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Inverted Spectra I have made the case for actual shifted spectra. Now I will argue that inverted spectra are possible and perhaps actual. Let us start with a questionbegging description of the scenario. The point of so doing is to highlight the contrast with another description which is not, I will argue, question-begging. See Figure 1. We start at Stage 1 with you at your 18th birthday, at which time you are a normal perceiver. You call red things ‘red’ and red things look red to you. In need of funds, you agree to undergo an experimental color inversion in which a chip is inserted in your optic nerve which changes signals from red things into the signals that would have been produced by green things, and so on for other colors.24 I have been calling this “crossing the wires in the visual system”.92 / Ned Block Figure 1. Question–begging Inverted spectrum scenario. The captions express the way things look to the subject at each stage in terms of the existence of ways of looking, R and G. R is the way the red tomato looks to the subject at Stage 1. G is the way the red tomato looks to the subject at Stages 2, 3 and 4. If we were relaxed about what counted as a visual “input”, we could imagine instead virtual reality goggles that do this trick without any surgery (as mentioned earlier). The operation is a success: at Stage 2, you are disposed to call red things ‘green’ and they look green to you, and so on: you see colored things as having the complementaries of their actual colors. You become famous to the point where you feel that the paparazzi are ruining your life. You change your name and your appearance withcosmetic surgery and move to another state, trying to blend in. At first, you have to fight your tendency to call red things ‘green’ and your tendency to stop at green lights, to suppose that red tomatoes are unripe and so forth, but after some years have passed, you naturally and spontaneously react to colors in the normal way. You unthinkingly call stop-lights ‘red’ and stop at them. Even though you unthinkingly call stop-lights ‘red’, at first you think of them as looking green, but your desire to put the operation and its unpleasant sequelae into the past leads you to work to think of stop-lights as looking red.Wittgenstein and Qualia / 93 You want to be normal and find it tiresome to be reminded of the operation you had at age 18. By the time you are 30, you spontaneously think of blood as not only being red but also looking red. How do we know that the colors have not reinverted so that the way things look is the same at Stage 1? According to the story—which I am claiming is a genuine possibility—you remember very clearly what things used to look like before the operation, and if asked by close relations in private, you say that everything used to look the complementary color of the way it looks now. At Stage 3, you are 50, and you haven’t thought about your operation in many years. Someone who recognizes you despite the cosmetic surgery says to you “Aren’t you the person who underwent the experimental spectrum inversion?” You say “Oh yes, I haven’t thought about that in many years. But I do clearly recall the look of the ripe tomatoes at my 18th birthday party. They looked to me then the way grass looks to me now, colorwise.” If asked to paint a picture of the way things look to you today, you paint the grass green and the sky blue. If asked to paint a picture of the way things looked to you before the operation thirty-two years earlier, you paint the grass red and the sky yellow (Taylor, 1966). Another 10 years pass, during which time no one asks you about the operation and during which time you don’t think of the days before 18 or any of the times someone has questioned you about the inversion. At age 60, you develop amnesia for the period up to age 50 (cf. (Putnam, 1981)). Now, and this is Stage 4, you have no memories for the period before your operation, nor do you have any memories for episodes of remembering that period. However, according to the story, the way red things look to you at Stage 4 is the way green things looked to you at Stage 1. If this is to be an argument against functionalism, Stage 1 and Stage 4 have to be functionally equivalent.25 However, if the purpose of the argument is to demonstrate qualia—and that is my main purpose here—the differences could be more substantial. For example, perhaps at Stage 4, red is no more exciting than green. The way in which this argument is question-begging is summarized in Figure 1. The subject at Stage 3 says “I do recall the look of the ripe tomatoes at my 18th birthday party. They looked to me then the way grass looks to me now, colorwise.” But what are these ways and why should we countenance them? And if these suspicious ways are coming in at Stage 3, presumably they must have been involved at the outset, in the argument at Stage 1. The relevant bones of the argument diagrammed in Figure 1 amounts to this: Stage 1: There is a way red things look to the subject, R. Stage 2: The way red things look to the subject is now G. Stage 3: The way red things look to the subject remains G. Stage 4: The way red things look to the subject remains G, even though the function of G is similar to (but not necessarily exactly the same as) the function of R in Stage 1. The subject at Stage 4 is a normal perceiver.94 / Ned Block The question-begging aspect is the postulation and naming of the ways things look, even at Stage 1. However, ways need not be brought in at the outset. It may seem that in saying that red things look red, I have sneaked in something illicit maybe something amounting to ways, for we would not ordinarily say that red things look red. Isn’t that “language going on holiday”? Actually, Wittgenstein is committed to red things looking red at Stage 1 in my view as I will now argue. Consider Stage 2: red things look green. If our subject, the person who has undergone something “peculiar” is asked how he sees red things, he says he sees them as green. (In Wittgenstein’s version, he says “I see everything red blue today and vice versa.”) But now if asked how the way he sees things now contrasts with the way he saw things yesterday, it is perfectly natural for him to say. “I see everything red as green today, but yesterday I saw everything red as red.” So we are justified in saying that at Stage 1, he sees red things as red. Imagine the subject talking to his doctor where it is better to err on the side of overexplicitness. The doctor is wondering whether there might have been something wrong with the patient even at Stage 1. To be absolutely clear, the patient says that red things look green today but yesterday red things looked red. And that justifies the descriptions given below in Figure 2 of Stage 1 and Stage 2. And once we have gone this far, it is difficult to see how to avoid the descriptions I have given of Stage 3 and 4. If red things look green at Stage 2, then they still look green at Stages 3 and 4. Here is a summary of the essential aspects of the argument. Stage 1: Red things look red. Stage 2: Red things look green. Stage 3: Red things still look green. Stage 4: Red things still look green even though the subject calls them ‘red’ and is in other respects a normal perceiver. However, there is a problem with the descriptions in Figure 2. At Stage 4, the subject is, I claim, a normal perceiver again. If so, it is false to say that red things look green to him—that would violate the Principle of Normality which says that normal perceivers in normal conditions perceive veridically. And that leads to a further variant of the argument, one that moves back part way to the version given in Figure 1. In this, the final variant, ways are introduced at Stage 4. The idea is that at Stage 4, the subject, who is now a normal perceiver, perceives veridically. White (1986) has suggested that the functionalist should say that once the amnesia hits, the subject’s experience instantaneously reinverts. Am I saying something similar? Do red things suddenly look red as soon as the subject gets amnesia? No. For an abnormal subject as in Stages 2 and 3, color terms have to be used relative to normality. At Stage 2, the obvious relativity is to Stage 1, just a day earlier, when the subject was normal. But at Stage 3, there is some indeterminacyWittgenstein and Qualia / 95 Figure 2. Version of the inverted spectrum scenario that is not question-begging but which violates the Principle of Normality. The same events as described in Figure 1, but described without explicit mention of the ways things look or of ‘R’ and ‘G’. The focus is on the colors that things look to have. about how color terms should be used—relative to the normal Stages 1 or 4. Since red things look red at Stages 1 and 4 and since there has been an inversion in between, the most plausible way to accommodate the inversion is in terms of ways. Perhaps ways could be introduced at Stage 3 as well, but in any case Stages 1 and 2 canbedescribed without recourse to ways, so the argument cannot be described as begging the question. The ways at Stage 4 are a conclusion, not a premise. That, in brief, is the argument. In the next section I will elaborate some of the premises.96 / Ned Block Figure 3. Version of the inverted spectrum scenario in which ways are introduced at Stage 4. 10. Premises in the Inversion Argument for Qualia I have given a way of conceiving of spectrum inversion, but conceiving spectrum inversion does not show that spectrum inversion is possible. It would be agreed by all—even those like Chalmers (2002) who argue that conceivability of the right sort entails possibility—that it is not a straightforward matter to move from conceivability to possibility. (Gendler & Hawthorne, 2002; Hill, 1991; Stoljar, 2006). My view is that the most significant reasons for thinking that spectrum inversion is not possible are all reasons that involve the asymmetrical nature of the color solid and thus allege that inversion would have to beWittgenstein and Qualia / 97 behaviorally detectable. But since I am not appealing to a behavioral indetectable inversion, these arguments do not apply here. David Cole(1990) appeals to experiments using goggles that invert the retinal image, claiming that these subjects adapt in the sense of experiencing a reinversion of experience. A recent study (Linden, Kallenbach, Heinecke, Singer, & Goebel, 1999) suggests previous reports greatly overplayed the extent to which behavioral adaptation to the goggles involve a reinversion of experience. Cole mentions other experiments which I think are irrelevant to the spectrum inversion case but I do not have the space here to discuss. (See also Hurley, 1998.)26 I said the subject at Stage 4 is normal. But he has undergone an operation in which the wires in his visual system were “crossed”. And what could be more abnormal than that? But wait! “Crossed” is a metaphor. The visual system of the subject at Stage 4 is different from that subject at Stage 1 as a result of an operation, but why suppose it is Stage 4 that is abnormal rather than Stage 1? An operation can—and often does if successful—restore normality. A hernia is stitched up, a tumor removed, a heart repaired—all cases in which the “after” is more normal than the “before”. If we were to discover that all the rest of us were born with the physiological formation of the visual system that obtains in Stage 4 and that it is Stage 1 that is “peculiar”, we would regard Stage 1 as “crossed”. If we were to find out that our subject at Stage 1 was born with an unusual visual system, we would naturally take the view that the operation “uncrossed” the wires in his visual system, making his visual system normal again. This way of talking makes it look as if the “crossed” visual system must be abnormal, but that is a mistake. For what would we say if half the population has a visual system like Stage 1 and half like Stage 4? Then we should say that both are normal, that there are two different varieties of normal visual systems. And in that case, both Stage 1 and Stage 4 are normal. The operation has succeeded in changing one normal visual system into another normal visual system. If Stage 1 and 4 are both normal—and possible—there are qualia, since neither our subject at Stage 1 nor our subject at Stage 4 can claim that he uniquely, sees red things as red and green things as green. I think the fact that “crossed” visual systems are normal can be shown by example. The example I have in mind was first advanced by Martine NidaR¨ umelin for a somewhat different purpose, as I will now explain. (See (Byrne, 2006; Byrne & Hilbert, 2003; Nida-R¨ umelin, 1996).) The three kinds of cones in the retina feed to three “opponent-process channels”, as discovered in the 19th Century by Hering, on the basis of purely behavioral data. The red/green channel operates as follows: If the activation of the R cones is greater than that of the G cones, the red/green channel is excited and the subject sees red (if the other channels are in approximate equilibrium). If the activation of the G cones is greater than the R cones, the red/green channel is inhibited and the subject sees green if the other channels are in approximate equilibrium. The three types of cones send both excitatory and inhibitory signals to three kinds of cells in98 / Ned Block the structure that is the basis of the next stage of processing beyond the retina (known as the lateral geniculate nucleus). These cells are called “color opponent cells” for obvious reasons. Oneformofcolor blindness occurs when the subject has a genetic defect that substitutes the photo-pigment in the G cones, chlorolabe, for the photo-pigment in the R cones, erythrolabe. With the photo-pigments in the two kinds of cones the same—both chlorolabe—the subject is red/green color blind. It can also happen that another genetic defect substitutes the photo-pigment in the R cones for the photo-pigment in the G cones. In this case, they are both erythrolabe. (See Byrne and Hilbert, 2003.) Again, with the photo-pigments in the two cones the same, the subject is red/green color blind. If the two genetic defects occur at once, the subject has the usual G photo-pigment in the R cones and the usual R photo-pigment in the G cones, resulting in normal discrimination. This case— known as pseudo-normal color vision—can be predicted to occur in 14 of 10,000 males, but as far as I know, no such case has ever been noticed. Apparently, the color vision of these people is sufficiently normal so that they do not consult an eye doctor about abnormal color vision. If the eyes and optic nerves from a pseudo-normal were switched with yours (assuming you are not pseudo-normal), the effect would be—as far as we know— that the red/green opponent cells would be activated in the opposite manner from those in your retina. Red things would look green and green things would look red. The point is that the pseudo-normal is a living example of crossed wires in the visual system.27 What we do not know is whether the development and history of visual experiences of the pseudo-normal yields something different from the imagined transplant. That is, what is controversial is how hard-wired the connection is between the cones and the color-opponent cells and between the color-opponent cells and the rest of the visual system in the brain. If those connections are hard-wired, then we can expect that in pseudo-normals, the red/green channel would be inhibited in input situations in which it is excited in normals and excited when it is inhibited in normals. Then these subjects are red/green inverted withrespect to normals suchas you and me. (Byrne & Hilbert, 2003, p. 19) give 3 arguments against Nida R¨ umelin. “First, even if pseudo-normal vision actually occurs, its frequency will be very low …; thus the possibility of pseudo-normal vision does not show that spectrum inversion might be widespread. Second, there is in any case no reason to suppose that pseudo-normal genes would preserve normal visual pathways: the opponent channels might be switched as well, in which case pseudo-normal subjects would not be red-green spectrally inverted. Third, there is evidence that for the M- and L-cones the development of the retinal circuitry for the red-green opponent channel is insensitive to which pigment the cone contains. In other words, pseudo-normal subjects would just be normal subjects.” The first point is irrelevant to the issue considered here, where normality rather than frequency is what is in question. On the second point: I think it would be rational to accept even odds on the experiential inversion of the pseudo-normal subjects and thatWittgenstein and Qualia / 99 is enough for the claim that inversion may be actual and at any rate is possible so far as we know. The third point seems to me to count in the opposite direction of what Byrne and Hilbert say. If the development of the visual system did react differently depending on whether the pigment was erythrolabe or chlorolabe, then that would count against the possibility that the cones are hard-wired into the opponent-process channels. The force of the pseudo-normal configuration depends on pigment-insensitive connections between cones and channels. Nida-R¨ umelin and others (Block, 1999; Nida-R¨ umelin, 1996, 1999a, 1999b; Ross, 1999) have used this case in an argument for the possibility of intersubjective inversion. I agree withthat argument, but I am using pseudo-normals for a less controversial purpose: as an example of crossed wires in the visual system, and crossed wires that are normal. It is a case of crossed wires because if a pseudo-normal’s eyes were switched with yours, you (and the pseudo-normal) would experience color inversion as in Wittgenstein’s original case of the person who wakes up one morning finding that red things look green and conversely. Pseudo-normals who live with their eyes from birth (and before) might not be inverted with respect to the majority, but if their eyes are switched with yours, the effect will be to stimulate the R-G channel in the opposite from normal way. So pseudo-normals have crossed wires. But are they normal? How can that be when pseudo-normal color vision is the combination of two genetic defects. Chlorolabe and erythrolabe must be more or less equally suited to the two kinds of cones as attested by the fact that none of the more than 4 million pseudonormals in the world have come to light—as far as I have been able to determine. A pseudo-normal person can equally say that normals are the result of two genetic defects: the cases are symmetrical. Pseudo-normals are less frequent, but I hope no one will take that to be decisive. If pseudo-normals were the more numerous, no doubt they would be in control of the terminology. The example of pseudo-normals shows I think that intersubjective inversion may be actual and is for all we know possible. But that is not my main point in introducing it. Recall that we are discussing intrasubjective inversion and the issue at hand is whether the visual apparatus of Stage 4 should be regarded as abnormal solely on the ground of difference from Stage 1. I offer the case of pseudo-normals as normal visual systems that differ in a way that could be like the difference that I am hypothesizing exists between Stages 1 and 4, namely “crossed”. The argument for qualia is supposed to be mainly based on the possibility of an intrasubjective inverted spectrum. I did detour through the pseudo-normals as an example of intersubjective inversion but also as an example of a kind of “crossed” visual system that is normal. And the argument can make do with the latter. I talked about others who have visual systems like that in Stage 1 and others who have visual systems like that in Stage 4, but without appealing to intersubjective inverted spectrum. The point is that there is no reason why bothvisual systems cannot be normal and so no reason why our intra-subjective inversion subject has to be abnormal at either the beginning or end of the process.100 / Ned Block Sydney Shoemaker and Daniel Taylor (Shoemaker, 1975; Shoemaker, 1982, 1996a; Taylor, 1966) have argued from the possibility of intrasubjective inversion to the possibility of intersubjective inversion. They argue that if Fred undergoes intrasubjective spectrum inversion, then the color experience of others must be radically different from Fred’s either before his inversion or after it (or both). My argument is different since my argument does not appeal essentially to intersubjective inversion. An opponent of the Shoemaker-Taylor intra/inter argument28 might acknowledge that crossed wires in the visual system makes for color inversion in the intra-subjective case—as is shown by the testimony of subjects who undergo the procedure—while resisting the claim as applied to the intersubjective case. The idea would be that congenital differences of that sort between different groups of normal perceivers are just alternative realizations of the same phenomenology of experience. I think that this refusal to accept intersubjective inversion can be defeated on its own terms, but that is not my main purpose here. Objection: “Although the result of the operation is a normal visual system, our subject at Stage 4 is abnormal because of the operation which produced it.” Notso, because an operation need not produce anything abnormal. An operation can correct an abnormal defect, yielding normality. “But the process leading to Stage 4 includes both the operation and the adaptation, and doesn’t that make Stage 4 abnormal?” No: adaptation to an operation is often an essential part of the normalizing process. For example, there is a congenital “heart inversion” condition called transposition of the great arteries in which the outputs from the ventricles are reversed. In the normal heart, the pulmonary artery rises from the right ventricle, taking deoxygenated “blue” blood to the lungs (which is then returned to the left side of the heart via pulmonary veins), whereas the aorta rises from the left ventricle pumping “red” blood to oxygenate the body. In the heart inversion condition, the aorta rises from the right ventricle, pumping “blue” blood to the body, whereas the pulmonary artery arises from the left ventricle, circulating “red” blood unnecessarily to the lungs. The effect is that the left ventricle does very little work, quickly losing muscle mass as a result. If an arterial switchoperation is done too late (more than about a month after birth), the left ventricle will fail and the child will die, but if the operation is done early enough, the left ventricle can build up mass after the operation via the process of making new heart cells, an ability that the heart loses. The point is that the operation does not immediately restore normality. First, there is a period of adaptation in which the left ventricle regains the lost cells. But the need for a period of adaptation after the arterial switch operation does not make the child’s heart forever abnormal.29