What do we see when we see?

I'm going to reproduce some recent correspondence of mine. My words in red, his words in blue. 

I see that this guy is saying the same thing that I've been saying for years. This is the paradox of scientific realism. Seems to me that a scientific theory of sensory perception immediately leads to indirect realism. But in that event, the apparently objective, 3rd-person description of the sensory processing system is a disguised subjective, 1st-person description of how the world merely appears to the percipient.

It seems to me that only divine revelation can broker this issue.

Mind you, I don't agree with the other stuff he says (which I don't quote). I don't agree with his alternative. But that's because, absent divine revelation, we are truly in the dark.

Because the word "consciousness" can be used in so many different ways, confusion often arises around statements about its nature. The way I use the word is not in reference to a particular state of consciousness, or particular way of thinking, but to the faculty of consciousness itself-the capacity for inner experience, whatever the nature or degree of the experience.

 

A useful analogy is the image from a video projector. The projector shines light onto a screen, modifying the light so as to produce any one of an infinity of images. These images are like the perceptions, sensations, dreams, memories, thoughts, and feelings that we experience-what I call the "contents of consciousness." The light itself, without which no images would be possible, corresponds to the faculty of consciousness.

 

We know all the images on the screen are composed of this light, but we are not usually aware of the light itself; our attention is caught up in the images that appear and the stories they tell. In much the same way, we know we are conscious, but we are usually aware only of the many different experiences, thoughts, and feelings that appear in the mind. We are seldom aware of consciousness itself. Yet without this faculty there would be no experience of any kind.

 

The faculty of consciousness is one thing we all share, but what goes on in our consciousness, the content of our consciousness, varies widely. This is our personal reality, the reality we each know and experience. Most of the time, however, we forget that this is just our personal reality and think we are experiencing physical reality directly. We see the ground beneath our feet; we can pick up a rock, and throw it through the air; we feel the heat from a fire, and smell its burning wood. It feels as if we are in direct contact with the world "out there." But this is not so. The colors, textures, smells, and sounds we experience are not really "out there"; they are all images of reality constructed in the mind.

It was this aspect of perception that most caught my attention during my studies of experimental psychology (and amplified by my readings of the philosophy of Immanuel Kant). At that time, scientists were beginning to discover the ways in which the brain pieces together its perception of the world, and I was fascinated by the implications of these discoveries for the way we construct our picture of reality. It was clear that what we perceive and what is actually out there are two different things.

 

This, I know, runs counter to common sense. Right now you are aware of the pages in front of you, various objects around you, sensations in your own body, and sounds in the air. Even though you may understand that all of this is just your reconstruction of reality, it still seems as if you are having a direct perception of the physical world. And I am not suggesting you should try to see it otherwise. What is important for now is the understanding that all our experience is an image of reality constructed in the mind.

http://twm.co.nz/prussell_bio.html

The key to this new model of reality is an understanding of how we perceive reality. Advances in physics, psychology, and philosophy have shown that reality is not what it seems. Take vision, for example. When I look at a tree, light reflected from its leaves is focused onto cells in the retina of my eye, where it triggers a cascading chemical reaction releasing a flow of electrons. Neurons connected to the cells convey these electrical impulses to the brain’s visual cortex, where the raw data is processed and integrated. Then—in ways that are still a complete mystery—an image of the tree appears in my consciousness. It may seem that I am directly perceiving the tree in the physical world, but what I am actually experiencing is an image generated in my mind.

 

The same is true of every other experience. All that I see, hear, taste, touch, smell and feel has been created from the data received by my sensory organs. All I ever know of the world around are the mental images constructed from that data. However real and external they may seem, they are all phenomena within my mind.

This simple fact is very hard to grasp; it goes against all our experience. If there is anything about which we feel sure, it is that the world we experience is real. We can see, touch and hear it. We can lift heavy and solid objects; hurt ourselves, if we're not careful, against their unyielding immobility. It seems undeniable that out there, around us, independent and apart from us, stands a physical world, utterly real, solid and tangible.

 

But the world of our experience is no more "out there" than are our dreams. When we dream we create a reality in which events happen around us, and in which we perceive other people as individuals separate from us. In the dream it all seems very real. But when we awaken we realize that everything in the dream was actually a creation of our own mind.

 

The same process of reality generation occurs in waking consciousness. The difference is that now the reality that is created is based on sensory data and bears a closer relationship to what is taking place in the real world. Nevertheless, however real it may seem, it is not actually "the real world". It is still an image of that world created in the mind.

 

It is important to distinguish between two ways in which we use the word "reality". There is the reality we experience, our image of reality; and there is the underlying reality that has given rise to this experience. The underlying reality is the same for all observers. It is an absolute reality. The reality I experience, the reality generated in my mind, is a relative reality. It is relative to my point of view, my past experience, my human senses and my human brain.

 

The fact that we create our image of reality does not mean, as some people misconstrue, that we are creating the underlying reality. Whatever that reality is, it exists apart from our perception of it. When I see a tree there is something that has given rise to my perception. But I can never directly perceive this something. All I can ever know of it is the image appearing in my mind.

 

When, two centuries ago, Bishop Berkeley proposed that we know only what we perceive, his contemporaries debated whether or not a tree falling in a forest made a sound if no one was there to hear it. From what we now know of the psychophysiology of perception, we can say the answer is "No". Sound is not a quality of the underlying reality. There may be movements in the air, but the interpretation of those movements as sound is something that happens in the mind—whether it be the mind of a human being, a dog or a woodpecker.

 

Similarly with light. Whatever the tree is in physical reality, it is not green. Light of various frequencies is reflected from the tree to the retina of the eye, where cells respond to the amount of light in three frequency ranges (the three primary colors). But all that is passed back to the brain are electro-chemical impulses; there is no color here. The green I see is a quality created in consciousness. It exists only in the mind.

 

The same is true of our perception of distance. The pattern of light that falls on the retina creates a two-dimensional image of the world. The brain estimates distance by detecting slight differences between data from the left and right eyes, the focus of the eyes, relative movement, and past experience as to the likely size of a tree. From this data it calculates that the tree is fifty feet away. A three-dimensional image of the world is then created with the tree placed "out there" in that world, fifty feet away. Yet, however real it may seem, the quality of space and distance that we experience is created in the mind.

http://twm.co.nz/prussell.htm#Perception

Divine revelation seems to be, in general, known by us through the senses. But then we don't have the sort of objective access to it that you think we lack in the case of the external world. How does divine revelation solve the problem of the external world's darkness (epistemically speaking) to us? 

You need to distinguish between divine revelation coming to us through a sensory medium, and what revelation tells us about the sensible world, including the medium of transmission.

It's like the difference between a radio wave as a carrier wave for a radio broadcast, and the content of the message.

Yes, but I'm having a hard time understanding what the distinction is supposed to help: if we are in the dark about the world because of the way our senses tell us about it, if we lack any objective reason to believe that the world is the way it appears to us through our senses, then this would count in any cases of ostensible divine revelation to be known by way of the senses as well.

To use the radio analogy, if I have a bad receiver or a receiver such that there's no problem in principle with the suggestion that it might greatly distort messages received from various transmitters, then I can't seem to use messages received by way of the receiver in support of its reliability; to take evidence from the receiver as evidence of its reliability is to presuppose its reliability already, after all.

If the receiver is bad, you get gibberish. The information you get isn't wrong–rather, it's unintelligible.

If, by contrast, what you hear is understandable, then you know that the message wasn't fundamentally corrupted or garbled in transmission.

Try a different comparison:

If I look at a garden through tinted glass, I won't know what color the flowers really are.

If, however, I read a poem with tinted glasses, the fact that my medium filters the input doesn't change the fact that I can know what the poem means. For the meaning is, abstract propositional–even if the medium by which I become acquainted with the meaning is concrete and filtered.

Or, to take a different example, what's the difference beyond white noise and a message in Morse code?

Both employ sensory media. But one has a meaningful, intelligible pattern whereas the other is random.

That may have been a bad analogy. Radios don't quite have the capability that sense organs coupled with human brains do.

This is what I am saying. If we are in the dark about what the world is like given only our senses, then we are equally in the dark about ostensible cases of divine revelation in the world and what they are like. The problem is that an epistemic "gap" between our senses perceptions and the actual way the world is would apply equally when the object of our sense perceptions are revelations from God (e.g., the bible).

Perhaps I am just unclear on what you mean when you say that "divine revelation can broker the issue". You should agree, I think, that if my senses, just taken by themselves, are inadequate at telling me what my computer or my favorite Starbucks location is really like, then they are equally inadequate at telling me what the Bible I hold in my hand is really like. But then what do you mean when you say that divine revelation can broker the issue?

No, it's not equivalent. There's a difference between raw sensory input (like shapes and colors) and structured information.

Okay, I think I am understanding better now, though I don't know how this helps. I only know of a piece of paper as having information on it through my senses; if my senses are unreliable in their suggestion to me that the paper is solid, colored, etc., why are they any more reliable in portraying the paper as containing information on it? or in portraying the information correctly?

First of all, I never said the senses are unreliable. The question is what they are designed to achieve. They could reliably aid us in navigating our physical environment even if they didn't tell us what things are really like apart from our perception. All that requires is a correlation, like a code.

Propositional information processing is self-correcting inasmuch as a statement on a page wouldn't make any sense unless it was transmitted with a fairly high degree of fidelity to the original.

That's not the case with mere sensation. To take a personal anecdote, when I was 35 I went to see a neuro-ophthalmologist . He wasn't your average eye doctor.

In the course of my examination he asked me, in passing, if I was color blind. I said that, to my knowledge, I was not.

He then had me look at something which revealed the fact that I'm partially color blind. I think in the blue-green spectrum or something like that.

Before then I never knew that I was partially color blind. I always took for granted that I was seeing the same spectrum as everyone with normal vision. I had no standard of comparison. No point of contrast. I'd lived and functioned for 35 years without being aware of that visual impairment.

However, linguistic propositions are different. Either they make sense or they don't. You can't have a severely corrupted content stream and still have something intelligible at the end of the transmission.

Of course, it's possible to have some errors in transmission, and we can generally correct that because, once again, we're dealing ideas, concepts–and not just sensory impressions that stand for nothing.

Where linguistic propositions are concerned, the check lies in the significance of the statement. Not just squiggles of ink, but squiggles of ink which must have a highly specified pattern to communicate meaning.