains the presence in living organisms of vestigial organs and of segments of DNA that once served a function but no longer do. It also explains the geographic distribution of organisms -- for example, why oceanic islands have plants, insects and birds similar to those of the closest mainland areas.
By contrast, as Coyne points out, ID offers no clear explanation of any of the above. Instead, it relies on assertions that certain features of the biological world could not have arisen through evolution (with design presented as a default assumption). Noting that he has been criticized for saying both that ID is false and that it is untestable, Coyne reiterates that both criticisms are accurate. ID, in his description, comes in two forms: "Weak ID" states that organisms contain some mix of evolved and designed features, but lacks sufficient specificity to be tested, while "strong ID" makes claims (such as that evolution of one species from another is impossible) that run contrary to the evidence.
Elsewhere in Intelligent Thought, paleontologist Tim D. White examines the fossil evidence for human evolution, focusing especially on bones and tools found in the Horn of Africa. He notes that his team's discovery of a 155,000-year-old specimen known as Herto man caused consternation among creationists. Historian Frank J. Sulloway recounts how Darwin abandoned the creationism of his time after learning that his Galápagos bird specimens included multiple species of finches. Biologist Neil H. Shubin analyzes the "great transition" wherein organisms moved from sea to land some 370 million years ago; this occurred, he points out, in a series of incremental stages, such that there was little difference between fish of that era and the first land-dwelling animals.
The book's essays cover a broad range of topics. Cognitive scientist Steven Pinker argues that evolutionary theory, rather than corroding morality, provides a framework for understanding how the human moral sense developed. Physicist Lee Smolin suggests that natural selection may occur in cosmology as well as biology, with universes reproducing themselves via black holes. Complexity theorist Stuart A. Kauffman contends that whether something was designed is a legitimate scientific question, but that ID has failed to provide convincing evidence of design. Philosopher Daniel Dennett's essay "The Hoax of Intelligent Design and How It Was Perpetrated" offers insights into ID debating tactics, but falls short of its title by providing little detail on ID's history as a movement.
Shermer's Why Darwin Matters emphasizes that there is a convergence of evidence from multiple fields -- geology, paleontology, molecular biology, zoology, botany, comparative anatomy, and population genetics, among others -- supporting evolution. Shermer recounts how recognizing this convergence brought his own conversion from the creationism he had espoused in his undergraduate years. In a refreshing departure from the personal animosity that characterizes much of the evolution-ID conflict, Shermer notes that he has had amicable debates, and shared friendly meals and car rides, with mathematician-philosopher William A. Dembski and other ID proponents.
Shermer recapitulates a number of key ID arguments and provides his responses. Regarding the view that the universe was "fine tuned" for life, he notes that much of space and time is inhospitable to life, and suggests that it is we (humans and other life) that are tuned to our corner of the universe, rather than the universe being tuned for us. Discussing the "explanatory filter," a technique devised by Dembski to identify design, Shermer counters that it is merely notional, relying on probability calculations that are not possible in practice. He cautions that the "design inference" touted by ID theorists is subjective and unreliable, particularly for detecting superhuman designers.
As for claims of "irreducible complexity," that some biological systems could not have evolved gradually, Shermer discusses how features that evolve for one purpose can be co-opted for other purposes, such as incipient wings serving as aids to running or grasping. He notes that the bacterial flagellum, given as a prime example of irreducible complexity, serves different functions in different bacteria, coming in various degrees of complexity. Shermer also points to research elucidating the biochemical pathways in the development of blood clotting, another supposed example of something that could not have evolved.
Similar to Pinker, Shermer argues that evolution enhances, rather than undermines, our understanding of morality. He also argues that ID aims to promote religious objectives but fails to do so; the designer that emerges from current ID theories seems to be an entity of limited powers, rather than a transcendent creator of the universe. A weak point in the book, however, is Shermer's discussion of methodological naturalism, the view that science is suited only for explaining natural phenomena, whether or not supernatural phenomena exist. Shermer sloppily blurs the distinction between this methodological approach and the philosophical naturalism that rejects the existence of the supernatural.
However, Shermer presents a cogent history of the ID movement, including its legal setbacks culminating in the late 2005 decision in Kitzmiller v. Dover, in which a federal court in Pennsylvania ruled against a move to introduce ID into science classes. Intelligent Thought closes with an excerpt of that decision, in the aftermath of which the ID movement has been struggling to regain political momentum.
Overall, both Why Darwin Matters and Intelligent Thought make strong arguments against Intelligent Design. They also show that debating beats ignoring the subject.
Kenneth Silber is a TCS Daily contributing writer who focuses on science, technology and economics.