Thomas Reid recognizes a distinction between qualities originally perceived by a given sense modality and an expanded range of qualities that can be perceived via that sense modality as the result of nature, custom/habit, or experience. Specific parts of Reid’s story generate a puzzle about color perception (though I should add the caveat that I haven’t yet looked through the secondary literature carefully to see if this has already been discussed).
Reid includes color on the list of original perceptions of vision, but he also makes the following remarks (all bolding added by me, for emphasis):
“Thus, if a sphere of one uniform color be set before me, I perceive evidently by my eye its spherical figure, and its three dimensions. All the world will acknowledge, that by sight only, without touching it, I may be certain that it is a sphere; yet it is no less certain, that, by the original power of sight, I could not perceive it to be a sphere, and to have three dimensions. The eye originally could perceive only two dimensions, and a gradual variation of colour on the different sides of the object.
It is experience that teaches me that the variation of colour is an effect of spherical convexity, and of the distribution of light and shade. But so rapid is the progress of the thought, from the effect to the cause, that we attend only to the last, and can hardly be persuaded that we do not immediately see the three dimensions of the sphere.
Nay, it may be observed, that, in this case, the acquired perception in a manner effaces the original one; for the sphere is seen to be of one uniform color, though originally there would have appeared a gradual variation of color: But that apparent variation, we learn to interpret as the effect of light and shade falling upon a sphere of one uniform color.”
The puzzle for Reid is that basically all ordinary color perception turns out to be a case where the original perceptions are in conflict with the acquired perceptions, and, what’s worse, if we have to choose one as “veridical”, it would be the acquired perceptions, not the original ones.
See, Reid takes color to be a real quality of objects. Now, (supposing the sphere in Reid’s example to be blue), if being blue is a quality of objects, the “uniformly colored” sphere is either uniformly blue, or it is not uniformly blue. Since Reid introduces the sphere as uniformly colored, let’s grant that the sphere is uniformly blue. But, recall that this is an acquired perception of the sphere’s color, which means that an unexperienced visual observer would see, as Reid points out, something with gradually varying colors. Note, however, that, ex hypothesi, the sphere is uniformly colored, and so, either original color perceptions are generally not veridical (contra Reid’s position on perception) or, the original color perceptions are not of the externally existing object (contra Reid’s position on perception). Put another way, Reid’s plausible story about acquired perception requires either non-veridical original color perceptions, or non-external objects of original perception. Reid doesn’t want either of these, so his view of color perception is in trouble.
So that’s the puzzle. My plan now is to see whether there is any way for Reid to wriggle out of this puzzle (or if I am radically misinterpreting him on the status of colors or on perception, or the like).