Professor Orr's review of Mind and Cosmos appeared in The New York Review of Books. I found Orr's review to be critical but respectful of Nagel's work. This is commendable because Orr appears to have rather firm confidence in the correctness of neo-Darwinism. Orr received his training in biology at the University of Chicago under Jerry Coyne. Coyne's treatment of Darwinian dissenters is generally less tempered and even hostile compared to Orr's review of Nagel. (Consider that Coyne's blog is entitled "Why Evolution is True" and a recent post about Mind and Cosmos is titled "Tom Nagel's antievolution book gets thrice pummeled.") In any case, let's look at some of Orr's criticisms of Nagel.
Orr primarily centers his review on Nagel's critique of neo-Darwinism, which makes sense given that Orr is a biologist. Orr has this to say:
[Nagel’s] emphasizing purported “empirical reasons” for finding neo-Darwinism “almost certainly false” and he’s suggesting the existence of new scientific laws. These represent moves, however halting, into science proper. But science, finally, isn’t about defining the space of all formally possible explanations of nature. It’s about inference to the most likely hypothesis. And on these grounds there’s simply no comparison between neo-Darwinism (for which there is overwhelming evidence) and natural teleology (for which there is none).
I want to draw attention to the claim that neo-Darwinism is supported by "overwhelming evidence." John Dupré used the same phrase to extol the merits of neo-Darwinism in his review of Mind and Cosmos (which I evaluated in my previous post). I put myself in a similar category to the one Nagel places himself: "[A] layman who reads widely in the literature that explains contemporary science to the nonspecialist"(Mind and Cosmos, p.5), but of course my expertise is by far inferior to that of Nagel's. Nevertheless, I do believe I comprehend some of the empirical reasons upon which one such as Nagel may base doubts about evolution. The fact that individuals like Nagel and I harbor doubts about the neo-Darwinian story are precisely because we do not find the evidence in its favor "overwhelming." This is not to say that neo-Darwinism is bereft of empirical support. Even prominent intelligent design advocates like Michael Behe fully concede the Darwinian mechanism has demonstrated its capacity to do some explanatory work (see his Edge of Evolution). Since the ambitions of neo-Darwinism are so lofty (it is attempting to explain the creation of all life forms on planet Earth, afterall), the proposition that our available data is sufficient to be "overwhelmingly" in support of Darwinism is conspicuously stripped of modesty. That being said, Orr's assertion that there is "overwhelming evidence" for neo-Darwinism may win some over (if they weren't already Darwinians) purely on his authority alone; but, for us "laymen who read widely in the literature," this claim reads more like a bumper sticker slogan than a piercing objection to skepticism over evolution.
Early in his article, Orr takes issue with Nagel's candid reference to his intuitions and common sense when evaluating the believability of the Darwinian story. Orr says this:
Nagel’s conclusion rests largely on the strength of his intuition....But plenty of scientific truths are counterintuitive(does anyone find it intuitive that we’re hurtling around the sun at 67,000 miles per hour?) and a scientific education is, to a considerable extent, an exercise in taming the authority of one’s intuition. Nagel never explains why his intuition should count for so much here.Let me take the last claim first. Nagel devotes an entire chapter of Mind and Cosmos to cognition, whereby he records the remarkable nature of reason to the effect that it can make direct contact with universal truths: "The distinctive thing about reason is that it connects us with the truth directly" (p.82). If nothing else, I would say that Nagel's chapter on cognition does go some distance toward explaining why intuition might count for something. To make this connection, of course, I am interpreting Nagel's intuition to be rational in nature--conceptual truths that are grasped immediately without mediation by sense perceptions. A salient example of rational intuition is the principle of non-contradiction--something cannot be both true and false simultaneously.
Even if we deny that Nagel's treatment of cognition explains why intuition should count for much, rational intuition by itself is by no means a poor epistemological tool. What Nagel likely means by intuition is simply his rational faculties acting on the sum total of his knowledge and experiences about the world. An application of this kind of intuition is properly said to utilize empirical data--much of it qualitative, but some quantitative where possible. The fact that the earth hurtles itself around the sun does not sit uncomfortably with the data one otherwise has about the world (changing of the seasons, alternations between day and night, pictures from space). One might say that despite a lack of expertise in the field of astronomy by the layperson, the majority of individuals do not find the motions of planets counterintuitive. This is evident by the fact that so many people today accept the motions of the earth. By contrast, a similar lack of expertise in the field of biology does not amount to a widespread embrace of Darwinian evolution--this despite its preeminence in high school biology courses. I would go so far as to say Orr's example of the earth actually reinforces Nagel's case: The fact that evolution has not reached the kind of widespread acceptance by the layman that the earth's motion has means that evolution--given its supporting evidence--is not as intuitive as the motions of the earth. This kind of intuitive test certainly detracts from the claim that evidence for evolution is "overwhelming."
Perhaps a better analogy for Orr would have been Einstein's theories of relativity or the bizarre findings of quantum mechanics. At least these examples are so counterintuitive that most of us don't even know how to talk about them. But, I suspect even these would undermine Orr's position. Neo-Darwinism is not supposed to be counterintuitive the way general relativity or quantum mechanics is. Unless I'm mistaken, relativity theory and quantum theory are largely based in complex mathematical equations. Neo-Darwinism, by contrast, is largely conceptual in nature--dog breeding without the dog breeder; slow, successive slight modifications over large periods of time; those sorts of things.
Conceptually, neo-Darwinism is not counterintuitive in the sense that people have a hard time understanding it. Instead, neo-Darwinism is counterintuitive in that it conflicts with what we otherwise understand about the world. Specifically, we habitually associate highly ordered, functionally-specified systems with intentional causation--something pure laws of physics do not possess. Our observations of biological creatures reveal organisms of strikingly sophisticated order and functionality. Our observations of chance and law-like processes reveal little by way of organization and specification powers. What is intuitive, then, given our sum total of reason and experience is that chance and natural law are poor candidates for building the biological creatures we see. This kind of intuition is similar to what Alvin Plantinga calls properly basic beliefs--beliefs that we are justified in holding unless we find strong defeaters for those beliefs. Alvin Plantinga flushes the idea out with respect to design in his recent book Where the Conflict Really Lies:
In many cases, so the thought goes, the belief that something or other is a product of design is not formed by way of inference, but in the basic way; what goes on here is to be understood as more like perception than like inference" (p.245, original italics).Plantinga makes the case that, in ordinary life, many of the beliefs we form do not come at the end of some formal reasoning process; instead, in a way consistent with Nagel's claim mentioned above, our rational minds simply make direct contact with apparent truths. This is most obvious with claims about the external world or the reality of the past--philosophers have long failed to formally justify our beliefs in these things, but nevertheless few of us feel foolish for believing that the exterior world of trees, clouds, and philosophy books is real, as well as the belief that the world didn't just pop into existence right now with the appearance of age. This kind of intuition is certainly plausibly reliable--Orr himself must concede both the realities of the external world and the past in order to embrace neo-Darwinism itself. For those of us who, despite a reasonable familiarity with its evidential foundation, find neo-Darwinism doubtful, our intuitions about the matter are not automatically defective.
Design is, as Plantinga argues, something we can perceive directly rather than inferentially. This thought is generally accepted when the field of inquiry is something non-biological--like archeological artifacts, abnormally large streaks of "luck" in a casino, or the discovery of geometrically precise objects in the middle of the woods. Richard Dawkins even wrote in The Blind Watchmaker that "Biology is the study of complicated things that give the appearance of having been designed for a purpose" (p.1). The immediate detection of design in biological systems is, therefore, even present in those most fiercely opposed to design. The relevant question is whether something exceptional undercuts our naïve perception of design in biological systems. Nagel writes:
Here, again for a layman reading widely in the popular literature, Nagel seems to be right. Take the case of the whale. We're told that the fully aquatic whale descends from a completely land-dwelling, wolf-like creature called Pakicetus. Presumably, the transition from Pakicetus to the fully aquatic creature Dorudon transpired in about nine million years. A Google image search for "evolution of whale" will reveal plenty of diagrams of this transition, most of them nicely illustrating intermediate creatures between Pakicetus and Dorudon. Neo-Darwinism asserts that this transition took place largely, if not fully, by the mechanisms of random mutations and natural selection, and I grant that there exists fossil evidence for each of the creatures depicted in the transition. This amounts to "a schema for explanation, supported by some examples." What's missing from this story, though, are fairly precise estimates pertaining to a) the number of unique anatomical changes required to engineer a Dorudon from a Pakicetus, b) the rates at which the neo-Darwinian mechanism can produce novel mutations and fix them in a population, and c) an account of how each significant engineering change simultaneously enhanced the fitness of the creature while drastically changing the creature from land-dwelling to water-dwelling. For a particularly powerful presentation of this problem, listen to Richard Sternberg discuss the whale transition in this debate. Sternberg's presentation begins around the 30 minute mark. The proposition that a blind process of random mutations and survival-based selection can fully explain this engineering marvel--by a mere schema for explanation supported by some examples--is by no means "overwhelming evidence." The intuition of incredulity is not only appropriate in this case, it may be the literal measure of intellectual responsibility.We are expected to abandon this naïve response, not in favor of a fully worked out physical/chemical explanation but in favor of an alternative that is really a schema for explanation, supported by some examples (p. 6).
Overall, Mr. Orr's review of Mind and Cosmos was adequate and thought provoking. My main response to the review was that Orr overestimates the power of neo-Darwinism by downplaying the role of common sense and declining to admit that there are serious quantitative gaps in the theory's explanatory apparatus. Laypersons who are apprised of the popular literature are all-to-aware of the forceful objections to neo-Darwinism that are as-yet unresolved. The fact that someone of Nagel's stature recognizes the shortcomings of neo-Darwinism ought to give individuals like Orr and Dupré pause when asserting the existence of "overwhelming evidence" for neo-Darwinism.