Like all claims, the neo-Darwinian claim is potentially true and potentially false. As such, it is subject to scrutiny. And, insofar as one wishes to be as circumspect as he can be when choosing which claims he will ultimately embrace, the more critical that scrutiny, the better--for it does not serve to accede a proposition in haste. It is those circumspect readers for whom Stephen Meyer's Darwin's Doubt was written. Indeed, it may be just those readers who can even get to the last page of the work without finding the nearest Internet outlet to decry the book's existence who even understand what Meyer is doing and why. This review is intended for an audience who does not take neo-Darwinism as sacrosanct, nor severe scrutiny of same as blasphemous.
Meyer's project is, primarily, twofold. The first is what I will call the "negative thesis." This is the argument that the central neo-Darwinian claim--that the mutation-selection mechanism is sufficient to account for the range of diversity of life on earth--is untenable. Meyer argues that the neo-Darwinian mechanism alone is insufficient to produce the diversity of life forms throughout Earth's history. Contrary to popular misconceptions, Meyer does not wage this argument from divine authority or revelation; rather, he presupposes all the assumptions the neo-Darwinian theory demands--e.g. the age of the earth, DNA-based reproduction, random genetic mutations, natural selection, and a mechanistic, law-like universe--and makes the case that neo-Darwinian theory nevertheless fails to provide a sufficient, adequate explanation of the diversity of life forms. Note well that nothing in Meyer's negative thesis depends on an alternative explanation like intelligent design, young-earth creationism, or alien engineers. Proposals to the contrary are chasing, as they say, straw men.
Meyer's second thesis is what I will call the "positive thesis." This is where Meyer proposes intelligent design as the best explanation of the diversity of life on Earth. Meyer argues against the validity of materialist (or naturalist) ontological commitments. This is to say, Meyer argues that the typical barring of immaterial explanations in philosophical and scientific thought--a barring that results largely from modes of thought often called methodological or metaphysical naturalism--is unjustified. If Meyer's arguments are successful in this regard, then he secures a slot for intelligent design amongst the list of possible explanations of the biodiversity of life on Earth. Assuming for the moment that he is successful in undermining materialist commitments and gets intelligent design into the race, he then goes on to argue that intelligent design is in fact the best of the competing explanations on offer. One can say what one will about the success of this line of argument, but one cannot refute this line of argument by misrepresenting it as faith-based creationism.
Meyer divides Darwin's Doubt into three main parts. The first two comprise the negative thesis and the third comprises his positive thesis. Part one, called "The Mystery of the Missing Fossils," introduces his analysis of the Cambrian explosion--a period of geological history which transpired some 530 million years ago and has fossilized a wide variety of life forms. Meyer's arguments with respect to the Cambrian event are rather straightforward: Neo-Darwinian theory requires slow, gradual diversification of life--something akin to the smooth stages of development from embryo to fetus to adult that we see in individual mammals. To the extent the strata of the earth produce fossils that deviate from the smooth dovetailing of life forms neo-Darwinian theory predicts, the theory is undermined. The Cambrian event, according to Meyer, exhibits many features at odds with neo-Darwinian theory and, therefore, supports a case against the merits of neo-Darwinian theory:
"Over the years, as paleontologists have reflected on the overall pattern of the Precambrian-Cambrian fossil record..., they too have noted several features of the Cambrian explosion that are unexpected from a Darwinian point of view in particular: (1) the sudden appearance of Cambrian animal forms; (2) an absence of transitional intermediate fossils connecting the Cambrian animals to simpler Precambrian forms; (3) a startling array of completely novel animal forms with novel body plans; (4) a pattern in which radical differences in form in the fossil record arise before more minor, small-scale diversification and variations. This pattern turns on its head the Darwinian expectation of small incremental change only gradually resulting in larger and larger differences in form" (p.34).This section of Meyer's book appears to have generated the largest push-back from neo-Darwinian advocates. Some argue that Meyer understates the length of the Cambrian event (and thus dispute the use of the term "explosion"), while others argue that certain Pre-Cambrian animals were insufficiently documented in Meyer's book, leading readers to believe there are fewer "transitional" animals than there really are. I have two responses to these kinds of criticisms.
First, Meyer's cumulative argument, surprisingly, depends very little on these particular features of the Cambrian event, so even if these criticisms were granted wholesale, they would do little damage to Meyer's cumulative case against neo-Darwinism. I say this because of the arguments of part two of Darwin's Doubt (discussed below). Briefly, part two of Darwin's Doubt analyzes the constructive powers of random mutation--the Darwinian mechanism solely responsible for the generation of novel biological structures--and highlights the astronomical probability hurdles it must surmount to produce even modest novelties. Meyer simply uses the Cambrian event as a kind of "case study" to highlight the most extreme difficulties neo-Darwinian theory must surmount if it is to succeed. Thus, even if the Cambrian event were many years longer than Meyer suggests (on page 71, Meyer cites estimates of the Cambrian window at 40 million years or less, but records that these numbers are disputed), or if Meyer's account of the totality of fossils in the record is flawed, the sheer diversity of life forms agreed upon by all sides is nevertheless troublesome for neo-Darwinian theory if part two of Darwin's Doubt is successful.
Second, I have thus far seen no good reason to believe that Meyer is either a) incompetent, sloppy, or otherwise underqualified to comment on the Cambrian event, or b) purposefully spreading misinformation about the Cambrian. With respect to (a), Meyer's two books (Signature in the Cell and Darwin's Doubt) were quite rigorously footnoted for each major claim (Darwin's Doubt, for example, has 48 pages of notes and 26 pages of bibliography). He often quotes from mainstream science journals and authorities rather than obscure or unnamed sources. The fact that his Ph.D. is in the history and philosophy of science appears to say little about whether he has expertise in a field as interdisciplinary as the origin and diversification of life. What seems to matter is whether he has a reasonable command of the subject as revealed in the quality of writing, awareness of complexities of the issues, and presence of citations where necessary. Meyer's effort, by my judgment, reasonably passes these tests. What's more, I should record my observations with respect to Meyer's professionalism. In spite of virulent criticisms and attacks on his character from opponents over Signature in the Cell--one cannot exaggerate the depths to which the word "insult" has been taken here--Meyer shakes it all off and writes a follow-up that refuses to retaliate in kind. Darwin's Doubt quite calmly and professionally lays out its case without derogatory comments, inflamed accusations, or personal attacks. This is the kind of professionalism I wish to see in the upper tiers of the intellectual community. On this point, I must quote the eminent atheist philosopher Thomas Nagel who defended Meyer and company in his most recent work, Mind and Cosmos:
"Even though writers like Michael Behe and Stephen Meyer are motivated at least in part by their religious beliefs, the empirical arguments they offer against the likelihood that the origin of life and its evolutionary history can be fully explained by physics and chemistry are of great interest in themselves. Another skeptic, David Berlinski, has brought out the problems vividly without reference to the design inference. Even if one is not drawn to the alternative of an explanation by the actions of a designer, the problems that these iconoclasts pose for the orthodox scientific consensus should be taken seriously. They do not deserve the scorn with which they are commonly met. It is manifestly unfair" (p.10).Nagel's comment segues nicely into point (b) mentioned above: Meyer is often dismissed as one whose judgment is clouded by his self-confessed embrace of Christianity and his employment at the Discovery Institute. While I agree with Nagel that Meyer is motivated in part by his prior commitments to Christianity and the mission of Discovery Institute, these facts hardly justify an outright dismissal of Meyer's arguments. Surely, any breathing human has prior commitments of one sort or another, so if one were to dismiss arguments merely on the basis that the one furnishing them has prior commitments, one would effectively nullify every argument advanced by anyone (including materialists, naturalists, and atheists). I note that in some (probably many) cases, one's judgment is effectively clouded by one's prior commitments; however, this fact is grossly insufficient to assess whether any particular individual's judgment is so clouded. Instead, one must look more closely for the tell-tale signs of excess bias: overly zealous language, hasty generalizations, abusive personal attacks, refusal to engage seriously with counterarguments,and the like. I fail to find these signs of bias in Meyer's professional work, and thus fail to find arguments asserting such bias of much weight. In other words, to treat Meyer as anything other than a serious researcher in the field is, as Nagel says, manifestly unfair.
Part two of Darwin's Doubt is called "How to Build an Animal," and contains, in my estimation, the most decisive criticisms of neo-Darwinian theory in the book. This section contains a quantitative analysis of the constructive power of random genetic mutations. Since building new animal forms requires new materials, new design plans, and new methods of assembly, building new animal forms requires new information. The only way the neo-Darwinian mechanism can generate new information is through random genetic mutations--that is, through random copying errors in DNA transcription and translation. Thus, the raw information-generating mechanism of neo-Darwinian theory is quite literally pure random variation. Natural selection can only preserve the novelties random mutations generate; it cannot generate new information on its own and thus does nothing to aid random mutations in generating novel information.
Given that neo-Darwinian mechanisms are only as efficient at generating new information as random trial and error, assessing the constructive powers of neo-Darwinian theory is basically an exercise in probabilistic reasoning. DNA is a four-character alphabet of nucleotide bases, where different sequences of bases code for different configurations and operations of body parts. One of DNA's primary functions is to coordinate the assembly of proteins, which carry out many of the machine-like functions of living systems. A protein is a chain of amino acids arranged in specific sequence in order to fold into stable, three-dimensional shapes that perform unique tasks. Since proteins are built from a pool of twenty different amino acids, amino acids can be likened to an alphabet of 20 characters. In all relevant respects, then, both DNA sequences and amino acid sequences are codes where some sequences are "functional" and others are "non-functional." The task of neo-Darwinian random mutation, consequently, is to simply search within the ocean of possible DNA--and, by extension, amino acid--sequences for functional combinations. The relevant probabilistic question is simply this: How often will a random search hit upon functional sequences? Basic probability theory suggests that the rate of success is just the ratio of functional sequences to possible sequences.
Quantifying the range of possible sequences, Meyer reports the following: "Most genes--sequences of DNA that code for a specific protein--consist of at least one thousand nucleotide bases" (p.175). If this is true--and I suspect it is--then the number of possible DNA sequences one thousand bases in length is four multiplied by itself one thousand times, or 41000. In base 10, that's about 10600 possible combinations, which is nothing short of astronomical. To appreciate the enormity of this number, Meyer offers for comparison the fact that there are "only" 1080 elementary particles in the known universe, e.g. protons, neutrons, and electrons. Furthermore, Meyer reports that a gene of one thousand nucleotide bases would code for a protein 300 amino acids in length. Since any of 20 amino acids can occupy a slot on the protein chain, the number of possible proteins 300 amino acids in length is 20300, or 10390. Again, nothing short of astronomical.
Quantifying the number of functional sequences proves much more difficult than quantifying the number of possible sequences. Since there is no "answer key" of functional nucleotide and amino acid sequences, one must find a way to approximate what counts as a potentially functional sequence. To estimate just this number, Meyer turns to recent work by chemical engineer Douglas Axe. Axe's research centered on identifying how many different configurations of amino acids led to stable three-dimensional protein folding patterns. The details are well beyond my ability to recount here, but Meyer walks the reader through the steps quite carefully. Meyer summarizes Axe's results as follows: "The probability of any given mutational trial generating (or 'finding') a specific functional protein among all the possible 150 residue amino-acid sequences is 1 chance in 1077--that is, one chance in one hundred thousand, trillion, trillion, trillion, trillion, trillion, trillion" (p.200). Remember, this number is only for the ratio of functional to non-functional amino acid sequences of one protein. Most life forms require many different proteins, some of which are far longer than 150 amino acids.
The last step in the probability computation is to approximate how many trials the neo-Darwinian mechanism would have had since the origin of life on Earth to search the ocean of possible sequence configurations. To be as generous to neo-Darwinian theory as possible, Meyer assumes that every organism that ever lived on Earth counts as one trial (a ridiculously generous assumption given that mutations are relatively rare). Assuming about 1040 organisms have lived in the entire history of Earth (including bacteria), the neo-Darwinian mechanism could only search 1040 out of the 1077 possible amino acid sequences; put another way, the neo-Darwinian mechanism, given all the resources of life in the history of Earth, could only search one 10 trillion, trillion, trillionth of the possible amino acid sequences necessary to find a single stable, functional protein. Meyer concludes, "the conditional probability of generating a gene sequence capable of producing a novel protein fold and function is only 1 in 1037" (p.203).
If Meyer's analysis here is reasonably accurate, the odds against the neo-Darwinian mechanism of successfully producing the remarkable protein systems we find in living organisms are outright staggering. It is for this reason that I say this section of Meyer's book presents the most formidable challenge to neo-Darwinian theory. Critics who choose to focus on his analysis of the Cambrian alone risk mistaking a flagship for the entire fleet.
Section three of Darwin's Doubt is titled, "After Darwin, What?" Here Meyer lays out his positive thesis of intelligent design. There is, unfortunately, a great deal of distortion in the popular press with respect to what intelligent design is and is not, and this final section of Meyer's work aims to clarify what exactly he wishes to propose as intelligent design. Although Meyer devotes chapter 19 to the interesting problem of defining what makes a theory "scientific" (while also defending the proposition that, on a reasonable definition of science, intelligent design is scientific), I will bypass this issue since I am more interested in whether the theory is true than whether it ought to be classified as scientific.
Meyer's argument to intelligent design rests on the premise that there exist intelligent causes in general. The obvious support for this premise lies in human beings as intelligent agents. Meyer takes it as more plausibly true than not that human beings create information-rich systems such as spoken languages, computer codes, and mechanical systems by way of intelligent causation. He asserts that our repeated and uniform experience of the world reliably ties the generation of specified information to mental causes. Wherever there are programs, there were programmers; wherever there are written works, there were writers; etc. The blind, mechanical forces of nature--which uniformly direct pieces of matter and energy in law-like ways--are never observed to generate specified information, for example, comedies or tragedies in the English language. Only intelligent agents--by way of deliberate, conscious activity--have been observed to write comedies or tragedies in the English language. Insofar as the sequences of nucleotide bases and amino acids represent a kind of code or language, they exhibit information-bearing properties habitually associated with intentional conscious activity. From these observations, Meyer argues that conscious, intelligent activity is a cause now in operation that is known to produce the effect in question--the effect in question being encoded information:
"Rational agents have repeatedly demonstrated the capacity to constrain possible outcomes to actualize improbable but initially unrealized future functions. Repeated experience affirms that intelligent agents (minds) uniquely possess such causal powers" (p.362).When we consider the nucleotide bases in DNA or the amino acid sequences in proteins, we find ourselves dealing with encoded information. Thus, Meyer argues, intelligent causation is a plausible explanation of the information in DNA and proteins; and, furthermore, it is a more adequate explanation than neo-Darwinian theory given the severe difficulties with neo-Darwinian theory outlined in the first two sections of the book.
There are, of course, many objections and replies to the intelligent design thesis, several of which Meyer addresses in the book. My own response to Meyer's proposition of intelligent design is overall favorable. The nature of mental phenomena and the mere existence of subjective, first-person awareness at all continues to defy all varieties of materialist explanation. As best I can gather, I see no overarching reason to bar immaterial mental causation from the universe, especially given my intimate, visceral, and continuous acquaintance with just such seemingly immaterial mental powers. Proposing, as Meyer does, that a kind of immaterial cause now known to operate in the physical world could have operated at the time of, for example, the Cambrian explosion is in all fairness a serious proposition. The mere fact that propositions invoking such immaterial mental powers are presently out of fashion in the academic community is, at bottom, just that--a mere fact.