Locating the Unique Hues

Variations in colour perception have featured prominently in recent attempts to argue against the view that colours are objective mind-independent properties of the perceptual environment: either physical properties, such as types of surface reflectance profile (e.g. Byrne and Hilbert 1997, 2003, 2007 and Tye 2006), or else sui generis mind-independent properties (e.g. Campbell 1993). My aim in this paper is to defend the view that colours are mind-independent properties in response to worries arising from one type of empirically documented case of perceptual variation: variation in the perception of the «unique hues». §1 sets out the challenge raised by variation in the perception of the unique hues. I argue in §2 that the empirical findings are less dramatic than they might initially appear, and in §3 that accounting for the inter-personal differences is consistent with the view that colours are mind-independent properties that normal subjects veridically perceive, at least roughly speaking. 1. The Location Problem Unique hues are «pure » instances of the hues red, green, yellow and blue: instances that do not appear to be a «perceptual mixture » or «phenomenally composed » of any other hues. Unique hues contrast in this respect with binary hues, every instance of which appears to be a perceptual mixture of two other hues: orange, for instance, appears to be phenomenally composed of red and yellow, purple appears to be phenomenally composed of red and blue