Consilience: The Unity of Knowledge 
E. O. Wilson
Knopf, $26

A work of art is the one mystery, the one extreme magic; everything else is either arithmetic or biology.
-Truman Capote1

E. O. Wilson has never been afraid of thinking big. Though he started with the small–ants, that is–he has, at each stage of his career, turned to bigger and bolder things. First The Insect Societies, his classic look at the evolutionary forces shaping the baroque social lives of insects. Then Sociobiology: The New Synthesis, his best-known book, setting out the biological principles that Wilson thinks underlie all animal societies. Then On Human Nature, his immensely controversial look at the role of genes in our behavior and culture. And now, several books, two Pulitzer Prizes, and one National Medal of Science later, Consilience, his most ambitious work yet.

As might be expected given his stature, Consilience has gotten a great deal of attention. While we’d expect theNew York Review of Books to take note, when’s the last time a book sporting a subtitle like “The Unity of Knowledge” got a four-page spread in NewsweekConsilience, not surprisingly, finds itself perched on the New York Times best-seller list.

The point of Wilson’s new book is simple enough. All knowledge–from the humanities through the social sciences to the natural sciences–can be unified. Wilson calls this “consilience,” literally a “jumping together” of knowledge by linking facts and theories at one level with those at another. The natural sciences already show such linkage–biology blurs into chemistry which blurs into physics. It is time, Wilson thinks, for the humanities and social sciences to join the party. Time for economists to worry about the biology of behavior and for biologists to worry about the origins of art. Such fusion will, he thinks, both invigorate the humanities and change the face of the social sciences, giving the latter a long overdue taste of progress. As you can probably already tell, Wilson’s consilience features a directionality. Pleading “guilty, guilty” to charges of crass scientism and reductionism, Wilson believes consilience will involve the collapse of at least some of the social sciences into biology. Even the humanities will “draw closer to the sciences and partly fuse with them.” Philosophy, “the contemplation of the unknown,” seems in a particularly bad way, as the consilience machinery will be set to “turning as much philosophy as possible into science.”

But the payoff from all this is potentially huge. Our fragmented intellectual landscape will meld into a single beautiful body of knowledge. More important, consilience might provide the sort of big-picture wisdom that’s needed to save both liberal education and the planet. And, last, a consilient science might even bring absolute objective truth within human reach (a possibility we’ll get back to).

As might be expected given the grand scale of his mission, Wilson’s book covers a lot of ground. Consilience begins with a retrospective on the unity of knowledge, paying special tribute to the Enlightenment and logical positivism, those two great bursts of unification optimism. But most of the book is given over to a link-by-link look at the chain of consilience: the sciences, the mind, culture, human nature, the social sciences, the arts, ethics, and the environment each get a chapter. At each stage, Wilson highlights connections linking higher levels to lower: the brain springs from genes, consciousness springs from brains, and culture springs from conscious minds. In a few cases he sketches connections that reach across several levels, as when he suggests that the ubiquity of serpents in Amazonian art (as well as in the drug-induced hallucinations of Amerindian mystics) reflects an inborn fear of snakes that is likely common to all Old World primates. In the end Wilson’s lesson is that present disciplinary boundaries are not reflections of real breaks in nature but mere “artifacts of scholarship”. The great intellectual challenge facing us is therefore clear: building links between artificially disjoined disciplines. The future will belong to synthesists.

There is much that is right about Consilience. The most immediately striking is the writing. Wilson possesses an elegant, spare style that could stand to be widely emulated even (or perhaps especially) by those who’ll disagree with his every sentence. Many will also be surprised by his cool tone. Though his claims might be revolutionary, his rhetoric is reserved. (The one exception involves his deft demolition of postmodernist nonsense. Wilson has, it turns out, immersed himself in the obscurantist scribblings of Derrida and company. The experience, to put it delicately, did little to change his prior impressions.) Wilson also does a good job of digging up interesting but obscure bits of science, such as prosopagnosia, in which specific brain lesions leave victims unable to recognize faces, but not other objects. And I, for one, enjoyed his reflections on what makes for a superior scientist. Though he never draws these thoughts together in a single discussion, what he does say –championing fly-by-the-seat-of-the-pants intellectual daring–is worth saying. All in all, Consilience is a gentle, enjoyable read.

But the book is not without flaws. Indeed I believe Consilience suffers from two classes of problems, one fairly general and the other specific. The general problems–vagueness and philosophical naiveté–are, in the end, probably the more important. Indeed they are problems that plague Wilson’s whole approach.

Wilson’s frustrating vagueness mars even his discussion of points that lie at the heart of his project. This begins with his vision of consilience itself. Sometimes consilience means something hard: a reduction of all knowledge to a few laws of physics. This is consilience in the strict sense of “unity of knowledge.” But at other times consilience means something soft: the notion, say, that economists and ecologists should put their heads together on the environmental crisis (an idea that Wilson discusses at considerable length). This is consilience in the weak pragmatic sense of “your discipline needs to talk to mine.” But it’s obvious that you can buy the latter kind of consilience (who wouldn’t?) without the former. Obvious that you can think it wise to incorporate measures of environmental health into traditional economic indices without thinking this involves the collapse of a social science into a natural one. This sort of ambiguity tends to work in Wilson’s favor. Consilience is a hazy target seen in a seductive soft focus and anyone airing doubts about its stronger claims tends to get greeted by indignant defenses of its weaker aspects (“Surely you don’t think economists can ignore the environment?”).

Wilson is also surprisingly vague about the methods that lead to consilience. He typically holds his approach up as an unapologetically reductionist one. But after fifty pages of such talk, he suddenly announces that emergent phenomena–qualitatively new beasts not predictable from the behavior of their parts–might also walk the earth, “especially at the living cell and above.” One would think this an issue someone espousing the unity of knowledge at book length would have fairly clear ideas about. After all, emergent phenomena–if real–change everything. But Wilson then reveals that there’s not only consilience by reduction but a holistic “consilience by synthesis” which works the other way round. By the end it gets hard to distinguish consilience from the idea that intellectual connections are good. Not an objectionable philosophy, but not a particularly precise one either.

Ambiguity also haunts Wilson’s description of the results of consilience, especially the relationship between art and science. In some places he says a consilient science will do things like uncover the biological basis of creativity–a strictly scientific enterprise that stays off the toes of artists. But in other places he suggests that science will help tell us why painting A is better than painting B–a traditionally artsy enterprise. (Wilson believes neurobiology will find innate rules that cause us to prefer some visual art to others. The fact that twentieth-century art has been virtually defined by the rise of styles that people at first hated doesn’t seem to bother him.) Finally, he suggests that science should determine not only if art is “steered by inborn rules of mental development” but if those rules are adaptive. But some of these roles for science are far more plausible than others. If I believe biology will shed light on creativity (plausible) but that it will make negligible contributions to art interpretation (more plausible), am I a consilience fan?

The second general problem plaguing Wilson’s book is one of philosophical naiveté. We scientists are, of course, notorious for thinking all philosophical problems straightforward. Scientists tend to swagger into town, confident that a bit of straight shooting will set all aright. Though typically modest, Wilson slips into this cowboy role all too easily. A number of philosophical problems– mind-body, free will, the failure of logical positivism– pop up in the course of his book. And Wilson guns them down at a staggering rate. Unfortunately, his solutions are often surprisingly superficial. In the end it’s hard to escape the conclusion that Wilson often just doesn’t see the problem. He sees half of it, or less than half of it, and sets diligently to whittling away at some corner of it. When he announces his solution–often in a one-liner–he seems mildly astonished that no one previously saw so simple an answer.

Let me give an example. As a champion of unity of knowledge, Wilson is anxious to explain away the demise of that last great unification craze, logical positivism. The positivists believed that by formalizing scientific language and by following a few formulaic guidelines (e.g., verificationism) scientists could “close in on objective truth.” But logical positivism crashed and burned. And Wilson thinks he knows why: “Its failure, or put more generously, its shortcoming, was caused by ignorance of how the brain works. That in my opinion is the whole story.” But the good news, Wilson assures us, is that neurobiology and artificial intelligence are coming to our rescue. Once they reveal how the brain works–once they show us how to correct the distortions our nervous systems impose upon reality–“the grail of objective truth” might be ours.

It’s hard to know where to start with this sort of argument. For one thing, the idea that absolute objective knowledge can be built on a foundation of brain sciences faces an obvious problem: our knowledge of the brain must itself remain uncertain, tainted by the very subjective distortion and outright error that Wilson is trying to get rid of. For another, there’s more standing between science and the “ultimate goal of objective truth” than ignorance of the brain’s blueprints. Almost all scientific truths take the form of universal propositions reached by induction and are therefore permanently subject to doubt. As Russell said somewhere, induction for a chicken means the farmer comes to feed him each morning. But one morning the farmer comes and wrings his neck. The point is that most scientific truths are logically fated to remain un-absolute. And none of this goes away no matter how well you understand the hypothalamus. Unfortunately this is not an isolated incident. Much of Wilson’s book consists of such superficially attractive–but ultimately just superficial-philosophical talk.

Bang for the Buck

On to the specifics. Three particular problems seem to beset Wilson’s vision of the unity of knowledge: He overestimates the return likely to result from connecting human culture to biology; he underestimates the difficulty of getting consilience, even where it would pay; and he neglects good reasons (having to do with the likely limits of our minds) for thinking consilience may not only be hard, but impossible. Let’s consider these in turn.

Wilson spends much of his time on a single consilient link, that hooking up culture to biology. Wilson believes, of course, that genes influence human behavior. But he bends over backwards to emphasize that he’s not a naive genetic determinist. Instead he leans heavily on a notion borrowed from developmental genetics: genes lay down “epigenetic rules”–inherited regularities of development that affect how an organism looks or behaves. These innate predispositions don’t determine your appearance or behavior, which may depend on the environment (including cultural) in which you find yourself. (For example, a genetic predisposition to some type of cancer doesn’t mean you’ll get it. Your diet, sun exposure, etc. also matter.) An epigenetic rule is therefore an innate bias and one that could be weak.

But the trick, according to Wilson, is that these genetic predispositions tend to trickle up, “bias[ing] cultural evolution in one direction as opposed to another, and thus connect[ing] the genes to culture.” That is, genes mean there is a human nature, and this nature affects the culture we make. Ergo, social scientists, or anyone else who wants to understand culture, had better know some biology.

I’ve never found this claim–the weak, non-genetic, determinist version–particularly troubling. In principle biology more or less has to predispose us to act in some ways and not others. The point is perhaps best made in reverse. Imagine an organism, even a smart one, whose biological make-up doesn’t affect its behavior or culture. It’s hard to do. An organism that’s six feet tall is unlikely to build cathedrals that are six inches tall. An organism with no eyes is unlikely to write bad poetry about azure skies.

But it’s equally clear that there will be a spread in the strength of epigenetic rules. Some phenomena that might interest social scientists will involve epigenetic rules and some of these may be strict (take grammar, for example). Other phenomena might involve epigenetic connections that, while real, are weak (maybe human cooperation) and others involve none at all (building with arches versus posts and beams). In the first case there’s some bang for the buck in talking about genes. In the last there is not. In the intermediate case, which might be common, it’s just not clear if vague talk of weak epigenetic predispositions gets us anywhere.

And getting somewhere is what it’s all about. Scientists are in the business of finding powerful explanations. Getting such explanations hinges on distinguishing first-order effects, which matter, from second- and third-order ones, which don’t. The question is not whether there’s some formal connection between A and B or whether our explanation of B properly descends to a lower level, fulfilling some consilient ideal. The question is: does it work? does our theory explain the interesting and important facts that need explaining?

But as genetic connections to a phenomenon grow weaker, their explanatory power falls. That’s simply what we mean by a weak genetic connection. In the case of culture, this decreasing power shows up in insights that get trivial fast. To see this, try making predictions about art or literature that follow from biology. (You don’t need any special training to do this; sociobiological predictions rarely spring from technical arcana about DNA-binding motifs or mutation-selection balance.) I performed this exercise before reading Wilson’s book, with the following results: Artists will depict a lot of naked ladies (assuming our artist is male); most love poems won’t be addressed to one’s sister (incest avoidance is possibly genetic); painters won’t use pigments that radiate solely in the ultraviolet and infrared (invisible to us). As it turns out, the last is remarkably close to Wilson’s favorite example of consilience. One can, it turns out, roughly predict the order in which color words enter language from knowing how the cones in our retina encode light as color. Not surprisingly, black, white, red and green are standard ingredients in most languages, while chartreuse kicks in later. While worth knowing, this seems a fairly thin consilient accomplishment. The fact that our eyes convert continuous wavelengths into fairly discrete colors is an interesting piece of biology, but the fact that this affects how we describe the world seems a bit obvious. (We’d all agree that if dogs could speak they’d lack color words.) If this is the stuff of consilience, we can hardly expect art critics to flock to biology summer school.

The point isn’t that these insights from biology are wrong. The point is they’re not insights. The leash connecting culture to biology (to use one of Wilson’s favorite images) may well be real, but it gets stretched so thin that it’s often just not worth worrying about.

By saying this, I’m not saying anything unscientific. Biologists, after all, ignore lower-level processes all the time and no one grumbles about that. To see this, consider one of the most famous of evolutionary arguments, Fisher’s theory of why most species have equal numbers of males and females2. Now if you’re a big consilience fan, you might insist on some explanation that dips down below biology, hooking up with chemistry or physics (e.g., the X chromosome has about the same mass as the Y, thus X- and Y-bearing sperm move at equal velocities through fluids giving each an equal chance of fertilization). The real explanation looks nothing like this. Instead Fisher saw that when one sex is rare the average individual of that sex produces more kids than the average individual of the common sex. Thus any innate tendency to make more of the rare sex enjoys an advantage and gets more common. A 50:50 ratio is the only stable equilibrium. This argument has nothing to do with the nuts and bolts of chemistry or physics. Indeed its great beauty lies in the fact that it is gloriously independent of such details. It’s not that these details–sperm, DNA, quarks–aren’t there. Of course they are. It’s just that they aren’t where the expanatory action is. To insist on a physico-chemical explanation would be to miss the real story, one told by abstract characters like “fitness” and “innate tendency” who are unknown at lower levels.

The important point in all this is that we have to distinguish between what we might call ontological consilience (higher levels are made of lower levels) and epistemic consilience (higher levels are explained by lower levels).3 Fisher’s theory doesn’t deny the fact that genes are made of DNA. But it doesn’t depend on knowledge of this fact–which is why he could offer it 23 years before anyone heard of Watson and Crick.

Wilson tends to mix up these two kinds of consilience. This leads him to suggest, for instance, that because consumers are made of neurons with evolutionary histories, economics must pay more attention to biology. Now it might be a good thing if economists knew more biology, but the notion that powerful economic explanations will reside at the biological level does not follow from the fact that consumers are made of gooey parts.

The same confusion (in reverse) leads Wilson sometimes to conflate talk of what things are made of with explanation. Here, for example, is his discussion of how biology might explain creativity in the arts:

And if during this process [of charting the brain] the creative mind is to be understood, it will need collaboration between scientists and humanities scholars. The collaboration, now in its early stages, is likely to conclude that innovation is a concrete biological process founded upon an intricacy of nerve circuitry and neurotransmitter release.

Well of course it will. What else could creativity (or, for that matter, counting to ten) be made of but nerve circuitry and neurotransmitters? As a claim about the physical building blocks of creativity, Wilson’s claim is right enough. But as an explanation of anything, it leaves a bit to be desired. One may as well predict that sex ratios are likely to be founded upon atoms.

This tendency to pass off claims about what things are made of as consilience has the unfortunate side-effect of encouraging a confusion about the legitimacy of higher-level phenomena. When Wilson “predicts,” for example, that ethical phenomena will also turn out to be neural, it’s unclear what interesting conclusion he thinks follows from this fact. Have we here “reduced” ethics to biology? Anyone who’s tempted to answer yes should consider one further “prediction”: Mathematical thoughts will also involve neurons. You’re free, of course, to conclude that ethical truths are just biology but only at the considerable risk of arriving at the same conclusion about “2 + 2 = 4”.

Consilience: Harder than You Think

Wilson spends a good deal of time on several problems that appear so deep and so stubborn that their solution will surely require new consilience. The most obvious of these is the mind. As Wilson explains, mental phenomena pose two essentially different challenges, the so-called easy and hard problems of consciousness. The easy problem is the stuff of classical brain research: How does the brain respond to stimuli, store memories, etc.? The hard problem is much harder: How does the brain give rise to subjective feeling? How, that is, does a few pounds of wrinkled grey tissue sitting atop our necks make it possible for us to feel anything?

Wilson understands that consciousness represents a (and likely the) critical link in his consilience project. For the mind sits at that crucial nexus linking art, literature, aesthetics, and religion–that range of enterprises concerned with human feeling–with biology, the domain of neurons and ion channels. Any attempt to map the range of humanities onto the domain of science inevitably runs through (and up against) the mind. Wilson appreciates this, calling consciousness the “master unsolved problem,” labeling the mind “supremely important to the consilience program,” and admitting that science’s failure to “deliver in the domain most crucial to its promise, the physical basis of mind” spelled the end of Enlightenment optimism. He also understands that a consilient science cannot repeat this failure. Mental life cannot be left to philosophers and poets.

But Wilson grossly underestimates the difficulty posed by the hard problem of consciousness and so grossly overestimates how easily consilience will come here. Indeed, in perhaps the most remarkable passage of the book, Wilson announces that he more or less has the solution: “Although it is the nature of philosophers to imagine impasses and expatiate upon them at book length with schoolmasterish dedication, the hard problem [of consciousness] is conceptually easy to solve.” Here’s his solution. First we must admit there’s something special about consciousness: Someone who knew all there was to know about the neurobiology of color vision but who was color blind could not know what the subjective experience of “blue” is like. But this incapacity, Wilson thinks, is beside the point. Instead, he curiously maintains that the critical distinction lies eleswhere, in an understanding of the proper roles of science and art. Science, Wilson tells us, answers the question of “who can feel blue and other sensations and who cannot feel them, and explains why that difference exists”, while art “transmits feelings among persons of the same capacity.”

And here’s where the trouble starts: for the hard problem of consciousness is nowhere to be found in this divvying up of turf between science and art. Science’s role gets reduced to pointing out facts like people feel blue and rocks don’t, and to explaining the basis of this difference (presumably, people have brains and rocks don’t). But surely this doesn’t exhaust the role of science. Just because one can point to several legitimate scientific questions about subjectivity doesn’t mean that these are the only legitimate questions. Here for instance is another: Just how does subjective feeling arise from brains anyway? The hard problem of consciousness, to belabor the obvious, is also a perfectly legitimate scientific question. And it doesn’t become any less so by pointing to other, easier, questions.

Wilson in effect introduces a subtle new species of eliminativism about consciousness. He doesn’t flatly deny the phenomenon the way Daniel Dennett does. Rather he divides up the intellectual turf in such a way that no one gets left holding the problem. If you buy his argument, the problem goes away not because it’s been solved but because no one feels obliged to talk about it. This is a strange “solution” for anyone to propose, but an especially bizarre one coming from someone who claims to be unifying, not partitioning, the intellectual landscape.

But it gets worse. For this is followed by a discussion of the “conventional wisdom” that scientific fact and art “can never be translated into each other.” As if to show that the artist’s feeling and the scientist’s fact can be brought together, Wilson has us imagine a fancy future science that lets us read out the mental contents of an experimental subject from a neurobiological printout. The subject reads a sad novel and we–reading this mind script–follow the narrative and also feel sad, and so on. Now I don’t doubt that such a thing is possible. In fact, I know it is. For this is just a high-tech version of what ordinary language does. When you speak to me, you reveal something about your mental state and I–given the technology in my head–know how to decode it. If you tell me a sad story, we both feel sad. If you tell me a joke, we both laugh. We have transmission of feeling. The only difference between this transmission and Wilson’s is that it takes some man-made (not biological) technology to do Wilson’s kind. But the force of this point is completely unclear.

More important, science’s big role here in the transmission of feeling gets us absolutely nowhere with the hard problem of consciousness. For the problem is not to explain if or how we can transmit subjective feeling, but how subjective feeling is possible in the first place. Deciphering some super-EEG is impressive but ultimately beside the point.

Wilson wraps up this section with a detour into how this futuristic mind script might resemble Chinese calligraphy (complete with a quote from a Sinologist). But while this display of erudition is impressive, it is quite irrelevant. Too many readers will likely walk away wowed by Wilson’s wide knowledge but oblivious to the fact that he didn’t make a dent in the allegedly “easy” problem of consciousness.

Mission Impossible?

The recalcitrance of the hard problem of consciousness combined with our inability to even imagine what its solution would look like suggest a possibility that might well pull the rug out from under Wilson’s whole program: Maybe consciousness is beyond us. Maybe we are simply incapable of figuring it out. Indeed maybe there are hosts of problems that lie beyond our intellectual grasp.

Although the modern version of this idea was first articulated by Noam Chomsky, it has grown closely associated with the philosopher Colin McGinn.4Despite McGinn’s occupation, his argument is essentially scientific, indeed evolutionary. It is this. Cat brains did not evolve to penetrate the deepest truths about nature but to get cats more or less intact from one day to the next. My cat Boris’s brain is not, therefore, infinitely adroit. It knows a lot about birds, mice, and how other cats behave, but is hopelessly lost when it comes to chess, the purpose of fax machines, or the multiplication table. Similarly our brains didn’t evolve to penetrate the deepest truths about nature but to get us from one day to the next. We have therefore no reason whatever for believing that we, Homo sapiens, have arrived at some acme of cognitive evolution, that our chimpish brains are the best that brains can be. Instead it seems far more natural to suppose that we, like every other species, are intellectually good at some things and hopelessly bad at others. In the lingo, we are likely “cognitively open” to some phenomena and theories, but “cognitively closed” to other phenomena (that are real) and theories (that are true).

This so-called “mysterian” position5 can and probably does lead to a conclusion diametrically opposite Wilson’s. True consilience, the seamless integration of all we know from ineffable aesthetic preference to hard-as-nails physics, may be extremely unlikely. It’s not just that we will suffer quantitative limits on our cognitive powers (we can’t memorize 942,921 digits). Rather, we may get hung up at key steps in our reductionist program, understanding a great deal about phenomenon A and a great deal about phenomenon B, but fated to perpetual cluelessness about the nature of their connection.6 Those brains of ours that Wilson reminds us were shaped in Paleolithic savannas did not evolve to crack, say, the master problem of consciousness. And consciousness is only the most obvious such problematic juncture. (Another might be that connecting free will, the stuff of human law, to physiochemical determinism, the stuff of natural law.)

Though McGinn and Chomsky don’t say so, a case might even be made that some, though certainly not all, of the borders between traditional intellectual disciplines represent the natural stress lines between our domains of cognitive competence. I.e., our inability to think clearly about some phenomena might underlie our tendency to draw boundaries where we do: the humanities to one side (telling me how you feel) and the sciences to the other (telling me that your brain does the feeling). If true, routine feats of reduction may be systematically easier within than between disciplines.

As an evolutionary biologist, I find it hard to see how something like the mysterian view cannot be true. The alternative–boundless percipience–seems downright unbiological. (And I’m certainly not the only biologist to reach this conclusion.7) But the news is not all bad. For while science may be consigned to permanent impotence over say, subjective feeling, it would get handed a new and likely tractable problem: feeling out the edges of our domains of cognitive capacity, a task first suggested by Chomsky.

It is unfortunate that Wilson, though clearly aware of these mysterian worries, does not discuss them at any length.8 It would have been interesting to hear why he finds his consilient scenario more plausible than one that takes our likely limitations seriously. Or why he thinks such limits, while real, will have surmountable effects on his program. I suspect, but obviously don’t know, that Wilson would argue that science has (thankfully) always turned a deaf ear to such defeatist worries and that it would be both foolish and irresponsible for scientists to give up the good fight. And I agree. But the issue is not whether scientists should or should not try to conquer consciousness, art, or free will, but whether we have any grounds for expecting success–any grounds, that is, for taking Wilson’s quixotic vision of the unity of knowledge seriously.

Be that as it may, I suspect the real reason Wilson favors his consilient scenario isn’t because he finds it more plausible but because he finds it more attractive. For as he admits near the start of his book, consilience isn’t science, it is a philosophy, a metaphysical view that he obviously finds both beautiful and deeply satisfying. The irony, of course, is that Wilson’s own science of evolution gives every reason for questioning this metaphysic, every reason, that is, for doubting whether our brains–jury-rigged and riddled with blindspots–are the stuff from which certain knowledge and seamless consilience can be obtained.



1 Capote, The Dogs Bark: Public People and Private Places (New York: Random House, 1973).

2 R. A. Fisher, The Genetical Theory of Natural Selection (Oxford: Oxford University Press, 1930).

3 John Searle makes a similar sort of distinction in a different context. See his “Consciousness and the Philosophers,” The New York Review of Books, 6 March 1997.

4Noam Chomsky, Reflections on Language (New York: Pantheon Books, 1975); Colin McGinn, The Problem of Consciousness (Cambridge, Mass.: Blackwell, 1991). See especially McGinn’s chapter 1, “Can we solve the mind-body problem?”

5 A misnomer. As McGinn explains, there’s nothing objectively mysterious much less mystical about phenomena to which we are cognitively closed. They justseem that way.

6 Although McGinn argues that our brains are well wired to do science and that cognitive closure will mostly involve philosophical problems (indeed that this more or less defines philosophical, not scientific, problems), he has a traditional picture of science in mind. But Wilson’s whole point is that questions traditionally sitting outside science– mind-body, aesthetics and ethics– are legitimate scientific problems. To the extent, then, that these problems are permanent mysteries, Wilson’s consilience is left with gaps.

7See for instance G. Stent, “Limits to the Scientific Understanding of Man,” Science 187 (1975): 1052-57.

8 He admits, for instance, that: “[R]eality was not constructed to be easily grasped by the human mind. This is the cardinal tenet of scientific understanding: Our species and its ways of thinking are a product of evolution, not the purpose of evolution.” But he draws few, if any, epistemological conclusions from this cardinal tenet.