Intro added 03/18/2012:
From The Romantic Manifesto, “Art and Cognition” by Ayn Rand
“The development of
human cognition starts with the ability to perceive things, i.e., entities.
Of man's five cognitive senses, only two provide him with a direct awareness
of entities: sight and touch. The other three senses—hearing, taste and
smell—give him an awareness of some of an entity's attributes (or of the
consequences produced by an entity): they tell him that something makes sounds,
or something tastes sweet, or something smells fresh; but in order to perceive
this something, he needs sight and/or touch.
"entity" is (implicitly) the start of man's conceptual development and
the building-block of his entire conceptual structure. It is by perceiving
entities that man perceives the universe. And in order to concretize his view
of existence, it is by means of concepts (language) or by means of his
entity-perceiving senses (sight and touch) that he has to do It.”
The Senses and Entities
By Thomas M. Miovas, Jr.
Leaving disputes about Kant aside for the moment, here's
what I'm getting at regarding our senses (and it's the same thing Ayn Rand says
in The Romantic Manifesto). We have a wall in the kitchen that has a floral
pattern wall paper on it, a wooden rack with knobs is nailed to it, and six cups
are hanging from the rack. With the eyes, I can see the cups and their color and
shape and that they are made of ceramic and are smooth, the rack is made of wood
stained a dark stain, and the floral pattern is easy to recognize with bright
colors and large flowers. With a blindfold on and feeling around, I can find the
cups, the rack, and the wall; but I wouldn't be able to tell there was a floral
pattern on the wall -- I might be able to detect the seams of the wall paper and
tell it has wall paper on it, but not the floral pattern. So, the fact that
there are cups on the wall and a rack (entities) is given via sight and touch.
With sound, if I had a very highly tuned set of ears and echolocation
capabilities, I could probably tell there was a wall in front of me and maybe
that it wasn't entirely flat. And as far as I can tell from blind people who
have echolocation capabilities, they cannot pick up individual entities via
sounds they make with their mouth or some sort of sonic broadcaster. The human
ears and nervous system are simply not geared towards picking up entities via
sounds bouncing off them in that way. On the other hand a bat and a dolphin
could pick up the individual cups and maybe even the rack using echolocation --
but it is not a skill that man has because his ears and nervous system are not
built with that type of accuracy on receiving sounds. You couldn't smell the
difference between cups and rack (well maybe if the rack had varnish on it and
it gave off an odor), but otherwise, the sense of smell will not give you the
cups or the rack and certainly not the floral design. Taste might give you a
slight difference between the items, but that would mostly be picked up by the
tactile sensors on the tongue (like your skin) but not taste per se.
* I’m not here trying to make a primary versus secondary attribute distinction. I’m merely pointing out the differences between sight and touch on the one hand versus hearing, taste, and smell on the other. All of the senses are valid and accurate, and give is existence the way it is; but some of the senses and their neurological functioning do not give us entities qua entities, like picking up a baseball and seeing that it is a small round ball with seams and is white and is used in a game. To Kant, all of these attributes regarding a baseball are a human mind generated non-real presentation of what the baseball really is in the noumenal world (the world as man does not perceive it, or aside from what is known about an entity via perception).
Added on edit: We can certainly distinguish things by the sounds they make – a bell ringing versus a bird chirping versus a man talking, but these are noises the entity is making and do not give attributes like shape, size, and texture. The term “entity” is developed by means of that which we can hold in our hand and look at, like a baseball, a cup, a pencil, something that is distinct qua entity. Afterwards, the concept of entity can be expanded to include something like a building, a planet, or a galaxy or a molecule or an electron. But the term entity must first be developed by that which we can grasp through sight and touch on a human immediately graspable level to distinguish it from something else; something that is separable from other entities.
I found some interesting articles on human echolocation, including claims that some details can be picked up from human echolocation, and one man who has taught up to 500 blind people how to echolocate using either their mouth making noises or by tapping on the ground using their cane. Reports vary as to how accurate it is and if entities can really be observed using echolocation in man, so I would have to see an actual scientific study and not just Wikipedia. Unfortunately, most of those are in PDF format, making it difficult to search for key words. Reports are, however, that it has to be a rather large object, like a tree, a pole, or a car. Studies have been made of blindfolded sighted people and echolocation giving some information that the visual cortex is involved in processing the information (the visual cortex is our largest and most complex processor in the brain). However, from my brief reading, I don't know that it is possible to echolocate something like six cups hanging on the wall, to go back to my example.
A brief follow-upon my understanding of Kant: If one holds
a baseball in one's hand, one can see and feel the shape, the texture, the size,
and the fact that it has large seams running along it. In Objectivism, this
ability is recognized as the ability to be aware of entities though in a
human-mode form. In other words, we see with our eyes and feel with our hands,
and these modes can be distinguished from one another, giving rise to what
Objectivists call "perceptual form." We are aware of the entities that
we are aware of directly, though it is dependent on our mode of perception, but
it is actual attributes of the entity. In Kant, he reverses this in his
"Copernican Revolution". Instead of saying we are aware of the
baseball as the real thing, he says there might be something out there but since
the mode of awareness is dependent on us being human, it is only that way (the
appearance) due to the human mode of perception. Therefore, the
baseball-in-itself (the noumenal baseball) probably doesn't even have seams or
shape or texture and may not be round -- these are just aspects of how the
baseball appears to us, but has no definite relationship between the real thing
and what we observe it to be.