Two pieces of common sense:
- We may believe that the rose is red, but this belief is strictly and literally false.
- Strictly and literally, nothing really is red.
It seems only fair to confront common sense with the metaphysics of today.
Antirealism about ‘secondary qualities’ derives its plausibility from early modern accounts of mental content. We acquire our concept of red from the contents of our perceptual experiences: ‘adventitious ideas’ (Descartes), ‘ideas of sensation’ (Locke). From these arise thoughts of red, as well as the meaning of ‘red.’ Both the sensory and the cognitive content are thus subjective, logically private, and transparent to the subject, who is infallible about them.
What happens when we combine the commonsense view of red with current views on mental content and concept formation? (And add in the arguments of philosophers like Barry Stroud, Jonathan Ellis, and John Campbell.)
We clearly run afoul of the Private Language Argument. A meaning, a concept, must follow a rule. But ‘purely private rule’ is an incoherent notion. As Wittgenstein said: “…(W)hatever is going to seem to me to be right is right. And that only means that here we cannot talk about ‘right’.”
We also get into trouble with Twin Earth-style arguments, from which Putnam concludes, “Meanings ain’t in the head!” They are not subjective, nor are we infallible about them.
It conflicts with externalist and representationalist accounts of mental content according to which we have no conscious access to our ‘ideas.’ Gilbert Harman asks, “Does your experience represent this redness by being itself red at a relevant place, in the way a painting of a ripe tomato might represent the redness of the tomato with some red paint the appropriate place on the canvas?” Harman concludes that there is no ‘mental paint.’ Our perception and thought represent the world as being a certain way.
Consequently, when we see something as red, this seeing must be a connection to the external world. What is its object? Some property of the rose, evidently: a structural property of the surface by which it absorbs certain wavelengths, or the dispositional property to do that. Or a dispositional property to represent an object thus and so. Or a simple, transparent property supervening (somehow) on physical properties.
Surely the natural candidate for being the referent of our concept red is that property.
But then our belief that the rose is red is true, not false.
Some things really are red.
The remaining issue, then, is what kind of property being red is. If it’s a structural property of surfaces, or even a dispositional property based upon its physical structure, then arguably colors are physical.
This would fit with the early modern denial of colors as having no function in scientific explanations. If they’re physical, they would.
But this moves a bit too fast. Colors function in explanations not because of purely physical interactions with the visual systems of animals, but in virtue of how they represent things. Color explains things not in terms of structural properties but in terms of how objects appear.
This would make color a real property of objects, but not a physical one.