Online research in philosophy

Despite a wealth of data we still have no clear idea what color experiences represent. In fact, color experiences vary with so many factors that it has been claimed that they do not represent anything at all. The primary challenge for any representational account of color experience is to accommodate the various psychophysical results that demonstrate that color appearance depends not only on the spectral nature of the target but also on the spectral, spatial and figural nature of the surround. A number of theorists have proposed that this dependence is an aspect of the visual system's constancy mechanism. However this does not in and of itself tell us what, if anything, is represented in color experience. Ultimately the answer to this question will be informed by one's theory of representational content. I will argue that adopting a molecular scheme of representation enables the development of an account of the represented object of color experience that can do justice to the psychophysical data.

What is color? What is color vision? Most philosophers answer by reference to humans: to human color qualia, or to the environmental properties or "quality spaces" perceived by humans. It is argued, with reference to empirical findings concerning comparative color vision and the evolution of color vision, that all such attempts are mistaken. An adequate definition of color vision must eschew reference to its outputs in the human cognition and refer only to inputs: color vision consists in the use of wavelength discrimination in the construction of visual representations. A color quality is one that is generated from such processing.

I disagree with Ross about the location of colors: They are in the brain, not in the external world. It is difficult to deny that there are colors in our conscious visual experience, and if we take the causal theory of perception seriously, we cannot identify these colors with the beginning of the causal chain in perception (external objects in the distal stimulus field), but we must search for them at the end of the causal chain (in the brain). Several lines of compelling evidence from cognitive neuroscience (e.g., synesthesia, dreaming, and achromatopsia) demonstrate unambiguously that color is in the brain. Furthermore, it seems that Ross has failed to consider one substantial version of subjectivism in his article. This monistic approach to color and consciousness appears to be the least implausible alternative when we try to understand what colors are and where they reside.

What is the relationship between color experience and color? Here, I defend the view that it is semantic: color experience denotes color in a code innately known by the perceiver. This semantic theory contrasts with a variety of theories according to which color is defined as the cause of color experience (in a special set of circumstances). It also contrasts with primary quality theories of color, which treat color as a physical quantity. I argue that the semantic theory better accounts for the kinds of knowledge we have regarding both the color of objects that we see and of the colors themselves.

This article was written as a commentary on a target article by Peter W. Ross entitled "The Location Problem for Color Subjectivism" [Consciousness and Cognition 10(1), 42-58 (2001)], and is published together with it, and with other commentaries and Ross's reply. If you or your library have the necessary subscription you can get PDF versions of the target article, all the commentaries, and Ross's reply to the commentaries here. However, I do not think that it is by any means essential for you to have read Ross's piece in order to understand this one. Ross defends a view called "color physicalism" or color realism that holds (simplifying somewhat) that colors are real physical properties (in typical cases, spectral reflectances of object surfaces). This is in opposition to what is probably a more widely held "subjectivist" view of color, holding that color qualities really exist only in the mind. In my commentary I suggest that a realist view of qualitative properties, such as Ross's, together with a direct, active view of perception, and a concept of "extended mind" (Clark & Chalmers, 1998) may provide the materials for a real solution to the notorious hard problem of consciousness. I sketch this solution in outline. - N.J.T.T.

According to color subjectivism, colors are mental properties, processes, or events of visual experiences of color. I first lay out an argument for subjectivism founded on claims from visual science and show that it also relies on a philosophical assumption. I then argue that subjectivism is untenable because this view cannot provide a plausible account of color perception. I describe three versions of subjectivism, each of which combines subjectivism with a theory of perception, namely sense datum theory, adverbialism, and the virtual color proposal, and argue that each version faces serious objections. Considering these three theories of perception to be exhaustive of those available to the subjectivist, I conclude that subjectivism is untenable and that the scientifically motivated argument for this view is unsound. I then offer the diagnosis that the philosophical assumption on which this argument relies is mistaken.

Color subjectivism is the view that color properties are mental properties of our visual sensations, perhaps identical with properties of neural states, and that nothing except visual sensations and other mental states exhibits color properties. Color phys- icalism, by contrast, holds that colors are exclusively properties of visible physical objects and processes.

In “The Location Problem for Color Subjectivism,” Peter Ross argues against what he calls subjectivism — the view that “colors are not describable in physical terms, ... [but are] mental processes or events of visual states” (2),¹ and in favor of physicalism — a view according to which colors are “physical properties of physical objects, such as reflectance properties” (10). He rejects an argument that has been offered in support of subjectivism, and argues that, since no form of subjectivism is able to account for our perception of color, we are better off adopting physicalism.

Color subjectivists claim that, despite appearances to the contrary, the world external to the mind is colorless. However, in giving an account of color perception, subjectivists about the nature of perceived color must address the nature of perceived spatial location as well. The argument here will be that subjectivists’ problems with coordinating the metaphysics of perceived color and perceived location render color perception implausibly mysterious. Consequently, some version of color realism, the view that colors are (physical, dispositional, functional, sui generis, or some other) properties of physical objects, is correct.