Color (Stanford Encyclopedia of Philosophy) Cite this entry Search the SEP • Advanced Search • Tools • RSS FeedTable of Contents• What's New• Archives• Projected ContentsEditorial Information• About the SEP• Editorial Board• How to Cite the SEP• Special CharactersSupport the SEPContact the SEP ©Metaphysics Research Lab,CSLI,Stanford University  Open access to the SEP is made possible by a world-wide funding initiative. Please Read How You Can Help Keep the Encyclopedia FreeColorFirst published Mon Dec 1, 1997; substantive revision Mon Sep 18, 2006Colors are of philosophical interest for two kinds of reason. One isthat colors comprise such a large and important portion of our social,personal and epistemological lives and so a philosophical account ofour concepts of color is highly desirable. The second reason is thattrying to fit colors into accounts of metaphysics, epistemology andscience leads to philosophical problems that are intriguing and hard toresolve. Not surprisingly, these two kinds of reasons are related. Thefact that colors are so significant in their own right, makes morepressing the philosophical problems of fitting them into more generalmetaphysical and epistemological frameworks. 1. The Philosophy of Color2. The Aim of Philosophical Theories of Color3. The Natural Concept of Color4. Science of Color or Color Science?5. A Unifying Framework for Colors6. The Illusion Theory of Colors7. Colors as Simple Intrinsic Objective Qualities8. Objectivism9. Objectivist and Subjectivist Accounts10. An Ecological View of Color11. A Pluralist Framework12. Colors as Phenomenal Qualities13. ConclusionBibliographyOther Internet ResourcesRelated Entries1. The Philosophy of ColorThe visual world, the world as we see it, is a world populated bycolored objects. Typically, we see the world as having a rich tapestryof colors or colored forms — fields, mountains, oceans,hairstyles, clothing, fruit, plants, animals, buildings, and soon. Colors are important in both identifying objects, i.e., inlocating them in space, and in re-identifying them. So much of ourperception of physical things involves our identifying objects bytheir appearance, and colors are typically essential to an object'sappearance, that any account of visual perception must contain someaccount of colors. Since visual perception is one of the mostimportant species of perception and hence of our acquisition ofknowledge of the physical world, and of our environment, including ourown bodies, a theory of color is doubly important.Despite much thought, over thousands of years, by philosophers andscientists, however, we seem little closer now to an agreed account ofcolor than we ever were. The disagreement is reflected in the factthat some theorists believe colors to be perceiver-relative, e.g.,dispositions or powers to induce experiences of a certain kind, or toappear in certain ways to observers of a certain kind. Others takethem to be objective, physical properties of objects. Among the lattergroup, some take these properties to be physical microstructures,while others regard colors as sui generis irreducible properties ofphysical bodies, and yet others take them to be dispositionalproperties to affect light. Finally, there are even some who deny thatthere are colors in the world at all: there are none of the colors, itis claimed, that we naturally and normally and unreflectinglyattribute to objects.The major problem with color has to do with fitting what we seem toknow about colors into what science, particularly physics, tells usabout physical bodies and their qualities. More specifically, weexperience color as an intrinsic feature of the surfaces of physicalbodies, or as a property spread throughout a volume, e.g., of wine.But, or so it seems, the physical account of these physical objectsfinds no place for such qualities. It is this problem thathistorically has led the major physicists who have thought aboutcolor, to hold a common view: that the colors we ordinarily andnaturally take objects to possess, are such that physical objects donot actually have them. Oceans and skies are not blue in the way thatwe naively think, nor are apples red, (nor green). Colors of thatkind, it is believed, have no place in the physical account of theworld that has developed from the 16th Century to thiscentury. Physicists who have subscribed to this doctrine include theluminaries: Galileo, Boyle, Descartes, Newton, Young, Maxwell andHelmholtz. In this doctrine, they were joined by a number of fellowtravelers, including most famously, John Locke.Such a view is clearly paradoxical, given what was said above, aboutthe ubiquity of colors in the perceived world, and about theimportance of colors in the identification and re-identification ofphysical objects. It is possible to mitigate the paradoxical characterof the doctrine by drawing a distinction between two concepts ofcolor: (i) color as a sensory, i.e., subjective, quality, intrinsic toour sensory experiences; (ii) color as a power, to induce sensoryexperiences with color, understood as a sensory quality. On thisaccount, color terms have a systematic ambiguity. Provided we takeaccount of the ambiguity, no harm is done, and much benefitderived. According to this view, then, in one sense of‘color’, physical objects have colors, for they have thepower to induce experiences of color, but in the other sense, they donot. That is to say, there is no problem if the second concept,color-as-it-is-in-experience, is restricted in its use so as to applyto the experiential quality. Problems arise, however, when it is used,naively and unreflectingly, to apply to physical bodies: we naivelysuppose the experiential quality to be an intrinsic quality of thephysical object. When we enjoy visual experiences, then in some sensewe project the sensory quality in our experience on to physicalobjects. One who exploited this idea to great effect was David Hume,who used our experience of color as a model for thinking about the waywe attribute causal connections, necessity and moral predicates toobjects and situations in the world (remembering that Hume adapted themodel to his own terminology of ‘impressions’ and‘ideas’).With this in mind, the Descartes-Locke position is best expressed asimplying that it is possible for perceivers when applying colorconcepts to physical bodies, to use different concepts, reflectingdifferent attitudes which one may adopt. One attitude is what might becalled a ‘natural’ attitude: a naive, pre-reflective,natural attitude; the other involves a more sophisticatedattitude. One concept is a pre-reflective, pre-theoretical concept,the other is more sophisticated. While the Descartes-Locke view hashad, and continues to have, a strong influence among many of thescientists who work on color, there has always been strong oppositionto it among the philosophical community.Various reasons have been given for dissatisfaction with thephysicists' position. It has been variously argued that: (i) thenotion of ‘color as it is in experience’ is incoherent;(ii) the physicists' doctrine encapsulates a confusion about what theordinary, natural concept of color is; (iii) those who defend thedoctrine forget that there are other sciences besides physics. Forexample, there are biological sciences such as zoology, botany,ecology, and so on, in which colors do have a role to play that theydo not have in physics and chemistry; (iv) those who defend thedoctrine forget that color has a social role to play; that colors areimportant in social life, and the criteria for application of colorpredicates are based on that social life; (v) the ordinary, naturalconcept of color, the ‘folk’ concept is not as thephysicists and their friends believe.This last criticism takes severaldifferent forms:according to the natural notion, colors are simple, objective,intrinsic qualities of objects, qualities whose natures are manifest inperception: John Campbell, P.M.S.Hacker;according to the natural notion, colors are unknown qualities ofphysical bodies, qualities which appear to us in distinctive ways:Thomas Reid, Frank Jackson, David Lewis, Brian McLaughlin.according to the natural notion, colors are dispositionalproperties, powers to appear in appropriate ways: Michael Dummett,Gareth Evans.The criticism of the physicists' position that their notion of‘color as it is in experience’ is confused is widely held.[See Westphal (1987), Hacker (1987) and Evans (1980)]. This criticismhas in turn been attacked on the ground that it is based onuncharitable interpretations of the texts, ones made without seriousattempt to make sense of the physicists' position. [See Maund (1991)and (1995) pp. 6-24; 30-33 ] The first of these formulations of the objection, we should note,opens the way for a modification of the physicists' position on color,as expressed by Descartes and Locke. It construes the natural/folkconcept of color in such a way that colors are taken to beperceiver-independent, intrinsic, qualitative features of physicalsurfaces, volumes and other physical entities such as skies, rainbowsand flames. This is the kind of color that our visual experiencesrepresent objects as having. The Descartes-Locke position can bereframed so as to adopt this formulation of the folk concept, and toargue that no instances of this concept are physically actualised.According to this way of thinking, Descartes and Locke were right thatgiven the natural (naive, pre-reflective) concept of color, we canconclude that, in this sense, objects do not have colors. Their way ofcharacterising the concept, however, is at fault. It should not bedescribed as ‘color as it is in experience’. There mayvery well be a coherent notion of‘color-as-it-is-in-experience’ or ‘color as asubjective quality’, but that notion is not the natural conceptof color. The natural concept is more plausibly construed as aconcept of a certain kind of property: it is a perceiver-independent,intrinsic, qualitative feature of physical surfaces (i.e. it is not adispositional property either to affect light or to appear toobservers). This re-formulation of the Descartes-Locke view may bedescribed as the Illusion theory of Colors.It is possible, moreover, to specify the natural concept in moredetail: to be red is to have a certain feature, one that satisfies arange of conditions. One such condition is that colors together form asystem of qualitative features, that resemble and differ from eachother in systematic ways. A second condition is that the color has acausal role to play in the visual identification or recognition of thecolor.Given that colors can be specified as properties of this kind, it isthen possible to argue that there are no actual properties thatsatisfy all the conditions set down. Accordingly, those in theLocke-Descartes-Helmholtz tradition who emphasize the need for adistinction between color-as-in-physical-objects andcolor-as-in-experience are best interpreted as thinking that there isno physical feature in physical objects that satisfies all therequirements (that serves all the required roles) of color, as it isnaturally conceived. This reconstruction of the Descartes-Lockepreserves the other element of that position, namely that the rightway to think of colors is as mind-dependent dispositionalproperties. This is the best way, it is claimed, to make sense ofcolors, taken to be properties of physical bodies.Clearly those in the Descartes-Locke tradition make two substantialclaims. One concerns the character of the ordinary, naive,pre-reflective concept of color; the other is a proposal, of what formour color concepts should take, for scientific and metaphysicalpurposes, i.e., if we want to think clearly and scientifically aboutcolors. The proposal is that color, thought of as a property thatphysical objects possess, should be thought of as dispositionalproperty: a power to induce experiences of color, in normalperceivers, in the right kind of circumstances. [This concept ofcolor, it should be noted, requires in addition, another concept ofcolor, color-as-it-is-in-experience.]There is a substantial body of opposition to this element in theDescartes-Locke tradition as well. For some thinkers, the onesreferred to above, the opposition is coupled with, and allows for, theordinary concept. For others, the question of what colors areessentially is decided on grounds separate from the question of howcolors are conceptualized, by ordinary perceivers.We can set out, in summary form, the set of leading rivaltheories:Colors are objective, intrinsic properties: they are sui generis,irreducible properties, supervenient on microstructural properties ofthe type cited in 2, below. [P.M.S. Hacker, J. Campbell]Colors are objective, intrinsic properties of physical bodies. Theyare to be identified with, or are reducible to, microstructuralproperties of the bodies that possess them. [T. Reid]Colors are objective properties of bodies but they aredispositional, light-related properties; dispositions to modify light(to emit, reflect, absorb, differentially reflect and absorb, transmitor scatter light), in the right way, and in the right proportion. [D.M.Armstrong, J. Westphal, D.R. Hilbert]Colors are dispositional properties: powers to induce in observersof a specifiable kind, physical responses of a kind that are peculiarto those observers.Colors are perceiver-dependent dispositional properties: powers toappear in distinctive ways, to normal perceivers, in contextualisedstandard conditions. [M. Dummett, G. Evans, J. McDowell]Colors are perceiver-dependent but hybrid properties: to have aspecific color is to have some intrinsic feature by virtue of which theobject has the power to appear in a distinctive way (e.g., as in 4).[R. Descartes, J. Locke]Colors are relational properties: they are physical properties,e.g., spectral reflectances, which are perceived in a distinctive way.[E. Thompson]Colors are objective, perceiver-independent properties: they arethe occupants of certain perceiver-dependent functional roles, e.g.roles defined in terms of the way objects look. [B. McLaughlin,J. Cohen, M. Tye, A. Byrne & D. Hilbert]Colors are socially or culturally constructed properties. To be redis for an object to satisfy such criteria that make it worthy of havingthe predicate "red" applied. [J. Van Brakel]2. The Aim of Philosophical Theories of ColorTo assess the rival claims about the status of color, we need toclarify what the aim of a philosophical theory of color should be.Philosophical discussions of color are sometimes framed in terms ofanswering such questions as "what is the nature of color?" "what iscolor essentially?" "what is the essence of color?". Sometimes, theyare framed in terms of answering the question of what kind ofunderstanding a person must have in order to understand color conceptsor to be able to use color terms with understanding. Here we are askinga question about color concepts and it will be important to clarifyfirst, whether the concepts in question are concepts are concepts ofnatural language, or technical concepts introduced for scientific orindustrial purposes, and then with respect to both, whether there aredifferent kinds of concepts. On the face of it, there are two different exercises here: identifyingthe nature of colors, i.e., what colors are essentially; andspecifying what the concept of color is. It seems that one exerciserequires looking at the world and the other looking at the thinkers.However both exercises would seem to be an integral part of anyphilosophical theory of color. For there appear to be two prominentfacts about colors that any theory would need to respect: (1) thatcolors are properties in the world (i.e., properties of physicalobjects), to which one's color vision is sensitive; (2) that colorsare qualities that perceptual experience represent (or presents)objects as having. At least, if any theory denies that these are factsabout colors, then an extremely good explanation is called for. Onetheory that comes close to denying that the first is a fact is theDescartes-Locke tradition. This theory is more subtle, however, thanthis would suggest. It draws a distinction between two concepts orsenses of color. In one sense objects do have colors but this is notthe sense in which objects are represented as having colors; while inthe other sense, objects are represented as having colors, but theseare not properties which objects actually have.There is a stronger reason for thinking that the two exercises mightbe related. This reason depends on the fact that there are differentavailable models for thinking about concepts. For certain kinds ofconcepts, the understanding required in order to possess the conceptof X provides the only answer to the question of what X's areessentially. (The nominal essence is the same as the real essence.)On the other hand, if externalists are right then the content of somemental states are broad. Hence, if concepts are constituents of thecontent then individuating these concepts will require identifyingsome object, property or natural kind. Accordingly, depending on whichmodel for color concepts we adopt, the two exercises (looking at theworld and looking at the thinkers) may be related.In any case, if those in the Descartes-Locke tradition are right indrawing distinctions between different concepts of color, then therewill be different answers to the question of what the essence of coloris, depending on which concept we have in mind. There are, within thistradition, two important distinctions. One is between color as aproperty of physical bodies and color as a quality in experience, i.ea phenomenal or subjective quality: color-as-it-is-in-experience. Inthe second place, if we concentrate on color conceived as a propertyof physical bodies, we can distinguish between a naive, pre-reflectiveconcept and a sophisticated, critical concept. For Descartes andLocke, the former concept is confused or at least has a faultyassumption built into it. Accordingly, the answer to the question ofwhat colors are essentially, will be "none" for the pre-reflectiveconcept and "a mind-dependent dispositional property" for the criticalconcept.Much of the opposition to the Descartes-Locke account consists inchallenging their characterization of the natural or folkconcept. Some philosophers, Dummett, Evans, McDowell, argue that thenatural concept is dispositional and does not need to be reconstructedin the way that Descartes and Locke suggest. A different form ofopposition is found among the many objectivists who claim that thenatural concept is objectivist. Opinion divides between those who holdthat colors have hidden essences, e.g., microstructural features suchas spectral reflectances, and those who hold that their essences aremanifest. Most modern objectivists believe not only that colors haveessences but that these essences have either been discovered byscientists, or are close to being discovered.It is possible, however, to take a different view: that the naturalconcept of color is objectivist, that is, that colors areconceptualized as objective, intrinsic features of physical bodiesbut, so it happens, there are no such features in nature. The essencesare virtual, not actual. On this account, colors are virtualproperties (have virtual essences) just as phlogiston and caloric arevirtual natural kinds. Given that color perceivers have experiences ofcolor, i.e., experiences which represent objects as having colors,this account implies an ‘illusion theory’ or ‘errortheory’ of color experience and perception. Objects areperceived as having colors which they do not in fact have: there areno such colors.However the dispute about the natural pre-reflective concept isresolved, we still need to answer the question of how we ought tothink of color. If Descartes and Locke are right, then the naturalconcept needs to be replaced by the critical concept. However, even ifthey are wrong and dispositionalists such as Dummett and Evans wereright about the natural concept, we might want to argue that theconcept should be either replaced by, or supplemented by, areconstructed, revised concept, in the way for example, that conceptsof heat, sound, force, and solidity have been refined or revised orsupplemented by scientific concepts.Caution is necessary, however. There appear to be two reasons whythere might be a need for a reconstructed concept of color. One couldbe that the natural concept needs to be eliminated. The other might bethat it needs to be supplemented by a new, technical concept. Eachreason is related to the fact that the natural concept serves a rangeof purposes. If it turns out that all, or nearly all, the majorpurposes are best served by a new revised concept then that would be acase for replacing the old concept. If only certain of the purposesare better served, then that constitutes a case for supplementing theold concept. Given that there is a natural concept of color which isemployed both in color vision and in the many social practicesconcerned with color, then it will be important to specify what thenatural concept is, in order to appreciate how if at all it needs tobe revised.It is crucial to remember, moreover, that in the case of color, almostall the purposes to do with colors and hence reasons for havingconcepts of color have to do with the perception of color. Colorsfunction predominantly as natural and conventional signs, i.e., forvarious practical epistemological and social purposes. To the extent,therefore, that the natural concept needs to be revised or replaced byany reconstructed concept, the new concept(s) would need to be capableof serving those various purposes. Accordingly an examination of whatthe natural concept is will be vital for the justification of anytheory about how colors should be conceived.3. The Natural Concept of ColorThe physicists' account of color, both in its original and in itsreconstructed version, depends on a certain view of the natural conceptof color. So too, in their differing ways, do the accounts of theirmost important critics. Getting clear about the natural concept ofcolor will thus be essential for resolving that philosophical debate.Quite apart from that, the natural concept is important to describe forits own sake. Getting clear about the natural concept of color isnecessary for a philosophical understanding of color. Discussions of what kind of property color can often be driven byepistemological and metaphysical concerns, which can cause us to losesight of what seem to be the plainest and most obvious truths aboutcolors. Two of the most obvious truths have already been cited: (1)that colors are properties in the world, (i.e., properties of physicalobjects) to which one's color vision is sensitive; (2) that colors arequalities that perceptual experience represent (or presents) objectsas having. There might be a theory according to which these are nottruths at all but only ‘truths’. Such a theory cannot beruled out, but to be acceptable it would need to explain why the‘truths’ have the force that they do as apparenttruths.There is another truth that is more often ignored: that colors playsignificant roles in the epistemological, personal and social lives ofhuman beings. Colors are important epistemologically, as natural signsor indicators for the identification and re-identification of physicalobjects. From a social point of view, colors serve a variety ofpurposes. While retaining their function as natural signs, they alsoserve as conventional signs, e.g., as badges, uniforms, in ceremony,ritual etc. They may also be said to have a ‘life of theirown’. As well as having emotional and aesthetic effects, colorsare used in social life to amuse, to entertain, to delight, to shock,to impress, to astound, to warn, to attract, to be enjoyed, and so on,in contexts having to do with pageantry, ceremonial, courtship,painting, lighting, plays, clothing, dining, drinking, and so on.Recognizing these obvious truths highlights the importance of thenatural concept of color, for it is the way in which colors play theirvarious roles that the natural concept is significant. In the firstplace, colors play their roles through the exercise of color vision,which in turn involves the exercise of color concepts. The perceivermust have perceptual experiences, or acquire perceptual states, whichhave a certain content. It is through such experiences that colorsserve as natural signs, i.e., for the identification andre-identification of objects. Some account needs to be given of whatconstitutes the content of these perceptual experiences or states,i.e., of what kind of property color is presented or represented asbeing.In the second place, there is a wealth of uses for color in ourcultural and social life, giving rise to a flourishing colorvocabulary. Examples of the sorts of practices are the use of colorlanguage, i.e., in the use of predicates such as ‘blue’,‘red’, ‘white’ etc.; the teaching and learningof color predicates, by the use of paradigm examples; the sorting andclassifying of objects; the placing of color samples in orderedstructured arrays, the use of colors to impress, delight, astound,court, entertain, and so on. Central among such practices are thoseinvolving the use of colors as both natural signs or indicators, andas conventional signs.If we concentrate on the use of color predicates such as‘red’, ‘blue’, ‘olive’ etc., innatural language, it is possible to specify what we might call the‘folk concept’ of color, one expressed by suchterms. There is some advantage, however, in using the term‘natural concept’ to emphasize that the folk concept isbuilt upon the use of a biological endowment, one that is exhibited inthe use of colors as natural signs, for the identification andre-identification of physical objects. Whatever it is called, it isclear that, if we wish to give an account of the epistemological,personal and social roles served by colors, then we need to give anaccount of the natural or folk concept of color, the concept which isembedded in the activities and practices that form the basis of suchroles.To specify the natural or folk concept of color, therefore, requiresstudying the variety of activities and practices, linguistic andnon-linguistic, in which colors play a role. To specify this conceptis a central task for any theory of colors to perform. Color is notjust a topic for scientific experts. The ordinary folk are expertstoo. They have expertise in recognizing colors, in sorting andclassifying them, in using colors and in responding to them. Colorexperts are not just those who study color in a scientific way, northose who paint in colors, nor those who are industrialchemists. There are, in other words, different ranges and levels ofexpertise. Those of us who are competent with colors know a lot: weknow what color blue is, how it differs from red and from yellow andgreen; we know how dark blue differs from light blue; we use termssuch as rich, pale, faded, intense, brilliant, bright, pure, mixed,and so on to convey and exploit what we know.Recognizing the expertise of the ‘folk’ should also makeus alert to the dangers of using the term "the folk concept" of color.The term ‘natural concept’ is much safer to use. For onething, ‘folk concept’ gets easily conflated with‘folk theory’, i.e., some doctrine that we in our naivemoments would articulate if asked, and if we had the time to reflecton. There are two things wrong with this slide. In the first place,the natural concept is a concept (or set of related concepts) not atheory (though its possession may presuppose certain beliefs). In thesecond place, by calling it a theory, it is easy is toover-intellectualize the concept. The concept is one embedded in avast set of conceptual practices, engaged in by color experts, thosewho are competent in the perception, recognition and use ofcolors. The knowledge is implicit as well as explicit, and it involvesknow-how besides.In providing an account of the natural/folk concept of color, thereare two sorts of description that we can provide: (i) a description ofthe way color is conceptualized, i.e., the kind of property color isconceptualized as being; (ii) a description of the kind of concept thenatural/folk concept is, i.e., a description of how the concept isacquired, how it is exercised, the purposes it serves, and so on. Inthis respect it is possible to describe the folk concept of color asfollows:color concepts are perceptual concepts;color terms such as ‘red’, ‘green’,‘blue’, etc are taught by the use of paradigmexamples;there is a distinctive color vocabulary the terms of which aretaught by paradigm examples.it is through the exercise of color concepts (through the waycolored objects appear), that colors fulfil their (practical)epistemological role: to serve as the signs for identification andre-identification of physical objects.it is through the exercise of color concepts (through the waycolored objects appear), that colors fulfil their social roles: toserve as conventional signsit is through the exercise of color concepts (through the waycolored objects appear), that colors fulfil their aesthetic andemotional roles.It is through the study of the activities and practices which involvethe acquisition and exercise of such concepts, that we can statecertain principles about the kind of properties colors areconceptualized as being. These principles are implicit or explicit inthe activities and practices. One such principle is that colors areperceptually salient, i.e are the sorts of properties that colorvision is sensitive to and which are presented or represented inperceptual experience. Other important principles are those having todo with fact that colors as a group form structured arrays, withcharacteristic internal structures.This last feature is perhaps the most significant feature aboutcolors, the colors objects are represented as having. Colors areproperties that as a group, form an internally-related 4+2 structure,built on the four unique, primary hues: green, red, blue and yellow,and related to the black/white pair. Colors can be placed insystematically ordered arrays, along three dimensions, e.g., hue,saturation, and brightness. There are different arrays according towhether the colors are surface colors, film(aperture) colors, volumecolors, light colors etc. Each array has a distinctive, complexcharacter: a fourfold structure, based upon four distinctive, uniquehues: green, red, blue and yellow. All colors can be mapped accordingto how near to or far from they are to any two of these unique,primary colors. Moreover, more than one such color system can beconstructed even for the one mode of appearance: the Oswald, Munselland Swedish Natural Color systems are examples. The last-named forexample, uses dimensions of hue, chromaticness andwhiteness/blackness, whereas the Munsell system uses hue, chroma andlightness. These dimensions are most suitable for surface colors,whereas hue, saturation and brightness are more appropriate foraperture colors.In short, we can state that, given the natural/folk concept of color,colors are the following kind of properties:Colors are perceptually salient: they are the sorts of properties that one discerns directly bylooking, that one recognizes the objects as having.they are qualities that are presented (or represented) in visualexperiences. Visual experiences characteristically are experiences ofcolors, and of shapes and other qualities of objects in a 3-dimensionalspace.they are properties causally connected with perception andidentification of specific objects as red, yellow, blue, and soon.Colors are the sorts of properties that can be arrangedsystematically in ordered arrays. That is, a set of internalrelationships hold between the range of colors.Colors comprise the kind of property which make true a wide rangeof first order color principles or statements. Some examples are thefollowing: tomatoes are red, so are sunsets and blood, and so on.red merges gradually into yellow in one direction, and into blue inanother direction, but not into green except through either yellow orblue; and so on.ripening bananas goes from green to yellow, certain ripening applesgo from green to red, and so on.The statements cited in 3 are meant to be illustrative examples.There is a considerable variety in the types of statement involved.Some are causal truths e.g., ripening pears and wheat go from green toyellow, acids turn blue litmus paper red, spiders with red stripes onthe back are venomous, black hair tends to grow grey with age, and soon. In the second place, there are certain aesthetic and emotionalfacts. For many people, green is soothing. Soft pastels are suitablein certain contexts; mauves and browns are not. Light colors and darkcolors have different effects on mood, and so on. Certain colors areharmonious, and others jarring. In addition, there are truthscomprising the way perceived colors vary with illumination, distance,orientation, and so on. There are other truths concerning how thecolor of surfaces is affected by the background against which anobject is seen.What has been just given is a partial characterisation of colors,given the natural or folk concept of color. It is plausible to holdthat a fuller characterisation than this minimalist version can beprovided. Unfortunately any such account is likely to becontroversial. Frank Jackson (1996) describes what he calls ‘aprime intuition’ about colors that there is something peculiarlyvisually conspicuous about colors: "Redness is visually presented in away that having inertial mass and being fragile, for instance, arenot, When we teach the meanings of the color words, we aim to get ourhearers to grasp the fact that they are words for the propertiesputatively presented in visual experience when things look colored."[p. 199.] This prime intuition, Jackson states, is simply that red isthe property objects look to have when they look red. This deceptivelysimple prime intuition is said to tell us something important aboutthe metaphysics of color when we combine it with plausible views aboutwhat is required for an experience to be the presentation of aproperty: a necessary condition for experience E to be thepresentation of property P is that there be a causal connection innormal cases. [p. 200.]The idea behind talk of ‘prime intuitions’ is that theyare the intuitions formed by those competent in the use of colorlanguage, especially in the identification and recognition of colors.Those competent perceivers and users of color language are personscapable of reflecting on the way in which colors are presented (orrepresented) in color experience. Accordingly, it is plausible to holdthat colors are presented as follows: as objective,perceiver-independent, intrinsic features of physical bodies, i.e.,physical surfaces, volumes, light sources, illuminations, films,media, and so on.The expression of this intuition adds little to the previousminimalist characterisation of the folk/natural concept of color. Itis plausible to go further and hold that colors are not only intrinsicfeatures of physical bodies, but are presented as manifest, sensuousproperties. The way they are manifest is that their nature is open andmanifest, not hidden. Some philosophers are prompted to respond tothis claim by saying that it begs the question against those theoristswho hold that colors have hidden essences, e.g., physicalmicrostructures. The counter-reply to this response is that the viewthat colors have hidden essences is not the right theory about thenatural concept or folk concept of color. It may be plausible as atheory of what a reformed concept of color is or should be, but not asa theory of what the folk concept is.Admittedly it is not easy to convince people that there are manifestproperties. One of the problems is that many concepts begin their lifeas concepts of manifest properties, but then evolve into more complexconcepts. Children's concepts of say ‘horse’,‘dog’, ‘man’ and so on, are cases inpoint. For them, the concept is almost exclusively defined by thecorresponding appearances. There are, however, more sophisticatedexamples. Take concepts such as brilliant, dazzling, sprightly,po-faced, cheery, glum, picturesque, grim-faced, pale, etc. These areterms that characteristically apply to appearances. All of them, it isplausible to suggest, are manifest properties with essences they‘wear on their faces’, and are not hidden.Many properties are not manifest: being poisonous, being made by arobot, containing water as a constituent, coming from Virginia, and soon, but some clearly are. Included among these are colors. Someone whois taught color terms and who understands how they are used, knowswhat it is for something to be red, to be blue, or whatever: it is tohave that feature which the perceiver is capable ofrecognizing. Reflecting on the way colors are represented, thethoughtful observer can say that the sort of property colors arerepresented as being are as color ‘stuffs’ spread on thesurface of physical bodies (or through volumes, etc.). They areintrinsic features of physical surfaces (volumes, . . .), spread overthe surface. It seems only too clear that we experience the redness ofa ripe apple as an objective quality of the apple, the redness beingin an objective space just as much as are the shape, the contour, thetexture of the apple. This point can be neatly illustrated by quotesfrom two eminent workers on the physiology/psychology of color, Heringand Boynton. Hering for example, writes:When we open our eyes in an illuminated room we see amanifold of spatially extended forms that are differentiated orseparated from one another through differences in their colors . . .Colors are what fill in the outlines of these forms, they are the stuffout of which visual phenomena are built up; our visual world consistssolely of differently formed colors; and objects, from the point ofview of seeing them, that is, seen objects, are nothing other thancolors of different kinds and forms. [Hering (1964), p. 1]In similar vein, the physiological psychologist Robert Boynton writesin ‘Color in Contour and Object Perception’: "From earlychildhood we are easily able to recognize a property of objects,usually associated with their surfaces, that we call color. No child,and relatively few adults, will doubt that color is on (or sometimesin) objects." [Boynton (1978), p. 175] In addition, one is aware of thedifferent character of the way colors appear in different modes, i.e.,for object surfaces such as apples, patches of light on screens,volumes such as wine, scattering media such as skies, light sourcessuch as globes, and so on. There is one more prime intuition which is one of the mostimportant. It is part of the folk concept, another ‘primeintuition’, that colors are represented as qualitative, sensuousfeatures. This point will no doubt be controversial, but it ought notbe. Reference to the sensuous nature of colors is crucial. Thesequalitative features that colors are represented as being are‘sensuous’ in the widest sense. This is not an issue ofdeep metaphysics. The term "sensuous" is often used on such a way asto apply to phenomenal, i.e., to ontologically subjective qualities.However, there is a wider sense which does not have this commitment.There is a neutral use for the term. An illustration is an examplewhich H.H.Price borrows from Husserl: ‘When I see a tomatohanging on a vine then a ripe tomato hanging on a vine is "leibhaftgegeben": it is given to me with its sensuous qualities.’ [Price(1932), p. 231.] This sound much better, of course, in German, but inEnglish the point is that the tomato (better still, grapes) and thevine are given in perception with the sensuous features. Englishspeakers understand that in perceiving tomatoes, grapes, etc one isacquainted with sensuous features. Price was acknowledging thatwhatever one's theory of perception, and especially whether onethought that the perceiver is directly aware of physical objects orsensory presentations, one was acquainted with sensuous features.A similar point is made by Evan Thompson (1995) though with respect tothe term ‘phenomenal’, rather than‘sensuous’. Research in psychophysics and visualphysiology, he writes, is constrained by the ‘phenomenalstructure of color’. By this term he means to refer primarily tothe three dimensions of color, known as hue, saturation and lightness,as well as to the relations that colors exhibit among themselves (p.39). As he points out, textbooks often classify these properties ofcolor as ‘subjective color phenomena’ or as features of‘color experience’. Thompson prefers to use the term‘phenomenal’ to describe them because they are first andforemost features of how colors appear: "I thus intend to use the term‘phenomenal’ in its older sense of pertaining toappearances, not in the current sense of subjective."The neutral notions of ‘sensuous’ and‘phenomenal’ are ones that can be shared by writers withvery different philosophical commitments. It is such a notion thatMichael Tye employs, when he states that when philosophers appeal tothe phenomenology of perceptual consciousness, in making claims aboutthe phenomenal character of experience, they are mistaking intrinsicfeatures of the content of experience for intrinsic features ofexperience itself.Accordingly, we can represent writers as diverse as Price, Thompsonand Tye, despite their philosophical differences, as in agreement.There is a neutral sense of ‘sensuous’, or‘phenomenal’, according to which it is possible forphysical objects to have sensuous or phenomenal properties. Mostimportantly, the color properties that the natural concept of colorattributes to physical objects are sensuous properties. It is ofcourse a separate question of whether physical objects do have thesensuous features that they are represented as having. Price thinksthat they do not, but he also thinks that a further argument isrequired to show that they are not.To conclude: given the characterisation of the natural concept ofcolor, color is a certain kind of property. Which kind it is can bespecified, in part, by saying that it is an objective,perceiver-independent, manifest and sensuous kind. In addition theproperty is one with certain kinds of causal powers vis a vis thepresentation of color in the perception, recognition andidentification of colors. Finally, colors are the kinds of propertiesthat fit together in characteristic ways to form structured colorarrays, with a distinctive 3-dimensional character. They areproperties that as a group, form an internally related 4+2 structure,built on the four unique, primary hues: green, red, blue and yellow,and related to the black/white pair. Some parts of thischaracterisation of the natural concept are contentious, e.g., theclaims that colors are manifest and sensuous. Some of the mostsignificant parts of the characterisation which have the mostfar-reaching implications are not controversial: that colors havecausal powers as described above, and that collectively formastructured system.4. Science of Color or Color Science?There is a flourishing field of color science, one that goes back toNewton and includes such famous figures as Young, Maxwell, Helmholtz,and Hering. Almost all of this field has to do with the perception ofcolor, that is, to studying the conditions that cause or contribute tocolors being seen, or to ways in which the colors as they appear may bestudied. An example of the second kind of research is the many studiesin colorimetry, involving the specification of colors. Typically theseinvolve matching techniques in which the subject is asked to match somestimulus with one or another of a range of standardized cases. One of the most vigorous areas of research, especially more recently,is the study of color vision, i.e., of the mechanisms involved in theperception of color. Helmholtz and Hering were pioneers in thephysiology of this area, but much has been done recently in researchon the neural processes involved in color perception. A crucialdevelopment has been the growth in opponent-process theory. [SeeKaiser and Boynton (1996) for technical discussion. See Hardin (1988)and Thompson (1995) for philosophically-informed discussions.] Alsoof significance are the experiments by Land and his colleagues and thedevelopment of his retinex theory of color vision. [See Land (1983)and also Hardin (1988) and Thompson (1995) for critical discussion.]Uncovering the mechanisms that underlie color vision is an excitingcurrent field of research. The major philosophical relevance of suchresearch is that it promises to help explain why some of theappearances of color have the character that they do, e.g., why thereare no reddish-greens nor bluish-yellows. If it becomes clear thatappearances have a certain character which no set of objectivephysical features have, and that character can be found to based onthe physiological/neural processes, then the research may be crucialin establishing that color is best thought of not as some objectivefeature of the world that color vision detects, but rather assomething constructed by one's color vision.Another area of color science has to deal with the construction ofcolor systems, i.e., of ways of ordering the range of colors in asystematic fashion. Usually this is done by constructing threedimensional color solids. It is interesting, however that there aredifferent systems that have been constructed. For one thing differentdimensions are used depending on the way in which colorappears. Colors as properties of surfaces, in general, have adifferent mode of appearance from colors as properties of volumes suchas wine, and yet again from that for film color or aperturecolor. These different modes of appearance suit different dimensionsof color. For surfaces the dimensions (at least in some systems) arehue, chromaticness and whiteness/blackness; for aperture or filmcolors the dimensions are hue, saturation and brightness.Yet another field in which the way colors appear is crucial is thefield of color psychology: the field in which color-constancy,simultaneous contrast, the effects of various backgrounds on colorperceptions, and so on, are examined, and competing explanationsdebated.Almost all of this research in color science is devoted to the waycolor appears, i.e., to the conditions under which one perceives coloror experiences it or to the character of the way color appears. Almostnone of it is concerned with the other color ‘truths’,that is, to what we might call ‘causal truths andprinciples’. This is not to say that those ‘truths’or principles are false or are invalid. Biology and chemistry andindeed physics all use color concepts and claims in their theories(some of them) and explanations, but there has not developed whatmight be called a "science of color", except for the study of the waycolor appears, or one might say, of the way colors are represented,and of the causes and conditions conducive to the way they appear andare recognized. That there is a flourishing field of color science butnot a science of color reflects the special place color has inscience.There is an important difference between color science, on the onehand, and the science of shapes, geometry, the science of heat andtemperature, and the science of sound, on the other hand. In the caseof shapes and heat/temperature, and sounds and weights, we haveproperties of physical objects which we can detect, naturally andunreflectingly, by the use of our senses. These properties, however,are different from colors. In the case of shape and heat and weightand sound, there has developed a science in which the principles ofsound, weight, heat, and shape are studied. There is however noparallel science of color. There are few color principles to serve asthe basis for a science of color. Color science is a large field, butit is built around the way that colors appear and to the conditionsunder which colors can be perceived, and the causes which lead to theperception of colors. If colors ceased to appear in the distinctiveways then color science would disappear.The field of color science has developed through building up theoriesand color facts which contribute to our understanding of theperception of color, as well as to provide an objective specificationof color. With both aims, the scientific account has to take accountof a range of color facts that hold of the practices and behaviour ofcolor-perceivers. That is, before we discovered any detailedscientific knowledge about color, we had - and still have - aconsiderable body of knowledge about color.This body of color knowledge is contained within the conceptualpractices specific to color. By studying these practices, we can drawup a set of general color principles and ‘truths’. Therange and extent of the general principles, have been emphasized byJustin Broackes (1992). [For further discussion, see Maund (1995).]These general facts or principles include causal truths, although thenature of the causal powers may be difficult to discern. It is easy tosee that color science has both filled out the details of some of thecolor principles described previously, e.g., in respect to theinternal relations and to the conditions under which color isperceived, and in some case modified them. Furthermore, the discoveryof color-mixing laws and of the mechanisms underlying color vision hasadded to our knowledge of color.5. A Unifying Framework for ColorsThere is a set of color truths and color principles that can be said tocomprise our color-knowledge. It is to this body of knowledge thatcolor science contributes. It is possible to find some unifying orderthat brings together in a unitary scheme these various color truths andprinciples. The set of truths and principles can be divided intoseparate categories, which bring out the different roles played bycolors and color-concepts in (i) the acquisition of color terms inlanguage; (ii) the appearances of colors (iii) the development offirst-order truths or ‘truths’ about colors and (iv)servicing social and epistemological purposes. L: Principles about the Use of ColorTerms: Color terms are taught and learned by the use of paradigms. This isto say that the paradigms are identified and recognized by the way theylook (appear).Colors are properties of bodies that play a causal role in thelearning of color terms and the communication about colors.Cross-cultural comparisons indicate that there are certain basiccolor terms which are systematically related. [See Berlin and Kay(1969), and Boynton and Olson (1990), and for a contrary view, VanBrakel (1993)]A: Principles about Appearances and the Perception ofColor: Specific colors have distinctive appearances, characteristic ofeach color.The way colors are identified and recognized is by the way theyappear to perceivers. There are no color thermometers or othermeasuring devices.Colors take a different mode of appearance, i.e., have a differentcharacteristic appearance, when they are features of physical surfaces,films, volumes, light sources, etc.There are principles governing the conditions under which colorsare perceived. Certain conditions are better than others foridentifying colors; certain people are better than others atidentifying colors. Colored bodies can appear differently when viewedat different distances, in different illuminations, and againstdifferent backgrounds.Among the principles in A4 are principles governing constancyeffects: tendencies for objects to look the same under differentconditions.There is a certain distinctive form to the way colors appear.Visual experiences represent colors in a certain way, as qualitativefeatures which are "sensuous" in the widest sense.T: Color Truths of the First Order: There is a vast range of specific color truths: ripe bananas areyellow; certain sunsets are golden; claret wine is claret red and soon.Colors can be combined together in structured, systematicallyordered arrays, with a distinctive character. They are qualitativefeatures which are "sensuous" in the widest sense. These arrays aredifferent depending on whether the colors are colors of surfaces,volumes, films, scattering media, lights and so on.There are general causal truths e.g., ripening pears, bananas andwheat go from green to yellow, acids turn blue litmus paper red,spiders with red stripes on the back are venomous, black hair tends togrow grey with age, and so on.Different colors have different specific aesthetic effects,including principles of harmony, balance, contrast, etc.Different colors have different emotional effects.R: Principles about Colors and Their Roles: Colors are natural signs, i.e., are easily identifiable features ofobjects that enable perceivers to identify and re-identify kinds ofobjects.Colors serve as conventional signs, for similar purposes as thosein R1.Colors, often because of effects in T4 and T5, serve certain socialand psychological roles.It needs to be emphasized that these categories are not meant to beexclusive. For example, principle R3, concerning the social andpsychological role of colors is related to principles T4 and T5,concerning the specific aesthetic and emotional roles of colors.Likewise the principles in A6 and T2 both refer to the sensuous natureof colors.6. The Illusion Theory of ColorsThe natural or folk concept of color conceptualizes color as a certainkind of property: an objective, perceiver-independent, intrinsicfeature of physical bodies. The property is, moreover, one with acertain character and with certain causal properties. The moststraight-forward view of colors is that they are what they seem. Colorsare properties whose essences are manifest. Since colors here are takento be simple, primary quality of objects, we might call this view "TheSimple Objectivist View of Color". It stands in clear contrast to thoseforms of Objectivism according to which the essences of colors arehidden, not manifest. [See OBJ]. Opposed to both forms of Objectivism is another view: ‘TheIllusion Theory of Colors’ or ‘Color Fictionalism’[For a recent account, see Maund (2006)]. In this account, it is heldthat once we spell out the character of the features specified by thefolk or natural concept, we discover that there is in nature no suchfeatures: colors as they are conceptualized are properties not foundin nature. The colors objects are represented as having, in visualexperience, are ones that no object actually has.The natural concept of color conceptualizes color as a certain kind ofproperty. Which kind it is can be specified, in part, by saying thatit is an objective, perceiver-independent, manifest and sensuous kind.In addition the property is one with certain kinds of causal powersvis a vis the presentation of color in the perception, recognition andidentification of colors. Finally, colors are the kinds of propertiesthat fit together in characteristic ways to form structured colorarrays, with a distinctive 3-dimensional character. They areproperties that as a group, form an internally related 4+2 structure,built on the four unique, primary hues: green, red, blue and yellow,and related to the black/white pair. Some parts of thischaracterisation of the natural concept are contentious, e.g., theclaims that colors are manifest and sensuous. Some of the mostsignificant parts of the characterisation which have the mostfar-reaching implications are not controversial: that colors havecausal powers as described above, and that collectively form astructured system.Defenders of the Illusion Theory of Color exploit the presence ofthese features in the natural concept to argue that, given thisconcept of color, there are in fact no colors in nature, that objectsare presented in experience as having colors which neither they norany object have. Crucially, there are no properties that both have thecausal powers in question and which collectively have the rightcharacter. In short, there are no colors that are intrinsic,non-relational, perceiver-independent properties and which satisfy therequirements of the three-dimensional color solid. None that is, thatallow us to make sense of the way in which we perceive and identifyand recognize colors.No properties of physical objects stand, it has been said, in theright kinds or relations that are characteristic of the structuredcolor arrays. It is true that we can arrange physical samples inordered arrays but the ordering principles depend on the way theyappear. What is crucial to the principle of ordering is the way thecolors are represented as being, or rather, the character of the waycolors are represented. It is because there is a distinctiveappearance associated with each color that the colors are capable ofbeing systematically ordered in the way that they are.It would seem that, as far as our conceptual practices governing colorare concerned, physical objects do not have the kinds of color theyare represented as having. The colors that objects are represented ashaving are illusory: no physical object actually has those colors.The colors might be said to be "virtual properties": they areproperties objects do not have, but might have had: in some otherpossible world but not in this one. If we speak of colors as havingessences, then they have virtual essences. Colors are virtualproperties, just as phlogiston and caloric are virtual naturalkinds.The illusion theory, or virtual essence theory, of colors leaves uswith a problem. If there are no properties that satisfy therequirements for being colors: how did the natural concept develop?The solution to this problem is found in the fact that the way thatthe concepts of color operate, to serve their various functions androles, is through the way colors appear. For these purposes and roles,objects do not need the actual colors. It will be sufficient if theyappear to have colors. For these purposes, it is sufficient that "itis as if they have the colors".There are two major functions for color concepts. One reflects anepistemological purpose: colors are signs used to indicate thepresence of objects of interest. The signs are either natural orconventional, the latter being ones designed for various socialpurposes. The purposes are equally well served even if objects do nothave colors, but have the right appearances. All that is needed isthat they are represented as having colors. The second major purposeof color concepts is aesthetic, understood in the widest sense. Coloris significant in painting, decorating, clothing, theatre, make-up,advertising, showing off, sexual appeal and so on. Again, it mattersnot in the least that objects do not have these properties. All thatis required is that they be represented as having them.The significance of appearances is widespread. As we have seen, theyprovide the basis for the ordering principles governing color systems.Likewise, the causal truths and principles that employ color terms areones connected with the way colors appear. For example, we can explainhow there are such ‘truths’ as "ripening pears (bananas,…) go from green to yellow". This is a truth. For a pear to berepresented as green under the right conditions is a sign that thepear is not yet ripe; for it to be represented as yellow is a signthat it is ripe. In other words, whatever causal truths we haveconcerning color, can be explained by interpreting colors as signs oras indicators for other physical features, where those physicalfeatures serve the causal roles.In a previous section a distinction was made between color science andthe science of color. While the former field is flourishing there islittle science of color. One way of understanding how this situationhas arisen is that there are no actual colors in physicalreality. What there are are experiences which represent objects ashaving colors, colors which in fact they do not have. That is, colorsare virtual properties. Our visual experiences present us withsystematic illusions. If this were the case, we would still have thesame color science, exactly as we have now, for we would still need toknow how colors are represented, and what causes them to berepresented in the way that they are, and how the various conditionsunder which we have color experiences systematically differ can beexplained. Since one of the central roles colors serve is to act assigns or indicators for physical objects, and any theory of color hasto acknowledge this role anyway, it would seem that any fledglingscience of color is best dispensed with in terms of other sciences,and color science left to the science of color perception. This doesnot stop it from being the case that there is an important theory ofcolor vision and perception, and of the role colors play as signs orindicators.Clearly, the concept of color can be used to serve many of its normalpurposes even if the representations of color are illusory, providedthat the illusions are systematic, which on a proper theory, ofcourse, they will be.7. Colors as Simple Intrinsic Objective QualitiesThe Simple Objectivist View of Color is that there are in nature colorsof the kind specified by the natural concept. Colors are simpleintrinsic, non-relational, non-reducible properties, supervenient onmicro-physical features. Such a view has been presented by P.M.S.Hacker (1987) and by J. Campbell (1994). The main problem the illusion theorist finds with the SimpleObjectivist View is with reconciling the putative character of theintrinsic color features that fit together to comprise color solidswith the distinctive structure, with the causal role of such featuresin the recognition and identification of colors. The problem isaddressed by Hacker in his defense of the claim that colors areintrinsic features of physical bodies. He forthrightly rejects notonly the physicists' view, and Reid's view on colors, but also thedispositionalist account offered by McGinn, McDowell and Dummett. Heinsists that colors are properties which are used to provide causalexplanations. There is no more reason to deny this, he says, thanthere is to deny the parallel claim for solidity and liquidity. Inparticular, he claims that we can provide causal explanations for whycolors affect color perceivers. The explanation is not vitiated by thediscovery that microstructural processes are involved, any more thanexplanations concerning solidity and liquidity are rendered otiose bythe discovery of the microstructural base for these properties.It is doubtful that this maneuvre works, for a number of reasons. Oneis that we would need to specify the criteria that make it the casethat an object is intrinsically red. Not all perceivers agree in theirjudgements. It is not that there are color blind people who can, afterall, be said to be color-deficient. There is a small but stillsignificant number of color-anomalous people, who can make all thesame color discriminations as regular people, but who disagree aboutwhich samples are pure red, green, etc. That is, it seems that theircolor solid is skewed from the normal. It seems arbitrary that wedecide that the real color is the one that the majoritypick. Secondly, if there were an evolutionary shift, or an eugenicsprogram, the minority could become the majority.There is a more important reason against Hacker's proposal, however,which depends on the fact that for colors, microstructuralexplanations cannot be provided for all the relevant, importantfeatures. Specifically the complex internal relationships between thecolors cannot be explained by the microstructural properties ofphysical bodies, except through their affecting the perceivers. Thatis, to explain why the colors have the relationships they do requiresgiving an account of the structure of the perceiver's perceptualapparatus. At a minimum, this requires an account of the responsecurves of cells in the retinae, but also required would be an accountof the appropriate neural processes. In short, the explanation willhave to work via an explanation of how things appear, that is, of howone's perceptual experiences have the content that they do.There is a difference between solidity/liquidity and the colors. Inthe case of solidity and its sister concepts, there is a range offeatures that are associated with them, including causalrelationships. If we have been given adequate scientific explanationsat the microstructural level for solidity, then adequatemicrostructural explanations will need to be given for these otherfeatures. The reason why it is important to preserve the concepts ofsolidity and liquidity is that such concepts unify sets of propertiesthat are useful to have unified, and this unification is lost if weretreat to the microstructural level.The important difference forcolors is that there are crucial features of colors that are notreproduced at the microstructural level of the physical objects, norare they explained at that level. The features are those that colorshave, by virtue of which they are capable of forming systems ofproperties with internal relationships. This structural property isnot explained at the microstructural level of physical samples ofcolors. To try to explain the structure physically, the best we couldhope to do is to try to explain it in terms of dispositions, e.g., toinduce a certain ratio of light sensitive retinal cells. Even if thatwere to work, it is the wrong kind of explanation to help Hacker. Hewants to hold that colors are intrinsic qualities of physical objects,not relational, dispositional ones.8. Objectivism The Simple Objectivist view is that the objective essences of colorsare manifest. The more common form of objectivism, however, is thatcolors have hidden objective essences. Intuitively, the thought isthat our color terms — blue, red, black white, etc. — namecertain properties in the world, that are perceived in certain wayscharacteristic of each. These properties are to be identified withproperties which to most of us are unknown, but which can bediscovered by scientific investigation. Thomas Reid was probably theearliest advocate of this theory. More recent examples areD.M. Armstrong (1969), J. Westphal (1987), D. Hilbert (1987),M. Mathan (1988). Frank Jackson (1996), M. Tye (2000), A. Byrne &D.Hilbert (2003) and B. McLaughlin (2003). Advocates of this view have differed, though, on whether thehidden essence of color is a microstructural feature, intrinsic to thecolored body or, more commonly, whether it is a light-relateddispositional property, e.g., one connected with reflectanceprofiles. Thomas Reid was probably the earliest example of the firsttype and Frank Jackson (1996) the latest. Recent examples of thesecond type are D.M. Armstrong (1969), J. Westphal (1987) and D.Hilbert (1987). The attempt to locate the essence of color among the microstructuralfeatures of colored bodies seems unpromising. One of the majorproblems is ‘the problem of multiple realizations’. Giventhe range of bodies that have colors — surfaces, volumes,light-sources, illuminations, luminescent bodies, films, expanses— the intrinsic physical features that provide the causes forthe way colors appear show a bewildering variety. Even if weconcentrate on the first type of color, surface color, : we find thatthere is a wide variety of underlying physical microstructures,responsible for objects' appearing blue, yellow, etc. The causes ofthe colors objects appear to have are many and varied. The same typeof micro-structure consistently appears the same color (within limits)under different conditions, but different microstructures may appearthe same.It would seem, therefore, that the most plausible candidates forobjective essences are light-related dispositional properties, e.g.,capacities to emit, reflect, absorb, transmit or scatter light tovarying degrees. However, the problem of multiple realizations hasmerely been postponed for, depending upon the type of object inquestion, a different candidate for the objective essence has to befound. For physical surfaces, it would have to be related to theobject's reflectance profile, e.g., the capacity to differentiallyreflect wavelengths from different regions of the incidentillumination; in the case of volumes, it would be related to theobject's transmittance; in the case of such objects as the sky, to thescatterance; in the case of aperture color or film color, it would berelated to the pattern of light received at a particular place or atthe source of the light (the reflecting source in the case of physicalsurfaces) and so on. Even in the case of ordinary objects, the colorsmay be caused in a variety of ways. The blue of a bird's coat mayresult from scatterance, the red in a different way.Nevertheless, progress can be made if we concentrate on one type ofcolor, surface color. The most plausible attempt is to try to identifysurface color with a light-modifying disposition, e.g., with adisposition to reflect (or absorb) certain proportions of standardizedillumination, or, if one prefers, certain proportions of light of thewavelengths from the visible spectrum. Objects with neutral orachromatic colors are ones which reflect all wavelengths to (roughly)the same degree, with whites reflecting a higher percentage than greysand blacks. Objects with chromatic colors are those whichdifferentially reflect or absorb light at different wavelengths.Accordingly surface color would be identified with some feature of anobject's spectral reflectance curve.A special case of the problem of multiple realizations is posed by theoccurrence of metamers. In the case of physical surfaces there aremetamers, i.e objects with very different reflectance curves that haveidentical appearances of color. The situation is far more pronouncedin the case of film colors or aperture colors. Here there areinnumerable different combinations of light that will give the samehue. It would seem that the property shared by physical objects withthe same film color is a disposition to incite the threelight-sensitive cones in the retinae according to the same ratio: x:y: z.The major problem, however, with any of the objectivist accounts ofsurface color is that, given the way the natural or folk concept hasbeen characterized, it is hard to see how there could be an objectiveessence with the right characteristics. For, given the natural or folkconcept of color, it seems that color is a certain kind of property: aperceiver-independent, intrinsic property of objects, one thatsatisfies certain constraints. But it is hard to see how there couldbe any intrinsic, physical features that satisfy all theconstraints. The most crucial requirement is that colors, as a group,have to stand together in the right kind of relationships. There areno manifest, intrinsic features that satisfy this requirement. Nordoes any set of microstructures stand the remotest chance ofsatisfying the appropriate constraints. In particular, there are nophysical features, either of microstructure, or of the object'scontribution to light, such that the right kind of internalrelationships hold. [See Hardin (1988) and Maund (1995).] Neither cancolor be a dispositional property, say spectral reflectance, or adisposition to produce physiological responses of a certain kind,since spectral reflectances don't fit together in the right kind ofways.There are two kinds of response an objectivist might make. One wouldbe to deny the account of the natural concept of color as expoundedhere. Instead, it is held, it is part of the way color terms operatein the language, that it is understood that colors may well turn outto be hidden essences. The other response involves not challenging theaccount of the natural concept but insisting instead that it needs tobe revised or reconstructed for, say, scientific purposes.There are two different kinds of response the objectivists havemade. One is to modify the objectivist account by making the kind ofreflectance properties that are relevant, more complicated. The secondis to combine the first step with a theory of how color terms namecolors, which opposes the one implied in the discussion up untilnow.David Hilbert (1987), illustrates the first type, with his accountknown as ‘Anthropocentric Realism’. It aims specificallyto provide a solution to the multiple realisations problem but, hethinks, solves the second problem as well. On Hilbert's view, colorsare identified with spectral reflectances, at least surface colorsare. A distinction is drawn between this kind of color andanthropocentric color. Individual anthropocentric colors areassociated with groups of spectral reflectances. Color perception andcolor language ‘give us anthropocentrically defined kinds ofcolors and not colors themselves’. (p. 27) Terms such as‘red’, ‘blue’, ‘yellow’, etc areassociated with anthropocentric colors. To be red, for example, is tohave a reflectance that falls within a particular class ofreflectances. These classes, in general, are highly anthropocentric,sharing few interesting causal powers, and being of littleconsequence, apart from how they connect with the peculiarities thatunderlie human color vision. The principle of grouping is that a givenperceived color is associated with ‘a triple of integratedreflectances’. This association is based on the fact that humancolor vision depends on the use of ‘three types of broad bandsensors’, i.e., the three types of light-sensitive receptors(p. 111).It is Hilbert's claim that with this analysis, many of thecommon-sense claims about color can be preserved, e.g., that orange ismore similar to red than it is to blue. The point is that the triplesof integrated reflectances can be taken as co-ordinates in athree-dimensional space, thus defining a color space. Similar colorswill be located at adjacent points in this space. It is claimed thatthe right interpretation of statements of color similarity anddissimilarity is in terms of statements about relative location incolor space. It is with this claim that scepticism will most naturallyarise. On the face of it, there is a certain qualitative character toostensively defined color space, e.g., as expressed in the Munsell orSwedish Natural color systems, that is not captured by thetriple-reflectance color space. One measure of this fact is thatchanges along the dimensions of brightness and saturation have adifferent character from changes of hue from unique green to uniqueyellow to red to blue. Changes in Hilbert's color space don't seem tobe of the right kind — which of course is not to deny that theymay not contribute to a causal explanation for why the psychologicalcolor spaces have the character that they do. [See Thompson (1995),Chapter 4, for an extended discussion.]The objectivist may fare better, if she adopts the second approachmentioned above, that which specifies a certain theory of colornaming. An example of such an approach is the‘functionalist’ proposal: red is the property thatdisposes its bearers to look red. [Cohen (2001), McLaughlin (2003)]This proposal conforms to a more general approach: to hold that thisdisposition to appear is not of what colors are essentially, but it ispart of the (folk) conceptualisation of a certainperceiver-independent property which is color. The folk, it is held,use the way colors appear in order to characterize a certain property,but the way objects appear is essential to the characterisation, notthe property. Here we are depending on a distinction between aproperty and the mode of presentation (or Fregean-type sense) throughwhich the property is presented (or thought about). Accordingly,appearances would be tied to the concept of colour, or to the way thecolor appears without being, even in part, constitutive of theproperty of color. It would then be open for us to identify theproperty through empirical, scientific investigation. The idea here isthat the way colours appear fits with the way colours are presented(the mode of presentation) and, hence, the system of similarities anddifferences that are ordinarily taken to characterise the colors fitsthe appearances and not the colors themselves. Hence the account doesnot face the same problem as that defended by Hilbert. McLaughlin presents an account of the spectral reflectances which issimilar to that of Hilbert (1987) and the more recent version in Byrne& Hilbert (2003). The more important aim, he holds, is to solvewhat I have been calling the problem of ‘multiplerealisations’ (he calls it ‘the problem of commonground’). McLaughlin sketches a strategy for dealing with theproblem. Here is the basic strategy for appealing toopponent-processing theory to locate colours among light-dispositionsas causing any color, C: look for a light disposition that, whenactivated, would affect the opponent-processing system in a mannerthat will produce a visual experience of C. [p. 498] The strategy thusinvolves appealing to opponent-processing theory ‘to try to findstructure in the light (to use a Gibsonian phrase) that is supplied tothe eyes’. The idea is that colours are dispositions to supplylight with the relevant structure.This sort of account, which is similar to that of Michael Tye (2000)and Byrne and Hilbert (2003) faces serious problems. One problem iswhether the theory that these authors appeal to is accurate enough forthe tasks set out. [See Thompson (1995), ch. 4; Mathan (2005)pp. 171-76.] Another set of problems have been brought out byC.L.Hardin (1988), (2003) and (2004). One major problem is that it ishard to see how the account can handle the important phenomenon ofsimultaneous contrast. In particular, there is a problem with suchcolors as black and brown, which are pure contrast colors. To treatthem as illusory ‘is to eliminate two whole colorcategories’ [Hardin (2003), pp. 196-97]. Second, the phenomenonof color-constancy which objectivists heavily rely on is veryweak-kneed. There are many situations in which it does not hold, andin those cases in which it does hold, it only does to varyingdegrees. To this point, we might add that there is considerabledispute on how the effect should be described.Yet another serious problem that Hardin brings out is that theobjectivist account will require that we will have to identify the‘real’ color for object x as the reflectance profile thatappears in a certain way to normal observers and in standardconditions. The problem is that there is no non-arbitrary way tospecify ‘normal observer’ and ‘standardconditions’. In determining the right objectivist candidate, ouraim is not simply to show how color vision enables, say, the observerto distinguish objects with different spectral reflectancecharacteristics. Rather we need to explain why one reflectance profiledeserves to be classified as blue, and likewise why other profiles arerelated to similar and differing colors. Consequently to identify onereflectance profile as that corresponding to unique green, say, weneed to be able to specify standard conditions and normalobservers. As Hardin has persuasively pointed out, in Hardin (1988),but more particularly, in Hardin (2004), this cannot be done except ina highly arbitrary way. Not only is there a minority of colorperceivers who are anomalous (only slightly, but appreciably so) withrespect to normal observers, but there is a considerable statisticalspread even within the group of normal observers. The reflectanceprofile for unique green will differ for different members of the"normal group". One can decide, of course, on a standard and fix onereflectance profile as green, but the procedure is highlyarbitrary. As we have seen, there are few interesting causal powersassociated with colors apart from the way objects affectperceivers. McLaughlin does suggest that we might cope with this problem byextending the proposal by another pair of objectivists, Frank Jacksonand Robert Pargetter (1987). They claim that each color can beidentified with a physical property, but in a way that overcomes theproblem of multiple realisations. They concede that there is no singlephysical feature that is the basis for each color say, blue, butmaintain that this does not matter. Blue is identified with adifferent physical property on different occasions, depending on whatkind of physical object has it. This means relativising the concept ofcolor, to kinds of objects and circumstances. McLaughlin's suggestionis that we could relativise the objectivist concept of color toindividual observers. In principle, we may be able to specify a concept of physical color,in the way outlined by Jackson and Pargetter, and McLaughlin, but wemight pause and ask why we should want to do so. Even if we canspecify this physical concept, the account will imply that there is animportant dispositional property that colored objects share: thedisposition to appear in characteristic ways. This dispositionalproperty can also be relativised to conditions and to observers. Onthe face of it, we have two concepts of colour; and why not, if whatwe are trying to do is to defend the best way of thinking of colour?It was what philosophers such as Descartes and Locke were doing whenthey specified two concepts of colour: colour as a subjective qualityand colour as a secondary quality. The point is this. Descartes andLocke were actually introducing two concepts of colour to replace one(which the folk applied to both sensations and to physicalobjects). They may have been wrong in detail, but it is plausible thatthere is a place for both concepts. It is possible that theobjectivist is giving us a third concept to go with the othertwo. Indeed there is reason to think that Descartes and Locke wouldhave accepted such a proposal, had their science been as advanced asours is. Jackson (1996) does provide an argument against color beingthought of as a dispositional property, namely that colors have toplay a causal role, which dispositions are unable to play (only theirbases can be causally effective). This argument, however, is not onethat the defender of spectral reflectances can rely on, forreflectances are also dispositional. (The argument in any case,overlooks the distinction between causal efficacy and causalrelevance.) McLaughlin might respond that his functionalist account of color is anaccount of the ordinary concept of color, and hence it follows thateither his account is right or it is wrong — and his claim isthat it is right. It is not clear whether there would be a good reasonto support a claim of this sort, were he to make it.9. Objectivist And Psychological Dispositionalist Accounts In the previous section, I argued that it makes a crucial differencewhether we take the objectivists (and their rivals) to be attemptingto give an account of how our ordinary concepts of color operate, oralternatively, they are offering a reconstruction (or revision) ofthose concepts. The objectivist account of color has its best chanceof success if it is thought of as a reconstruction of thoseconcepts. This consideration is useful in comparing the account withits leading rivals.Major opposition to the objectivists come from those philosophers whohold that colors are essentially mind-dependent dispositionalproperties: powers to appear in distinctive kinds of ways toperceivers of the right kind. Such accounts are often called“subjectivist”, though it would be more accurate to callthem “psychological-dispositionalist”. In comparing themerits of objectivist and the dispositionalist accounts, it is helpfulto study the examples of solidity and liquidity, for these examplesprovide a set of parallels for thinking about color.In the case of solidity and liquidity, there is a range of causalcapacities that historically have been thought to be constitutive ofthese properties. The growth of science has seen the discovery of themicrostructural properties that form the causal ground of thesecapacities and powers (at least in broad terms). This discovery doesnot mean that such microstructures constitute the essences of solidityand liquidity. There are at least two ways of thinking about whatsolidity and liquidity are essentially. On one model, solidity isessentially the microstructural property and the description of thecausal powers forms an essential part of the way the property ischaracterized, rather than an essential part of the property itself.There is a second way of thinking about solidity, according to whichsolidity is not identified withe microstructural basis even if thelatter is unique. Rather the causal powers are essential to solidity,either because solidity is identified with them, or because solidityis taken to be a second order property: for something to be solid isfor it to have some property which is the basis for the relevantcausal powers.As far as color is concerned, it would seem that the objectivist wouldneed to depend on either of the last two models. For most objectiviststake colors to be essentially dispositional properties, onescharacterized in terms of reflectance profiles. An object'sreflectance curve represents a dispositional property: a power todifferentially absorb or reflect light from the range of wavelengthsconstituting daylight (or a standardized equivalent).It would seem, therefore, that as far as revisionary accounts of colorare concerned, the choice is between different kinds ofdispositionalist accounts: objectivist and perceiver-dependent(subjectivist). On both analyses, what colors are essentially is givenby a description of appropriate causal powers. In one case thesecausal powers are objective ones; in the other, they are specialperceiver-dependent causal powers. Let us call the respective kinds ofcolor ‘objective color’ and ‘psychologicalcolor’. In assessing these accounts as providing revisionaryproposals, the important question to ask is what can be achieved byadopting the respective proposals. There is reason to think thatpsychological color is superior, or at least as good.The psychological, i.e., mind-dependent property is usually presentedas being a pure disposition: to call something ‘red’ is tosay that it has the power to appear red to observers of theappropriate kind. A far better proposal, which can be found in thewritings of Descartes and Locke, is one that presents color in termsof a mixed disposition:x is red = x has some feature by virtueof which x appears red, …This concept has all the advantages of the objectivist concept, andadded virtues of its own. It allows for multiple realizations of thedisposition, and hence of the color. It does not require that for eachcolor there is a unique physical basis. Second, by placing emphasis onappearances, it provides the means to unite the various kinds of color:surface color, volume-color, aperture color, illumination-color, etc.And finally, it can perform the one function that the physical conceptdoes very well: it shows how colors can have a causal role in relationto the perception of color, and the social roles played by colors. That the mixed dispositionalist account readily solves the problem ofmultiple realizations is obvious. It is one of the central advantagesof the psychological account, however, that it both provides aconnecting link between all the various kinds of color: surface color,volume-color, aperture color, illumination-color, etc., in that itunites them all as colors while at the same time it makes intelligibletheir differences. For each of these colors, there is a distinct modeof appearance. For each mode of appearance, colors can be organizedinto systematic 3-dimension color arrays. And for each array, hue isone of the dimensions: colors can be ordered with respect to how closethey are to red, green, yellow and blue. There are, however, importantdifferences. For aperture colors, the other dimensions are saturationand lightness. for surface colors, they are chroma and value, orchromaticness and blackness/whiteness. As well, the greens, blues,yellows, etc of surfaces are different types of green, blue, yellow,etc from those of films — but they are greens, blues, yellows,etc, for all that. It is through characterising surfaces, films,illumination-sources, and so on, as providing appearances that sensecan readily be made of the range of similarities and differencesbetween the various kinds of color. The point of having adispositional concept framed in terms of the way things appear is thatit helps provide principles of unity and diversity for the availablerange of color systems.Finally the mixed dispositional concept can perform the same functionthat the objectivist concept can serve: it can be used to show howcolors are causally relevant to the perception of color. The mixeddispositional concept retains the emphasis on red objects having theright kind of power, but it allows that the object, in having thatpower, has some physical feature (which may be different in differentobjects) which is the basis for that power. Clearly, on this analysis,the underlying physical feature has all the causal powers one couldwish. The mixed dispositional analysis combines this with theadvantage of keeping colors tied to the way they appear.In addition, there is reason to think that colored objects appear isan essential part of the range of conceptual practices. The point hereis that while reflectances are causally relevant, as for that matterare microstructures, so too are appearances. In the case of colorthere is a deeply entrenched set of activities and practices centralto which is the operation of causal powers to appear, i.e., powers tocause perception of objects as red, blue, etc. These causal powers arealso central to the field of color science. Given this twofold fact,then if we are considering a revisionary concept of color, then, byanalogy with solidity, there is good reason to propose adispositionalist concept of color, for which the power to appear in away distinctive for individual colors is essential.The important point, as far as colors are concerned, is that coloredobjects have characteristic appearances and that those appearances areof great interest to us. It is because we have that interest thatthere is point to having a concept of dispositional color - the powerto appear in characteristic ways. It is because of the way colorsappear that they are important to us both biologically andsocially. It is because colors have a characteristic appearance that:the colors can be ordered systematically in color arrays; they haveemotional effects; principles of harmony and contrast apply; there areprinciples governing phenomena of color contrast. It is true thatphysical features both of physical objects and of retinal cellscontribute causally to these phenomena, but central to all of thesecolor principles is the way color appears.At this stage, an objectivist might argue that there is a morefundamental causal power, one associated with reflectance curves, andfor this reason it would be preferable to adopt, as a revisionaryproposal, a concept of color whereby this more fundamental causalpower is essential. If these two proposals are seen as competingtheories, it is not clear that one is preferable to theother. Moreover it is not clear why we could not adopt both proposalsand have two concepts of color, just as in the case of the geometricalproperty, size, we have two concepts: absolute (intrinsic) size, andangular size. That this ecumenical solution represents a viable optionreceives support from the consideration that if we are thinking of theproposal for the objectivist concept we have at least two proposals:one framed in terms of intrinsic microstructural properties, and oneframed in terms of dispositional light-related properties. Againrather that having to choose between them, we could adopt bothproposals and admit that there are different kinds of color.In conclusion, therefore, it would appear that in so far as theobjectivist is offering us a reconstruction of our original concept ofcolor, there is reason to think that a dispositional analysis wouldprovide a construction that is at least as good. There is strongreason, however, to think that an ecumenical solution to the problemsof color can be found: that there is a place for different concepts ofcolor, and with them different essences.10. An Ecological View of Color There is another theory of colors which has something in common withthe illusion theory, in that it rejects objectivist accounts, butwhich is crucially different. It is the theory defended by EvanThompson, the Ecological View of Colors, and is designed to beconsonant with J.J.Gibson's views on perception. On this account,colors are taken to be dependent, in part, on the perceiver and so arenot intrinsic properties of a perceiver-independent world. Thisaccount is not the same as an illusion theory. Being colored, instead,is construed as a relational property of the environment, connectingthe environment with the perceiving animal. In the case of the colorof physical surfaces, "being colored corresponds to the surfacespectral reflectance as visually perceived by the animal". [Thompson(1995) Ch. 5, pp. 242-50.] In more detail this account is spelled out in the following way:"being colored a particular determinate color or shade is equivalentto having a particular spectral reflectance, illuminance, or emittancethat looks that color to a particular perceiver in specific viewingconditions" [p.245]. Thompson insists that this account is to bedistinguished from both a Lockean dispositionalist account and anillusion theory of colors. It is difficult to see, however, how he canmaintain this stand. For one thing, he concedes that we see colors asperceiver-independent properties of things while maintaining thatcolors are perceiver-dependent properties. His answer to thisdifficulty, i.e., to why this is not a form of the illusion theory, isthat on the ecological view it is not possible to perceive color asrelational. That is, the relational nature of color does not allow theperceiver to perceive colors as relational. But this answer is not ananswer to the question posed. What it explains is why one should notbe surprised to find that, on the ecological view, that colors areexperienced as perceiver-independent properties. But this is to admitthat the way colors are represented in experience is not the way theyare. The illusion theory denies that objects have the property (thecolor) they are represented as having. It need not deny that it ispossible to formulate another concept of color that objects dosatisfy. One of the most important recent contributions to the philosophy ofcolor is the book by M. Mathan (2005). In this work, Mathanarticulates a theory of sense-perception in which color plays aprominent role. The work is significant for the theory of color thathe presents, one that draws heavily on comparative studies of colorvision among different species. Mathan replaces his earlierobjectivist views on color by an account that has more in common withthe ecological theory favoured by Thompson. Mathan agrees with Hardin,Thompson and others that the phenomenology of color is not captured,or accounted for, by any of the standard objectivistaccounts. Nevertheless, he claims to be defending a realist theory ofcolor and to be rejecting standard irrealist theories, includingHardin's. Mathan's account is complex. The idea is that the senses(the visual sensory system) do categorise objects as‘blue’, ‘yellow’, etc., but these qualitiesare related to actions that perceivers can perform, and in particular,to ‘epistemic affordances’. The sensory systems are held to be devices that are in the business ofclassifying distal stimuli (physical objects) as having certainproperties which stand in similarity and difference relations witheach other. These categories are constructed by the system and do not,at least in the case of color, correspond to any objective propertiesthat are independent of perceivers. When one has an experience ofblue, then this state is a visual signal that system provides —a signal that it has classified the object as blue. In such acircumstance the object looks blue. This leaves us with the problem ofsaying what exactly it is for something to be blue. Mathan explainswhat it is, through his theory of ‘primary content’ ofvisual experiences, that is, in terms of the actions the perceiver isprepared to make on the basis of having the visual state. WhereMathan's account is distinctive is that for him, these actions areepistemic actions. As he says: x and y resemble each other in colourif there is a colour based epistemic practice E such that the colourlooks presented by x and y signal that x and y are to be treated asequivalent with regard to E. The crucial question is whether whatMathan means by ‘color’ is the same as what others mean,especially the main opponents. He defines color-vision in a functionalway, so that it covers comparative studies, i.e., so that it appliesto honey bees, humans, pigeons, and so on. Accordingly, color isdefined in a functional way: “A colour classification is onethat is generated from the processing of difference of wavelengthreaching the eye, and available to normal colour perceivers by suchprocessing (p.167). On this account, there is no set of propertiesthat color vision is always characterising (as color) and there is noclass of types of experience that any colour perceiver mustpossess. There is a revealing remark when he says, with respect to Lewis'sdefinition of color (which mirrors that of McLaughlin): “Lewiswas perhaps of the view that ‘red’, ‘blue’,etc., are our terms, human terms, and that the colours that a pigeonexperiences should not be named by these terms.”; (p. 163]Mathan concedes that we might allow that Lewis's anthropocentricdefinitions of ‘red’, ‘blue’, etc., areappropriate for these human colors. However, he says, it is not soreasonable to define colour anthropocentrically. “Colour is not‘our term’: we can make it so only at the exorbitant costof abandoning the comparative (i.e., cross-species) study of colourvision.” But Mathan's conclusion does not follow. We can makeall sorts of pragmatic moves in defining color-vision, so as to allowthe comparative studies, while preserving a concept of color thatapplies to the terms ‘red’, ‘blue’,‘yellow’, etc. All that Mathan has provided a case for, atbest, is that we should have an additional concept to theanthropocentric one. 11. A Pluralist FrameworkIf analysis of the natural concept of color leads to an illusiontheory, or to the theory of colors as virtual properties, we still needto develop an account that prescribes how we should, in the future,think about color, at least in general terms. For practical purposes,it does not matter at all that colors are virtual properties. For thesepurposes, it is sufficient if "it is as if there are colors"; i.e,these purposes are served equally as well if objects appear to becolored. They do not need to be really colored. There are other, more theoretical purposes for which we need todevelop a more comprehensive account of color, one that specifiesother concepts of color. The best such account is one that sets out apluralist framework, one that allows for a variety of differentconcepts of color, including objectivist and psychological concepts,and arguably, ecological and phenomenal concepts. Moreover, such aframework does not require us to reject the natural or folkconcept.That there is scope for more than one concept of color should not besurprising. The natural concept of color is intended to serve a rangeof purposes. We find, though, that nothing exists that satisfies allthe requirements. However, all is not lost. It is possible to developa new set of color concepts that as a whole serves all or most of theprevious purposes. None of them taken singly serves all, but eachserves some. It is built into the natural or folk concept that colorshave, broadly speaking, two major roles: (i) colors have a causal roleto play in color perception; (ii) colors serve a variety ofepistemological, aesthetic and emotional purposes. Colors serve thelatter set of purposes through the way colors appear. Once it isrecognized that colors, as specified by the traditional concept, arevirtual properties and that there is no property that serves all thefunctions relevant to that concept, the way is open to recognize twonew concepts of color: dispositional, psychological color, to takeover and consolidate the role served by the appearance, and physicalcolor, to take over the causal role. Moreover, once it is revealedthat the cause of color perception are complex, it is open for us tosee the point of having several physical or objectivist concepts ofcolor, one framed in terms of microstructural properties, the other interms of light-related properties.To argue in this way for the place of a number of concepts of color,and for the possibility of an objectivist concept, to supplement otherconcepts of color, is to argue for a pluralist framework for colors.This framework has the advantage of allowing a place for an objectiveconcept of color, while not making it mandatory. Whether or not thereis any point in having an objective concept, there is, as we haveseen, a need for a dispositional concept, one tied to the appearanceof color. The dispositional concept is a crucial part of the pluralistframework.But once we become enlightened by accepting the theory of virtualcolors, how should we then think of the dispositional concept? Whatexactly does the exercise of the disposition consist in? What exactlyis the content of the dispositional concept? The right answer is thatthere are two parts to the dispositionalist concept. One part refersto the way objects appear, and the other to the feature, whatever itis, which is the causal basis for the appearance. That is, thedisposition is not pure but ‘mixed’. BlueD objects areobjects that have some feature by virtue of which they look as if theyare blue, i.e., blue in the intrinsic sense, i.e., blue in thevirtual-color sense. To say that this sense of color is thevirtual-color sense is not to say that colors are ordinarily conceivedof as virtual. It is to say that the properties colors are conceivedof as being are virtual. The content of the dispositional conceptthus presupposes the virtual-color concept. This means that there ispoint in retaining this concept, even when we come to know that noobjects have the property. The fact that I do not believe that thisproperty of intrinsic blueness is ever instantiated does not mean thatI should give up the concept, any more than disbelievers in Satanshould give up the concept of satanic.In this state of theoretical sophistication, my use of the naturalconcept to describe things requires me to adopt the naive attitude tocolor or, preferably, the engaged attitude typical of the playgoerwho, at the theatre, suspends his belief that ‘it is all a packof lies’. Of course as philosophers, we need to understand whywe have this virtual-color concept and what role it plays, and how itworks. But none of that stops me from continuing to employ thevirtual-color concept, whether as scientist, artist, consumer,town-planner, interior decorator or philosopher. As for servingfunctions such as being signs or as being aesthetically or emotionallysignificant, virtual colors are as good as real colors.There is no need therefore to jettison the natural concept. Realizinghowever that the color properties are virtual properties means that,for our understanding of how such a concept should apply and why it isso beneficial. Part of this understanding is provided by theexplanation for why we have the natural concept that we do. Theexplanation for why the natural concept is beneficial is that thepurposes served by the concepts are equally well served if objectsmerely appear to be colored and are not actually colored.12. Colors as Phenomenal QualitiesGiven the virtual colors theory, there is a further problem that needsto be resolved: to explain how it is that the natural concept takes theform that it does, and in particular how it contains the basis for thestructure that underpins the color systems for ordering colors. One ofthe characteristics of the color properties captured in the naturalconcept is that colors are the sorts of properties among which a set ofinternal relationships hold. That is, colors as a block, have aqualitative, sensuous character that enables objects having them to besystematically ordered and arranged. There are no physical featuresthat have this character. One explanation for why this character ispart of the virtual color property is that our sensory representations(or the elements/aspects in our visual experiences) have thequalitative character. It is because the sensory representations havethe qualitative character that they do, that they represent physicalobjects as having the qualitative character in question. The way that the phenomenal concept, i.e., the concept of color as aphenomenal property is introduced is that it serves to explain why thenatural concept of color has the character that it does. When we havecolor experiences, typically we form sensory representations of theworld. These representations represent objects in the physical worldas having (virtual) colors, and they do so because the representationshave the character implicit in three-dimensional color arrays. Therepresentations do not have virtual colors (they have the right kindof structure, but they do not have the right causal powers), but theyrepresent physical objects as having those colors. Sensoryrepresentations, in other words, have the phenomenological characterthat physical objects might have had but do not.The qualitative character that the sensory representations have issensory and phenomenal in the strongest sense. The character isontologically subjective. In visual experience we experience thesensory color qualities as being in a public three dimensional space.That is, our experiences, and our sensory representations, representthe color qualities as being on the surfaces of physical objects, oras otherwise located in physical space. Contrary to what somephilosophers believe, there is no more problem in experiencingphenomenal qualities in such a way than there is in feeling a pain ina foot or an elbow. In the case of pains, the phenomenal quality isfelt on a bodily location, e.g., behind the eye, or in an elbow,etc. It needs to be said that although our sensory representationshave phenomenal color qualities, which we are aware of, we are notaware of them as phenomenal qualities, that is, as phenomenalqualities of physical objects. We use the sensory representations assigns for physical objects, but we are not aware of the sign as asign. It needs to be stressed that this account does not requirecolors, either phenomenal or virtual, to be projected into space. Justas they represent objects as having virtual colors, so they representobjects as having spatial properties (and relations) throughthemselves having phenomenal spatial properties.13. ConclusionIt has been argued an adequate account of color must, in the firstplace, provide an account of the folk concept or natural concept ofcolor. Such an account, there is reason to believe, is an illusiontheory of color. Supposing that colors, as we normally think of them,are virtual properties, we are faced with the question of how, if atall, should we adjust our ideas in thinking of colors. If normally ourperception of color involves ‘false consciousness’, what isthe right way to think of colors? The answer to that is that for manypurposes we should continue to think of them in the same way as wealways did. In the case of color, unlike other cases, falseconsciousness should be a cause for celebration. Although for most practical purposes, it does not matter that colorsare virtual properties, there are more theoretical purposes, however,for which we need to develop a more comprehensive account, a pluralistaccount of color. The different elements of the natural concept ofcolor reflect different functions that colors are meant to play. Giventhese different functions and the fact that there is no property thatsatisfies all of them, it is open to us to develop a pluralistframework in which different concepts of color take over differentfunctions. This pluralist framework makes room for the introduction ofobjectivist concepts of color, but such concepts need to stand besidea dispositionalist concept which makes reference to the way colorsappear to perceivers, and arguably, with the latter, a phenomenalconcept. It is such a framework that is necessary to give an adequateaccount of the rich epistemological and socially important roles thatcolors play.BibliographyAgoston, G. (1987), Color Theory and Application in Art andDesign, Berlin: Springer.Armstrong, D. M. 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(2005), Seeing, Doing and Knowing, Oxford:OUP.Maund, J. B. (Barry) (1991), ‘The Nature of Color’,History of Philosophy Quarterly, 8, pp.253-63.Maund, Barry (1995), Colors: Their Nature andRepresentation, Cambridge: Camb.University Press.Maund, Barry (2006), ‘The Illusion Theory of Colour: AnAnti-Realist Theory', Dialectica, 60: 245-68.Mausfeld, R. and Heyer, D. (2003), (Eds.), Color Percepton:From Light to Object, New York: Oxford University Press.McLaughlin, B. (2003), ‘The Place of Color in Nature’,in R.Mausfield and D.Heyer (2003)Nassau, K. (1983), The Physics and Chemistry of Color, NewYork: Wiley.Price H. H. (1932). Perception, London: Methuen.Ross, P. (2001), ‘The location problem for colorsubjectivism’, Consciousness and Cognition, 10, pp.42-58.Stroud,B. (2000), The Quest for Reality: Subjectivism and theMetaphysics of Color, New York: Oxford University Press.Thompson, Evan (1995), Color Vision, London:Routledge.Tye, M. (2000), Consciousness, Color, and Content,Cambridge, Mass.: MIT/Bradford.Van Brakel, J. (1993), ‘The Plasticity of Categories: TheCase of Color’, British Journal for the Philosophy ofScience,XL 44, pp. 103-35.Westphal, Jonathan (1987), Color: A PhilosophicalIntroduction, 1st ed., Oxford: Blackwell Publisher.Other Internet Resources[Please contact the author with other suggestions.] Related Entries concepts | Descartes, René | Locke, John | qualia | realism | reduction Copyright © 2006 byBarry Maund<jbmaund@arts.uwa.edu.au> |
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