»  National Review Online

April 9-13, 2008

  Toward a Science of Consciousness

[The eighth biennial "Toward a Science of Consciousness" conference was held at the University of Arizona in Tucson, April 8-12, 2008. Among the 800 participants from 45 countries was me. I blogged the event for National Review Online, April 9-13. Here are all the blogs gathered together.

Later I wrote up a more formal article about the conference for the print edition of National Review: see here.

The headings, except the last one, refer to the day whose lectures I am blogging
about. Most of the blogs were actually posted to National Review Online the following day.]


•  Tuesday, April 8

OK, I've arrived here in Tucson for the Toward a Science of Consciousness conference.


Didn't really absorb much from the first day's meeting. I caught a really bad cold the day before leaving New York, so to protect my ears from damage when flying, I dosed up on Benadryl. Didn't work. At least, the drying properties didn't work: I have a left ear full of fluid. The soporific properties worked great, though. I was stumbling around in a half-doze all day. This didn't help a bit when trying to grasp the fine points of Global Neuronal Workspace Theory, or parsing sentences like (actual example): "A fact f necessitates a fact g if and only if a proposition q that constitutes a complete representation of g can be deduced from a proposition p that constitutes a complete description of f." Well, duh.

So today (Wednesday, second day) I'm going to forswear the Benadryl and let those little rhinoviruses run wild. There's some good stuff today. In the morning, a discussion of Benjamin Libet's astonishing results. He showed that neurophysiologically speaking, your intention to do something precedes the conscious decision to do it. Then "Sex and Consciousness," with a panel discussion of "The Varieties of Sexual Experience." Now that's more like it! (You can't get away from William James at these events, by the way. Three different speakers quoted him yesterday — the same quote in two of the cases.)

Then in the evening, a joint lecture on panpsychism, which seems to have been gaining a lot of ground with the metaphysicians recently. Very approximately, it's the notion that consciousness is just the out-cropping or concentration of a "psi field" that pervades everything. Even electrons and neutrons possess eensy-teensy little specks of consciousness, according to the panpsychists. Panpsychism seems, according to its adherents, to offer a glimmer of hope that we might resolve what they call "the hard problem of consciousness," viz.: "How do mental events arise out of matter?"

Far as I'm concerned, the hard problem of consciousness this next couple of days will be trying to stay conscious while only having one functioning ear and a couple pounds of liquid mercury sloshing around in my head.

Tucson seems like a nice place, very nice. Dry. Dry is good.


•  Wednesday, April 9 (Part 1)

Some great fireworks Wednesday morning on the Libet thread. First we got some worthy-but-dull quantitative stuff from Bill Banks (experimental psychologist) and Francesca Carota (neuroscientist).

Then John Jacobson (philosopher/information scientist) came up and described his work at creating an unbeatable rock-paper-scissors computer program, throwing out all sorts of witty and penetrating observations on free will, "folk volition" (i.e. what we rubes think volition is all about, as opposed to what it is really all about), and something called Pessimistic Indeterminism, which naturally I like the sound of. He declared his aim as being "to explain free will without exotic physics."

Which may not be easy. Physicist Daniel Sheehan (University of San Diego) gave us a physicist's account of the nature of time. Down at the quantum level, things get radically weird, we all know that. The issue here this morning was: Do brain processes partake of the weirdness?

Sheehan believes they do. He offered some arguments from physics, and some experimental results. Most startling of the latter were experiments that seemed to show presentiment. In brief: You show your suspect a blank screen. Then you randomly display a picture, either an "emotional" one, that will evoke a strong neuro-response (e.g. naked woman) or a "calm" one (e.g. seascape). Then you quickly go back to the blank screen. You are monitoring neural reactions all the time. The "emotional" pictures show a strong reaction after they are shown, of course; but they seem to show a measurably stronger reaction before being show, too.

It's possible to explain this via known quantum effects. You just have to drop some common-sense assumptions about time and causation! Sheehan argued that the explanatory power you get by bringing quantum weirdness into biology makes it worthwhile.

This "retrocausation" is very startling when you see the numbers and graphs on-screen. I thought I felt a cold breeze as the shade of J.B. Rhine flitted through the hall. (One questioner from the floor actually mentioned psychokinesis. Uh-oh.)

Then Susan Pockett of the University of Auckland (in New Zealand) came up. I don't know what it is about the antipodes, but New Zealanders and Australians seem determined to live up to their stereotype as down-to-earth, no-nonsense practical types. J.J.C. Smart, founder of "Australian Materialism," illustrates the point. This is a particularly strict style of materialism (more properly "physicalism" in today's jargon). Beliefs, desires, intentions … material, material, material, says Smart. Read his riposte to Galen Strawson in the latter's 2006 book.

In any case, Susan — a stocky, feisty-looking woman who looked quite capable of knocking down anyone who disagreed with her — poured cold water on all that had gone before. She doubted Libet's famous results, saying he'd made unjustifiable assumptions. She pooh-poohed Sheehan's quantum weirdness, arguing that there were less-strange explanations for the phenomena. She scoffed at the "presentiment" experiment, mocking its statistics (justifiably, it seemed to me).

In questions afterwards, Susan didn't give an inch. Some academic tag-wrestling broke out. ("Didn't X counter Y's criticisms?" "Yes, but then Z pointed out that …" etc., etc.) Great theater, though all very collegial and good-humored. This is what we come to academic conferences for. I love this stuff. More shortly.


•  Wednesday, April 9 (Part 2)

The rest of Wednesday was a mixed bag. We had an address from Andy Clark of the University of Edinburgh, who I'd been told was a superstar in the field. Well, he was good, but not that good. His big thing — his shtick, if you like — is the "extended mind." This is the notion that, as he himself put it, "skin and skull are porous." A person's mind can (he says) fairly be taken to include things other than the brain. Cute anecdote: "A person asks me, 'Do you know the time?'  'Yes,' I reply … and then I look at my watch …  So my 'I' includes my watch." A good speaker with interesting things to say; but going over the material afterwards I found my self thinking "Hey, wait a minute" rather a lot.

One thing you wonder in advance about conferences like this is what the proportions will be of (a) real research results and original insights, as opposed to (b) academic log-rolling, tenured self-indulgence, flogging of dead horses, and content-free arm-waving. In the afternoon plenary session we got some of the (b).

The topic was "Sex and consciousness." Barry Komisaruk of Rutgers started with an interesting account of some neurophysiological experiments, then wandered off into the arm-waving zone. Sample: "If time is a fourth dimension, why can't consciousness be a fifth dimension?" Uh, because you can quantify time, but you can't quantify consciousness. How are you gonna set up a co-ordinate axis if you can't quantify?

Then Jenny Wade (not sure of her affiliation) got up and told us about some research she'd done. She'd got a sample heavily loaded with middle-aged university women and asked them about their mind states during sex. For heaven's sake: I can get this stuff from reading Erica Jong. I left when she started talking about Tantric sex. I know Tibet's in the news, but really.

On to panpsychism in the evening sessions. I was mildly expecting to get converted to panpsychism. Galen Strawson has come up with some arguments that seem plausible to me. If he can sign on to panpsychism, I'm pretty much ready to as well.

Unfortunately the speakers weren't that convincing. I want to reread my notes and some of the abstracts, but I thought there was a fair amount of arm-waving here, too. Bill Seager (University of Toronto) had some fun with words and syllogisms, but I had trouble seeing anything behind it all. Leopold Stubenberg wants to resurrect Russell's "neutral monism" of 80 years ago. Can't we make some progress here? ("Monism" — reality is made of only one kind of stuff. "Neutral" — the stuff is neither mental nor material.) Steve Deiss (UCSD) seemed to me to be taking things too far, defining matter down: "Things are interpretations of qualia." Na-uh, they're things. Doctor Johnson's famous refutation of Bishop Berkeley came to mind.

David Skrbina (U. Mich.) gave a lucid exposition of a Dynamical Systems Theory approach to thinking. Nice to see good old statistical mechanics make a showing, but David left me feeling he'd just put together a model of brain function without telling me anything about consciousness. (Though in fairness, his presentation was pretty dense, and I really need to reread my notes here.) Then Jonathan Powell from the University of Reading took us back to quantum weirdness, but getting to nitty-gritty with it at the level of neuronal microtubules, which I haven't seen done before. This looks really promising.

As part of the session, we were asked to vote on a new name for panpsychism. We were offered nine choices.

  1. Stick with panpsychism: "Panpsychism is either the view that all parts of matter involve mind, or the more holistic view that the whole universe is an organism that possesses a mind …"
  2. Hylozoism is the philosophical conjecture that all or some material things possess life, or that all life is inseparable from matter.
  3. Animism is the belief in souls, which may, depending on your religious preference, be present in animals, plants, and objects, as well as in people.
  4. Panexperientialism credits all entities with phenomenal consciousness but not necessarily with cognition.
  5. Panprotoexperientialism is a weaker form of panexperientialism, crediting entities only with latent consciousness.
  6. Quantum Animism attributes spirit, mind, or mentality only to quantum-realm particles.
  7. Vitalism invokes a non-physical "élan vital" or "life spark."
  8. Neo-Psychism: a new term we might coin to detach ourselves from traditional panpsychism and its connotations.
  9. Neo-Animism (on the same principle).

I think "hylozoism" is the prettiest of these possibilities (and surprisingly old — it was coined in 1678 by Ralph Cudworth), but I voted to keep "panpsychism."


•  Thursday, April 10

Thursday was a half day here at the "Toward a Science of Consciousness" conference. We had four plenary sessions in the morning, then most of the participants went off on a trip in the afternoon. I went back to the hotel to nurse my cold and catch up on reading.

The morning lectures were all neuroscience: good meaty material from folk who spend their working days in labs, twiddling controls, peering at dials, running graphing and stats programs, that sort of thing. First up was Bernard Baars of the San Diego Neuroscience Institute on "Is Consciousness Local or Global?" What this means is: Is the faculty of conscious awareness located at some particular point(s) of the brain, or smeared across the whole structure? His answer: Both. This takes some understanding, especially if you haven't, as Baars has (he is a big name in his field) spent thirty years up to your elbows in this stuff. The key phrase here is "Global Workspace Theory," roughly speaking a theory about how processing of sensory data can trigger conscious activity, which may fire off chains of unconscious activity, which may in turn fire back more conscious processes, and so on. The experimental key is to compare the conscious with the unconscious processes. Baars brought it nicely together with some "theater of consciousness" analogies, the "bright spot on stage" being the focus of conscious attention, while stage hands move around behind the scenes, bells go off in dressing rooms, and the audience laughs or yawns.

Then Nao Tsuchiya from Caltech described some experiments on monkey perception. Nao has some very well-designed experiments from which he can deduce what his monkeys are seeing from the firing patterns of as few as eight individual neurons across 0.1 seconds. Interesting stuff, though I didn't quite get the connection to reflective consciousness.

Then the Simpson's Neuron. Neurobiologist Rafael Malach of the Weizmann Institute talked about why a particular neuron responds to certain particular stimuli but not others. His show-stopper was a screen on which he flashed brief, random video clips in quick succession with, along the bottom, a synchronous trace of the activity in one particular neuron belonging to a subject watching the stream of clips. The neuron was pretty much idle until a cip of The Simpsons came on, when it went into a rapid burst of firing. The Simpsons neuron! There was a follow-up of the subject's voice, in a later interview, being asked to recall as many of the video clips as she could. Again, not much activity in the neuron till she mentioned The Simpsons, then YA-DA-DA-DA- … Neat stuff. I guess I'm missing the Simpson's neuron — never could sit through that show.

[I note in passing that I have never been to an academic math/science conference that didn't include at least one major address from one of the big Israeli research institutes. Nor have I ever been to a conference that did include an address from anywhere in the Muslim Middle East. Just mentioning it.]

Finally a long and deep address by Wolf Singer of the Frankfurt Institute of Advanced Study, concentrating on the global aspect of consciousness and its correlates in the waves of electrical activity that surge back and forth through the brain when it's conscious. That's a gross oversimplification, but these are really deep experimental and theoretical waters. Singer is another superstar in the field, gave a well-organized lecture and zapped right back at all the follow-up questions afterwards. Only problem for me was that his steady, monotone delivery in good but heavily-accented Dr. Strangelove English had a hypnotic effect on me, so that several times I found myself … losing consciousness. Well, I guess this is the right place to lose it. Someone's sure to find it and return it to you.

I took time off from reading and cold-nursing in the afternoon to drive down to Nogales (it's about an hour from Tucson) to take a look at the Mexican border. Was surprised at the density of Border Patrol vehicles and agents — they're everywhere. Coming back on Route 82, I passed through a BP roadblock about ten miles from the border, agents checking every vehicle. On the other hand, the border fence itself — it goes right through the town, with houses on both sides only a dirt-track-width away from it — is unimpressive. Some pretty simple equipment would get you and a dozen compadres over the thing in a jiffy, if the BP weren't around. Nogales otherwise a dull place, with an extraordinarily high proportion of seriously overweight citizens. Residents, whatever.


•  Friday, April 11

Friday was a stellar day here at Consciousness Central. I can only offer some scattered highlights.

The first round of plenary sessions, from 8:30am to 10:40, were heavy on philosophy and experimental psychology, all under the heading "First-Person Methodologies and the Richness of Consciousness." The second half of that translates as: "Just how much are we consciously aware of?" The first half tackles the question: "How can we get reliable reports from people about their private mental states?" Without such reports, it's hard to get a handle on the other question.

The "richness" point is a very contentious one, in fact two very contentious ones:

  1. "Rich" vs. "thin":  Are we consciously aware of a lot of things all the time ("rich")? Or are we only sporadically conscious, with most of our mental life composed of what Virginia Woolf called "cotton wool" — vague impressions and reflections instantly forgotten ("thin")? This is a historic divide among writers about consciousness, with e.g. William James arguing that consciousness is "rich," while Julian Jaynes, Daniel Dennett, and John Searle see it as "thin." Philosopher Eric Schwitzgebel of U. Cal. argued this one.
  2. "Rich" vs. "poor":  This comes at the issue from a different angle, asking:  Are the contents of experience "poor," in the sense of being only immediate sense impressions, with second-order judgments about things like causation generated by upstream neural events, or do we perceive the whole package in a "rich" way? Philosopher Susanna Siegel of Harvard argued this for us, bringing in Hume and Kant on causation. (She thinks Hume was wrong — that there is an "impression of causation," and cited some experimental evidence. In Philosophy of Mind, even philosophers get to do experiments!)

Psychologist Chris Heavey (Univ. Nevada) told us about his methodology for getting at the facts of the matter. He gives his subjects beepers which go off at random intervals through the day. Subjects report exactly what they were conscious of just before the beep.

Then some really heavy-duty speculations on quantum neurobiology from Gestav Bernroider of the University of Salzburg and Stuart Hameroff of this very place, the University of Arizona. (Stuart is the main organizer of this conference.) This was very thrilling, especially Stuart's presentation.


Stuart worked up a plausible model of the brain as a quantum computer, with the tubulin protein molecules of those neuron microtubules as the qubits — "Schrödinger's protein". There's a slight drawback here: Far as we know, quantum computing can only work at temperatures near absolute zero, i.e. 590 degrees Fahrenheit colder than a working brain. Stuart phrased this objection as: "The brain is too warm and wet for delicate quantum-mechanical effects." He suggested some possible work-arounds.

He wound up with a brilliant pyrotechnic display taking in quantum mechanics, spacetime geometry, Penrose's Road to Reality, Libet's results (quantum collapse propagating backwards in time), and a neutral-monist flavor of panpsychism, consciousness being a process embedded in fundamental spacetime architecture, "units" of reality collapsing quantumly as either matter or, in the highly particular circumstances of brain function, as mind. Phew!

On to some experimental brain science with Adrian Owen of Cambridge, UK on what may really be going on in "persistent vegetative states" (some awareness and speech comprehension, in at least a few cases); and Daniel Langleben on using brain scans for lie detection. Mind reading is just over the horizon, folk, though you'll need a bulky, expensive piece of equipment to do it. Langleben gets D.o.D. grants, he told us … a bit hopeful at this point, since the other thing you need is a co-operative subject.

In the evening electives, I opted for a 5-speaker session on the evolution of consciousness. At what point in evolution did consciousness show up? How might we find out? Did it first show up as late as the Bronze Age? Were Homer's Greeks actually zombies, as Julian Jaynes suggested? Their self-descriptions of their own mental lives do seem to be different from ours. (E.g. not "He'd made up his mind to do it, so he up and did it," but "A god appeared and told him to do it, so he did it.") Alex Gamma of the University of Zürich gave some useful reminders about the clumsy, non-optimizing, non-parsimonious, Rube Goldberg way that evolution actually works, putting the kibosh on arguments like: "If consciousness had no function, evolution wouldn't have come up with it." These are useful points, that even biologists sometimes need reminding of. Not every trait is an adaptation. In fact, as Alex reminded us, not every trait is a trait!

The last speaker of this evening session was Carl Johan Calleman. I think Stuart must have included him for light relief. It was a relief, too, after a day of really good, nutritious lectures.

[I got in the last question of the day. Calleman had played with a lot of numerological flapdoodle about sequences of thirteen, based on seven-day/six-night cycles in the Mayan calendar. I drew his attention to the fact that the U.S. flag has thirteen stripes, seven red and six white. "Surely this is not a coincidence," I teased. Calleman took it perfectly seriously — pseudoscience has no sense of humor — and patiently explained the links between Mayan cosmology and the founding of our Republic. I expected Nicholas Cage to walk in at any minute.]


•  Saturday, April 12

Saturday's topics were ESP, altered states, and the development of consciousness.

"Consciousness Studies" has a problem with its boundaries. If you're trying to get a science of consciousness going, what do you leave out? There has been some good rigorous stuff here at the Tucson conference: brain imaging, neuroscience, experimental psychology of a pretty traditional sort, solid philosophy. Obviously, though, a topic like this is going to attract some New Ageism, magic-mushroom types, and the sort of people whose claims get lengthily debunked in Skeptic magazine. How many of them should you let in?

The organizers seem to have taken a fairly generous line, giving time to a few oddities like the Mayan calendar guy I wrote about last time. I think that's reasonable in a conference titled "Toward a Science of Consciousness." I just hope the organizers know that once you let the cranks get a foot in the door, it can be hard to get rid of them.

So here we were Saturday morning with biologist Rupert Sheldrake of Cambridge University, probably best known for his book Dogs That Know When Their Owners Are Coming Home. Dr. Sheldrake came to us with a limp, and delivered his address from a chair, having been stabbed in the thigh by a lunatic at a different consciousness conference earlier in the week. The incident didn't seem to have affected his good humor, and he gave us a witty presentation on the dog business, "telephone telepathy," and the awareness some of us seem to have that we are being stared at from behind, even though we can't see the starer. ("Telephone telepathy":  you find yourself unexpectedly thinking about someone when suddenly the phone rings, and it's the person you were thinking about. For the younger telepath, Dr. Sheldrake has extended his inquiries into "email telepathy" and, yes, "texting telepathy.") Sheldrake has done some experiments, and showed us his results in summary.


I confess I can't be much bothered with this kind of thing. ESP investigations have been going on for over a century, some of them very elaborate and well-funded, like those of J.B. Rhine, whom I mentioned a couple of days ago. Yet nothing ever seems to come of it, and whenever any really interesting result shows up, it always evaporates on careful inspection, as Rhine's did. Heavyweight intellectuals, like Arthur Koestler in the 1970s, sometimes lend their support, but the sheer lack of good reproducible results, or of any coherent, testable hypotheses, keeps ESP out on the fringe.

So as entertaining as Sheldrake's presentation was, I got more from the three following speakers, who all debunked him to various degrees. Dick Bierman of the University of Amsterdam had repeated some of Sheldrake's experiments, with deeply unimpressive results. John Allen of this university (Arizona) threw more cold water, noting that to explain these odd anecdotal events by ESP is "conclusion by exclusion," a statistically very weak procedure. Steven Barker of this same university was especially effective, demolishing Sheldrake's being-stared-at "results" with a neat bit of Bayesian analysis.

Mind you, though, it is funny the way dogs know when we're coming home …

The second of today's three sessions was on "Psychedelics and Consciousness." The main presentation was zoologist Thomas Ray of the University of Oklahoma, taking us deep into neurochemistry. The key words here are receptors, which are protein molecules on the surface of nerve cells, and the neurotransmitters that go with them. A lot of these little devils affect consciousness. Did you know, for example, that those antihistamines you take for hay fever "may inhibit one's ability to form gut feelings about people"? Or that one way to lose your religious faith is to get Parkinson's disease, because dopamine, the thing Parkinson's sufferers don't have enough of, enhances religious sensitivity?

Ray claims to have found what he calls a "meta-receptor," modulating the effect of other receptors. His meta-receptor turns joy into ecstasy, anger into paranoia, ordinary religious enthusiasm into the conviction that you are the Messiah. He hasn't published yet, though, so he wouldn't tell us much more about it.

The other presentation on this thread was a New Agey thing from a fellow calling himself a practitioner of "transpersonal psychotherapy." Uh-huh. His chief enthusiasm is something called Ayahuasca, "a shamanistic psychedelic brew." I made a bet with myself that we'd hear something about the Dalai Lama before the end of the lecture. Sure enough, there he was, in a video clip with the lecturer. You can't avoid Tibet these days, it seems.

The wind-up session was three talks on the development of consciousness in babies, infants, and adolescents. This was all very down-to-earth, and a relief after shamanistic brews and the Dalai Lama.

The best of the three lectures was Alison Gopnik of Berkeley on "What's it like to be a baby?" I should explain here that Consciousness Studies folk are very big on "What's it like …?" inquiries. There was a very famous 1974 paper in the field titled What Is It Like To Be A Bat?. However, these lectures were real dev-psych research, with brain scans, beepers, questionnaires and all, not mere philosophical ruminating.

Well, what is it like to be a baby? Something like being in a foreign country, where everything is new to you: a flood of sensations, making it difficult to fix your attention on any particular thing. Babies are good at exogenous, "bottom up" attention, but not much good at the endogenous, "top down" variety. The "bottom" here is raw sensory input; the "top" is the executive self, the "I." Babies don't have much of an "I." Sample quotes from the very quotable Ms. Gopnik:

We ended up with Sarah Akhter of the University of Nevada telling us about adolescent consciousness. She'd done one of those beeper studies to probe the inner lives of adolescents. I tell you, these researchers know no fear. Her most alarming results were from an adolescent girl who, from her self-reporting, seemed to have no inner life at all. I know that girl.

I learned a new word here: "alexothymia," the inability to describe feelings in words. Academic conferences are great for your vocabulary. I picked up some lovely words here at Tucson, though I think "alexothymia" is my favorite. Runner-up: "anosognosia".

All in all an excellent conference, with a good broad variety of topics and some great speakers. There's an "End of consciousness" party this evening (Saturday), but I have to miss it as my plane leaves in the wee hours. My thanks to the University of Arizona for organizing this great event, and to Stuart and Abi for letting me sign up.


•  Follow-up; posted Monday, April 14

Couple of follow-ups on my bloggings about the consciousness conference. These are just taking the two biggest categories of reader-response emails.

(1)  Dogs that know when their owners are coming home.

You can say anything you like about political or cultural issues and reader-land barely stirs. Mention dogs, though, and the emails pour in. This says something about human nature — something good, in my opinion.

As skeptical as I am about Sheldrake and his findings, give the guy credit for some attention to scientific rigor. "It's just that dogs have really acute hearing," said several readers. Do you really think that a guy who's written an entire book about the phenomenon hasn't thought of that?

In fact Sheldrake's presentation included a split-screen movie showing (a) dog at home and (b) owner several miles away in the town having lunch with a friend. At a random time, the owner decided to go home. She said goodbye to friend and got on an ordinary town bus. At precisely that moment the dog, several miles away, got up and went to the window, to sit there waiting.

Now that's striking. It might of course be faked — bigger hoaxes than that have been perpetrated in the name of scientific inquiry, and one wants to see other researchers replicate Sheldrake's results — but it at least shows that Sheldrake knows that to be credible at all, he has to meet the kinds of objections that naturally come first to mind, like the ones my readers have raised. If he didn't know that, he wouldn't be worth our attention, even as a possible faker.

(2)  What about the soul?

As I said, the conference organizers cast their net wide, and there were a couple of elective sessions (i.e. in the evenings, when several sessions go on at once and you have to decide which one to attend) on religious topics. I didn't attend them, just because there was in each case something more interesting to me that I wanted to listen to.

Speaking in general, though, the "consciousness studies" approach to these things is neo-Jamesian. I mean that by analogy with "neo-Darwinian," i.e. that modern Consciousness Studies inquirers do what James did:

… then apply methods of scientific comparison, classification, and analysis. In addition — this is the "neo-" — they use techniques not, or not very much, available to James:

Where does any of that get you with the soul? Not very far. Of course, if you take the weakest possible meaning of the word "soul" ("soul" = "consciousness" = "inner self" = "I"), then that is what they are studying. In common usage, though, "soul" means more than that: something like "the consciousness, or inner self, which can be in contact with some supernatural agent external to itself."

To clarify the issue, take a subject's report that "I feel a pain." If our subject has put his hand on a hot stove, then what happened was:

Might C, D, and E have occurred without there being any natural (visible, audible, tactile, measurable) agent, in this case the stove, being present as a precipitating cause? Certainly, as shown by the well-known phenomenon of pains felt by amputees in "phantom limbs." The nervous system can generate its own Cs, Ds, and Es without any As or Bs being present at all.

Now replace "I feel a pain" with "I am having a religious experience" or one of its equivalents ("I feel God within me," etc.) Might this be a purely internal occurrence — a C, D, and E, with no causal A and B? It might be. Might it, alternatively, be a full A-B-C-D-E sequence? Sure it might: only then, since an outside observer watching someone having a religious experience can see, hear, touch, etc. no natural cause, we'd have to say that the agent is supernatural.

But see, we just stepped outside the domain of science, which is a systematic enquiry into natural phenomena. The religious experience itself (D) and its neural correlates (C), being events in the natural world, are legitimate subjects for scientific enquiry. The originating cause though — the A, the "stove" — is not, since it is supernatural … if it exists: which, as the "phantom limb" phenomenon shows, may not necessarily be the case. Science has, and can have, nothing to say about it, though individual scientists, as free citizens, may offer opinions about whether supernatural agents actually do exist. Those would be metaphysical opinions, though, not facts about the natural world, which is what science trades in.

The fascination of Consciousness Studies is the causal relation between C and D, the so-called "hard problem" of consciousness. My inner subjective experiences are part of the natural world; so are the electrochemical processes of my brain. The two are plainly connected somehow, but how? That's why people go to conferences with titles like "Toward a Science of Consciousness." Well, that's why I went.