Reflectance and spectral power functions are poor predictors of color experiences. Only in completely relativized conditions (single observer, non-metameric set of stimuli, and single set of viewing conditions) is the relationship close. Variation in reflectance of Munsell chips experienced by color-normal observers as having a unique green hue encompasses approximately sixty percent of the complete range of hues falling under the category “green”; and in recent determinations of unique hues, ranges of yellow and green as well as green and blue (...) unique hues overlap. (shrink)

Those who identify colours with physical properties need to say how the content of colour experiences relate to their favoured identifications. This is because it is not plausible to hold that colour experiences represent things as having the physical properties in question. I sketch how physical realists about colour might tackle this item of unfinished business.

The problem of nonreflectors perceived as colored is the central problem for Byrne & Hilbert's (B&H's) physicalism. Vision scientists and other interested parties need to consider the motivation for their account of “productance physicalism.” Is B&H's theory motivated by scientific concerns or by philosophical interests intended to preserve a physicalist account of color as a posteriori necessary?

Our reply is in four parts. The first part, R1, addresses objections to our claim that there might be “unknowable” color facts. The second part, R2, discusses the use we make of opponent process theory. The third part, R3, examines the question of whether colors are causes. The fourth part, R4, takes up some issues concerning the content of visual experience.

Byrne & Hilbert argue that colors are reflectance properties of objects. They also claim that a necessary condition for something's being a color is that it causally explain – or be causally implicated in the explanation of – our perceptions of color. I argue that these two positions are in conflict.

Our reply is in three parts. The first part concerns some foundational issues in the debate about color realism. The second part addresses the many objections to the version of physicalism about color ("productance physicalism") defended in the target article. The third part discusses the leading alternative approaches and theories endorsed by the commentators.

B&H understate the difficulties facing their version of color realism. We doubt that they can fix reflectance types and magnitudes in a way that does not invoke relations to perceivers. B&HÂ’s account therefore resembles the dispositional or ecological accounts that they dismiss. This is a good thing, for a dispositional account is promising if understood in an ecological framework.

In many cases of variation in color vision, there is no non-arbitrary way of choosing between variants. Byrne and Hilbert insist that there is an unknown standard for choosing, while eliminativists claim that all the variants are erroneous. A better response relativizes colors to perceivers, thereby providing a color realism that avoids the need to choose between variants.

The target article is an attempt to make some progress on the problem of color realism. Are objects colored? And what is the nature of the color properties? We defend the view that physical objects (for instance, tomatoes, radishes, and rubies) are colored, and that colors are physical properties, specifically types of reflectance. This is probably a minority opinion, at least among color scientists. Textbooks frequently claim that physical objects are not colored, and that the colors are "subjective" or "in (...) the mind." The article has two other purposes: first, to introduce an interdisciplinary audience to some distinctively philosophical tools that are useful in tackling the problem of color realism and, second, to clarify the various positions and central arguments in the debate. (shrink)

This is the Stanford Encyclopedia of Philosophy entry on the contents of perception.

If two subjects have phenomenally identical experiences, there is an important sense in which the way the world appears to them is precisely the same. But how are we to understand this notion of 'ways of appearing'? Most philosophers who have acknowledged the existence of phenomenal content have held that the way something appears is simply a matter of the properties something appears to have. On this view, the way something appears is simply the way something appears to be . (...) This identification supports a Russellian theory of phenomenal content, according to which phenomenal content is exhausted by facts about what specific properties are represented by an experience. The present paper motivates and develops an alternative Fregean theory of phenomenal colour content. According to Fregean theories, the phenomenal content that is shared by any two phenomenally identical experiences is a matter of how the world is represented, and need not involve sameness in what is represented. It is argued that ways of appearing are modes of presentations of external properties and objects, and a detailed theory is presented about the nature of the modes of presentation involved in colour experience. (shrink)

The debate between relationalism and representationalism in the philosophy of perception seems to have come to a standstill where opponents radically disagree on methodological principles or fundamental assumptions. According to Fish (this volume) this is because, not unlike Kuhnian scientific paradigms, the debate displays some elements of incommensurability. This diagnosis makes advancing the debate impossible. I argue that what is hindering progress is not a clash of research programmes, but a series of misunderstandings that can be avoided by disentangling the (...) different questions each theory is invested in and by making explicit the hidden assumptions at play in the debate. One such central assumption is what I call the Superficiality Constraint. This is the idea that the phenomenal character of experience is superficial with respect to introspection. I argue that we can make progress in the debate by assessing to what extent and at what cost relationalism can accommodate this constraint. (shrink)

The debate between relationalism and representationalism in the philosophy of perception seems to have come to a standstill where opponents radically disagree on methodological principles or fundamental assumptions. According to Fish (this volume) this is because, not unlike Kuhnian scientific paradigms, the debate displays some elements of incommensurability. This diagnosis makes advancing the debate impossible. I argue that what is hindering progress is not a clash of research programmes, but a series of misunderstandings that can be avoided by disentangling the (...) different questions each theory is invested in and by making explicit the hidden assumptions at play in the debate. One such central assumption is what I call the Superficiality Constraint. This is the idea that the phenomenal character of experience is superficial with respect to introspection. I argue that we can make progress in the debate by assessing to what extent and at what cost relationalism can accommodate this constraint. (shrink)

Some philosophical theories of the nature of color aim to respect a "common sense" conception of color: aligning with the common sense conception is supposed to speak in favor of a theory and conflicting with it is supposed to speak against a theory. In this paper, we argue that the idea of a "common sense" conception of color that philosophers of color have relied upon is overly simplistic. By drawing on experimental and historical evidence, we show how conceptions of color (...) vary along several dimensions and how even supposedly "core" components of the contemporary "common sense" conception of color are less stable than they have been thought to be. (shrink)

“The problem of color realism” as defined in the first section of the target article, is crucial to the argument laid out by Byrne & Hilbert. They claim that the problem of color realism “does not concern, at least in the first instance, color language or color concepts” (sect. 1.1). I argue that this claim is misconceived and that a different characterisation of the problem, and some of their preliminary assumptions makes their positive proposal less appealing.

Byrne & Hilbert propose that color can be identified with explicit properties of physical surfaces. I argue that this claim must be qualified to take into account constraints needed to make recovery of surface color information possible. When these constraints are satisfied, then a biological visual system can establish a correspondence between perceived surface color and specific surface properties.

Revelation, the thesis that the full intrinsic nature of colors is revealed to us by color experiences, is false in Byrne & Hilbert's (B&H's) view, but in an interesting and nonobvious way. I show what would make Revelation true, given B&H's account of colors, and then show why that situation fails to obtain, and why that is interesting.

Byrne & Hilbert's thesis, that color be associated with reflectance-type, is questioned on the grounds that it is far from clear that the human visual system is able to determine a surface's reflectance-type with sufficient accuracy. In addition, a (friendly) suggestion is made as to how to amend the definition of reflectance-type in terms of CIE (Commission Internationale de l'Eclairage) coordinates under a canonical illuminant.

We argue that any theory of color physicalism must include consideration of ecological interactions. Ecological and sensorimotor contingencies resulting from relative surface motion and observer motion give rise to measurable effects on the spectrum of light reflecting from surfaces. These contingencies define invariant manifolds in a sensory-spatial space, which is the physical underpinning of all subjective color experiences.

When I open my eyes and look at a Rubik’s cube, there is something it is like for me visually in looking at it. Various color qualities are presented to me, and they are arranged in a specific pattern. By having an experience with this particular phenomenal character I am also thereby visually representing the world outside my experience as being a certain way. If I experience a blue square to the left of a red square, the world outside my (...) experience is represented as being one way. As I turn the cube, and come to view a green square to the left of another green square, I have an experience with a different phenomenal character. But I also come to represent the world differently. In virtue of the difference in phenomenology there is a corresponding difference in how the world is represented as being. Moreover, it seems that any two experiences with the same phenomenal character will share a certain sort of intentional content.1 If two subjects have phenomenally identical experiences, there is an important sense in which the way the world appears to them is precisely the same. I will call this intentional content that supervenes on phenomenal character “phenomenal content”. But how are we to understand this notion of “ways of appearing”? Most philosophers who have acknowledged the existence of phenomenal content have held that the way something appears to a subject is simply a matter of the properties.. (shrink)

Color vision provides accurate measures of the phase and intensity of daylight, and also a means of discriminating between objects. Neither property implies that objects are colored.

According to the perceptual model, our knowledge of others' minds is a form of perceptual knowledge. We know, for example, that Jones is angry because we can literally see that he is. In this essay, I argue that mental states do not have the kind of distinctive looks that could sufficiently justify perceptual knowledge of others’ mentality. I present a puzzle that can arise with respect to mental states that I claim does not arise for non-mental properties like being an (...) apple and argue that this is explained by the fact that the looks of non-mental properties adhere to a certain explanatory principle that does not hold for mental states. This shows, I argue, that, even if we think mental states do have looks, these cannot offer sufficient grounds for perceptual knowledge of others' minds. In the final section of the essay, I suggest an alternative way of thinking about our knowledge of others' minds and about the sorts of looks or appearances that might be associated with mental states. (shrink)

Byrne & Hilbert conceive of color perception as the representation of a physical property “out there.” In our view, their approach does not only have various internal problems, but is also apt to becloud both the intricate and still poorly understood role that “ color ” plays within perceptual architecture, and the complex coupling to the “external world” of the perceptual system as an entirety. We propose an alternative perspective, which avoids B&H's misleading dichotomy between a purely subjective and a (...) realist conception of “ color.”. (shrink)

Reflectance physicalism only provides a partial picture of the ontology of color. Byrne & Hilbert’ account is unsatisfactory because the replacement of reflectance functions by productance functions is ad hoc, unclear, and only leads to new problems. Furthermore, the effects of color contrast and differences in illumination are not really taken seriously: Too many “real” colors are tacitly dismissed as illusory, and this for arbitrary reasons. We claim that there cannot be an all-embracing ontology for color.

The sensory colors that figure in visual perceptual experience are either properties of the object of consciousness (naïve realism, sense-data theory), or properties of the subject of consciousness (adverbialism) (Section 1). I consider an argument suggested by the work of A. D. Smith that the existence of certain kinds of perceptual constancies shows that adverbialism is correct, for only adverbialism can account for such constancies (Section 3). I respond on behalf of the naïve realist that naïve realism is compatible with (...) the existence of such constancies, so long as naïve realism adopts the view that sensory colors are relational properties of physical objects, not intrinsic properties (Section 4). In other words, the naïve realist should adopt the theory of appearing (Section 5). (shrink)

I argue that Byrne & Hilbert (B&H) have not answered Hardin's objection to physicalism about color concerning the unitary-binary structure of the colors for two reasons. First, their account of unitary-binary structure seems unsatisfactory. Second, pace B&H, there are no physicalistically acceptable candidates to be the hue-magnitudes. I conclude with a question about the justification of physicalism about color.

As demonstrated by several example displays, color illusions challenge color realism, because they involve a one-to-many reflectance-to-color mapping. Solving this problem by differentiating between veridical and illusory colors corresponding to the same reflectance is hampered because of the lack of an appropriate criterion. However, the difference between veridical and illusory color perception can still be maintained.

In this paper I shall defend a projectivist view of sensory experience. The case I shall focus on is that of color experience. Projectivism has recently been criticized by some authors who claim that it is unintelligible, or at least implausible, and that it makes a severe category mistake. I shall argue that despite some prima facie impressions of implausibility, projectivism can be made intelligible, and plausible, if its details are spelled out in a reasonable way. In addition, projectivism is (...) ubiquitous in human psychology, and certain cases of projection are reasonably viewed as making a category mistake. Viewed from this perspective, sensory projection is just one instance of projectivism, brought about by low-level perceptual processing. Whether sensory projection is one that makes a category mistake is not obvious. However, even if it does, this is perfectly compatible with the evolutionary advantage of sensation and perception. (shrink)

There are 2,000 hair cells in the cochlea, but only three cones in the retina. This disparity can be understood in terms of the differences between the physical characteristics of the auditory signal (discrete excitations and resonances requiring many narrowly tuned receptors) and those of the visual signal (smooth daylight excitations and reflectances requiring only a few broadly tuned receptors). We argue that this match supports the physicalism of color and timbre.

Byrne & Hilbert defend color realism, which assumes that: (a) colors are properties of objects; (b) these objects are physical; hence, (c) colors are physical properties. I accept (a), agree that in a certain sense (b) can be defended, but reject (c). Colors are properties of perceptual objects – which also have underlying physical properties – but they are not physical properties.

The thesis is intended to contribute to the growing understanding of the indispensable role played by phenomenal consciousness in human cognition, and specifically in making our concepts of the external world available. The focus falls on so called observational concepts, a type of rudimentary, perceptually-based objective concepts in our repertoire — picking out manifest properties such as colors and shapes. A theory of such concepts gets provided, and, consequently, the exact role that perceptual consciousness plays in making concepts of this (...) sort available gets settled. In the first half of the thesis, observational concepts get construed as a special type of recognitional concepts. On an analogy with perceptual demonstratives, having such concepts would involve having non-trivial knowledge of their reference. The experiential basis of such concepts would, among other things, provide for such constitutive knowledge. The theoretical background relevant to the hypothesis gets provided in the first chapter. A defence of the hypothesis follows in the second. In the second half of the thesis, care is taken to distinguish among two ways in which the constitutive knowledge of the reference of an observational concept could be fleshed out. In the third chapter, perceptual experience is shown to provide the basis both for knowledge of observational properties by acquaintance, and for knowledge of the essence of such properties — provided that knowledge of essence gets construed in the right, modest way. It might be natural to take knowledge by acquaintance to be the sort relevant to observational concept possession, especially given that in the case of perceptual demonstratives this is the role likely played by experience. However, this initial impression proves to be mistaken. The constitutive knowledge of the referent of an observational concept turns out to consist in the capacity to determine a priori the essence of the respective property. To show this, an argument gets provided in the penultimate fourth chapter, based on the key role played by experiences of instances of observational properties in optimal viewing conditions in enabling the possession of the respective observational concept. (shrink)

The reflectance types that Byrne & Hilbert identify with colors count as types only in a way that is more dependent on, and more relative to color perceivers, than their account suggests. Their account of perceptual content may be overly focused on input conditions and distal causes.

Visual percepts are called veridical when a “real” object can be identified as their cause, and illusions otherwise. The perceived position and color of a flashed object may be called veridical or illusory depending on which viewpoint one adopts. Since “reality” is assumed to be fixed (independent of viewpoint) in the definition of veridicality (or illusion), this suggests that “perceived” position and color are not properties of “real” objects.

We make three points. First, the concept of productance value that the authors propose in their defense of color physicalism fails to do the work for which it is intended. Second, the authors fail to offer an adequate physicalist account of what they call the hue-magnitudes. Third, their answer to the problem of individual differences faces serious difficulties.

The authors favor a “color realism” theory that considers colors to be physical properties residing in objects that reflect, emit, or transmit light. It is opposed to the theory that colors are sensations or visual experiences. This commentary suggests that both theories are correct, and that context usually indicates which of these dual aspects is being considered.

Vision scientists are interested in three diverse entities: physical stimuli, neural states, and consciously perceived colors, and in the mapping rules among the three. In this worldview, the three kinds of entities have coequal status, and views that attribute color exclusively to one or another of them, such as color realism, have no appeal.

In this commentary I argue that Byrne & Hilbert commit a number of philosophical solecisms: They beg the question of “realism,” they take the phenomenon and the theoretical model to be the same thing, and they surreptitiously substitute data sets for the life-world.

In visual science, color is usually regarded as a subjective phenomenon. The relationship between the specific color experiences that are evoked by a visual scene and the physical properties of the surfaces viewed in that scene are complex and highly dependent on spatial context. There is no simple correspondence between experienced color and a stable class of physical reflectances.

For all animals, color is an indicator of the substance and state of objects, for which purpose reflectance is just one among many relevant optical properties. This broader meaning of color is confirmed by linguistic evidence. Rather than reducing color to a simple physical property, it is more realistic to embrace its full phenomenology.

While color realism is endorsed, Byrne & Hilbert's (B&H's) case for it stretches the notion of “physical property” beyond acceptable bounds. It is argued that a satisfactory account of color should do much more to respond to antirealist intuitions that flow from the specificity of color experience, and a pointer to an approach that does so is provided.

Byrne & Hilbert are right that it might be an objective fact that a particular tomato is unique red, but wrong that it cannot simultaneously be yellowish-red (not only objectively, but from somebody else's point of view). Sensory categorization varies among organisms, slightly among conspecifics, and sharply across taxa. There is no question of truth or falsity concerning choice of categories, only of utility and disutility. The appropriate framework for color categories is Nominalism and Pluralistic Realism.

Because our only access to color qualities is through their appearance, Byrne & Hilbert's insistence on a strict distinction between apparent colors and real colors leaves them without a principled way of determining when, if ever, we see colors as they really are.

Metamerism is a rather common feature of objects. The authors see it as problematic because they are concerned with a special case: metamerism in standard conditions. Such metamerism does not, however, pose a problem for color realists. There is an apparent problem in cases of metameric light sources, but to see such metamers as problematic is to fail to answer Berkeley's challenge.

The colors we perceive are the outcome of an attempt to meaningfully order the spectral information from the environment. These colors are not the result of a straightforward mapping of a physical property to a sensation, but arise from an interaction between our environment and our visual system. Thus, although one may infer from a surface’ reflectance characteristics that it will be perceived as “colored,” true colors only arise by virtue of the interaction of the reflected light with the eye (...) (and brain) of an observer. (shrink)

Byrne & Hilbert (B&H) assert that reflectances embody the reality of color, but metamerism smears the authors' “real” color categories into uselessness. B&H ignore this problem, possibly because they implicitly adopt a sort of subjectivism, whereby an object is defined by the percepts (or more generally by the measurements) it engenders. Subjectivism is unwieldy, and hence prone to such troubles.

To identify the set of reflectances that constitute redness, the authors must first determine which surfaces are red. They do this by relying on widespread agreement among us. However, arguments based on the possible ways in which humans would perceive colors show that mere widespread agreement among us is not a satisfactory way to determine which surfaces are red.