I Am a Strange Loop

by Douglas R. Hofstadter

  To put this in perspective, consider the criteria that we effortlessly apply (I first wrote “unconsciously”, but then I thought that that was a strange word choice, in these circumstances!) when we watch the antics of the humanoid robots R2-D2 and C-3PO in Star Wars. When one of them acts fearful and tries to flee in what strike us as appropriate circumstances, are we not justified in applying the adjective “frightened”? Or would we need to have obtained some kind of word-usage permit in advance, granted only when the universe that forms the backdrop to the actions in question is a universe imbued with élan mental? And how is this “scientific” fact about a universe to be determined?

  If viewers of a space-adventure movie were “scientifically” informed at the movie’s start that the saga to follow takes place in a universe completely unlike ours — namely, in a universe without a drop of élan mental — would they then watch with utter indifference as some cute-looking robot, rather like R2-D2 or C-3PO (take your pick), got hacked into little tiny pieces by a larger robot? Would parents tell their sobbing children, “Hush now, don’t you bawl! That silly robot wasn’t alive! The makers of the movie told us at the start that the universe where it lived doesn’t have creatures with feelings! Not one!” What’s the difference between being alive and living? And more importantly, what merits being sobbed over?

  Quibbling in Universe Q

  At chapter’s end, we are thus brought back full circle to the “pedantic semantic” pronoun issues with which we began. Should we use different pronouns to refer to Universe Q’s Dave Chalmers (which is clearly a “he”) and to its indistinguishable zombie twin in Universe Z (who is just as clearly an “it”)? Of course such semantic quibbles aren’t limited to humans and their zombie twins. If a mosquito in our universe — our warm and fuzzy Universe Q overflowing with élan mental — is unquestionably a swattable “it”, then what about a turkey? And if a turkey is unquestionably just a Thanksgiving dinner, then what about a chinchilla? And if a chinchilla is just a fur coat, then what about a bunny and a cat and a dog? And then what about a human fetus? And what about a newborn baby? Where lies the “who” / “which” cutoff line?

  As I said at the chapter’s outset, I see these as important questions — questions that in the end have everything to do with matters of life and death. They may not be easy to answer, but they are important to ponder. Semantics is not always just pedantic quibbling.

  CHAPTER 23

  Killing a Couple of Sacred Cows

  A Cerulean Sardine

  THERE’S an idea in the philosophical literature on consciousness that makes me sea-blue, and that is the so-called “problem of the inverted spectrum”. After describing this sacred cow as accurately I can, I shall try to slaughter it as quickly as I can. (It suffers from mad sacred cow disease.)

  It all comes from the idea that you are supposedly so different from me that there is no way to cross the gap between our interiorities — no way for you to know what I am like inside, or vice versa. In particular, when you look at a bunch of red roses and I look at the same bunch of red roses, we both externalize what we are seeing by making roughly the same noise (“red roses”), but maybe, for all you know, what I am experiencing as redness inside my private, inaccessible cranium is what you, if only you could “step inside” my subjectivity for a moment or two, would actually call “blue”. (By the way, advocates of the inverted-spectrum riddle would spurn any suggestion that you and I actually are already inside each other, even the littlest bit. Their riddle is predicated upon the existence of an Unbridgeable You–Me Chasm — that is, the absolute inaccessibility by one person of any other person’s interiority. In other words, belief in the inverted spectrum is a close cousin to belief in Cartesian Egos — the idea that we are all disjoint islands and that “you can’t get there from here”.)

  Bleu Blanc Rouge = Red, White, and Blue

  Let’s consider this idea. Maybe, just maybe, when all fifty million French people look at blood and declare that its color is “rouge”, they are actually experiencing an inner sensation of blueness; in other words, blood looks to them just the way melted blueberry ice cream looks to Americans. And when they gaze up at a beautiful cloudless summer sky and voice the word “bleu”, they are actually having the visual experience of melted raspberry ice cream. Sacrebleu! There is a systematic deception being pulled on them, and simultaneously a systematic linguistic coverup is going on, preventing anyone, including themselves, from ever knowing it.

  We’d be convinced of this reversal if only we could get inside their skulls and experience colors in their uniquely bleu-blanc-rouge way, but alas, we’ll never do that. Nor will they ever see colors in our red-white-and-blue way. And by the way, it’s not the case that some wires have been crossed inside those French skulls — their brains look no different from ours, on every scale, from neurotransmitters to neurons to visual cortex. It’s not something fixable by rewiring, or by any other physical operation. It’s just a question of, well, ineffable feelings. And what’s worse is that although it’s true, nobody will ever know that it’s true, since nobody can ever flit from one interiority to another — we’re all trapped inside our own cranium.

  Now this scenario sounds downright silly, doesn’t it? How could it ever come about that the fifty million people living inside the rather arbitrary frontiers of a certain hexagonally shaped country would all mistakenly take redness for blueness and blueness for redness (though never revealing it linguistically, since they had all been taught to call that blue sensation “red” and that red sensation “blue”)?

  Even the most diehard of inverted-spectrum proponents would find this scenario preposterous. And yet it’s just the same as the standard inverted spectrum; it’s simply been promoted to the level of entire cultures, which makes it sound as it should sound — like a naïve fairy tale.

  Inverting the Sonic Spectrum

  Let’s explore the inverted spectrum a little further by twisting some other knobs. What if all the chirpy high notes on the piano (we do agree they are chirpy, dear reader, don’t we?) sounded very deep and low to, say, Diana Krall (though she always called them “high”), and all the deep low notes sounded chirpy and high to her (though she always called them “low”)? This, too, would be the “inverted spectrum” problem, merely involving a sonic spectrum instead of the visual one. Now this scenario strikes me as much less plausible than the original one involving colors, and I hope strikes you that way, too. But why would there be any fundamental difference between an auditory inverted spectrum and a visual one?

  Well, it’s pretty clear that as musical notes sink lower and lower, the individual vibrations constituting them grow more and more perceptible. If you strike the leftmost key on a piano, you will feel very rapid pulsations at the same time as you (sort of) sense what pitch it is. Such a note is so low that we reach the boundary line between hearing it as a unitary pitch and hearing it — or rather, feeling it — as a rapid sequence of individual oscillations. The low “note” floats somewhere between singularity and plurality, somewhere between being auditory and being tactile. And if we had a piano that had fifteen or twenty extra keys further to the left (some Bösendorfers have a handful, but this piano would go quite a ways further down than they do), the superlow notes would start to feel even more like vibrations of our skin and bones rather than like pitches of sound. Two neighboring keys, when struck, wouldn’t produce distinguishable tones, but just low, gruff rumbles that felt like long, low, claps of thunder or distant explosions, or perhaps cars passing by with subwoofers blasting out their amazing primordial shaking rather than a singable sequence of pitches.

  In general, low notes, as they sink ever lower, glide imperceptibly into bodily shakings as opposed to being pitches in a spectrum, whereas high notes, as they grow higher, do not do so. This establishes a simple and obvious objective difference between the two ends of the audible spectrum. For this reason, it is inconceivable that Diana Krall could have an inverted-spectrum experience �
�� that is, could experience what you or I would call a very high sound when the lowest piano note is struck. After all, there are no objective bodily shakings produced by a high note!

  Glebbing and Knurking

  Well, all right. If the idea of a sonic inverted spectrum is incoherent, then why should the visual inverted spectrum seem any more plausible? The two ends of the visible range of the electromagnetic spectrum are just as physically different from each other as are the two ends of the audible sonic spectrum. One end has light of lower frequencies, which makes certain pigments absorb it, while the other end has light of higher frequencies, which makes other pigments absorb it. Unlike rumbles, though, those cell-borne pigments are just intellectual abstractions to us, and this gives some philosophers the impression that our experiences of redness and blueness are totally disconnected from physics. The feeling of a color, they have concluded, is just some kind of personal invention, and two different people could “invent” it differently and never be the wiser for it.

  To spell this idea out a little more clearly, let’s posit that knurking and glebbing (two words I just concocted) are two vastly different sensations that any human brain can enjoy. All humans are created in the womb with these experiences as part of their built-in repertoire. You and I were born with knurking and glebbing as standard features, and ever since our cradle days, we’ve enjoyed these two sensations countless thousands of times. In some folks, though, it’s red light that makes them knurk and blue that makes them gleb, while in others it’s the reverse. When you were tiny, one of the colors red and blue happened to trigger knurking more often, while the other one triggered glebbing more often. By age five or so, this initial tendency had settled in for good. No science could predict which way it would go, nor tell which way it wound up — but it happened anyway. And thus you and I, dear reader, may have wound up on opposite sides of the gleb/knurk fence — but who knows? Who could ever know?

  I must stress that, in the inverted-spectrum scenario, the association of red light (or blue light) with knurking is not any kind of postnatal wiring pattern that gets launched in a baby’s brain and reinforced as it grows. In fact, although I stated above that to knurk and to gleb are experiences that all babies’ brains come innately equipped with, they are not distinguishable brain processes. It’s not possible to determine, no matter how fancy are the brain-scanning gadgets that one has access to, whether my brain (or yours) is knurking or glebbing. In short, we are not talking about objectively observable or measurable facts about the brain.

  If objectively observable facts were all the inverted-spectrum riddle was about, it would be as easy as pie to tell the difference between ourselves and the fifty million French people whose inner sensations are all wrong! We would just examine their gray matter and pinpoint the telltale spot where certain key connections were flipped with respect to ours. Then we could watch their French brains engage in glebbing when the identical retinal stimulus would provoke knurking in our brains. But that’s not in the least the meaning of the inverted-spectrum idea. The meaning is that, despite having identical brain wirings, two people looking at the same object experience completely different color sensations.

  The Inverted Political Spectrum

  This hypothetical notion makes our inner experiences of the colors in the rainbow sound like a set of floating pre-existent pure abstractions that are not intimately (in fact, not at all) related to the physics outside our skull, or even to any physics inside it; rather, these inner experiences are arbitrarily mappable onto outside phenomena. As we grow up, the rainbow colors get mapped onto the spectrum of prefabricated feelings with which our brains all come equipped “from the factory”, but this mapping is not mediated by neural wiring; after all, neural wiring is observable from a detached third-person perspective, such as that of a neurosurgeon, so that rules it out.

  Let’s now ponder the implications of this notion of the independence of subjective feelings and external stimuli. Maybe, just to pick a random example, the abstraction of “liberty” feels to me like what the abstraction of “imprisonment” feels like to you — it’s just that we both use the same word “liberty” for it, and so we are deluded into thinking that it is the same experience for both of us. This sounds pretty unlikely, doesn’t it? After all, liberty is pleasant whereas imprisonment is unpleasant. But then again, who can say for sure? Maybe experiences that I feel are pleasurable are unpleasurable for you, and vice versa.

  Or maybe that churning feeling that I feel inside me when I run into right-wing flag-wavers and pro-lifers (those who dominated in the “red” states in the 2004 election) is identical to that churning feeling that you feel inside you when you encounter left-wing flag-burners and pro-choicers (those who dominated in the “blue” states in the 2004 election), and vice versa! This would be the inverted political spectrum! Are you getting a bit dizzy at this point? (Perhaps what you experience as dizziness I experience as clarity, and vice versa. But let’s not go there.)

  The philosophers who take the inverted visual spectrum with total seriousness would not take the inverted political spectrum in the least seriously. But why not? Presumably because they don’t think our brains come from the factory with prefabricated political “feelings” inside them, feelings that can be arbitrarily attached to right-wing or left-wing politics as we grow up. And yet they truly do think that we come with knurking and glebbing built in (although they don’t use my words).

  I once again wish to remind you that knurking is not an identifiable physical phenomenon in a brain (nor is glebbing). Knurking is that inherently incommunicable sensation that you supposedly have when red light (or blue light, if you’re French, reader) hits your eyes. French people have all the same internal physical events happen in their brains as we do, but they don’t have the same experiences as ours. French people experience glebbing when red light hits their retina, and knurking when blue light hits it. So just what is this knurking “experience”, then, if it isn’t anything physically identifiable in a brain?

  The inverted-spectrists say it is pure feeling. Since this distinction is completely independent of physics, it amounts to dualism (something we already knew, in effect, since belief in Cartesian Egos is a kind of dualism).

  Violets Are Red, Roses Are Blue

  Why is it that those who postulate the inverted spectrum always do so only for experiences that lie along a one-dimensional numerical scale? It seems like a great paucity of imagination to limit oneself to swapping red and blue. If you think it’s coherent to say to someone else, “Maybe your private inner experience of red is the same as my private inner experience of blue”, then why would it not be just as coherent to say, “Maybe your private inner experience of looking at a red rose is the same as my private inner experience of looking at a blue violet”?

  What is sacrosanct about the idea of shuffling colors inside a spectrum? Why not shuffle all sorts of experiences arbitrarily? Maybe your private inner experience of redness is the same as my private inner experience of hearing very low notes on a piano. Or maybe your private inner experience of going to a baseball game is the same as my private inner experience of going to a football game. Then again, maybe your private inner experience of going to a baseball game is the same as my private inner experience of going on a roller-coaster ride. Or maybe it’s the same as my private inner experience of wrapping Christmas presents.

  I hope that these sound ridiculously incoherent to you, and that you can move step by step backwards from these variations on the inverted-spectrum theme to the original inverted-spectrum riddle without losing the sense of ridiculousness. That would be most gratifying to me, because I see no fundamental difference between the original riddle and the patently silly caricatures of it just offered.

  A Scarlet Sardine

  The inverted-spectrum riddle depends on the idea that we are all born with a range of certain “pure experiences” that have no physical basis but that can get attached, as we grow, to certain external stimul
i, and thus specific experiences and specific stimuli get married and from then on they are intimately tied together for a lifetime. But these “pure experiences” are supposedly not physical states of the brain. They are, rather, subjective feelings that one simply “has”, without there being any physical explanation for them. Your brain state and mine could look as identical as anyone could ever imagine (using ultra-fine-grained brain-scanning devices), but whereas I would be feeling blueness, you would be feeling redness.

  The inverted-spectrum fairy tale is a feeble mixture of bravado and timidity. While it boldly denies the physical world’s relevance to what we feel inside, it meekly limits itself to a one-dimensional spectrum, and to the electromagnetic one, to boot. The sonic spectrum is too tied to objective physical events like shaking and vibrating for us to imagine it as being inverted, and if one tries to carry the idea beyond the realm of one-dimensional spectra, it becomes far too absurd to give any credence to.

  Yes, People Want Things

  There’s something else in the philosophical literature on consciousness that gives me the willies, and that is the so-called “problem of free will”. Let me describe this second sacred cow, and then try to dispatch it, too, as quickly as possible. (It, too, suffers from sacred mad cow disease.)

  When people decide to do something, they often say, “I did it of my own free will.” I think what they mean by this is usually, in essence, “I did it because I wanted to, not because someone else forced me to do it.” Although I am uncomfortable with the phrase “I did it of my own free will”, the paraphrase I’ve suggested sounds completely unobjectionable to me. We do indeed have wants, and our wants do indeed cause us to do things (at least to the extent that 641’s primeness can cause a domino in a domino chain to fall).