Philosophy of Color
The philosophy of any live topic is a matter of puzzles and problems and debates about their solution. Philosophical debates about color go back to the ancient Greeks, e.g., to Plato, Aristotle, the early atomist Democritus, and many others, and they are still alive. One of the most important reasons why colors are of philosophical interest is that they raise serious metaphysical issues, concerning the nature both of physical reality and of the mind. Central among these issues are questions concerning whether color is part of a mind-independent reality or not and what account can be given of experiences of color.
The Scientific Tradition
Serious thinking about color raises important philosophical puzzles and questions. One of the major problems with color has to do with fitting what people seem to know about colors into what science, particularly physics, tells about physical bodies and their qualities. It is this problem that historically has led the major physicists, who have thought about color, to hold the view that physical objects do not actually have the colors people ordinarily and naturally take objects to possess. Oceans and skies are not blue in the way that people naively think, nor are apples red (nor green). Colors of that kind, it would seem, have no place in the physical account of the world that has developed from the sixteenth century to the twenty-first century.
Not only does the scientific mainstream tradition conflict with the common-sense understanding of color in this way, but as well the scientific tradition presents a very counterintuitive conception of color. There is, to illustrate, the celebrated remark by the eighteenth-century philosopher David Hume: “Sounds, colors, heat and cold, according to modern philosophy are not qualities in objects, but perceptions in the mind” . Physicists who have subscribed to this doctrine include the luminaries: Galileo, Boyle, Descartes, Newton, Young, Maxwell, and Helmholtz. Maxwell, for example, wrote: “It seems almost a truism to say that color is a sensation; and yet Young, by honestly recognizing this elementary truth, established the first consistent theory of color” .
People universally believe that objects look colored because they are colored, just as we experience them. The sky looks blue because it is blue, grass looks green because it is green, and blood looks red because it is red. As surprising as it may seem, these beliefs are fundamentally mistaken. Neither objects nor lights are actually ‘colored’ in anything like the way we experience them. Rather, color is a psychological property of our visual experiences when we look at objects and lights, not a physical property of those objects or lights. The colors we see are based on physical properties of objects and lights that cause us to see them as colored, to be sure, but these physical properties are different in important ways from the colors we perceive. 
The examples of authorities who say similar things can be multiplied, e.g., W. D. Wright, E. H. Land, S. Zeki, and R. G. Kuehni. It should be noted, in passing, that there is considerable variation in how the subjectivist component is expressed, with colors being variously described as sensations, psychological properties of visual experiences, mental properties, representations, constructions of the brain, and properties of the brain.
The Complexities of the Scientific Tradition
The traditional scientific thinking on color is more complex, however, than has been presented so far. Central figures such as Descartes, Boyle, and Locke think that there are no colors in the physical world – no colors, as people ordinarily and naively understand them to be. But they also speak of colors as secondary qualities, i.e., as powers or dispositions, in bodies, to cause experiences of a certain characteristic type. It is instructive to try to understand this dual position.
It was common for such theorists to make a distinction between colors as they are in physical bodies and colors as they are in sensation. And then, with respect to the first kind of color, they made a distinction between a philosophical way of thinking and the common, everyday way of thinking of such qualities (which Newton describes as “such conceptions as vulgar people . . . would be apt to frame”). As Descartes explains, the ordinary way involves the mistake of “judging that the feature of objects that we call ‘color’ is something ‘just like the color in our sensation’” or of believing that “the self-same whiteness or greenness which I perceive through my senses is present in the body.” The philosophical way of thinking, by contrast, is illustrated in his following remark: “It is clear then that when we say we perceive colors in objects, it is really just the same as saying that we perceived in objects something as to whose nature we are ignorant but which produces in us a very clear and vivid sensation, what we call the sensation of color” .
So, there is a way – a philosophical way – of thinking of objects as having colors. However, three things are important: (1) it is different from the ordinary way of thinking; (2) it involves a revision, or a reconstruction, of people’s ordinary thinking about color; and (3) it presupposes a notion of “sensation of color” or “color as it is in sensation.” It is crucial how this last notion is understood.
It should also be noted, however, that such theorists as Descartes, Boyle, and Locke sometimes wrote, as well, of colors in physical bodies as those features (“textures”) which grounded the associated powers/dispositions to induce the relevant experiences (sensations). Some commentators think that, in so doing, these theorists were either inconsistent or muddled or found it difficult to make up their minds. However, if Descartes, Boyle, Locke, etc. are in the business of revising or reconstructing ordinary concepts, there is no particular reason why they should not introduce several new concepts to replace the single old one, each one serving a different purpose.
For as Sound in a bell, or musical String or other sounding body, is nothing but a trembling motion, and in the Air, nothing but that Motion propagated from the Object, and in the Sensorium ‘tis a sense of that Motion under the form of sound; so Colors in the Object are nothing but a Disposition to reflect this or that sort of Rays more copiously than the rest; in the Rays they are nothing there but Dispositions to propagate this or that motion into the Sensorium, and in the Sensorium they are Sensations of those Motions under the Forms of Colors. 
Here, he writes of the colors in the object, colors in the rays, and colors in the sensorium, by analogy with sounds in the object, sounds in the air, and sounds in the sensorium.
The term color is commonly used in three distinctly different senses. The chemist employs it as a generic term for dyes, pigments and similar materials. The physicist, on the other hand, uses the term to refer to certain phenomena in the field of optics. . . Physiologists and psychologists often employ the term in still another sense. They are interested primarily in understanding the nature of the visual process and use the term, on occasion, to denote sensation in the consciousness of a human observer. 
One might wonder what unites these various senses of the color terms. Why, that is, should color terms be used to apply to each of these types of conditions or properties – the same terms for each? A plausible answer to this question is the following. If one is interested in the detailed causal mechanisms that underlie color perception, then there is good reason to be interested in different stages of the causal process in which objects cause experience of color: chemists and painters would be interested in the pigments, lighting engineers and physicists would be interested in the light-modifying features of objects, physiologists and psychologists would be interested in the cones and rods in the retinas, other physiologists and neuroscientists would be interested in other neural processes and pathways, and psychologists and philosophers would be interested in the experience of color and in how colors appear. What unites them all is that the theorist is interested, at each stage, in that feature of the stage that contributes to the perception of color, i.e., to the way colors appear.
Within the philosophical community, there has been a mixed response to the view expressed in this scientific tradition. While some philosophers share key aspects of the view, at least in broad terms and with certain modifications, there have been many who have rejected the view. There has been strong resistance from many philosophers, both to the eliminativist tendency within the scientific tradition and to the related subjectivism.
One form this resistance takes reflects the fact that each component of this traditional view is very puzzling. One response is to say that color terms – red, blue, purple, orange, yellow, green, brown, etc. – are in order; there are paradigms of colors to which the color terms apply: ripe lemons are yellow, tomatoes and rubies are red, and so on. There is no trouble, by and large, in learning these terms and teaching them in ostensive practices to children and others. Moreover, colors play a central role in so many of human social practices, such as painting, art, fashion, decoration, ceremonial, enjoying nature, etc. In the second place, it is hard to make sense of the claim that colors are properties of sensations or are psychological properties; if they are anything, they are, surely, properties of objects and light sources – of peaches and emeralds, of skies, of rainbows, of glasses of wine, of headlamps, and so on.
Qualities of the sensation
Qualities presented in sensation (or experience)
Qualities represented by the sensation
Each of these views has had, and continues to have, its champions. Some philosophers have argued that the first candidate makes no sense, that it commits something like a category mistake. It is interesting that one of the first to argue this way was not a philosopher, but the famous color scientist Ewald Hering . Not surprisingly, perhaps, there are other philosophers who reject this charge. One way to do so is to argue that the perceiver is not aware of the qualities as qualities of sensations, even though that is what they are.
One issue that complicates the debates is that psychologists have become increasingly reluctant to use the term “sensation.” For example, modern psychological texts, even ones with titles such as Sensation and Perception, tend not to use the term “sensation,” opting for “perception” instead. Indeed, in many of the situations in which traditional color theorists would have used the term “sensation of color,” modern theorists would use such terms as “perceived color” and “apparent color.” Interestingly, it can be found, in Newton, examples of both usages. In the famous passage in which he declares that the rays are not colored, “in them there is nothing else than a certain Power and Disposition to stir up a Sensation of this or that Color,” he begins by saying: “The homogeneous light and rays which appear red, or rather make objects appear so, I call red-making; those which make objects appear yellow, green, blue and violet, I call yellow-making, green-making, blue-making, violet-making, and similarly for the rest.”
A quality of the experience
A quality which is presented in the experience
A quality which the experience represents the object as having
Not only that, but, supposing that the experience does have representational content, there is a further question as to whether it has other features as well (ones that are open to introspective access). One view is that there are sensory qualities which are presented in sensory experience and which are “projected” onto physical objects. In this way, objects appear to have qualities that they do not actually have. Since this “projection” is not a literal one, it requires explanation of course, but its defenders think that it can be provided. On this theory, the sensory qualities presented in experience also form part of the representational content of the experience. This view is sometimes combined with color fictionalism, the view that ordinary color language is a language about properties which objects appear to have (but do not actually have). Objects in the world are such that “it is as if they have the colors.”
These debates raise questions about the strength of the argument against the reality of color. Consider the passage from S. E. Palmer, quoted in the first section. It is possible to see it as presenting an argument against the reality of colors. It takes the form: when objects are seen as colored, the objects are experienced in certain ways, they are seen as having certain qualities, but the objects do not have those qualities; the colors perceived are different from any the physical objects possess. There are two claims implicit here: (i) the colors objects are perceived as having – the “apparent colors” – a certain distinctive character, and (ii) the physical sciences have shown that no qualities with that particular character play any causal part in the perception of colors. From this, it is concluded that neither objects nor lights are colored in anything like the way they are experienced.
This argument depends on one’s being able to characterize the distinctive character of the “apparent colors.” Here is an important point on which philosophers divide. One group holds that it is obvious that this distinctive character includes a qualitative aspect, one that is familiar to common perceivers. It is by virtue of having this qualitative character that the various colors fit together collectively, in system of relationships of similarities and differences (a psychological color space). In this system, for example, orange is between red and yellow, resembling each, whereas it is not between blue and green, nor blue and red. Another group of philosophers, however, holds that any such qualitative aspect is no part of colors themselves, where the colors are the properties one’s experiences represent objects as having. (It may be part of the way colors are represented, rather than essential to the color itself. Think here of the difference between heat in a body and the way things are experienced as hot or cold.) The claim may be put as follows: (1) colors are certain properties, ones that objects look to have (appear to have) when one sees the objects; (2) the properties objects look to have are the qualities one’s experiences represent the objects as having.
Everything now turns on what theory of representation one can call upon. Once again opinions (“carefully considered positions”) differ. On one view, the qualities are ones that play the appropriate causal role in the production of the experiences of color. As a consequence, so it is argued, these qualities are ones that it requires scientific inquiry to locate. Accordingly, it is thought there are good reasons to think that surface colors of objects, for example, are spectral reflectances. On the other hand, another group of philosophers reject that theory of representation, arguing that the qualities represented are dispositional properties: dispositions to cause experiences of the right type.
Then again, there are other philosophers who defend a different version of color realism. They accept that the colors do have the relevant qualitative character, but deny that the scientists provide good argument against the reality of color. That is to say, they accept that the ordinary conception of color is of features with a simple, qualitative character, one that is typically revealed in color perception, but they deny that the scientific argument against the reality of such qualities is cogent. Contemporary defenders of this view appeal to the claim that colors are qualities that are supervenient on light-modifying features of physical bodies. The light-modifying features cause visual experiences, but, so it is argued, colors are qualities that are revealed in experience.
There is another argument against color realism, which has a long pedigree, but which has come to prominence in recent times. One of its strongest advocates has been C. L. Hardin . Any defense of color realism has to acknowledge and defend a distinction between real color and (merely) apparent color or between real color and illusory color. Any such distinction, however, needs to rely on a distinction between standard conditions and nonstandard ones and between normal, or standard, observers and nonstandard observers. Things which are really blue, say, are ones that will look blue to standard perceivers, in standard conditions. In other sorts of conditions, or to other kinds of perceivers, they may look to have other colors. If so, those other colors will be illusory ones, or “merely apparent” ones.
Hardin has argued that there is no way of identifying such conditions, and such perceivers, that is not arbitrary. A uniformly colored square, for example, will appear differently if the sides are, respectively, 2 cm, 10 cm, and 100 cm. And they will look to have different colors, when set against different backgrounds. The problem is even more pronounced in the case of standard observers. Competent human color perceivers divide into a number of groups that differ, for example, on which hues are instances of the unique hues: unique blue, red, green, and yellow. The differences are quite dramatic. Not only that, but there are significant differences between males and females, with respect to these abilities.
This kind of problem has led some theorists, e.g., Jonathan Cohen, to defend another form of color realism, a version of color relationalism . On this theory, color is a relational property, defined with respect to relations between the object, the environmental viewing conditions, and the kind of perceiver. On this view, there are no such properties as blue simpliciter, red simpliciter, etc.; there is only blue-for-perceiver kind A, in conditions C; blue-for-perceiver kind B, in conditions C*; and so on. It should be noted that although Cohen calls the account “realist,” it is a special type of realism. On this account, a whole host of relational properties are equally real.
There are other forms of color relationalism which have links to action-based theories of perception, as developed principally by the psychologist J. J. Gibson. A leading example is the theory defended by Evan Thompson, the Ecological View of Colors. On this account, colors are taken to be dependent, in part, on the perceiver and so are not intrinsic properties of a perceiver-independent world. Being colored, instead, is construed as a relational property of the environment, connecting the environment with the perceiving animal. In the case of the color of physical surfaces, “being colored corresponds to the surface spectral reflectance as visually perceived by the animal” .
Goethe’s Theory of Colors
This entry would not be complete without reference to the color theory of the famous German author Johann Wolfgang von Goethe. Goethe was deeply critical of Newton’s analytical approach and of his theoretical explanations of color phenomena . While mainstream color science has been mostly dismissive of Goethe’s attack, there are thinkers who find a positive side to Goethe’s work.
There are two aspects to Goethe’s critique. One is that he describes experiments that, he claims, contradict Newton’s theory. The second aspect is that he provides a set of observations that Newton’s theory does not, and cannot, explain. Additionally, he claims to provide an alternative explanation for these phenomena. H. Helmholtz, the nineteenth-century physicist and color scientist, rejected the criticisms of Newton’s science as based on serious misconceptions . First of all, Newton was well aware of some of the experiments described, and, more importantly, all of these experiments can be satisfactorily handled by Newton’s theoretical approach. With respect to the other observations, it is true that Newton does not explain them, but these phenomena are not ones that his theory is designed to explain. Nevertheless, Helmholtz praised Goethe’s descriptions, of both the experiments and the other observations, as accurate and important.
The issues are perhaps best brought out by a response to Goethe’s work, by the philosopher L. Wittgenstein . For a clear exposition, see an article by another philosopher, Zeno Vendler . Wittgenstein points out that Goethe, despite what he thinks, does not provide a scientific theory at all; his activity has a different nature. What he is doing is better described as providing phenomenological observations, i.e., observations of how colored objects appear and of the relations between those appearances, e.g., that yellow (of the fullest saturation) is lighter than red. The resulting propositions that emerge from this sort of activity are not ones that Newton’s theory is designed to address, but they are very important, nevertheless. (Whether they can be explained by Newton’s theory supplemented by neuroscience is not so easily decided.)
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