central role color plays in our lives, in visual experience, in art,
as a metaphor for emotions, has made it an obvious candidate for
philosophical reflection. Understanding the nature of color, however,
has proved a daunting task, despite the numerous fields that
contribute to the project. Even knowing how to start can be difficult.
Is color to be understood as an objective part of reality, a property
of objects with a status similar to shape and size? Or is color more
like pain, to be found only in experience and so somehow subjective?
Or is color more like what some have said about time–that it seems
real until we reflect enough, where we come ultimately to dismiss it
as mere illusion? If color is more like shape and size, can we give a
scientific account of it? Various strategies exist for this
option–taking the color of an object to be just a complicated texture
of that object, one that reflects certain wavelengths. Or perhaps
color is merely a disposition to cause experiences in us, as salt has
a disposition to dissolve. On the other hand, if color is more like
pain, and found only in subjective experience, what is the nature of
color experience? How, for instance, does an experience of red differ
from an experience of blue, or from an experience of pain for that
matter? Finally, if color is mere illusion, how do we continue to be
so taken in by that illusion and how can something unreal seem so real
and important to us?
There are just some of the questions that have been raised about
color, ones we will address in this article. Of course, this is only a
beginning, for it is not only the scientist or scientifically-inclined
philosopher that wonders about color. Accounts of color have been
given by anthropologists, artists, philosophers interested in
metaphysics, and many others. How their accounts go, and how they all
fit together makes for fascinating philosophy. This article will offer
an introduction to philosophical issues of color, with an eye to
exploring some of the answers that have been offered to some of the
puzzles. As always in philosophy, the discussion has to begin
somewhere, though it need not ever end.
1. Color, Philosophy, and Science
Many contemporary debates about color have their origin in the rise of
modern science. The emerging scientific picture of the 16th and 17th
centuries demoted color, sound, taste and other aesthetically
interesting properties to second-class status, according them the
pejorative title of "secondary qualities". Primary qualities, such as
shape, size, motion, and number, in contrast, seemed necessary and
sufficient to explain the behavior of physical objects and were
thereby countenanced by the new physics as the truly real. From the
perspective of physics, secondary qualities such as color were deemed
explanatorily idle, and thus at best were said to be present in bodies
only as complex structures of primary qualities, and so do not
resemble our ideas of them. At worst, color and the like were
dismissed as mere illusory appearances. Color would no more be in
objects than pain is. Either way, the world was seen as not colored–or
at least, if there is color in reality, it bears little resemblance to
the color we are so intimately aware of.
With this background, contemporary philosophers face a choice of
sorts. Should color be assimilated, on the one hand, to shape and
size, and thus accountable in a scientific manner, not requiring
appeal to sensory experience? Or, on the other hand, are colors more
like sensations of pain, and thus personal, subjective features of
experience? These questions trigger different responses, and so
determine numerous accounts of the nature of color. Early portions of
this article will examine the interplay between common sense and
science on the nature of color, with an eye to answering those
questions.
But philosophical issues of color are not limited to these debates.
Color plays such an important role in our lives, in so many different
ways, that it is not surprising that other issues should arise. We
will explore some of these as well. Like children then, philosophers
are fascinated by color. Unlike children, we have sophisticated
concepts and tools at our disposal to help us understand the mysteries
of color.
To begin let us ask, "Are physical objects, independently of
perceivers' experiences, colored? Again, were we to discard what is
found in experience, would it still be correct to say that objects are
colored?"
Realism about color, as understood here, maintains that yes, objects
are colored. In particular, Realism holds that objects are colored,
regardless of whether anyone is looking at an object, regardless if
the color is perceived. In so maintaining that objects are colored, we
are saying that the essence of color is to be found in the nature of
the objects that are colored, as opposed to being within the minds of
perceivers. Subjectivism, on the other hand, holds that it is false to
say that objects are colored. But even if objects are not colored,
surely there are experiences of color. And in this way we can find a
place for color, by including the perceivers and perception of color.
Subjectivism gets its name because of the role of the subjects of
experience, where color is now to be found. In saying that color
exists within subjective experiences of color, however, we need not
mean there is something arbitrary or illusory about color. Color could
be something that really does exist within perceivers, which can be
studied, measured, and explained.
As we articulate these positions more precisely, we will discover that
there are various ways to claim that objects are colored, just as
there are various ways to understand the claim that there are only
experiences of color. Due to limitations of space, we can only hope to
introduce the reader to some of the positions and complexities of the
debate, and hope that is enough to both satisfy one's initial
curiosity and to also spur one to learn more.
a. Realism
Realism holds that objects are colored. So does common sense. Science,
particularly physics, apparently threatens that view. For science
tells us, in the first place, that ordinary objects– trees, houses,
cars, are themselves just complexes of more basic items (atoms,
protons, electrons, quarks, and so forth). And in the second place,
these scientific objects are not colored. We thus seem on the verge of
paradox as we consider the following two claims.
CS: (Ordinary) objects are colored.
CP: Ordinary objects are bundles of basic scientific objects.
PS: Basic scientific objects are not colored.
(Though CP is clearly relevant to this discussion, it will not be
explored further.) What then should we say about CS, the claim that
common sense objects are colored, given the hard to deny threat posed
by PS, the claim that the physicist's entities are not colored?
Several strategies emerge.
i. Non-Reductive Realism
Non-Reductive Realism about color holds there to be no distinction
between what are called the primary and secondary qualities of
objects. Both types exist in the object just as they present
themselves. A red ball looks to have primary qualities (the shape,
size, mass, and so forth) and secondary qualities (the color, the
smell, the warmth, and so forth) and on this view, the object truly
does have both kinds of qualities. The color exists "cheek by jowl"
with the shape. Using some technical terms, we might say that on this
view, shape and color are both irreducible qualities; they are basic
and appear as they really are. In contrast, as we will see, other
versions of Realism will deny color exists as such a basic quality.
Instead, such views will reduce color to something more basic.
The motivation for Non-Reductive Realism, otherwise known as
Primitivism, is clear enough, namely to allow us to take seriously our
common sense view of the world, in which color plays an obvious and
significant role. But as we have said, the scientific view of reality
threatens common sense. On many fronts, science tells us to be
suspicious of our everyday, common beliefs. When it comes to color,
science typically seeks to explain our experiences of color by
invoking scientifically respectable properties, the ones that lend
themselves to mathematization, namely the primary qualities. In
schematic form, we are said to perceive red, for instance, because of
the shape and texture of a given object, which in turn reflects
certain wavelengths of light to our eyes, which then send electrical
impulses to our brain, resulting in the experience of color. More
generally, the thought is that we should attribute to physical objects
only those properties necessary and sufficient to explain their
physical behavior, and that this can be accomplished by reference
solely to the so-called primary qualities (hence their status as
"primary".) Since the property of red, for instance, seems to play no
causal role in our experience of red, it should not be included in the
list of properties that characterize physical objects. What does the
explaining instead is the texture of the object, the wavelengths of
light that are reflected, and so forth. Worse still, even if objects
were colored in the irreducible, or what we could call the occurrent
sense, it is not clear how that would help our perception of red
objects. For again, the mechanism used to explain the perception of
red makes use only of light, surface texture and the like. Color is
left as explanatorily idle and should not be said to be part of the
physical world. So goes the threat from science, as we have said.
How might the Non-Reductive Realist reply? One strategy denies that CS
and PS are truly incompatible. Each might be argued to be true in
their own way, and that therefore no problem arises. Why? Because 1)
common sense and physics, and thus CS and PS respectively, operate at
different levels of analysis and 2) there is no ultimately right level
of analysis, and so, 3) we are not forced to choose between them.
Consider another area where we do not feel the need to choose one
level of analysis over another. For instance, we accept explanations
of people's behavior by describing their beliefs and desires. Even
though we suspect that those beliefs and desires could (eventually) be
given a description at the level of brain processes, we do not think
we must appeal to that level in order to genuinely describe and
explain. So too a level of discourse that speaks of objects'
irreducible properties seems autonomous and respectable, even if there
is another level according to which there are not such colors. The
autonomy of this level then could withstand the encroaching scientific
perspective, allowing us to maintain both, if we like.
Of course, someone who takes science's dictates to be the ultimate
word on what does really exist–that science is the measure of all that
is, will not be swayed by these considerations. And for those
philosophers, they now must face that conflict between common sense
and science. But again there is possibility for reconciliation. This,
however, requires a reinterpretation of the claim that objects are
colored, one that makes use of the notion of reduction.
ii. Reductive Realism
Since the Modern era, scientifically-inclined philosophers have sought
a way to reconcile common sense claims with the philosophic-scientific
view that color plays no role in physical explanations, should not be
countenanced as basic, and thus is not in the objects in a basic
sense. Faced with the inadequacies of Non-Reductive Realism, and with
the general sentiment that our ontology should be given by science (or
at least not be inconsistent with our best scientific theory), we
might seek a scientifically respectable account of red and the like.
The hope has been to give a scientific account of these qualities by
showing them to be just complicated physical properties, that is,
primary qualities. If we can show how color is really just a
combination of say, complex, microphysical properties that
characterize the surface of objects, ones that cause certain
wavelengths to be reflected, we will have given an account of their
nature comparable to what has been done with observable shape, size,
weight, texture, motion and the like. Objects can be now said to be
colored, where that color now is understood as really just a complex
of physical, primary, properties. We will have reduced color to
properties and relations that do not include occurrent or basic color.
Our original conflict, then between:
CS: Objects are colored
PS: Basic scientific objects are not colored
disappears as CS is reinterpreted to mean that objects are colored in
a reduced, non-occurrent sense. Just as scientists have shown sound to
be nothing more than wavelengths in a medium, and shown heat to be
kinetic energy, a similar reduction has been proposed for color.
1) Physicalism
How exactly does this reduction go? One broad strategy, known as
Physicalism, seeks to reduce color to those physical properties
(primary qualities) sufficient to explain why we see objects as
colored in the basic, self-presenting, occurrent sense. But saying we
can give a reductionist account of color that appeals only to the
physical properties of objects and light is far from actually doing
it. And there are many obstacles to the actual reduction. Here is why,
in part: There are many, many different physical causes which, when
they impinge upon our highly sensitive visual system, yield the same
experienced color. Consider the color blue, and the many places blue
appears. It turns out there are drastically different physical causes
for the blue of sapphire; the blue of lapis; that of turquoise; from
blue dye to blue in the rainbow; the blue of water compared with the
sky; the blue on tv, compared with the blue of a bluish star. In
short, identity or even similarity in color of objects does not imply
similarity in physical structure of object. (Making matters worse,
similarity in physical structure does not even imply similar color
appearances. The same reflected range of light, but at different
angles of reflection, will make for different colors–this is part of
the explanation of the phenomenon of iridescence).
For simplicity, let us ignore the differing physical mechanisms that
explain the blue of the sky (dispersal of light), the blue of water
(reflection), and the blue of a rainbow (refraction). Instead, just
focus on the blue of ordinary objects. Can we give a reductive,
physicalist account of this blue, one that allows us to say the object
is blue, but in a non-basic way? Here is how one version of
Physicalism goes. (We have referred to this as "Reductive Physicalism,
but as we are noting now, this is but one of various forms of that
approach. We might think of the version about to be discussed as
Disjunctive Reductive Physicalism.) A given color is defined by
reference to the (micro)physical features that characterize the
surfaces of objects; features which are then responsible for
reflecting particular wavelengths to perceivers' eyes. What is a color
then? It is that complicated set of primary qualities which
characterize the surface of an object. Some surfaces are structured to
cause experience of red, some to cause blue, and so forth. The color
itself, of an object, is that surface structure, which can be
accounted for in physical terms–that is, describable by physics,
chemistry and the like.
An immediate problem arises, even for this simplified phenomenon. This
is the phenomenon known as metamerism, according to which different
combinations of wavelengths (in the same conditions) give rise to
identical color experiences. The reason metamers make things difficult
is that two objects can have very different surface textures–at the
microphysical level–and thus can reflect very different wavelengths to
perceivers. But these very different wavelengths can be experienced as
the exactly same color. For instance, light that is 100% 577nm (a
nanometer is a billionth of a meter) will appear as pure yellow. But
light that is composed of 50% 540nm and 50% 670nm will appear
qualitatively indistinguishable. Since different physical structures
can produce different wavelengths, all of which yield the same color
experience, it appears we are left defining color as the structure of
an object by saying:
Yellow= microstructure1 OR microstructure2 OR microstructure3 OR…
This is, in other words, a disjunction and yellow looks to be
definable as a disjunction only. There is apparently no single
physical property of objects, of wavelengths, of reflections of light,
and so forth. that all yellow objects have in common–let alone yellow
of non-ordinary objects like the sun, after-images, and so forth.
With these scientific facts in hand we approach the matter now as
philosophers. What should we say about the reduction of a property, in
this case, a color, to a disjunction? Consider various problems
raised. First, if the list of conditions that characterize yellow (or
any color) is infinite, as it might be, then it hardly seems that we
have reduced color. Even were it just a long finite list, as seems
equally possible, we also might object to the claim that such
disjunctive properties are real properties at all. Most troubling,
however, is that there does not seem to be a unifying physical
condition which explains why these all are instances of yellow. The
only thing that explains why these various physical conditions are
yellow is that they cause experiences of yellow. Thus our seemingly
perceiver-independent account of color actually seems to require
reference to perceivers. For without perceivers of color in the
picture, we no way to explain why some physical conditions are yellow
and some are not. And that leaves us with the disturbing sense that
our list of physical conditions is just a hodgepodge, a gerrymandered
set of properties, not a genuine explanatorily useful reduction. And
while there are other ways to develop such Physicalism, the problems
we have outlined have sufficed to send philosophers looking elsewhere
for an account.
2) Dispositionalism
Failing to find a single (micro)property that explains an experience
of a certain color, while still hoping to reconcile the claim that
objects are colored with the scientific claim that color is not basic,
philosophers have hit upon another reductive strategy. John Locke is
usually credited here as the originator of this Dispositionalism, as
he writes,
"Such qualities, which in truth are nothing in the Objects
themselves, but Powers to produce various Sensations in us by their
primary qualities, that is, by the Bulk, Figure, Texture, and Motion
of their insensible parts, as Colours, Sounds, Tastes, and so forth.
These I call secondary qualities." (Locke, An Essay Concerning Human
Understanding. Bk.II, Chpt. VIII, §10.)
To appreciate this claim, recall that we are still looking for a
reductive account of color, but as well, have rejected Physicalist
attempts at reduction. With that in mind, we might step back and
notice that the Physicalist account of color was given by focusing
largely, if not completely, on the object itself, leaving aside our
experience of color–what it is like and how it might play a role in
understanding color. Perhaps the absence of even a reference to
experience is the source of the trouble. For certainly our motivation
to understand color itself comes from reflection on our experience of
color–especially as we put that alongside an account of reality that
tells us to be suspicious of our common sense experiences of the
world. Maybe we will do better by approaching the nature of color with
a role for the fact that color is an experienced quality. With this in
mind, we might develop an account of color that brings out the extent
to which the particular nature of color is linked with experiences of
color, though the color itself is still said to be a property of
objects.
To develop this account, philosophers draw attention to the following
true biconditional:
(C): x is red if and only if x appears red under standard conditions.
Red objects, that is, appear red in standard conditions (to normal
perceivers), and if an object appears red to a normal perceiver, in
normal conditions, then that object is red. What explains this? Here
it is claimed that C is true because of a deeper truth about color,
namely, that the color of an object just is the disposition of that
object to appear red. Let us call this DC, and let it be the
Dispositionalist's definition of color.
(DC): x is red = x is disposed to appear red (to normal perceivers
in standard conditions).
Of course, there are also corresponding biconditionals for shapes of
objects. Examination of their different status will make clearer the
goal and nature of Dispositionalism. Consider then,
(S): x is square iff x appears square under standard conditions
(to normal perceivers)
This too is true, but does not entail a parallel treatment of square's
essence. For we will not accept,
(DS): x is square = x is disposed to appear square (to normal
perceivers in standard conditions).
The reason we will not move from S to DS is instructive. For when it
comes to such properties as being square, we believe that an account
of its nature can be given by simple appeal to an objects' physical
properties, without appeal to how it appears to perceivers. We have no
temptation to give a dispositionalist account of square for the
essence of square. In contrast, color can be thought of as a property
of physical objects, but only in a thin sense, namely, the disposition
to cause in us certain experiences. Which experience? The appearance
of the very color in question.
The merits of this account are numerous. First, we have found a way to
keep our common sense claim, CS from above, though with a
reinterpretation of CS. Objects are colored, though not in a basic
sense. Second, we now also have room to take seriously the dictates of
science according to which the basic entities of reality are not
colored. What we can say is that if those basic entities are put
together in suitable ways, ordinary objects come to have certain
powers or dispositions, namely in this case, to cause experience of
colors such as red. This makes for another merit. Objects can said to
be red, or blue, and so forth, and we can distinguish veridical from
non-veridical perceptions of color. One might experience a truly blue
object as green, because either the viewing conditions are not
standard (for instance, in certain kinds of light), or because
something is amiss with the perceiver. In the second case, the
perception was not veridical, for there is a way the object really is
colored. This allows, in other words, for intersubjective agreement
about the colors of objects, and thus keeps color from being purely
subjective or relative. Finally, we can say that objects do have their
colors even when not being observed, or even when they are in the
dark. For even in the dark, objects do have the disposition to appear
certain ways, and of course, that is what we are saying color really
is. In this way color is said to be real, as we want when considering
the matter from common sense. Yet in another sense, color is relative
to a perceiver–for an object only has a disposition to appear red–and
the experience of red, for instance, does require a perceiver, and an
element of subjectivity. The total package then is a nice blend of
objective and subjective elements, and for many is just what we should
expect from a good explanation of color.
In sum, these features have made Dispositionalism a tempting and
popular position. We now explore some objections to this view, leaving
it to the reader to decide for themselves whether or not these
objections are compelling.
It is often complained against Dispositionalism, for instance, that
colors do not look like dispositions. They look like basic, occurrent
properties, just like the shapes of objects. How then, it is
questioned, could color really be a disposition, if it does not look
like one at all? Here we might expect the Dispositionalist to ask us
to specify exactly how we would expect a disposition to look in the
first place. The Dispositionalist will then argue that once we
actually figure out how we would expect color as disposition to
appear, we discover that that is just how colors do appear. For
example, if color were a disposition to appear red in standard
conditions, then in standard conditions, a red object would look red.
And is not that just what it does look like?
Perhaps more troubling, however, is that Dispositionalism seems
circular. What is red? A disposition to appear a certain way. Which
way? To appear as red, of course. Red, then, is a disposition to
appear red. If "red" is being used the same way here, then we have
explained "red" by reference to "appears red". That seems
straightforwardly circular, and thus problematic. Interestingly, some
philosophers have taken this to be a serious problem, while others
have suggested it is a harmless and even expected result. After all,
they say, we have wanted an account of color that appeals to our
experience of it. Thus the only way to explain what red is is to
describe our experiences of red. In this case the circularity is not
threatening, but simply an indication that our desired account of
color required appeal to the experience of color to make sense of it
in the first place. That, again, was what made explanation of red
different from explanation of shape. On the other hand, circular
accounts do not provide much information, and as such we might still
wonder what we have really learned about the nature of red, if that is
just a disposition to appear red.
Finally, some have worried that if color is a disposition, we are now
incapable of explaining why we have experiences of color at all.
Consider this parallel. We can taste the saltiness of a pretzel. Why?
Because the pretzel was salty. And the salt has a disposition to
dissolve and cause experiences of tasting salty. But it is not the
disposition to dissolve that is responsible for the taste of salt. It
is the non-dispositional properties of salt that both cause it to
dissolve and which cause the taste of salt. Again, it is not salt's
dispositions that cause our experiences of salty taste. It is the
non-dispositional properties that ground that disposition. In fact, we
say that what is essential to salt is whatever properties explain
those dispositions, and it is those more basic properties that do the
causing. So too it might be said for color. Dispositions do not cause
anything, but rather the ground of those dispositions does. Color as a
disposition cannot cause a perception of color. Instead, it must be
the non-dispositional ground that causes experiences of color. But
that means we have located color in the wrong place. Instead of
speaking of color as a disposition, it now seems we should be
considering the ground of that disposition to be the heart of color.
And that might take us away from Dispositionalism and back to
Physicalism, with all of its problems. Or maybe not, as some
philosophers have sought here a third way.
As noted, these discussions of different kinds of Realism have only
skimmed the surface. The broad strategies we have outlined, of course,
can and have been developed in quite a number of different ways.
Enough has been said, however, to both give a sense of these positions
and to show the need some have felt for a completely different
approach. We turn to that now, the broad strategy we have designated
as Subjectivism.
b. Subjectivism
Recall that conflict between science and common sense over the status of color.
CS: Ordinary objects are colored.
PS: Basic scientific objects are not colored.
Our discussion of Realism has been an extended exploration of this
conflict, with focus on preserving the truth of CS and common sense.
Let us now cease attempting to reconcile these claims, and simply
reject CS as false. Common sense is just wrong, we might claim.
Objects are not colored in any sense, reduced or not; and thus we are
free to embrace a scientific ontology which does not include color
among the basic properties of its basic entities.
Common sense is wrong then, but it certainly does not seem wrong. The
world presents itself as colored, afterall, and if it really is not
colored, we are owed at least an explanation of how we could have been
so wrong. Here is where Subjectivism gets its name and appeal. For
while the world itself has no color, there are undeniably experiences
of color. And while we will need to give a philosophical account of
those experiences, we can say for now that color is subjective in the
sense of being perceiver dependent, just as pain is. Objects can be
round or square, but they are not colored. Since it does not make
sense to say objects have the properties of pain and pleasure, we say
that pain and pleasure, instead, are merely types of subjective
experience. Those experiences may be caused by physical objects, but
the qualities of pain and pleasure are in us, not in the objects. So
too we may say for color.
In thus locating color within perceptual experience, we make it
perceiver dependent, and thus, in some sense, cease to view color as
part of the objective world. How we choose to account for experience
itself, however, will give us different versions of Subjectivism.
i. Mentalism
Let us call any position that posits color as a genuine property of
subjective, personal experience, a version of Mentalism. The
inspiration for this view is Descartes, who thought that color and
other secondary qualities were merely sensations, and as such, mere
occurrences within a mental substance. The parallel again with pain is
instructive here. Pain and color, then, occur in a substance that is
also the locus of thinking. As occurrences in a mental realm, they
fall outside the scope of the physical sciences that study material
substance.
Contemporary philosophy, however, has had little sympathy for this
kind of substance dualism, whereby two distinct types of substances
exist side by side. Not only does this mental substance fall outside
the scope of the physical sciences, difficult questions about the
connection and interaction of these independent substances arise. As
we will see next, some have left the letter of mental substance
behind, while retaining the spirit in a related, but slightly less
problematic metaphysics, one that comes in handy when accounting for
the nature of color.
In the earlier parts of the twentieth century, philosophers made much
use of a special class of entities dubbed, sense-data. These are a
class of particulars, or individuals, which have existence only in
minds. They are often held to be private, special objects, of which
each person has direct, infallible access to and knowledge of.
Knowledge of sense-data in turn allegedly provided foundational
knowledge on which all other knowledge rests. As for sense-data
themselves, they were introduced to explain the appearance of
perceptual qualities when there were in fact no such qualities in the
physical objects one is perceiving. In a famous example, one could
explain a perception of an elliptical coin, when presented with a coin
that is really round, by claiming that the actual object of experience
is an elliptically-shaped item (an elliptical sensum), which one
experienced directly. Sense-data would be the bearers of properties we
take physical objects to have, and so could explain the possibility of
perceptual error.
With this metaphysics in hand, color can now be categorized as a
property of such sense-data. Though the physical world may lack such
properties as color, the world causes each of us to have experiences
and present in such experiences would be special, private, mental
entities that have the qualities in question. Presented then with an
apple that really is not red or sweet, we have experiences of red
sensa; sweet sensa, and so forth. We thereby account for the existence
of such qualities–having them qualify these subjective, perceiver
dependent entities, and we also explain our belief that the world is
colored. We think there is color, because in fact there is, though we
mistakenly believe the color of sense-data is really to be found in
physical objects.
Sense-data themselves, however, have fallen on hard times, especially
since the middle of the twentieth century as various philosophers
objected both to their nature and the epistemological role they were
to play. Though many are now reluctant to speak of sense-data as a
class of particulars, some contemporary philosophers have preserved
some of the functions of sense-data, and now speak of qualities that
characterize our visual field, or perhaps that qualify our mental
states or mental events. Color on this understanding is categorized as
a "phenomenal property", maintaining the Cartesian legacy that such
properties are mind-dependent and subjective, but in a way that frees
them of excessive ontological baggage.
ii. Eliminativism
In opposition to Mentalism, but still within what we have called
Subjectivism, lies another popular position, Eliminativism. This view
agrees that objects are not colored, but it does not wish to trade the
color of objects for color as now an irreducible property of something
inner or mental. Instead, it wishes to rob color of any ontological
significance at all. We can still speak of our experiencing color, of
course, but we are not to understand this as claiming that color does
really exist, only now as a property of mental substance or of
sense-data or of our visual field. Color experiences themselves, we
could say, are to be reduced to non-color properties, just as
Reductive Physicalism sought to reduce the color of objects to
non-colored properties and relations. For Eliminativism the reduction
of color experiences is to be to properties and facts about our visual
processing systems, facts about the behavior of rods and cones, about
transmission of information along neural pathways and the like. (We
will explore some of the details below in our discussion of the
universality of color experience.) In the end, nothing, anywhere,
answers to our common sense description or account of color. That type
of property just does not exist.
Put positively, Eliminativism can be understood as follows. Our
experience of a seemingly colored world is the result of a systematic
error. Simply put, we take features found in our visual experience and
project them upon the world, mistakenly believing that color is "out
there"–when in fact color is but subjective response to an achromatic
reality. This Projectivism about color does not deny that this is an
important projection, or that it might help us navigate the world more
easily, or that we can continue to speak of the world as colored, but
it does point out the fundamental error nevertheless. An analogy might
help, and in fact much recent philosophy has involved discussion of
the aptness of the following analogy.
In ordinary moral discourse, we are inclined to speak of an action as
moral or immoral, right or wrong. We seem in these cases to be
claiming that a particular act has (or lacks) a special, moral
property or nature. Taken literally, though, such predication would
commit us to the existence of rather strange properties, that is,
rightness and/or wrongness, ones that are not easily described or
explained. Wanting to avoid commitment to those properties, some have
suggested a similar projectivist account. In this case, certain
actions create in us feelings of pleasure or pain, approval or
disapproval. We project these attitudes upon the world, taking the
world to really have such properties, when in fact they are nothing
but subjective responses. (Talk of "projection" in the psychoanalytic
sense is another helpful parallel, where again, something "inner" is
mistakenly claimed to be found "outside" us.)
Such Projectivism, as one way of developing Eliminativism, clears the
road for a fully scientific account not only of objects, but now of
perceivers as well. In particular, only properties that can do genuine
explanatory work will be included, and color will be sorted into the
group of properties that contribute nothing to our understanding of
causal relations between objects and perceivers. There is a downside,
however. Besides indicting common sense as systematically wrong, we
are bound to be left with a nagging feeling that a most treasured
property has completely disappeared. This has provoked some to reply
along the following lines: "We started with a belief that objects are
colored. Having reduced physical objects to items with only primary
qualities, we were left to relocate color and similar qualities within
perceivers. Now, however, we have made perceivers and their
experiences also bereft of secondary qualities. Without color in the
picture at all, we fail to explain how we thought there was color in
the first place. How can we explain the appearance of color, our
experience of color, now that color is nowhere to be found?"
This question might lead one to rethink the steps that led to this
puzzling conclusion, and to raise the possibility that a mistake was
made along the way. If so, where exactly did we go wrong, and what
would be a better route? If not, how exactly then do we come to
believe there is color, if it appears nowhere in our account of
reality and perceivers? These difficult questions explain why
philosophers continue to debate this interplay between what common
sense says about color and what science would have us believe.
2. Color and Metaphysics
One should not conclude that the only philosophical questions about
color involve science. The remaining portions of this article offer
introduction to other important and exciting issues. In particular, we
turn to some questions of metaphysics, and then turn to ones about the
universality of color experience, questions that get at the heart of
the nature of color from other perspectives.
To begin, consider how much energy we have devoted to explaining the
color of objects. Is the color of an object a basic property, a
disposition, a combination of micro-primary qualities? Let us pause,
however, and ask about color itself. What exactly is color in the
first place? What is the essence of this quality that is capable of
being a property of objects, or a property of sensations, and so
forth? (We can also ask, of course, "What is a quality? And what is
the difference between qualities that are colors and those that are
sounds?) Focusing our attention on a specific color seems to make
things even harder. Consider the questions, "What is the essence of
red?" "What is the difference between red and blue"? How do we even go
about answering them? Let us explore some attempts.
a. Color Skepticism
Faced with such as question as, "What is the essence of red?" one
might respond by pointing to something red, or by looking for a
metaphor, claiming that red is like a trumpet sound. The first does
not tell us much though–in fact, pointing at a red ball does not
suffice to even indicate the redness as opposed to the round shape.
Similarly, though metaphors might help convey something about the
experience of red, they tell us little about the nature of redness.
Can we do better? Can we actually articulate the nature of individual
colors? Can we even say what colors in general are, in a rich,
philosophically satisfying manner?
One possible source of the prima facie difficulty is that we tend to
think that the red we experience is something essentially private and
subjective. We are drawn to a picture whereby the essence of red, or
blue, or yellow for that matter, is given in sense-experience, where
the experience itself is something ineffable. Just as it is hard, if
not impossible, to articulate what a pain feels like, we may think
that the qualitative difference between blue and red is similarly
inexpressible. Let "color skepticism" be the view that the essence of
color is ineffable, and let us explore the merits of such skepticism.
One source of the supposed ineffability of color, as we have seen,
lies in the belief that color's nature is revealed only in private
experience. The language of color, and language as a whole, however,
is public in the sense of both being suitable for reporting public
events and learnable by appeal to public objects. How then could the
allegedly private, subjective nature of color be reconciled with the
public, intersubjective nature of language? Color skepticism gains a
foothold here, for it seems it cannot. As a result, we are tempted to
conclude that our experiences of color are akin to pain in being
private, personal and ineffable. No surprise that many have been led
to wonder whether the qualitative experience they associate with, say,
red, is the same for each person, or instead, whether it is possible
that what I experience as red, you experience as green, though we both
use the same public word, "red". Such color skepticism leads to this
familiar problem, the Inverted Spectrum. At its worst, we imagine that
all of our color experiences might be systematically different from
another's, though we all use "red" to refer to the color of
firetrucks, "yellow" for the color of bananas, and so forth. In this
case, each of us is trapped within our minds, forever cut-off from
truly sharing our experiences of things that matter dearly to us.
How we might extricate ourselves from this depressing, solipsistic
trap? One route is to rethink our starting point, namely that there is
nothing more to say about red than pointing to red objects or
reverting to metaphor. As an alternative, some have sought to
articulate the metaphysical nature of color in a surprising
direction–by understanding the intrinsic features of individual colors
as a product of their relations to other colors. These relations are
known as "internal relations" and to them we turn.
b. Color and Internal Relations
First we need to distinguish such internal relations from so-called
external relations. External relations are ones in which the relation
plays no role in making the relata the relata that they are. For
instance, my glass of water is externally related to the table. The
relation, 'being on top of' is external in that it is not part of the
nature or essence of the glass or table to be in that relation. Were
the glass and table to cease to being so related neither will undergo
a change in their nature. They will not cease to be the things they
are. The relata here are external to each other in the sense of not
depending on each, or the relation, for their identity.
In contrast we have internal relations. For internal relations, the
relations are essential to the being and nature of the related items.
Without that particular relation, an entity would not be the thing
that it is. To say that colors are internally related to colors would
mean that the natures of individual colors depend on the relations
those colors have to other colors, to other members the color-array.
Orange is related to red and yellow in a particular, unique way, for
instance. That relation therefore helps make orange the color it
is–that relation as well as the other ones that orange bears to other
colors. No other color has those particular relations, and thus no
other color is orange. Put differently, orange would cease to be
orange were it to not have that relational structure to other colors.
(Another example is numbers. Seven would not be the number it is, for
instance, were it not between 6 and 8.)
To speak then of a particular color requires reference to its
relational place within a color array. What is the nature of the
relation between colors? Most abstractly, it is that relation which
includes only colors. More specifically, we might say that it is the
betweenness relation colors bear to one another. Orange, for instance,
is between yellow and red, while green is between blue and yellow, and
so forth. Such betweenness relations capture the essence of color.
Taken as a whole, these complex betweenness relations can be modeled,
allowing us to understand the logical structure of the entire color
array. And though many models have been proposed, one particularly
illuminating one captures these betweenness relations by modeling
color's structure on that of a double cone. (We can even now speak of
the difference between different types of qualities by talking about
their different spatial models–color is nicely modeled on a double
cone, sound perhaps by a spiral staircase, with each octave recognized
as another turn on the staircase.)
The following diagram helps illustrate the structure of color, making
use of the HSL (hue, saturation, lightness) model. We can even use it
to spell out in some detail a claim about a particular color's nature
and its betweenness relations.
Relying as we have on internal relations might seem paradoxical. On
the one hand, each color has its proper place within the color array
because of the particular color it is. On the other a color is the
particular color it is because of that place within the color array.
This suggests colors have their intrinsic properties because of their
relations–as opposed to saying they have the relations they do because
of their intrinsic property. But what could be plainer than saying red
is what it is because of its intrinsic properties? The intrinsic
nature of color, we might object, is prior to any of its relations and
it is that essence we should try to articulate. Have not we forgotten
this important point? Have not we ignored the intrinsic nature of
color, and thus what is most important about color in the first place?
In reply, it is acknowledged that this account of internal relations
does appeal to the relations a color has to other colors in order to
individuate it. But, crucially, that does not make the relations
conceptually or ontologically prior to colors' intrinsic properties.
For to make sense of the particular relations a color has we have to
return to the relata, the color itself. A color has the particular
relations it does because of the color it is, just as we want to say.
The difference is that on this story, the relata and the relation are
intimately and necessarily involved. The relationship and dependence
goes in both directions. We are talking about internal relations here,
after all. As such, the relata and the relation figure as essential
elements. Both balance each other, making both important, but neither
prior. That is what is so special about internal relations. In
conclusion, we can now say that we have still paid proper respect to
the intrinsic nature color.
With this account in place, perhaps we finally have an answer to the
color skeptic. We now have something, in fact a lot, to say about each
color. True, we need to speak of other colors to explain what a single
color is, but we have gone well beyond mere pointing or metaphor. We
say what a color is by talking about how it relates to other colors,
about its color relationships, its intrinsic properties that make for
those relations, and those relations that make for those properties.
If that is not good enough to satisfy our skeptic, we might begin to
wonder whether the skeptic is willing to be convinced.
3. Is Color Experience Universal?
A final issue we will discuss in this article concerns the
universality of color experience. We have already seen one threat to
the notion that we all experience color the same way, namely the
possibility of an inverted spectrum. A deeper threat comes from
another direction, this time borne from wondering about the connection
between language and perception. An important theme in the background
of this threat lies in the rise and development of a view according to
which our perceptual experience is mediated by our language. This has
been an important strand in post-WWII philosophy, and as such draws on
various themes that fall far outside the scope of this article. We can
gain enough of an appreciation of the issue by considering for
starters a relatively uncontroversial sense in which our familiarity
with a concept influences what we see. To use a well-worn example, a
physicist looking at a technical apparatus in a lab sees, in some
sense, something different that what the layperson sees and
experiences. In this way, different concepts can play some role in
what is seen. We move from this innocuous example to tougher ones when
we wonder whether different cultures that have completely different
languages experience the same world. Or, instead, do the different
linguistic resources they bring to experience give them experiences of
quite different worlds? It is not hard to be swayed to a perspective
from which we see such different languages as yielding very different
worlds of experience. Now take these general questions and apply them
to experiences of color. Would speakers of languages that have
different color terms see the world differently, see different colors?
a. Linguistic Determinism
A particularly strong version of the view that language influences
perception was advanced by the anthropologists, Whorf and Sapir. On
their view, language plays such an essential role in perception that
cultures that use different language can be said to inhabit quite
different worlds. What we all see, what we take ourselves to touch, to
conceive as real, is a function of language. Vary the language and you
change the world experienced. Dubbed the thesis of Linguistic
Determinism, this view clearly has interesting implication for color
experience once it is realized that there is great diversity in color
language across cultures. There are well-documented languages that
have only 2 color terms, or three, or only four, and so forth.
What then would Linguistic Determinism have us expect for people who
speak a language with only three color terms, for instance?
Presumably, if that thesis of determinism is correct, those people
would experience only three colors. We would expect these people to
simply not be aware of the colors we have terms for; they would fail
to make the color discriminations we make, and they would organize
their color field in very different ways than we do. This hypothesis
was put to the test in the 1960's by the researchers, Berlin and Kay.
Compiling data from a great number of languages, their results seem to
contradict the Whorf-Sapir thesis and open a whole range of questions
and interesting debates
b. Berlin and Kay
To help appreciate the significance of their findings, we need to
distinguish a color's "foci" from its "boundary". When presented with
an array of color samples (such as ones found at a paint store) we can
ask how many of those samples are properly called by a certain color.
We could ask, that is, how many of these samples are appropriately
called "red", and where do we draw the line between samples that are
red and those that are not? To answer these questions is to speak of
the red's boundary. We might also ask about what is the best sample or
paradigmatic sample of red. This is to ask about red's foci, or more
generally, to look for focal samples.
Berlin and Kay found, quite interestingly, that though there are
differences across cultures of color boundaries for shared color
terms, there was significant consensus on what counted as a focal
color–even across languages with very different numbers of color
terms. So, in a culture that had only three basic color words, say
ones for "white", "black", and "red", people in that culture would
point to the same samples as the foci for each of these colors as
people with 11 basic color terms, such as English speakers. What they
consider as truly red, or white, or black, would be nearly the same
samples that we do, though we carve up the world with many different
color terms. Prima facie, this suggests something quite other than
Whorf-Sapir would have us expect. Something besides color vocabulary
seems to be at work in our experience of color. Why else would we all
gravitate to the same samples, when for some what is red would
presumably include many more colors than us? After all, with only
three terms to cover the whole range of color, many more things would
have to be called "white" or "black" or "red" in this example. Why
would certain samples stand out, even when so many other things are
conceived and experienced as red?
In addition, Berlin and Kay found that languages exhibit great
similarities on which color terms they have; and great similarities in
the relationships between differing numbers of color terms. The
following graph summarizes their results, where movement from left to
right indicates what color terms would be added as a language
increases its number of terms.
Here we see that if a language has two color terms, the terms are
"white" and "black". If a language has a third term, it is "red"; if
more than three, then either "green" or "yellow"; and next the other
"green" or "yellow" term; and so on. This suggests, as they
interpreted it, a development suitably conceived as evolutionary. Thus
if a language evolves from two colors to three, the one it will add
will be "red", then "green or "yellow", and so forth.
What is the philosophical significance of these findings, if true?
Simply put, they again suggest that there is something other than
language that determines what colors are seen. Berlin and Kay conclude
that there are universal, non-trivial constraints on color terms.
Color experience is not simply a function of a language's terms and
arbitrary conventions. Instead, there seems something about how the
world is that causes different speakers to experience certain colors
as best samples, to develop terms for "red" before terms for "brown",
for privileging "white" and "black" over "pink", and so forth.
If not language, what would explain these findings? One answer comes
from facts about the biology of color perception, facts about how our
visual system processes certain kinds of electromagnetic radiation,
that is, light. (These are the very facts our previously discussed
"color-eliminativist" might offer to show that there really is no such
thing as color, that is, might make use of to reduce color experience
to facts, properties, and relations that make no mention of color at
all. Thus what follows can be called upon to serve two
functions–explain similarity of color experience across language, and
also be used by a color eliminativist to reduce away color.
Importantly, these issues are logically independent, and a solution to
one problem need have no bearing on the truth of the other.)
Here is a quick summary of the proposed biological account. Our visual
system includes rods and cones. Cones are responsible for color vision
and do so with three different types of cones. Two of these cones
operate according to what is known as opponent-processing. For these
two types of cones, they each have two cells, one which has its rate
of firing increase when hit by a certain range of light and decrease
when another range of light hits it, and a second cell that operates
just the opposite way. For example, there is a cell that maximizes its
output when hit by light around 610nm and is at its lowest output
around 500nm. It sits alongside another cell that works just the
opposite–its maximum is around 500nm and its lowest is at 610nm. (Call
these our Y+B- and Y-B+ cells, respectively.) Thus when the cone with
this cell package is hit by that 610nm light, there will be a pure,
highly stimulated response as the Y+B- cell will be at its highest,
and the Y-B+ cell will be at its quietist. 610nm happens to be the
range of light we call yellow; and thus when this cone is hit by that
light, it will give its purest, most intense output of energy. Yellow
will be experienced, in other words, in a pure, intense manner. But
when the received light is at around 440nm, this Y+B- cell is at its
lowest output, but its partner, the Y-B+ cell, is at its highest
output. Blue then also can appear as a particularly strong, pure
color. Other places where we get these pure peaks of cell stimulation
occur at 520nm and 660nm–the very ranges that correspond to green and
red respectively. Here we can speak of our R-G+ and R+G- cells. (White
and black have their own cells, but these do not work in opposition to
each other, so both the black cell and the white cell can be activated
at the same time, yielding experiences of different shades of gray.)
This all suggest that any person with a normal operating visual system
is going to experience certain ranges of light with intense neural
stimulation which happen to correspond to the four basic colors:
yellow, red, blue, and green (yes, green is a primary color when it
considering our visual system.) And it also explains why no one seems
to experience reddish greens–for when the "red" cell is active, the
"green" cell is not. We can only have one or the other, and not both.
Further, these facts might be able to explain why different speakers
in different languages hone in on the same color samples–because for
everyone these samples trigger the same intense cell stimulation. Our
shared judgments about focal colors, as well as why all people
gravitate towards certain colors in a similar order, now seem
explainable. And the explanation goes beyond what language creates,
contrary to Whorf-Sapir.
To be sure, there are many questions left–such as why it is that red
always is the first color to appear in languages after "white" and
"black" even though other colors trigger similarly intense responses.
So too have Berlin/Kay's results been subjected to many criticisms and
objections, from the philosophical to the methodological. What emerges
then is a fascinating debate the ranges across numerous disciplines.
In a way, that seems most proper and fitting. For color appeals to all
who can see it, and it makes sense to suppose that we are still drawn
to color, whatever our intellectual interests, just as we have been
since we were kids.
4. References and Further Reading
a. Overviews and General Discussions
Berlin, B., & Kay, P. (1999). Basic color terms : their universality
and evolution. Stanford, Calif: Center for the Study of Language and
Information. The landmark book that summarizes their cross-cultural
findings of color terms, boundaries, and foci.
Byrne, A., & Hilbert, D. R. (1997). Readings on color. Cambridge,
Mass: MIT Press. This two volume set contains a wide range of
important article on various issues on color. Volume 1 is on the
philosophy of color, and the second volume on the science. Besides
containing numerous landmark articles, there is a detailed
bibliography and glossary of terms. A must have set for those wishing
to explore the various debates in more detail.
Kay, P., McDaniel, C. "The Linguistic Significance of the Meaning of
Basic Color Terms". Language, vol. 54, 1978, pp.610-46. Provides a
biological based explanation for the anthropological findings in
Berlin/Kay.
Harrison, Bernard. (1973). Form and Content. Oxford: Basil Blackwell.
An extended discussion of what we have called "color skepticism", with
a detailed account of color as a system of internal relations. Covers
many issues in a careful, interesting manner.
Wittgenstein, L., & Anscombe, G. E. M. (1978). Remarks on colour.
Oxford [Eng.]: B. Blackwell. An interesting, but difficult,
examination of a number of puzzles about color. Hard going but shows a
brilliant mind struggling to make sense of difficult problems about
color.
b. Specific Positions
Armstrong, D. M. (1987) "Smart and the secondary qualities." In
Metaphysics and Morality: Essays in Honour of J. J. C. Smart, ed. P.
Pettit, R. Sylvan, and J. Norman. Oxford: Blackwell. Reprinted as
chapter 3 of Readings on Color, vol. 1.) Classic statement of
Physicalism.
Cornman, J. "Can Eddington's `two tables' be identical?". Australasian
Journal of Philosophy vol 52, 1974. pp. 22-38. A defender of
Non-Reductive Realism.
Hardin, C. L. (1988). Color for Philosophers: Unweaving the Rainbow.
Indianapolis: Hackett Pub. Co. Written by a philosopher who knows lots
of the science of color perception, this book provides an excellent
introduction to debates over the scientific status of color, and
provides an extended argument for what we have called Color
Eliminativism.
Jackson, F., and R. Pargetter. "An objectivist's guide to subjectivism
about colour." Revue Internationale de Philosophie. vol. 41. 1987.
pp.127-41. (Reprinted as chapter 6 of Readings on Color, vol. 1.) An
alternative to Physicalism about color.
Johnston, M. "How to speak of the colors". Philosophical Studies, vol.
68, 2 1992. pp. 21-63. Extended defense of Dispositionalism.
McDowell, J. "Values and Secondary Qualities", in Ted Honderich, ed.,
(1985) Morality and Objectivity. Routledge & Kegan Paul. Discusses the
pros and cons of a Projectivist strategy that compares secondary
qualities and moral properties.
Peacocke, C. "Colour concepts and colour experience". Synthese vol.
58, 1984. pp. 365-82. (Reprinted as chapter 5 of Readings on Color,
vol. 1.) Another version of Dispositionalism.
Sellars, W. "Philosophy and the Scientific Image of Man" in Science,
Perception and Reality. (1991) Ridgview Publishing Company. A
difficult but interesting argument against Eliminativism, in favor of
a different version of Subjectivism.
Shoemaker, S. "Phenomenal character." Noûs. vol. 28, 1994. pp. 21-38.
(Reprinted as chapter 12 of Readings on Color, vol. 1.) From a
defender of what we have called Phenomenal Subjectivism.
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