What Darwin Got Wrong
Jerry Fodor and Massimo Piattelli-Palmarini
Farrar, Straus and Giroux, $26 (cloth)
In On the Origin of Species, published in 1859, Charles Darwin made two remarkable scientific contributions. First, he presented an overwhelming case for the relatedness of all living things. Biological diversity, he argued, results from a process of “transmutation” of species—via “descent with modification.” Second, he recognized that the basic mechanism of such change is natural selection: a combination of variations in traits and a selective retention of the variations that contribute to reproductive success.
Descent with modification was accepted quickly. As early as 1872, Thomas Henry Huxley described Darwin as having achieved a revolution comparable to that brought about by Newton’s Principia. Natural selection, by contrast, remained controversial until the 1930s, when Darwin’s ideas were integrated with the genetics of Gregor Mendel and Thomas Hunt Morgan, creating the “Modern Synthesis.” More than 70 years later, thanks to a proliferation of evolutionary explanations and significant new theoretical contributions, the fundamentals of evolutionary biology are reasonably well settled.
To be sure, religiously inspired opposition to evolution persists. Although religious opponents seem to have accepted—at least officially—the relatedness of organisms, proponents of “intelligent design” continue to insist that natural selection is unable to explain some prominent instances of evolutionary change. Their skepticism is based on alleged examples of “irreducible complexity”—an intricate interdependence in the features of organisms that supposedly cannot be explained by Darwinian mechanisms of step-by-step improvement.
Other critics—more sophisticated and scientifically informed—wonder whether natural selection explains as much about evolution as biologists commonly assert. They urge, for example, that causes other than natural selection (such as genetic drift) are important in explaining evolution. Or they argue—overemphasizing something all evolutionary biologists agree with—that natural selection operates against a background of constraints, perhaps stemming from features of genomes. Darwin himself was aware of these complexities about the role of natural selection, and throughout the Origin laments his own ignorance about the extent of that role and what alternative causes of evolutionary change there are. His awareness of how much he did not know led him to cautious formulations: for example, he writes, “Natural Selection has been the main but not exclusive means of modification.”
As in other areas of science, then, lively debate continues, and an interest in deeper and more comprehensive understanding moves the field forward. But even as some scientists suggest that natural selection may be limited in ways Darwin could not envisage, they accept his basic insights and work to improve our biological understanding within the framework he set forth.
In their controversial new book, What Darwin Got Wrong, Jerry Fodor and Massimo Piattelli-Palmarini set out to dismantle that framework. They argue that standard evolutionary thinking—what they call Darwinism—is guilty of a basic logical error, not a mistake in biology but an “intensional fallacy.” That fallacy, they say, undermines the entire enterprise. To be clear, the authors preface their demolition with a disclaimer: in attacking Darwin, they are not supporting any religious view of “origins”; thoroughgoing materialists, they do not think that biological patterns require an intelligent designer. But their criticisms are intended to knock evolutionary theory from its scientific pedestal by demolishing the scientific credentials of natural selection.
Fodor and Piattelli-Palmarini are not biologists. Fodor is a leading philosopher of mind and cognitive scientist, best known for his ideas about the modularity of mind and language of thought; Piattelli-Palmarini is a cognitive scientist. They do not have new data, new theory, close acquaintance with the everyday practice of evolutionary investigations, or any interest in supplying alternative explanations of evolutionary phenomena. Instead, they wield philosophical tools to locate a “conceptual fault line” in contemporary Darwinism. Apparently unshaken by withering criticism of Fodor’s earlier writings about evolutionary theory, they write with complete assurance, confident that their limited understanding of biology suffices for their critical purpose. The resulting argument is doubly flawed: it is biologically irrelevant and philosophically confused. We start with the biology.
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In 1979 evolutionary biologists Stephen Jay Gould and Richard Lewontin published an influential article, criticizing what they called the “adaptationist programme” in evolutionary theory. Some of their contemporaries, they lamented, were much too quick to accept stories about the adaptive advantage of every trait of an organism. According to Gould and Lewontin, adaptationists suppose that every trait contributes to an organism’s reproductive success (its fitness), and exists because of that contribution.
Gould and Lewontin’s critique of adaptationism begins with the observation that the characteristics of organisms are often correlated with one another. Because of those correlations, they argued, evolutionary biologists need to explore the possibility that an allegedly favorable characteristic might be a side effect of something else (a “correlation of growth,” Darwin said). Entering the basilica of San Marco, you might marvel at the wonderful use of spandrels—the tapering triangular spaces filled with mosaics where the dome adjoins the columns. (Too much ink has already been spilled about whether the term “spandrels,” usually confined to two-dimensional spaces, should be used to cover the three-dimensional pendentives in San Marco. We will spill no more.) Struck by the spandrels, you might conclude that the architect designed those spaces so that they could contain mosaics showing the four evangelists.
The basic problem, according to Fodor and Piattelli-Palmarini, is that the distinction between free-riders and what they ride on is ‘invisible to natural selection.’
As Gould and Lewontin observed, however, spandrels are not the result of a design: if you have arches supporting a dome, you also have spandrels. Spandrels are hitchhikers on arches-plus-dome. Or, to take one of Gould and Lewontin’s biological examples, consider the diminutive front legs of the tyrannosaurus. Instead of inventing an adaptive story (“the legs promoted the skill of tyrannosaurus males in sexual foreplay”), the reduction of size may simply be a byproduct of increased growth rates elsewhere. The problem for adaptationism is that it can be hard to know which trait was selected for and which was the free-rider: maybe architects wanted spandrels in order to display mosaics, and built arches-plus-dome as a solution; maybe the tiny legs are for mating, and produce huge hind limbs and an impressive tail as byproducts.
In the architectural case, we can be fairly sure of the intentions of the builders, and so conclude that the use of the spandrels for mosaics was an afterthought. But in a natural case we would need to know how differences in reproductive success were brought about before we could distinguish the selected-for traits from the free-riders. Gould and Lewontin think that we can sometimes figure out the answer, and urged evolutionary biologists to do so by remaining mindful of all the tools provided by Darwin and his successors rather than falling back on an easy adaptationism.
Fodor and Piattelli-Palmarini believe that the spandrels problem is much deeper. While Gould and Lewontin had a nice insight about “correlations of growth,” they ultimately affirmed a “very sophisticated kind of adaptationism” because they took for granted that there can be a genuine fact about which of two correlated properties—say, large hind-quarters and tiny forelimbs—is selected for and which is a free-rider.
The basic problem, according to Fodor and Piattelli-Palmarini, is that the distinction between free-riders and what they ride on is “invisible to natural selection.” Thus stated, their objection is obscure because it relies on an unfortunate metaphor, introduced by Darwin. In explaining natural selection, the Origin frequently resorts to personification: “natural selection is daily and hourly scrutinising, throughout the world, every variation, even the slightest” (emphasis added). When they talk of distinctions that are “invisible” to selection, they continue this personification, treating selection as if it were an observer able to choose among finely graded possibilities. Central to their case is the thesis that Darwinian evolutionary theory must suppose that natural selection can make the same finely graded discriminations available to a human (or divine?) observer.
Neither Darwin, nor any of his successors, believes in the literal scrutiny of variations. Natural selection, soberly presented, is about differential success in leaving descendants. If a variant trait (say, a long neck or reduced forelimbs) causes its bearer to have a greater number of offspring, and if the variant is heritable, then the proportion of organisms with the variant trait will increase in subsequent generations. To say that there is “selection for” a trait is thus to make a causal claim: having the trait causes greater reproductive success.
Causal claims are of course familiar in all sorts of fields. Doctors discover that obesity causes increased risk of cardiac disease; atmospheric scientists find out that various types of pollutants cause higher rates of global warming; political scientists argue that party identification is an important cause of voting behavior. In each of these fields, the causes have correlates: that is why causation is so hard to pin down. If Fodor and Piattelli-Palmarini believe that this sort of causal talk is “conceptually flawed” or “incoherent,” then they have a much larger opponent then Darwinism: their critique will sweep away much empirical inquiry.
We can clarify their criticism of what natural selection can see by translating it into causal language that avoids personification. Their specific charge is that, with respect to correlated traits in organisms—traits that come packaged together—there is no fact of the matter about which of the correlated traits causes increased reproductive success. In other words they appear to be making the very ambitious claim that whenever there are correlated traits there is no fact of the matter about which of the traits causes any effect.
Consider the famous case of industrially induced melanism in the peppered moth. Supposedly, in landscapes where pollution has destroyed the lichens on the trunks of trees, melanic (black) variants of the moth are better camouflaged when they rest on tree trunks than their lighter, speckled relatives. With improved camouflage, birds and other predators are less likely to pick the moths off the tree trunks. In polluted environments, then, melanic moths are more likely to survive, and hence to leave descendants in later generations. So far, so familiar.
Enter Gould and Lewontin. Maybe moth coloration is a spandrel, and some other property of the moths is both relevant to their proliferation and correlated with their color. For example, evolutionary biologists have observed that moths usually rest by day on the undersides of branches rather than on the trunks of trees. So is the familiar black-as-camouflage story really true? Perhaps a characteristic of the larvae of melanic moths makes them more likely to survive. Or perhaps melanic moths have a tendency to move around less at night, which makes them less vulnerable to being eaten by bats (who care nothing for color). These are interesting alternatives to the familiar story, and the causal hypotheses they introduce can be tested in obvious ways: by examining the rates of larvae survival or by investigating nocturnal motions of moths. And this is what biologists have done. Concerned that an apparent adaptation (a camouflaging color) may be a side effect, they have looked for correlated traits that might figure in some alternative process that would culminate in greater representation of the melanic moths. Despite some controversy in the 1990s, the traditional story seems to be standing up well.
If Fodor and Piattelli-Palmarini acknowledge the evidence that favors the camouflaging-color hypothesis over the moth-larvae and moth-mobility hypotheses, they will have to say that the biologists have not been imaginative enough—that they have overlooked some other correlated trait for which there could be no fact of the matter about whether it, or the black coloration, caused the reproductive success.
What exactly could this trait be? One possibility, suggested by remarks in some of Fodor’s previous writings, would be that there are two different properties: being black, on the one hand, and matching the environment on the other. Is there a fact of the matter as to which of these causes the reproductive success?
There are two ways to interpret the question, and each one has a good answer. The first focuses on the specific environments in which melanic moths are selected: the woods that have suffered from industrial pollution. In these environments, being-well-camouflaged and being-black come to more or less the same thing. In a polluted environment, a black moth matches the surroundings better than a lightly speckled moth. The result is less predation and hence increased survival and procreation. Biology focuses on the process, and biologists are quite willing to identify how selection is acting by picking out any feature of the organisms that is central to the process. So if you are focused on this specific environment, then it is a matter of indifference whether you talk of selection for black color or for camouflage or for decreased predation. Among these options, you can talk as you like. Any of them will distinguish the selection process of the traditional industrial-pollution story from the potential rivals, such as larval resilience, or lower nocturnal mobility.
A second interpretation would consider all the woody settings in which the moths can be found. Speckled moths will be at a disadvantage if they rest on polluted trees (they will be picked off more easily), and melanic moths will be similarly vulnerable in unpolluted surroundings. Biologists can test and confirm these causal facts, and can report their conclusions by finding that, across the whole spectrum of environments, matching the color of the trees causes increased reproductive success. Of course, saying that accords perfectly with, and generalizes in a particular direction, the thought that, in the polluted woods, being black causes a moth to match its environment better. There are no great mysteries, no inscrutable distinctions between spandrels and properties selected, no general troubles about distinguishing between the causal powers of correlates.
Why then do Fodor and Piattelli-Palmarini think that problems about selection-for are omnipresent? Because they envisage a vast space of properties and expect proponents of natural selection to discriminate among all the rivals. Not only is there a property of being-a-melanic-moth, there is also a property of being-a-melanic-moth-and-smaller-than-Manhattan. These properties are not only correlated in the world’s actual moth populations, they are correlated universally. Maybe it is impossible, even with the most rarefied genomic technology, to build a moth bigger than Manhattan. If so, the correlation between these properties could not be broken. How then could there be a sense in which one of the properties—being-a-melanic-moth—rather than the other—being-a-melanic-moth-and-smaller-than-Manhattan—caused the increased reproductive success?
We suggest that the question deserves a shrug. Serious evolutionary biology is concerned with comparative causal claims among interestingly different alternatives. Is it the black coloration rather than the larval resilience or the nighttime lethargy? Good question. Is it the coloration rather than coloration-and-being-smaller-than-Manhattan? Silly question. Fodor and Piattelli-Palmarini create the idea that natural selection is a fine-grained discriminatory enterprise that distinguishes among all the properties philosophers can discover (or invent?) precisely so they can demolish it. The authors’ error is to note correctly that there is some indeterminacy and then to conclude that indeterminacy is total: that there can be no matter of fact with respect to causal efficacy as between any of a set of correlated properties. Evolutionary theory, Fodor and Piattelli-Palmarini say, contains, at its core, a causal notion—selection-for—that picks out the properties that cause increased reproductive success. They then declare that there is no fact of the matter about what causes increase reproductive success when the candidate properties are correlated with others. But correlation is omnipresent, so evolutionary biology totters.
This critique makes no contact with the practice of evolutionary biology, where the focus is on the causal processes (for example, camouflage) that lead to reproductive success, the salient properties (say, melanism) that play a role in them, and whether other causal processes (say, stillness at night) might have been at work.
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A different example (due to the philosopher Elliott Sober) can offer further clues to the ways in which the authors inflate the position they attack. Sieves are very simple selection devices. Imagine a sieve with a mesh that will allow balls with radii of one inch to fall through, but that will retain those that are even a tiny bit larger. Suppose that balls with several different radii—one inch, two inches, three inches, and four inches—are placed in the sieve. The one inch balls are blue, while the larger ones have different colors. The blue balls fall through, and the others remain. In one sense the sieve has “selected” the blue balls, although it has not “selected for” being blue. That is because size not color is what matters to the transmission. Using the language Fodor and Piattelli-Palmarini employ, we might say that the property of having a particular color (blue) is a spandrel or free-rider.
Yet we might divide the properties up more finely. The balls with radius one inch have a diameter of two inches, a circumference of 2π inches, a cross-sectional area at the equator of π square-inches, a volume of 4π/3 cubic inches, etc., etc. Lots of geometrical properties are correlated—indeed perfectly so. Which of these properties caused the balls to fall through? The question is idle. A person could select for radius rather than diameter, but the sieve cannot. Yet that makes absolutely no difference to the judgment originally made: the sieve selects for size, rather than for color. To recur to the language of indeterminacy, there is a determinate matter of fact as between color and size but not as between radius and diameter.
If Fodor and Piattelli-Palmarini’s criticism is taken seriously, then there are no facts of the matter about causal claims in any field of inquiry.
Just as ordinary people recognize that sieves select for size and not color, evolutionary biologists work hard to discover the mechanisms at work in producing increased frequency of types of organisms. They are happy if they can trace the prevalence of melanic moths to coloration, camouflage, and decreased predation rather than to superior survival of larvae. They remain unperturbed when asked if it is coloration rather than camouflage, or rather than lowered predation, or rather than being-melanic-and-smaller-than-Manhattan.
We can know the fact that the sieve selects for size rather than color without the presence of any actual environments in which size and color are not correlated because we understand the causal mechanisms: we know what would have happened if size and color were de-correlated in this device, namely, there would still be selection for size rather than color. A real causal difference is a feature of the world that can be investigated in different ways, for example, by looking at mechanisms; by considering real cases of de-correlation; or by looking at cases where the selection pressures are slightly different, such as unpolluted environments in which light moths are at a disadvantage. The way evolutionary biologists think about causation allows for the discussion of causal process in any of a number of ways—even those strange ways that invent peculiar properties. Fodor and Piattelli-Palmarini almost grasp this point where they discuss the “prima facie” plausibility that polar bear color is a result of selection for matching the environment rather than selection for whiteness, a difference that, as we saw in the analogous case of the moths, can be real and can be investigated.
Have we dismissed the questions the authors would foist on evolutionary biology too quickly? We think not. As already noted, if their concerns are taken seriously, correlated properties pose a general problem. For example, since human beings are smaller than Manhattan, the properties being-obese and being-obese-and-smaller-than-Manhattan are perfectly correlated in the human population. So there are no facts of the matter about causal claims in epidemiology. And the same goes for atmospheric science, geology, engineering . . . and, indeed, everything else.
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Despite the powerful claims of evolutionary biologists and all other scientific investigators, suspicion might linger that these insightful outsiders have identified commitments the practitioners have missed, that they have exposed presuppositions that have gone unrecognized because of the fuzziness of everyday reflections. To address such suspicions, we need to treat Fodor and Piattelli-Palmarini’s critique in its own terms. Setting the scientific practice to one side, let’s see if they have the philosophy straight.
They allege that Darwinism is guilty of an “intensional fallacy.” To explain what they have in mind, we need to introduce two ideas: intensionality and coextensive properties.
The authors introduce intensionality by considering the substitution of terms for one another in sentences. There are some sentences in which, if you substitute one name for another, and both are names for the same thing or person, you always go from a true sentence to a true sentence, or from a false sentence to a false sentence. “Madonna” and “Louise Ciccone” name the same person. The sentence “Madonna is a woman” is true. If you substitute “Louise Ciccone” for “Madonna,” you obtain the sentence “Louise Ciccone is a woman,” which is also true. Not all sentences work this way. Our world is full of people who do not know that Madonna is Louise Ciccone. If Bert is one of these people, then the sentence “Bert believes that Madonna is a star” may well be true, even though “Bert believes that Louise Ciccone is a star” is false.
This phenomenon is not a trivial linguistic matter but actually reveals something deep about something real. Thinking that someone is a star always works via some specific way of thinking of the person; you may think of the person under another guise as well, and under that guise you may not think the person is a star. An important feature of our thought—that we can think about the very same things under very different guises—is expressed by the linguistic facts. There are some contexts, such as “ is a woman,” in which substitution of names that name the same entity preserves truth (or falsehood); these contexts are said to be extensional. Other contexts, such as “Bert thinks that is a star,” allow for changes from truth to falsehood under similar substitutions; these are intensional.
The authors’ entire argument depends on their claim about the intensionality of selection-for. Are they right about this?
Now for the second piece of terminology: two properties are said to be coextensive if and only if they apply to exactly the same objects. Such properties are (in the more familiar terminology we used earlier) correlated. Being-a-melanic-moth-and-smaller-than-Manhattan is coextensive with being-a-melanic-moth; being a sphere whose radius is less than one inch is coextensive with being a sphere whose diameter is less than two inches.
Turning from terminology to substance, Fodor and Piattelli-Palmarini’s central thesis is that selection-for is intensional:
There can be coextensive but distinct phenotypic properties, one (but not the other) of which is conducive to fitness, but which natural selection cannot distinguish. In such cases, natural selection cannot, as it were, tell the arches from the spandrels. That being so, adaptationist theories of evolution are unable, as a matter of principle, to do what they purport to do: explain the distribution of phenotypic traits in a population as a function of its history of selection for fitness.
The idea is that natural selection will favor individual organisms which carry both of two coextensive properties: having large hind-quarters and having diminutive front legs. Since all individuals who have one of the two coextensive properties must have the other as well, their reproductive success will not distinguish the two properties. But selection-for requires distinguishing such coextensive properties: the large hind legs and tail are selected-for, the tiny front legs are not. That is what the authors mean when they say that selection-for is an intensional context.
Here, then, is the problem restated: the causal processes at work in evolution cannot distinguish between coextensive properties, but selection-for requires that they be distinguished. In cases of selective breeding (or church architecture), the breeder (or architect) knows what he is selecting for, and that distinguishes the two coextensive properties. In natural selection, however, there are no intentions of a breeder to appeal to, no intelligent designer, no architect who is aiming to build a dome and happily creating spandrels as necessary byproducts. We cannot appeal to the intentions of Mother Nature, so the intensionality must come from something else: Fodor and Piattelli-Palmarini suggest that the only possibilities are to suppose that there are laws of nature or facts about how things would have been under somewhat different circumstances that determine that one, but not the other, of the coextensive properties is the property selected for.
Fodor and Piattelli-Palmarini take this intensionality of selection-for to be central to Darwinian theorizing:
Not just selection-for but a whole galaxy of other concepts that adaptationist explanations routinely employ suffer from the same disease. These include, notably, such notions as ‘ecological niche’, ‘problem of adaptation’ and ‘biological function’, all of which are interdefined with ‘selection-for’ and thus inherit the problems that intensionality occasions.
The upshot is that intensionality sinks the whole apparatus of evolutionary theorizing: “Darwinists have a crux about free-riding because they haven’t noticed the intensionality of selection-for and the like; and when it is brought to their attention, they haven’t the slightest idea what to do about it.”
Describing the issues this way simply restates in technical philosophical terms the basic charge: in the face of spandrels, evolutionary theory requires that there be a process that makes discriminations that natural selection cannot make. So the entire argument depends on the authors’ claim about the intensionality of selection-for. Are they right about this?
In a word, no. In the only way that matters for evolutionary biology, selection-for is extensional rather than intensional—and this suffices for making sense of the use made in evolutionary thinking of the notion of selection-for and correlative notions such as adaptation and biological function.
To see why, consider the notion of causation. If decreasing temperature causes freezing and decreasing temperature is the same property as decreasing mean molecular kinetic energy, then decreasing mean molecular kinetic energy causes freezing. The causal powers of a property—temperature, say—do not depend on how we refer to it or think about it. In that respect, causation is extensional.
But if causation is extensional, then so is selection-for, since selection-for is a causal idea. Consider, once again, the sieve and the balls. The balls that are blue and small fall through, leaving the larger (and differently colored) spheres in the sieve. What is causally responsible for the blue balls passing through the sieve is that they are small, not that they are blue; what is selected for is smallness, not blueness. In sum: being small is the cause, just as being black is the cause of the moths’ reproductive success rather than (say) correlated nighttime lethargy.
Why, then, do Fodor and Piattelli-Palmarini think selection-for is intensional? Perhaps because they are drawing the line between intensional and extensional in a way different from ours, and on their way of drawing the distinction both causation and selection-for come out as intensional. Suppose having-a-heart is coextensive with having-a-kidney: every animal with a heart is also an animal with a kidney and vice versa. Consider “Ernie has a heart, and that caused the blood to flow through his veins. Substituting “has a kidney” for “has a heart” in that context would yield a falsehood: Ernie’s blood does not flow through his veins because he has a kidney. Because of this failure of substitution, we might describe causation as intensional (in a different sense from the one we originally explained). But this kind of failure of substitution is of no significance for evolutionary theory, as we will now see.
When we introduced the notions of intensionality and extensionality, we did so by talking about substitutions of terms that name the same entity. If the substitution of a term leads from truth to falsehood (or from falsehood to truth), even though the term substituted names the very same thing as the term it replaces (as with Bert’s musings on Madonna), that fact is significant because it reveals something important about our thought: that we think about things under guises. It is a quite different matter to consider contexts in which you cannot always replace one term associated with a property with another term associated with a different property that applies to exactly the same things, with preservation of truth and falsity. Different properties—having-a-heart, having-a-kidney—can apply to exactly the same objects. When you are interested in causation, however, you are not concerned about guises. What is of concern is the identity of the causing property. Having a heart but not having a kidney is causally efficacious in pumping blood, no matter how you describe having a heart. What we have are not two guises for the same thing, thus not intensionality in our sense, but two distinct properties that apply to the same things.
If the authors want to mind their neighbors’ business, they should spend a little time discovering just what those neighbors do.
The authors are entitled to pick how they want to use the term “intensional.” Maybe they will suppose (as we do) that intensionality is marked by the failure to preserve truth (or falsehood) when terms are replaced by other terms that name the same thing—when one guise is substituted for another. Or perhaps they will prefer a different notion, signaled by failure to preserve truth (or falsehood) when terms that are associated with distinct but coextensive properties are substituted. The essential point is that however they choose, causation and selection-for always travel together. If they take the first approach, both will be extensional; if they opt for the second, both will be intensional. Their argument turns on mixing criteria, taking one version in one place and a different one elsewhere.
We can explain the notion of selection-for in evolutionary reasoning so that both selection-for and causation are extensional. Further, on this way of reconstructing both notions, there can be a fact about which of two correlated properties is selected for and which is a free-rider. Fodor and Piattelli-Palmarini’s argument collapses.
As mentioned earlier, they think that because of the extensionality of causation and the intensionality of selection-for, causation alone cannot be the basis of selection-for, so appeal must be made to something else—the intentions of a breeder or claims about what might have been or laws of nature. As a result, their book is filled with discussions of philosophical issues about contrary-to-fact claims and scientific laws. But all of these discussions—lengthy and obscure—explore ways out of a false impasse. They are needed only because of the authors’ misunderstandings of the basic issue: that selection-for is a causal notion, and, since causation is extensional, so is selection-for.
That said, however, one final detail bears notice: although contexts of causation and selection-for are extensional in the respect mentioned, contexts of explanation are notoriously intensional. Does that mean that there can’t be evolutionary explanations? Not at all. Nature determines which properties are causally efficacious, and hence what is selected for. Then we theorists can find out about this and give explanations based on what is selected for. Thus if nature tells us that it is melanic color rather than larval resilience or nightime lethargy that was selected for, then we thinking beings can give (intensional) explanations in terms of melanic color rather than the other properties. In giving the explanation, we (thinking beings) describe the property in our preferred way.
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Fodor and Piattelli-Palmarini take the role of philosophy to consist in part in minding other people’s business. We agree with the spirit behind this self-conception. Philosophy can sometimes help other areas of inquiry. Yet those who wish to help their neighbors are well advised to spend a little time discovering just what it is that those neighbors do, and those who wish to illuminate should be sensitive to charges that they are kicking up dust and spreading confusion. What Darwin Got Wrong shows no detailed engagement with the practice of evolutionary biology, nor does it respond to the many criticisms that have been leveled against earlier versions of its central ideas. In this latter respect, the authors resemble the creationist debaters who assert that evolution is incompatible with the second law of thermodynamics, hear detailed refutations of their charge, and repeat their patter in the next forum.
We admire the work that both Jerry Fodor and Massimo Piattelli-Palmarini have produced over many decades. We regret that two such distinguished authors have decided to publish a book so cavalier in its treatment of a serious science, so full of apparently scholarly discussions that rest on mistakes and confusions—and so predictably ripe for making mischief.