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Colour Constancy and the Mind-Independence of Colour

According to the naïve realist, colours are mind-independent properties of objects that are distinct from their physical properties. In today’s post I outline the argument for the first part of the view: the claim that colours are mind-independent.

To say that colours are mind-independent properties is to say that their nature and existence does not depend on the experiences (or psychological responses more generally) of conscious subjects. This means that colours are not, for instance, dispositions of objects to produce colour sensations in suitably placed perceivers, as they are according to the dispositionalist (or ‘secondary quality’) view famously defended by Locke and traditionally popular among philosophers.

The line of argument that I develop in support of the claim that colours are mind-independent appeals to colour constancy. Colour constancy is the phenomenon whereby the colours of objects are perceived to remain constant throughout variations in the conditions under which they are perceived, and so throughout variations in the way that they appear as the perceptual conditions vary. A simple way of illustrating the phenomenon is to turn on a desk lamp in an already illuminated room. Turning on the desk lamp will bring about a noticeable change to the appearance of the desk and the objects on it, but the colours of the objects illuminated by the lamp will not appear to change.

Colour constancy is incredibly important for perceivers. Colours allow perceivers to distinguish, identify, and reidentify objects. And they allow us to do this in perceptual conditions that vary constantly: at different times of day, under natural and artificial illuminants, depending on whether objects are directly illuminated or in shadow, and against different backgrounds. In order for colours to play this role in our lives, we need to be able to perceive objects’ constant colours—colours that do not vary with the conditions under which we perceive them.

Colours are not the only properties that exhibit perceptual constancy. Paradigmatically mind-independent properties like shape and size do, too: we don’t perceive tables to change shape as we move in relation to them, and cows in the distance are not perceived to be smaller than cows that are nearer. This, I suggest, is no coincidence. Properties that exhibit perceptual constancy, like shape, size, and colour, manifest a distinction between appearance and reality: between the way objects instantiating the property (merely) appear in particular conditions, and they way that they really are – and, when everything goes well, can be perceived to be. Exhibiting this kind of distinction between appearance and reality is the mark of something that is mind-independent.

The problem for dispositionalist theories of colour—a problem noted by, amongst others, Mark Johnston and Mark Kalderon—is to account for the perceived constancy of colours throughout variations in the perceptual conditions. Take, for instance, a form of dispositionalism which holds that objects produce colour sensations that vary constantly as the perceptual conditions vary, and which identifies the ‘real’ colours of things with dispositions to produce particular kinds of sensations, in particular perceivers, in particular conditions (for instance, ‘normal’ perceivers in ‘normal’ conditions). A basic difficulty with this kind of view is that it seems to predict that the colours of objects should appear to be constantly changing with changes in the perceptual conditions—which they do not. It is true that views of this kind can make some sense of the idea of the ‘real’ colours of things. But ‘real’ here carries no metaphysical weight: what is identified as the ‘real’ colour is just one disposition to produce colour sensations among many. And, if nothing else, it is difficult to understand how that can be perceived to remain constant throughout variations in the conditions.

Fully developing this argument against the dispositionalist requires extending the argument to more complex forms of dispositionalism, defending the claim that we literally perceive colours, shapes, and sizes to remain constant—rather than simply believing that they do on the basis of constantly varying experience—and explaining the way in which things nevertheless do appear different as the conditions in which we perceive them vary. The claim that colours are mind-independent properties also needs to be defended against various forms of the Argument from Perceptual Variation, which uses variations in colour experience across conditions and perceivers to undermine the claim that there are colours that objects ‘really are’ (in any robust sense). I consider these issues in Chapters 2 and 3 of A Naïve Realist Theory of Colour. In tomorrow’s post, however, I want to move on to consider the second of the claims made by naïve realists: that colours are distinct from the physical properties of objects.

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