Discussing Thomas Nagel’s Mind and Cosmos, Edward Feser says:

Take a stock example of reductive scientific explanation like the reduction of sound to compression waves, color to surface reflectance properties, or heat and cold to molecular motion.  The way these explanations work is by treating the appearance that sound, color, heat and cold present to us in conscious experience as mere appearance, as a projection of the mind that corresponds to nothing in objective, mind-independent reality.  What common sense understands by color, sound, heat and cold — the way red looks, the way a musical note sounds, the way a hot stove feels, and so forth — is held to have no objective reality, any more than the redness a person unknowingly wearing red-tinted contact lenses thinks he sees in all the objects around him really exists in those objects.  Instead, color is for scientific purposes essentially redefined by the method in terms of the surface reflectance properties that cause in us the subjective appearance of color; sound redefined in terms of the compression waves that cause in us the subjective appearance of sound; and heat and cold redefined in terms of the molecular motion that causes in us the subjective appearance of heat and cold.

Thus, as common sense understands color, sound, heat and cold, etc., the reductive method ends up treating the world as essentially colorless, soundless, devoid of temperature, etc.  What the method calls “color,” “sound,” “heat” and “cold” is in fact something different from what the man on the street thinks of when he hears these terms.  The “red” that the method says exists in the material world is just the tendency of an object to absorb certain wavelengths of light and to reflect others.  The “red” that the man on the street thinks exists in the object does not really exist in the object itself at all but only in his perceptual experience of the object.  The “heat” that the method says really exists in the material world is just the motion of molecules.  The “heat” that the man on the street thinks exists in the object does not really exist in the object at all but only in his perceptual experience of the object.  And so forth.

Now, Nagel’s point is not that there is something wrong per se with overthrowing common sense in this way.  It is rather that whatever value this method has, it cannot coherently be applied to the explanation of conscious experience itself.  If the reductive method involves ignoring the appearances of a thing and redefining the thing in terms of something other than the appearances, then since our conscious experience of the world just is the way the world appears to us, to ignore the appearances is in this case just to ignore the very phenomenon to be explained rather than to explain it.  Consciousness is for this reason necessarily and uniquely resistant to explanation via the same method scientific reductionism applies to everything else.  For the application of the method in this case, writes Nagel, “does not take us nearer to the real nature of the phenomenon: it takes us farther away from it.”  To treat the appearances as essentially “subjective” or mind-dependent is precisely to make them incapable of explanation in entirely “objective” or mind-independent terms.

Feser is quite right that consciousness cannot be explained in such a way even in principle. I have touched on this point in a previous post. This is why eliminative materialists such as Daniel Dennett effectively deny the existence of consciousness: if the only things that exist are material things as described by modern science, then consciousness cannot even exist, because it cannot possibly be described in that terminology. John Searle, in a reply to Dennett, says:

In spite of its strident tone, I am grateful for Daniel Dennett’s response to my review because it enables me to make the differences between us crystal clear. I think we all really have conscious states. To remind everyone of this fact I asked my readers to perform the small experiment of pinching the left forearm with the right hand to produce a small pain. The pain has a certain sort of qualitative feeling to it, and such qualitative feelings are typical of the various sorts of conscious events that form the content of our waking and dreaming lives. To make explicit the differences between conscious events and, for example, mountains and molecules, I said consciousness has a first-person or subjective ontology. By that I mean that conscious states only exist when experienced by a subject and they exist only from the first-person point of view of that subject.

Such events are the data which a theory of consciousness is supposed to explain. In my account of consciousness I start with the data; Dennett denies the existence of the data. To put it as clearly as I can: in his book, Consciousness Explained, Dennett denies the existence of consciousness. He continues to use the word, but he means something different by it. For him, it refers only to third-person phenomena, not to the first-person conscious feelings and experiences we all have. For Dennett there is no difference between us humans and complex zombies who lack any inner feelings, because we are all just complex zombies.

I think most readers, when first told this, would assume that I must be misunderstanding him. Surely no sane person could deny the existence of feelings. But in his reply he makes it clear that I have understood him exactly. He says, “How could anyone deny that!? Just watch…”

Dennett is obviously wrong about consciousness. But what about color, sound, heat, and cold? Is it true that “reductive scientific explanation” holds that these things are a “mere appearance” that “correspond to nothing in objective, mind-independent reality?”

Feser may be quite honest personally in his description of what he considers to be two opposing views. But it seems to me that he is inheriting this description from a long tradition of putting Aristotle and common sense, on the one hand, into an unnecessary opposition with modern scientific views on the other. I think that this tradition is in essence wishful thinking: this tradition came to be historically through the efforts of people who wished for disagreement between Aristotle and modern science.

I touched on this wish in an earlier post when I said that John Locke’s understanding of secondary qualities “is actually mostly true, and mostly consistent with the philosophy of Aristotle, even though Locke would likely wish that the latter were not the case.” The early moderns did differ from Aristotle regarding the purpose of the sciences, as I pointed out here in the case of Francis Bacon. Having a different purpose requires employing different means. Consequently it was favorable for their purposes to emphasize their disagreements with the philosophy of Aristotle, regardless of how much agreement or disagreement existed in reality when the positions themselves are properly understood. If people could be persuaded to abandon Aristotelian thought and focus on the new science, the purposes of the new science would be more easily obtained.

Let us ask the question directly: if color for example consists in the reflectance properties of a surface, does this mean that colors as we see them are “mere appearances” that have no objective reality? Elsewhere, Feser says that this view implies that “Objectively there are only colorless, odorless, soundless, tasteless, meaningless particles in fields of force.”

The scientist can presumably reply in this way: Color consists in surface reflectance properties. These properties are objective properties of physical objects in the world. So color is an objective property of physical objects in the world.

Feser’s response can be found in the original quotation above:

What common sense understands by color, sound, heat and cold — the way red looks, the way a musical note sounds, the way a hot stove feels, and so forth — is held to have no objective reality, any more than the redness a person unknowingly wearing red-tinted contact lenses thinks he sees in all the objects around him really exists in those objects.  Instead, color is for scientific purposes essentially redefined by the method in terms of the surface reflectance properties that cause in us the subjective appearance of color; sound redefined in terms of the compression waves that cause in us the subjective appearance of sound; and heat and cold redefined in terms of the molecular motion that causes in us the subjective appearance of heat and cold.

Of course, the scientist would say that when a person wears red tinted contact lenses, the physical objects around him do not have the properties that constitute red, and consequently it is true that the objects are not objectively red. But other objects like red apples and the like do have those properties, and so they are objectively red. The two cases are not the same. Feser is replying by saying that whether he wants to or not, the scientist is denying the existence of red as we know it.

According to Feser, “what common sense understands by color” is something like “the way red looks,” and it is this to which, according to him, the scientist is denying objective existence. This is to say, if it true that red bodies have a certain way of reflecting light, and this fact is all there is in the body which explains why red bodies look red, Feser would say that this means that “the body is red” is a false statement. This is necessary for his position to be true: “the body is red” has to be actually false in the sense that we normally understand it, since he made the comparison with red tinted glasses, where in fact it is false that the body is red.

What do we mean when we say that something is red? We don’t just mean that it looks a certain way, because we know that sometimes things appear to be a color which they are not, as in the case of the tinted glasses. We don’t mean that it looks some way; we mean that it is that way. Take something that looks red. If we say that it is actually red, we mean that it actually is the way it looks.

All this is true, but it causes Feser to fall into error. “This is actually red” no more describes the nature of red than “this looks red” does. We know how red things look, because we experience it directly. But this experience is not a description. It is not something that can be true or false, so that we can say “surface reflectance is a false description of this experience.” It is a sensible experience, not a claim to truth or falsehood, and we consider sensible experiences accurate when they do not mislead us. Red tinted glasses do mislead us, and so we consider those experiences “false”, and say that the things are not really red. But even if color consists in surface reflectance properties, the experience of color never misled us. It never said, “This is not a reflectance property,” because it never said anything at all. It was not a statement but a sensation.

In order to determine whether something is actually red, we do not turn sensation into a description and check whether the thing matches that description. This is probably not even possible. We simply recognize that “this is actually red” when it looks red to a normal person in normal circumstances. And this is true regardless of what is present in the body that causes red things to look red to us, whether that is the properties of the surface or something else. Thus the scientist has no need to deny the objectivity of color, nor to deny his physical explanation of color.

Feser may actually have a different concern about objectivity, not merely whether statements about color are true or false. Are the distinctions in question natural distinctions, or are they essentially arbitrary from an objective point of view? Is the line between blue and green a natural one, or do our senses make that distinction in a basically arbitrary manner? Locke and others called certain qualities “secondary” because it seemed to them that the distinctions in question were basically arbitrary. We have good evidence that at least in some cases, they were right. An object feels hot or cold depending on the current condition of the one who feels it, without having to change from “being objectively hot” to “being objectively cold.” While the evidence is less conclusive in the case of color, something similar appears to be the case there. The line between different colors is in a different place for different people, as is most evidently the case in colorblind persons, and much more are the dividing lines in different places for different species of animal. This means that we have some reason to believe that green and blue things are objectively distinct, but that this objective distinction is much like the objective distinction between persons who are under six feet tall and persons who are over six feet tall. The distinction itself is objective, but the choice of distinction is basically arbitrary, if the thing is considered in itself.