Opponents of Functionalism and the Qualitative Features of Consciousness

Opponents of functionalism point out that some conscious mental states have distinct quality features. For example, when I look at a red surface under normal lighting conditions, I have a visual experience of a particular type, which is qualitatively different from the kind of experience I have when I look at a green surface under the same lighting conditions. To me, red surfaces look qualitatively different from green surfaces under the same conditions. The point is that it seems quite conceivable that the way red roofs look to me in normal lighting conditions may be the same as the way green roofs look to you in normal conditions, and more generally: our color experiences may be "reversed" regularly for each other. Now if it were reversed, each of us would have the same powers of color discrimination (with the other things being equal) despite this situation, each of us would apply color words in exactly the same way, we would agree, for example, that describing tomatoes and sunsets as "red" is correct, and describing grass, emeralds and "go" signs in the traffic sign as "green" is correct. True. It actually seems -- and this is the crucial point -- that we would be functionally equivalent to color experiences, which is to say that my color experiences and your color experiences exhibit exactly the same pattern of causal relationships to environmental states and other mental states and behavior, that is, they have the same "causal role," but that apparently means that functionality can't find a difference between each My chromatic experiences and your chromatic experiences in the hypothetical "inverted spectrum" state, but it seems in this hypothetical state that our chromatic experiences actually differ as much as you imagine, and the obvious conclusion is that functionalism failed to properly characterize chromatic experiences, because it completely neglected its most prominent feature, which is the qualitative feature. - Reza Zeidan. — Source: Published on Facebook's "Braheen Center" page