"The exquisite environment of fact. The final poem will be the poem of fact in the language of fact. But it will be the poem of fact not realized before."

— Wallace Stevens, "Adagia", in Opus Posthumous

Edge 166
April 29, 2005

[4,700 words]

SHOW ME THE SCIENCE [August 29, 2005]
by Daniel C. Dennett

Since there is no content, there is no "controversy'' to teach about in biology class. But here is a good topic for a high school course on current events and politics: Is intelligent design a hoax? And if so, how was it perpetrated?


John McCarthy, Daniel Gilbert, Spencer Reiss, Robert Provine, Verena Huber-Dyson respond to John Horgan's "In Defense of Common Sense". Horgan replies.



Since there is no content, there is no "controversy'' to teach about in biology class. But here is a good topic for a high school course on current events and politics: Is intelligent design a hoax? And if so, how was it perpetrated?

SHOW ME THE SCIENCE [August 29, 2005]
by Daniel C. Dennett


"The proponents of intelligent design use an ingenious ploy that works something like this," writes Tufts philosopher Daniel C. Dennett, and author of Darwin's Dangerous Idea. "First you misuse or misdescribe some scientist's work. Then you get an angry rebuttal. Then, instead of dealing forthrightly with the charges leveled, you cite the rebuttal as evidence that there is a "controversy" to teach."

To date, scientists have held back with regard to engaging the proponents of "intelligent design" on the battlefield of scientific discourse, reasoning being that by simply having a discussion, the ID crowd gains a respectable platform for their views.

"The fundamental scientific idea of evolution by natural selection," Dennett writes, "is not just mind-boggling; natural selection, by executing God's traditional task of designing and creating all creatures great and small, also seems to deny one of the best reasons we have for believing in God. So there is plenty of motivation for resisting the assurances of the biologists. Nobody is immune to wishful thinking. It takes scientific discipline to protect ourselves from our own credulity, but we've also found ingenious ways to fool ourselves and others."

In this connection, in the past week, the 43rd President of the United States as well as the Majority Leader of the United States Senate have both come out in support of "teaching the controversy". The stakes are high. The battle must now be joined.  

"Is 'intelligent design' a legitimate school of scientific thought?" asks Dennett? "Is there something to it, or have these people been taken in by one of the most ingenious hoaxes in the history of science? Wouldn't such a hoax be impossible? No. Here's how it has been done." he continues.

Read on.


DANIEL C. DENNETT is University Professor, Professor of Philosophy, and Director of the Center for Cognitive Studies at Tufts University. Among his books are Consciousness Explained; Darwin's Dangerous Idea; and Freedom Evolves.


[Editor's Note: First published as an Op-Ed Page article in The New York Times on Sunday, August 28th.]


Blue Hill, Me.

PRESIDENT BUSH, announcing this month that he was in favor of teaching about "intelligent design" in the schools, said, "I think that part of education is to expose people to different schools of thought." A couple of weeks later, Senator Bill Frist of Tennessee, the Republican leader, made the same point. Teaching both intelligent design and evolution "doesn't force any particular theory on anyone," Mr. Frist said. "I think in a pluralistic society that is the fairest way to go about education and training people for the future."

Is "intelligent design" a legitimate school of scientific thought? Is there something to it, or have these people been taken in by one of the most ingenious hoaxes in the history of science? Wouldn't such a hoax be impossible? No. Here's how it has been done.

First, imagine how easy it would be for a determined band of naysayers to shake the world's confidence in quantum physics — how weird it is! — or Einsteinian relativity. In spite of a century of instruction and popularization by physicists, few people ever really get their heads around the concepts involved. Most people eventually cobble together a justification for accepting the assurances of the experts: "Well, they pretty much agree with one another, and they claim that it is their understanding of these strange topics that allows them to harness atomic energy, and to make transistors and lasers, which certainly do work..."

Fortunately for physicists, there is no powerful motivation for such a band of mischief-makers to form. They don't have to spend much time persuading people that quantum physics and Einsteinian relativity really have been established beyond all reasonable doubt.

With evolution, however, it is different. The fundamental scientific idea of evolution by natural selection is not just mind-boggling; natural selection, by executing God's traditional task of designing and creating all creatures great and small, also seems to deny one of the best reasons we have for believing in God. So there is plenty of motivation for resisting the assurances of the biologists. Nobody is immune to wishful thinking. It takes scientific discipline to protect ourselves from our own credulity, but we've also found ingenious ways to fool ourselves and others. Some of the methods used to exploit these urges are easy to analyze; others take a little more unpacking.

A creationist pamphlet sent to me some years ago had an amusing page in it, purporting to be part of a simple questionnaire:

Test Two

Do you know of any building that didn't have a builder? [YES] [NO]

Do you know of any painting that didn't have a painter? [YES] [NO]

Do you know of any car that didn't have a maker? [YES] [NO]

If you answered YES for any of the above, give details:

Take that, you Darwinians! The presumed embarrassment of the test-taker when faced with this task perfectly expresses the incredulity many people feel when they confront Darwin's great idea. It seems obvious, doesn't it, that there couldn't be any designs without designers, any such creations without a creator.

Well, yes — until you look at what contemporary biology has demonstrated beyond all reasonable doubt: that natural selection — the process in which reproducing entities must compete for finite resources and thereby engage in a tournament of blind trial and error from which improvements automatically emerge — has the power to generate breathtakingly ingenious designs.

Take the development of the eye, which has been one of the favorite challenges of creationists. How on earth, they ask, could that engineering marvel be produced by a series of small, unplanned steps? Only an intelligent designer could have created such a brilliant arrangement of a shape-shifting lens, an aperture-adjusting iris, a light-sensitive image surface of exquisite sensitivity, all housed in a sphere that can shift its aim in a hundredth of a second and send megabytes of information to the visual cortex every second for years on end.

But as we learn more and more about the history of the genes involved, and how they work — all the way back to their predecessor genes in the sightless bacteria from which multicelled animals evolved more than a half-billion years ago — we can begin to tell the story of how photosensitive spots gradually turned into light-sensitive craters that could detect the rough direction from which light came, and then gradually acquired their lenses, improving their information-gathering capacities all the while.

We can't yet say what all the details of this process were, but real eyes representative of all the intermediate stages can be found, dotted around the animal kingdom, and we have detailed computer models to demonstrate that the creative process works just as the theory says.

All it takes is a rare accident that gives one lucky animal a mutation that improves its vision over that of its siblings; if this helps it have more offspring than its rivals, this gives evolution an opportunity to raise the bar and ratchet up the design of the eye by one mindless step. And since these lucky improvements accumulate — this was Darwin's insight — eyes can automatically get better and better and better, without any intelligent designer.

Brilliant as the design of the eye is, it betrays its origin with a tell-tale flaw: the retina is inside out. The nerve fibers that carry the signals from the eye's rods and cones (which sense light and color) lie on top of them, and have to plunge through a large hole in the retina to get to the brain, creating the blind spot. No intelligent designer would put such a clumsy arrangement in a camcorder, and this is just one of hundreds of accidents frozen in evolutionary history that confirm the mindlessness of the historical process.

If you still find Test Two compelling, a sort of cognitive illusion that you can feel even as you discount it, you are like just about everybody else in the world; the idea that natural selection has the power to generate such sophisticated designs is deeply counterintuitive. Francis Crick, one of the discoverers of DNA, once jokingly credited his colleague Leslie Orgel with "Orgel's Second Rule": Evolution is cleverer than you are. Evolutionary biologists are often startled by the power of natural selection to "discover" an "ingenious" solution to a design problem posed in the lab.

This observation lets us address a slightly more sophisticated version of the cognitive illusion presented by Test Two. When evolutionists like Crick marvel at the cleverness of the process of natural selection they are not acknowledging intelligent design. The designs found in nature are nothing short of brilliant, but the process of design that generates them is utterly lacking in intelligence of its own.

Intelligent design advocates, however, exploit the ambiguity between process and product that is built into the word "design." For them, the presence of a finished product (a fully evolved eye, for instance) is evidence of an intelligent design process. But this tempting conclusion is just what evolutionary biology has shown to be mistaken.

Yes, eyes are for seeing, but these and all the other purposes in the natural world can be generated by processes that are themselves without purposes and without intelligence. This is hard to understand, but so is the idea that colored objects in the world are composed of atoms that are not themselves colored, and that heat is not made of tiny hot things.

The focus on intelligent design has, paradoxically, obscured something else: genuine scientific controversies about evolution that abound. In just about every field there are challenges to one established theory or another. The legitimate way to stir up such a storm is to come up with an alternative theory that makes a prediction that is crisply denied by the reigning theory — but that turns out to be true, or that explains something that has been baffling defenders of the status quo, or that unifies two distant theories at the cost of some element of the currently accepted view.

To date, the proponents of intelligent design have not produced anything like that. No experiments with results that challenge any mainstream biological understanding. No observations from the fossil record or genomics or biogeography or comparative anatomy that undermine standard evolutionary thinking.

Instead, the proponents of intelligent design use a ploy that works something like this. First you misuse or misdescribe some scientist's work. Then you get an angry rebuttal. Then, instead of dealing forthrightly with the charges leveled, you cite the rebuttal as evidence that there is a "controversy" to teach.

Note that the trick is content-free. You can use it on any topic. "Smith's work in geology supports my argument that the earth is flat," you say, misrepresenting Smith's work. When Smith responds with a denunciation of your misuse of her work, you respond, saying something like: "See what a controversy we have here? Professor Smith and I are locked in a titanic scientific debate. We should teach the controversy in the classrooms." And here is the delicious part: you can often exploit the very technicality of the issues to your own advantage, counting on most of us to miss the point in all the difficult details.

William Dembski, one of the most vocal supporters of intelligent design, notes that he provoked Thomas Schneider, a biologist, into a response that Dr. Dembski characterizes as "some hair-splitting that could only look ridiculous to outsider observers." What looks to scientists — and is — a knockout objection by Dr. Schneider is portrayed to most everyone else as ridiculous hair-splitting.

In short, no science. Indeed, no intelligent design hypothesis has even been ventured as a rival explanation of any biological phenomenon. This might seem surprising to people who think that intelligent design competes directly with the hypothesis of non-intelligent design by natural selection. But saying, as intelligent design proponents do, "You haven't explained everything yet," is not a competing hypothesis. Evolutionary biology certainly hasn't explained everything that perplexes biologists. But intelligent design hasn't yet tried to explain anything.

To formulate a competing hypothesis, you have to get down in the trenches and offer details that have testable implications. So far, intelligent design proponents have conveniently sidestepped that requirement, claiming that they have no specifics in mind about who or what the intelligent designer might be.

To see this shortcoming in relief, consider an imaginary hypothesis of intelligent design that could explain the emergence of human beings on this planet:

About six million years ago, intelligent genetic engineers from another galaxy visited Earth and decided that it would be a more interesting planet if there was a language-using, religion-forming species on it, so they sequestered some primates and genetically re-engineered them to give them the language instinct, and enlarged frontal lobes for planning and reflection. It worked.

If some version of this hypothesis were true, it could explain how and why human beings differ from their nearest relatives, and it would disconfirm the competing evolutionary hypotheses that are being pursued.

We'd still have the problem of how these intelligent genetic engineers came to exist on their home planet, but we can safely ignore that complication for the time being, since there is not the slightest shred of evidence in favor of this hypothesis.

But here is something the intelligent design community is reluctant to discuss: no other intelligent-design hypothesis has anything more going for it. In fact, my farfetched hypothesis has the advantage of being testable in principle: we could compare the human and chimpanzee genomes, looking for unmistakable signs of tampering by these genetic engineers from another galaxy. Finding some sort of user's manual neatly embedded in the apparently functionless "junk DNA" that makes up most of the human genome would be a Nobel Prize-winning coup for the intelligent design gang, but if they are looking at all, they haven't come up with anything to report.

It's worth pointing out that there are plenty of substantive scientific controversies in biology that are not yet in the textbooks or the classrooms. The scientific participants in these arguments vie for acceptance among the relevant expert communities in peer-reviewed journals, and the writers and editors of textbooks grapple with judgments about which findings have risen to the level of acceptance — not yet truth — to make them worth serious consideration by undergraduates and high school students.

SO get in line, intelligent designers. Get in line behind the hypothesis that life started on Mars and was blown here by a cosmic impact. Get in line behind the aquatic ape hypothesis, the gestural origin of language hypothesis and the theory that singing came before language, to mention just a few of the enticing hypotheses that are actively defended but still insufficiently supported by hard facts.

The Discovery Institute, the conservative organization that has helped to put intelligent design on the map, complains that its members face hostility from the established scientific journals. But establishment hostility is not the real hurdle to intelligent design. If intelligent design were a scientific idea whose time had come, young scientists would be dashing around their labs, vying to win the Nobel Prizes that surely are in store for anybody who can overturn any significant proposition of contemporary evolutionary biology.

Remember cold fusion? The establishment was incredibly hostile to that hypothesis, but scientists around the world rushed to their labs in the effort to explore the idea, in hopes of sharing in the glory if it turned out to be true.

Instead of spending more than $1 million a year on publishing books and articles for non-scientists and on other public relations efforts, the Discovery Institute should finance its own peer-reviewed electronic journal. This way, the organization could live up to its self-professed image: the doughty defenders of brave iconoclasts bucking the establishment.

For now, though, the theory they are promoting is exactly what George Gilder, a long-time affiliate of the Discovery Institute, has said it is: "Intelligent design itself does not have any content."

Since there is no content, there is no "controversy" to teach about in biology class. But here is a good topic for a high school course on current events and politics: Is intelligent design a hoax? And if so, how was it perpetrated?


Computer Scientist; Artificial Intelligence Pioneer, Stanford University

John Horgan pontificates:

"But computers fail miserably at simulating the ordinary, experience-based intelligence that helps ordinary humans get through ordinary days. In other words, computers lack common sense, and that's why even the smartest ones are so dumb."

Horgan regards a lack of common sense as an intrinsic characteristic of computers; I assume he means computer programs. However, much artificial intelligence research has focussed on analyzing commonsense knowledge and reasoning. I refer to my 1959 article "Programs with common sense", my 1990 collection of articles "Formalizing common sense", Erik Mueller's forthcoming book "Commonsense reasoning", and the biennial international conferences on common sense. I fear John Horgan would find this work as distressingly technical as he finds physics. Common sense has proved a difficult scientific topic, and programs with human-level common sense have not yet been achieved. It may be another 100 years.

The AI research has identified components of commonsense knowledge and reasoning, has formalized some of them in languages of mathematical logic, and has built some of them into computer programs. Besides the logic based approach, there have been recent attempts to understand common sense as an aspect of the human nervous system.

Research on formalizing common sense physics, e.g. that objects fall when pushed off a table, are not in competition with physics as studied by physicists. Rather physics is imbedded in common sense. Thus applying Newton's F = ma requires commonsense reasoning. Physics texts and articles do not consist solely of equations but contain common sense explanations.

When Horgan says that string theory is untestable, he is ignoring even the popular science writing about string theory. This literature tells us that the current untestability of string theory is regarded by the string theorists as a blemish they hope to fix.

Psychologist, Harvard University

Horgan's Op-Ed piece is such a silly trifle that it doesn't dignify serious response. The beauty of science is that it allows us to transcend our intuitions about the world, and it provides us with methods by which we can determine which of our intuitions are right and which are not. Common sense tell us that the earth is flat, that the sun moves around it, and that the people who know the least often speak the loudest. Horgan's essay demonstrates that at least one of our common sense notions is true.

Contributing Editor, Wired Magazine

Surely Susskind is joking:

"Why, after all, would nature provide us with the capacity to visualize things that no living creature had ever experienced?"

Art? Music? Heaven? God? The Red Sox win the World Series? Science fiction, for chrissake!

Buy the man a drink! This is the kind of stuff that gives scientists a bad name.

Psychologist and Neuroscientist, University of Maryland; Author, Laughter

Hunter-Gatherers Make Poor Physicists and Cognitive Neuroscientists:
Horgan 0, Susskind 1

Horgan continues to expand his franchise that is based on the technique of assertively posing provocative and often reasonable propositions. The boldness of his assertions earns him an audience that he would not otherwise achieve. But as in The End of Science, he picks a fight that he is not prepared to win and never delivers a telling blow. Susskind effectively exploits a basic weakness in Horgan's thesis, the fallibility of common sense, especially in scientific context.

Researchers working at the frontiers of many sciences use mathematical and theoretical prostheses to expand the range of phenomena that can be studied, escaping some of the limits of their evolutionary history and its neurological endowment. The startling truth is that we live in a neurologically-generated, virtual cosmos that we are programmed to accept as the real thing. The challenge of science is to overcome the constraints of our neurological wetware and understand a physical world that we know only second-hand and incompletely. In fact, we must make an intuitive leap to accept the fact that there is a problem at all. Common sense and the brain that produces it evolved in the service of our hunter-gatherer ancestors, not physicists and cognitive neuroscientists. Unassisted, the brain of Horgan or any other member of our species is not up to task of engaging certain scientific problems.

Sensory science provides the most obvious discrepancies between the physical world and our neurological model of it. We humans evolved the capacity to detect a subset of stimuli available to us on the surface of planet Earth. Different animals with different histories differ in their absolute sensitivity to a given stimulus and in the bandwidth to with they are sensitive. And some species have modes of sensation that we lack, such as electric or magnetic fields. Each species is a theory of the environment in which it evolved and it can never completely escape the limitations of its unique evolutionary history. But the problem of sensing the physical cosmos is even more complicated, because we do not directly sense physical stimuli, but are aware of only their neurological correlates. There is not, for example, any “blue” in electromagnetic radiation, pitch of B-flat in pressure changes in the air, or sweetness in sucrose. All are neurological derivatives of the physical world, not the thing itself.

Neurological limits on thinking are probably as common as those on sensing, but they are more illusive — it's harder to think about what we can't think about than what we can't sense. A good example from physics is our difficulty in understanding the space-time continuum — our intellect fails us when we move beyond the dimensions of height, width, and depth. Other evidence of our neurological reality-generator is revealed by its malfunction in illusions, hallucinations, and dreams, or in brain damage, where the illusion of reality does not simply degrade, but often splinters and fragments in unanticipated ways.

The intellectual prostheses of mathematics, computers, and instrumentation loosen but do not free our species of the constraints of its neurological heritage. We do not build random devices to detect stimuli that we cannot conceive, but build outward from a base of knowledge. A neglected triumph of science is how far we have come with so flawed an instrument as the human brain and its sensoria. Another is in realizing the limits of common sense and its knowledge base of folk wisdom.

Logician; Emeritus Professor, University of Calgary


It seems to me that John Horgan in his Edge piece "In Defense of Common Sense" is confusing "common sense" with "prejudice". The human capacity for common sense reasoning is undergoing an evolutionary process as science and technology are progressing. Just look back over the last two millennia for spectacular illustrations of this pretty obvious observation. Presumably Mr. Horgan watches TV, uses his personal computer and takes airplanes to get places he cannot reach on foot nor by his questionably commonsensical motor car. If he does not know how to fix whatever trouble his car may come up with — like some people do — he really should not drive it.

To some of my colleagues the telescope serves as the extension of their vision to others the cloud chamber extends the reach of their cognition, just the way his car serves Mr Horgan to get around. In the cloud chamber we witness effects of events too small to see directly. Oh there are so many wonderful illustrations of this evolution of the human cognitive faculties. Ideas, models, conjectures acquiring reality by circumstantial evidence and repeated reasoning become part of our life; as they get entrenched our common sense expands through familiarity. Sometime our notions have to be adjusted, or some, like the idea of the ether, become obsolete. That too is progress.

Common sense that refuses to evolve becomes prejudice, or bigotry to use a more bold expression.

I have seen quite a bit of scientific evolution in my time. In my childhood the planetary model of the atom was the way we were thinking of matter; now it has become a metaphor or a handy tool, useful under certain conditions. The same is about to happen with strings. We have learned to think more abstractly, we do not really need to think of strings as wiggly worms much too small to see. We have become quite adept at mathematical modeling. I'd love to be around to see the evolution of cognition happening ever so much faster. Even the men in the street are keeping pace. Let us not encourage spoil-sports like Mr Horgan.


My modest defense of common sense as a guide for judging theories — particularly when empirical evidence is flimsy — has provoked a predictable shriek of outrage from Lenny Susskind. His attempt to lump me together with advocates of intelligent design is more than a little ironic, since in rebuking me he displays the self-righteous arrogance of a religious zealot damning an infidel. Moreover, as a proponent (!!) recently acknowledged in the New York Times, string theory and its offshoots are so devoid of evidence that they represent "a faith-based initiative."

Susskind urges me to "take courses in algebra, calculus, quantum mechanics, and string theory" before I mouth off further about strings. In other words, I must become a string theorist to voice an opinion about it. This assertion recalls the insistence of Freudians — another group notoriously hostile to outside criticism and complaints about testability — that only those fully indoctrinated into their mind-cult can judge it.

Susskind’s protestations to the contrary, string theory can be neither falsified nor verified by any empirical test. At best, experiments can provide only necessary but insufficient evidence for components — such as supersymmetry — of certain variants of string theory. That is why in 2002 I bet the physicist Michio Kaku $1000 that by 2020 no one will be awarded a Nobel prize for work on string theory or similar quantum-gravity theory. (I discuss the bet with Kaku, Lee Smolin, Gordon Kane, and other physicists at "Long Bet"). Would Susskind care to make a side bet?

As to the other respondents: John McCarthy merely confirms my assertion that computer programmers have failed to simulate common sense — except that McCarthy expends many more words to make his point than I do. And like Lenny Susskind, Robert Provine and Verena Huber-Dyson merely point out that many scientific theories violate popular, common-sense intuitions about nature and yet prove to be empirically correct.

No kidding. I said just that in my essay. The question that I raised — and that all these respondents have studiously avoided — is what we should do when presented with theories such as psychoanalysis or string theory, which are not only counterintuitive but also lacking in evidence. Common sense tells me that in these cases common sense can come in handy.


John Brockman, Editor and Publisher
Russell Weinberger, Associate Publisher

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