Consider, please, the following statement:

“Although mental experiences are private, they are certainly real.”

I expect most readers will not be impressed by this statement: typical responses might range from indifference to suspicion.  But there is important substance to it, and there is no trick.  For me, and I hope eventually for the reader, this simple observation opens the door to profound insights and investigations.  Hang with me please, let me take you there.

 The reason the statement seems boring is that I cannot explain it to you by logic, argument, or learned citations. Rather, I have to guide you so that you grasp the meaning on your own.  My task is a little like trying to give you the nourishment of a ham sandwich by talking to you about ham and bread.  To get the benefit of a ham sandwich, you have to eat one. But I can’t eat the sandwich for you.  The only thing I can do is to guide you to the deli counter and persuade you to eat.  Stay with me, please.

The easiest kind of mental experiences to explain are those based on the senses.  Unfortunately, an example based on a particular sense will not be useful to those without that sense.  My first example will be based on the visual experience, and so will not be useful to those without sight.  Actually, it will be based on the experience of color, and so may not be meaningful to those who are color blind to some degree.  Not to worry. I will give other examples based on other senses.  Hang in there.

For those with normal color perception: I want to point out what is meant by the mental experience of the color red. Take a look at some object in your surroundings that is red. How did you learn what objects to label as red?  By reading a textbook, or a dictionary, or hearing a lecture?  No.  You learned it by example, probably on your mother’s knee. In any event, someone pointed out various objects to you, and said “red” about each one.  After a few examples, you caught on that what these objects had in common was their color, and so you learned to call that color, “red.” In other words, you learned about the experience of redness by example.  (The ability to abstract common features from a series of events is a capability of the human brain having all sorts of other consequences, but that’s a topic for another blog.)

Now consider an expert physicist who has been totally blind since birth.  Ask him or her to explain the color red. He (or she) will say,

“Oh I know what red is.  Electromagnetic energy with a certain spectral distribution impinges on the lens of a sighted person’s eye, where it is focused on the retina.  There structures called rods and cones convert the electromagnetic energy into neural impulses that travel along the optic nerve to the brain where they are processed by the visual centers.  Eventually impulses are sent to the speech centers, causing the subject to utter the word, ‘red.'”

After complimenting the physicist on the depth of his understanding, you might respond, “I understand that this is what happens physically when someone sees red, but can you tell me what redness, the experience, is?  What is the color red?”  The blind physicist will answer,

“Sorry, I can’t answer that.  Being blind, I’ve never experienced redness, or greenness, or grayness, or anything else that I am told is an aspect of the visual experience.  I can only tell you the physical correlates of these things.  You’ll have to ask a sighted person what the experience of red is.”

So you seek out the nearest sighted person and ask, “What is the experience of the color red?” After some explanation of what you want, the person may point to some examples of red objects.  “No, no,” you insist.  “What is red like for you?  What is your experience of the color red?”  After some more conversation, you will find that the person cannot explain to you what their experience of the color red is!  But their inability to explain the red experience is different from the blind person’s inability to do so.  The blind person has no experience of red.  The sighted person experiences red, but cannot communicate what the experience is.

 I tell these vignettes just to make sure we are on the same page regarding the difference between the mental experience of a color, and the physical correlates of that experience.  Before we go any further, let’s bring on board those whose visual apparatus is not fully normal.

For those with normal hearing:  For those who are color blind or otherwise lack normal visual function, a similar explanation can be based on an auditory experience, such as dissonance.  Find a piano and strike any three adjacent keys (including at least one black key).  That sound is dissonance.  Compare that with, say, a C-E-G chord.  That’s harmony.  The deaf physicist’s explanation involves sound waves in air, and the listener’s ear drum, but otherwise the substitution of “dissonance” for “red” yields a similar explanation.

For those with normal sense of taste, smell, or touch:  Similar explanations can be constructed around the experiences of sweet, rose scent, or tickle.  For example, if someone has no sense of smell (there are folks so handicapped), it is impossible to explain to them what the scent of a rose is, even though they can understand how chemicals emitted by the flower stimulate the olfactory organ.

Conclusions:  Please verify that your personal experience of red, dissonance, or rose scent is real.  By that I mean, real for you. Just because you can’t communicate to someone else what these personal experiences are like for you does not mean they are not real.

By the way, philosophers have a name for such mental experiences.  They are called “qualia.”  (One experience is a “quale.”)  [refs]

For me, mental experiences (we have only discussed sensory experiences so far) are actually more real than the statements I read in a book or the news I see on TV.  Having read thus far, you might well respond, “So what?”  Follow me to the next post, please.

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