Wavelength and Color

We are told that wavelength determines color. But what does “determine” mean here? It is not in doubt that the wavelength of incoming light causes the perception of a specific color, though we should note that it only does so in conjunction with non-trivial facts about the perceiver’s eyes and nervous system. This is compatible with allowing that other types of stimulus could causally determine color vision: for example, the wavelength of sound waves might conceivably cause colors to be seen, or indeed a knock on the head. The causal relation is quite contingent and extrinsic with respect to the nature of color. What we know is that wavelengths are causally correlated with the perception of particular colors, but this is a far cry from supposing that they constitute what colors are. Kicks to the shins are causally correlated with bruises of various hues, but no one would suppose that bruises are kicks.

            Is there any closer relation? It might be supposed that an identity theory is possible: that way we would have a nice materialist account of what color properties are. It is worth being very clear about what this would mean, which requires us to be explicit about what wavelength is. According to the wave theory of light, light has a wavelike structure analogous to the waves you can see in the ocean: waves have both frequency (how many cycles reach a certain point in space per unit of time) measured in Hertz units, and they have length (the distance between successive crests or troughs) measured in meters. Wavelengths are very short for light waves and hence are measured in nanometers. The visible spectrum (between 400 and 700 nanometers) is just one part of the much wider electromagnetic spectrum.  Thus the identity claim is that a given color can be identified with waves of light with a specific distance between incoming peaks—this being nothing other than the phenomenon you can observe on many a beach (though involving a light medium not a water medium).  So the contention is that colors have a wavelike structure, travel through space, and have specific distances between their wave crests: red, say, is shaped like a wave, traverses space, and has a certain wavelength (longer than other colors). These are attributes of light, so by Leibniz’s law they must be attributes of color, if colors are identical to light waves. That is the nature of the color red, its true character, its inner essence: to be red is to have a particular wavelength, i.e. a certain distance between successive crests.

            But is this the way red looks? If you stand on a beach and look out to sea, you will see waves rolling into shore, and these waves will look to have a specific wavelength, generally of several meters: the shape and height of the waves is apparent to you and the distance between them is also apparent. These waves look precisely like the waves they are. But do colors look like waves? Evidently not: when you look at a red apple you don’t have an impression of waves of light approaching your eyes—you don’t see anything wavelike at all. You don’t see crests and troughs, or wave heights and the distances that separate them. The phenomenology of seeing colors does not include any perceiving of wavelike structure—you don’t, say, see red as having a longer wavelength than blue. Why not if colors just are wavelengths of light? You might say these waves are too small to see, that’s why you don’t see them—but they are still what visible color actually is. But if red were made of much bigger waves would we see them when we looked at a red object? Would red look like the waves it is if the waves were big enough to see? Clearly not: it would presumably look something like colorless ocean waves.  And if we looked through a microscope and could see our actual light waves, would we still be seeing red? No, the redness would disappear, to be replaced by magnified waves of light. So colors don’t appear to be wavelengths, as we ordinarily perceive colors—yet we are seeing some sort of property. The property we see cannot then be the property of being a wave with a specific wavelength.  [1] Some philosophers will respond by saying that these color appearances are actually appearances of light waves with their corresponding wavelengths, with no further property interposed between them and the perceiver. But this is a bad theory of perception: we clearly do perceive color properties when we see colored objects–we see things as red, blue, green, etc. But the property that we see can’t be identified with a wavelength property, because it looks nothing like a wavelength property. At the very least we would need to be given an explanation for why colors don’t look the way they intrinsically are, according to the identity theory; but no such explanation is forthcoming. So the phenomenological unreality of the alleged wavelike nature of color is a count against the theory that colors are identical with such properties.  [2] And it isn’t as if the way colors look gives us a hint of their real wavelike nature: there is nothing wavelike about the way color looks to us. If anything, colors look non-wavelike. We could, of course, go eliminative about colors, claiming that colors don’t really exist as properties, though light waves do—then there would be nothing that is not covered by the physics of color. But if we insist instead that colors are real and also reducible to wavelengths, then we have to face the question of why they don’t seem that way. On the face of it, the identity theory of color is refuted by the appearances. To be sure, wavelengths trigger the perception of color properties—they are the external cause of color perception—but they are not what color properties are. These properties are ontologically separate, a distinct realm of existence.

            There isn’t even a supervenience relation here, since the same wavelengths could correlate with distinct colors in different possible worlds, depending on the eyes that respond to these wavelengths. The correlation in the actual world is just that—a contingent correlation. Waves in the ocean often correlate with gleaming peaks and a crashing sound, but it would be quite wrong to think that there is some necessary connection here; a trip to a nearby possible world would quickly disabuse you of that misconception (in that world ocean waves form only at night and merely murmur). We must not mistake correlation for identity. The relationship between wavelengths and colors is an external contingent relationship not a relationship of identity or constitution. The reason colors don’t look like waves of light, equipped with frequency and wavelength, is that this is not what they are. The same can be said of heard sounds and sound waves in the atmosphere: pitches don’t sound like waves with frequency and wavelength because they are not such waves. We can hear waves in the ocean and gauge their frequency and wavelength, but nothing analogous is true of heard sounds themselves—they are not phenomenologically wavelike. Sound waves cause sound perceptions, certainly, but the sounds heard are not identical to sound waves in the atmosphere: one doesn’t hear middle C as a particular spatial separation of wave crests. Sensible qualities like these are not reducible to wave patterns in a physical medium.

  [1] A further point: if colors are identical to wavelength formations, which are invisible to the human eye, how come we can distinguish colors from each other? How can we tell that red is not the same as blue if we can’t see the wavelength difference that constitutes the difference of color? The obvious answer is that the property we see when we see red is not the same as the property of having a certain wavelength but is a property that is entirely visible to the human eye.

  [2] We may note, too, that wavelength is a continuous quantitative property, being simply distance between two points, but colors vary qualitatively and are discontinuous: red is not simply “longer” than blue. So wavelength is unable to capture the way the visible spectrum is divided up. There ought to be just one color, varying along a single dimension, if colors were definable in terms of wavelength.

I have been writing songs lately, so I thought I’d share this one with you: think of it as sung in Country and Western style. 

The Ballad of Dolores Haze

He broke my heart

But you broke my life

He was a creature of art

You were a monster equipped with a knife

A pentapod monster, I’d agree with that

His pen and photography were never so bad

I loved him so, I don’t know why

It’s not as if he was much of a guy

You killed my mother

So you could get to me

He saved me from another

Who would never let me be

Clare Quilty was his name

He was impotent, or so he claimed

You were anything but

But I’d rather be trapped in a desolate hut

No, I never vibrated to your touch

How could I when I hated it so much?

You loved me, you say

You’d take me far away

But I’d rather stay in this town of hicks

With my ironically named Dick

Than hitch myself to your terrible beam

And live again in that despicable dream

You broke my life, you see

And that’s not nothing, that’s all of me

Oh, you are hurting, I can tell

And I do pity you in your self-made hell

Goodbye honey, please dry your tears

They’re nothing compared to my childhood years

And the motels and the cars

And the bars and the barmen and the cold gray stars

Stereotypes

Wittgenstein warned against the “craving for generality”: the mistaken desire to find uniformity where there is only diversity. Thus philosophers are apt to suppose that all words are names, all sentences are assertions, and all states of mind are experiential—despite a heterogeneity that is evident to unbiased inspection. In a word, they overgeneralize, often based on preconceived ideas. Hence his admonition: “Don’t think, look!” Evidently this is a natural tendency of the human mind, which we need to resist. At roughly the same time Nabokov was inveighing against what he called “generalities”, particularly on the part of historians. He begins his 1926 essay “On Generalities” with these words: “There is a very tempting and very harmful demon: the demon of generalizations. He captivates human thought by marking every phenomenon with a little label, and carefully placing it next to another, also meticulously wrapped and numbered phenomenon.”  He goes on to excoriate historians for indulging in the tendency to find spurious similarities, thus erecting oversimplified “epochs”, “ages”, and “periods”. Walter Lippmann in his 1922 book Public Opinion first introduced the word “stereotype” in its modern sense (before that it was used in the printing industry), i.e. as connoting a tendency towards social overgeneralization and simplistic grouping. Here again the fault lies in not looking, observing and recording, but instead relying on overly simple and homogenizing ideas. Thus, according to these three thinkers, we find people mistakenly supposing (a) that all words are names, (b) that all authors of a certain period are to be classified as (say) Romantics, and (c) that all people of a certain culture or ethnic group have such and such characteristics. In each case we have what we would now call stereotypical thinking; and the problem with it is that it is false and can be very harmful. Yet people keep on doing it: they keep on ignoring the facts, the details, and the individualities, preferring instead the meritless generalization, the lazy grouping, and the prejudiced espousal of alleged commonalities. In some cases this is clearly deplorable, contemptible, and just plain stupid; but human beings seem intent on indulging their craving for generality no matter the cost. It is as if they have a demented love of identity.

            I emphasize the pervasiveness of the phenomenon because social stereotyping is not some isolated and unique failing: it is built into the fabric of human cognition (which is not say it is incurable). It is entirely possible to stereotype animals, fictional genres, popular music, athletes, professors, and even rocks. Overgeneralization and preconceived ideas are the stuff of weak minds. Today there is a tendency to stereotype certain individuals as “powerful white males” and then run away with all sorts of misguided and erroneous ideas about this supposed class. Philosophers and other academics are not immune to this, shameful though it may be.  [1] Often it is done in order to advance a certain political agenda, but it is also just plain lazy thinking and good old-fashioned stupidity. It needs to be identified for what it is and condemned in the strongest terms. Stereotyping is never an acceptable way to think (sic). No doubt it has its biological origins in a need to economize on time—to make thinking more efficient. Fine, but not at the cost of accuracy and justice: because stereotyping people is a vicious and idiotic habit. It needs to be stamped out (is jail time too much to ask?). Children need to be educated strenuously in its fatuity and danger. It has to go.

            Under what circumstances does stereotyping take hold? I think it’s when people feel overwhelmed by the sheer diversity of the world (of course, there can also be emotional reasons, meme transmission, indoctrination, imitation, and the like). If the world is perceived as intolerably complex, people will want to simplify it and make it more manageable: it’s easier to think that every word is a name, every writer from a certain period belongs to a certain “school”, and that every person of a certain appearance is thus-and-so (generally a negative thus-and-so). This is no doubt understandable, but it is not commendable, or even forgivable. In a society like America, which has a very diverse population, the urge to oversimplify and classify is particularly strong: it’s just easier to try to subsume everyone under certain crisply defined categories. The task of education should be to combat this cognitive weakness. This is a type of therapy (as Wittgenstein recommended therapy for the disease of philosophical overgeneralization): people need to be cured of their stereotyping, as if it were a disease. In fact, it really is a type of mental disease—just an exceptionally common one (like the common cold). The first step here is to get a proper sense of its pathological character, its demonic morphology, its onset and progression. A stigma needs to be firmly attached to it. As it is stereotyping gets reinforced and solidified, but it needs to be exposed and ridiculed. But don’t count on academic philosophers to do any of this good work; they seem as prone to it as anyone else, sad to say. It really is a problem, despite its obvious malignity.  [2]

  [1] In fact academics are professionally prone to it, because they make a living erecting generalizations, producing taxonomies, and promoting theories; they would feel thwarted if restricted to reporting the facts. Recalcitrant facts are the enemy of the ambitious theoretician.

  [2] This is generally recognized, though people seem oddly blind to it in themselves (they just have betterstereotypes). I am attempting here to describe it succinctly and clearly so that its malign presence can more readily be eradicated.

How Things Really Look

I wish to defend the legitimacy of a metaphysical concept that I have not seen discussed before: the concept of what might be called objective appearance. We are familiar with the concept of subjective appearance—the ways things appear to specific organisms with specific sensory faculties. These vary from case to case and may involve distortions, errors, and biases; perceptual illusions fall into the class of subjective appearances. Appearances in this sense are supposed to contrast with objective reality: there is only one objective reality, but there are many ways it can subjectively appear to organisms. Some appearances can be wildly inaccurate; others close to fully veridical. The same physical stimulus can elicit widely divergent types of appearance in different creatures, e.g. bats and humans. There is thus a question as to whether appearance matches reality: does reality appear to us as it really is or only as our contingent sensibility paints it (to use Hume’s metaphor)? This can be a matter of degree: appearances can approximate more or less closely to objective reality. It makes sense to say that one appearance is more veridical than another. But does it make sense to speak of how things objectively appear, i.e. how they appear when perceived as they objectively are? Is there such a thing as ideal appearance—the kind that gets things exactly right? We might picture God as enjoying such appearances: when things appear to God’s mind they appear exactly as they objectively are without any distortion, error, or specific viewpoint. His is a view from nowhere: things appear to God purely in their objective nature. When God sees an object it appears to him as it really is in itself sans any sensory specificity. Thus we arrive at the idea of how things really look: there is the way things look to imperfect terrestrial organisms such as ourselves and the way they look to a being that sees things as they objectively are. We can ask what difference there might be between how things actually look and the way they really look (say to a being like God—though we can drop this heuristic). The way an object really looks is the way it looks to a being that sees it purely as it objectively is—the way it looks in its own being, as it were.

            This is a commonsense idea, at least in its origins. If you see something in the dark you can ask what it looks like when properly illuminated. If you see someone in heavy makeup you can wonder what he or she really looks like without makeup. If you are subject to the Muller-Lyer illusion you can form the idea of what the lines would look like to someone not subject to that illusion (whether or not such a being exists). This is the concept of an ideal perceiver, analogous to the concept of an ideal observer in ethics: an ideal perceiver sees things according to how they really look not how they happen to look in particular circumstances. So there are subjective appearances of the kind ordinary perceivers experience and there are appearances of the kind that an ideal perceiver would experience. It is true that things really look a certain way to given perceivers even when the appearance is subjective, but there is also the notion of how things look to perceivers that see them as they really are.      [1] There is how something looks to me now and there is how it really looks when we exclude all subjective intrusions. This gives rise to philosophical questions such as: “How would the world look if it were seen as it really is?” That is, how would an idealized perceiver experience the world? Would such a perceiver see the world as colored, as Euclidian, as containing discrete objects? How would an ideal perceiver see space? How would such a perceiver see the physical world as described by Einstein? How would the quantum world look? How does the world really look when all subjectivity is subtracted leaving only the naked object? We even have questions like, “What would people look like if we could see into their souls, a la Dorian Grey?” That is, we have the idea of how things would look if we could see them just as they are in themselves. Maybe we never have such experiences, but we can conceive of them—we can apply our concept of vision in such a way as to allow for their possibility. We can conceive, that is, of objective visual appearances: how things would look if the mask were removed, so to speak.      [2]

            We can even ask this kind of question about colors: what does red really look like when you remove its specific appearance to humans? Maybe it looks the way it looks when the perceiver has taken LSD—brighter, deeper, sharper, and more resonant. We ordinarily see colors through our limited visual system (rods and cones, the optic nerve, the occipital cortex), but maybe other perceivers would see them differently, more accurately. An ideal perceiver of color confronted with our perception of color might assure us that there is a lot more to red than we think given our limited perspective on it. This would be the analogue of a dog telling us that there is a lot more to the scent of freshly mown grass than we suppose. The way things really smell far exceeds our contingent olfactory resources, as the way red really looks transcends our impoverished sense of sight. Similarly, the way the world of physical objects really looks is far removed from the way it looks to us, given the truth of relativity and quantum theory. If you could see the world as it really is, you might see far more dimensions to space—that’s what the world really looks like if you have the sense to see it right. There is the way pond water looks to the human eye and there is the way it really looks when you have eyes that can see the microorganisms swimming in it. If there were people with eyes this acute, they would assure us that the way we see things is not the way they really look—any more than actors on a movie screen really look the way they do when so presented.

            The metaphysical point of all this is that we need to replace the appearance- reality distinction with a threefold distinction between subjective appearance, objective appearance, and reality. Subjective appearances are not the only kind; we need the category of objective appearances, whether there are any such items in actual reality or not. But we also need to distinguish objective appearances from reality itself: although objective appearances represent nothing but reality, they are not the same thing as reality. Objects and their properties are never the same as conscious representations of them: here as elsewhere we need to respect the act-object distinction. So we need a robust division between these three items; total reality has a place for all three, none reducible to the others. Centrally, we need to acknowledge a double level of appearance—actual and ideal, subjective and objective, relative and absolute. This bears on the question of idealism: is reality to be identified with subjective appearance or objective appearance? In effect, Berkeley’s idealism is of the latter kind, since reality for him consists in ideas in the mind of God, which are not to be regarded as in any way biased, erroneous, limited, or subjectively tinged. Or it might be maintained that reality consists in a realm of ideal appearances in the mind of no actual conscious being but existing as potentialities (a kind of Platonic idealism). Reality, according to this conception of idealism, isn’t a motley collection of all the subjective appearances enjoyed by actual biological creatures but a far more streamlined and unified set of ideal appearances. We might call this “ideal idealism” or “objective idealism”. It certainly has advantages over the subjective type of idealism, which is wide open to charges of excessive plurality or stipulated favoritism. In any case, we have a new metaphysical option once we accept the category of objective appearances. We also have a new imaginative option: we can try to imagine how the world  would appear if it appeared as it is really constituted. We already do this, to some extent, but we could adopt it as an intellectual project: don’t just tell us how things really are; tell us how they would look if we could see them as they really are. We could call this “real phenomenology”: the phenomenology of reality as such—how reality would present itself to an ideal consciousness. This is the study of objective appearance: not a form of empirical psychology but a philosophical study of a certain ideal subject matter. It is an investigation of how things really look—rarified, no doubt, difficult, certainly, but not outside the realm of possibility.      [3] I would like to read a work of physical phenomenology that describes what electrons look like, or fields of force, or curved space-time: that is, what their objective appearance consists in under idealized conditions. This would enable me to link these things with the world I normally perceive—or explain what kind of alien sense perception would be necessary to perceive them. Think of it as a kind of conceptual empiricism: finding a link between reality and sense perception—though this is not empiricism of the classical type. Some enterprising theorist might even try to resurrect the empiricist view of concepts by proposing that concepts are equivalent to ideal sensory appearances not actual ones. Like possible worlds, objective appearances give us new theoretical entities to play with, opening up new theoretical options. We might even manage to elicit some of those “incredulous stares” of which David Lewis was so fond (I prefer to call them “stupefied frowns”). Do we dare to quantify over these entities? Sure, go right ahead and quantify over them, there’s no harm in that, quantification being a enjoyable diversion; but more seriously we should suppose that reality contains not just objective things and their subjective appearances to sentient beings but also objective appearances that are written into the very nature of things. Reality itself consists of how things are and how things (ideally) look. Even before perceiving beings came along things looked a certain way—ideally, objectively. Eyes just picked up on that fact. Reality can’t avoid appearing a certain way, even if there is no one to appear to. If that sounds paradoxical, consider the fact that square things have a square-like appearance no matter how, or whether, actual perceivers perceive them. That is just how the concept of appearance works.      [4]

      [1] Color blindness provides a good example: we say that the color blind fail to see things as they really appear, since they really appear to have colors. Of course, compared to other perceivers normal human color vision might be similarly limited with respect to how things really appear. We might not be sensitive to the full appearance of things (obviously that is true of the reality of things).

      [2] When things look blurry that is not part of how things really look, since things in themselves are not (generally) blurry, this being a feature of a specific sensory apparatus. Objective appearances would not be blurry appearances.

      [3] I don’t rule out the possibility that we can’t know what certain things look like, even though they do look a certain way; we might be imaginatively limited in this regard. Still, we can make a concerted effort to come to know how things look to ideal perceivers.

      [4] I am well aware that this is an especially thorny area, conceptually speaking. We need to recognize and then hang onto certain basic distinctions, and fight against the propensity of language to confuse and bamboozle us. The concept of appearance is by no means simple and straightforward.