A materialism of qualities?

In a previous post, I suggested that some people who proclaim to adhere to the materialist metaphysics in fact misapprehend what materialism is. One example of misapprehension I mentioned was the implicit notion that, although the brain produces the felt qualities we call thoughts and emotions—that is, endogenous experiences—the qualities of perception, such as color, flavor, smell, etc., are thought to really exist out there in the world, not inside our skull. These people subliminally assume that the physical world is the qualities displayed on the screen of perception, which contradicts mainstream materialism.

Indeed, according to materialism all qualities, including those of perception, are somehow—materialists don't know how—generated by the brain inside our skull. The external world allegedly has no qualities at all—no color, no smell, no flavor—but is instead constituted by purely abstract quantities, such as mass, charge, spin, momentum, geometric relationships, frequencies, amplitudes, etc.

Triggered by my post, a long-time reader of mine, who also writes about philosophy, wondered if we could conceive of an alternative form of materialism precisely along the lines above. That is, can we devise a coherent 'qualitative materialism' according to which the qualities of perception are really out there in the external world—whether they constitute that world or are merely objective properties of it—while only non-perceptual experiences, such as thoughts and emotions, are generated by the brain? The answer is no, but if such a smart and well-informed reader felt tempted to entertain the thought, I think it is worthwhile to elaborate more here.

For starters, notice that the qualities of perception—color, smell, flavor, etc.—also appear in dreams, imagination, visions, hallucinations, etc. Many dreams and hallucinations are qualitatively indistinguishable from actual perceptions, something I have verified multiple times—to my own satisfaction—during lucid dreams and psychedelic trances. So if colors and other perceptual qualities are really out there in the external world, then somehow our inner mental imagery can also incorporate the exact same qualities independently of the external world.

This is problematic for qualitative materialism, for it entails postulating two fundamentally different grounds for the same qualities: in one case, the qualities are inherent to the matter out there in the world; in the other case, the exact same qualities are somehow generated by material arrangements in our brain, which themselves do not have those qualities.

For instance, the brain—that reddish object inside our skull—does not itself display the colors of the rainbow when we look at it on an operating table. Yet it can generate—under the premises of qualitative materialism—the dream-imagery of a rainbow. Analogously, the brain itself does not sound like anything. Yet, it can generate—still under the premises of qualitative materialism—the dream of a lovely concert. So the same qualities must be both fundamental to matter when they occur outside our skull, and also epiphenomena of material arrangements when they occur inside. This doesn't seem coherent to me.

You see, even if the perceptual qualities of our inner mental imagery are just remembered from earlier perceptions, under qualitative materialism the brain still has to epiphenomenally generate the experience of re-living the memories, despite not having the entailed qualities in its own matter. For instance, the brain has to epiphenomenally generate the re-experiencing of a rainbow—which entails experiencing many colors—without having all those colors in its own matter. So we still end up with two fundamentally different grounds for the same qualities.

But that's not all. The defining principle of all formulations of metaphysical materialism is that the classical, macroscopic world beyond our private mentation, as it is in itself, is objective; that is, its properties are independent of observation. Under qualitative materialism, this means that the perceptual qualities of an object—such as e.g. its color—are objective, intrinsic to the object itself, not private creations of our personal mind. Therefore, these qualities can only change if the object itself changes.

Let's make this more specific with an example. Consider the squares marked A and B, respectively, in the figure above. We clearly perceive square A as dark grey and square B as light grey. Under qualitative materialism, these perceived qualities are in the squares themselves; their colors are objective, beyond our personal mentation; dark grey is a property intrinsic to square A as it is in itself, whereas light grey is a property intrinsic to square B as it is in itself. Therefore, for as long as we don't change anything about squares A and B themselves, their colors should remain the same.

In the figure below, squares A and B are shown again, with no modification except for some zooming; only the rest of the original figure above has been removed (if you can't believe it, watch this). Can you still perceive the light grey color? If by altering merely what was going on around squares A and B, without touching the squares themselves, we managed to make a color disappear, how could this color—this perceived quality—have existed 'out there,' beyond our personal mind, to begin with? How could it have been objective in the first place?

Mainstream materialism preserves the objectivity of the classical, macroscopic world around us by stating that the colors—or any other quality, for that matter—we perceive are generated by our brain, inside our skull. This internal generation of qualities depends not only on the internal characteristics of our visual system, but also on the external context of observation. This is why we perceive the colors of the squares differently depending on context.

Qualitative materialism, on the other hand, has problems accommodating not only color illusions, but any perceptual illusion. Do you see the circles in the figure below rotate? (Click on the figure for a higher resolution version, where the effect is more powerful.) If so, qualitative materialism would presumably say that this perception is objective; that the circles on the screen, outside your private mental life, are themselves moving. Yet, this would contradict myriad other ways of observing the circles (e.g. through instrumentation), which would destroy the illusion of movement. Thus the qualities associated with experiencing the rotation cannot be objective.

Qualitative materialism can't work. Self-declared materialists who unwittingly associate the plausibility of their position with this misapprehension of what materialism means should rush to review their worldview.