Proving the senses

[Christopher]

Let us go back 2000 years to the time of Aristotle. We are adept in 21st century logic, but we lack sophisticated technology and medicine. In Athens, we encounter an intelligent but congenitally blind scholar. He states vociferously that sight does not exist. Of course all his colleagues (and you) know he is incorrect. Yet, he has never experienced sight.

How can we logically offer an argument to this man about sight such that he must be rationally forced to acknowledge its existence? Would the same argument work for other senses such as taste or smell?

[Selene]

Chris:

Interesting exercise.

First:

I would ask the man whether or not he can touch his ears?

Adam

[tjohnson]

Let us go back 2000 years to the time of Aristotle. We are adept in 21st century logic, but we lack sophisticated technology and medicine. In Athens, we encounter an intelligent but congenitally blind scholar. He states vociferously that sight does not exist. Of course all his colleagues (and you) know he is incorrect. Yet, he has never experienced sight.

How can we logically offer an argument to this man about sight such that he must be rationally forced to acknowledge its existence? Would the same argument work for other senses such as taste or smell?

I don't know that you can "rationally force" anyone to accept anything - I guess you mean convince?? You could get him to pick up some pebbles and then hold out his hand and let us count them without touching them.

[jordanz]

Isn't this, essentially, the brain in a vat argument? I'm not technical enough to write a response, but David Kelley has a tape that addresses it.

In this particular case, I believe that blind people have some "internal" sight - i.e. they dream (unless blind from birth). The point is that they can form the concept sight. Once that's done, it's just a matter of deduction to give them enough evidence that you can see even though they can't.

[Christopher]

Isn't this, essentially, the brain in a vat argument? I'm not technical enough to write a response, but David Kelley has a tape that addresses it.

In this particular case, I believe that blind people have some "internal" sight - i.e. they dream (unless blind from birth). The point is that they can form the concept sight. Once that's done, it's just a matter of deduction to give them enough evidence that you can see even though they can't.

I'd be interested to listen to D.K.'s tape. Do you have the title or where I might find it?

Thanks,

Chris

[BaalChatzaf]

.......

In this particular case, I believe that blind people have some "internal" sight - i.e. they dream (unless blind from birth). The point is that they can form the concept sight. Once that's done, it's just a matter of deduction to give them enough evidence that you can see even though they can't.

That would be visual recall.

Even without visual recall a simple experiment might convince a blind person who had never seen and has no concept of sight some indication that another sense (which he does not possess) is at work.

A blind person (who can hear, but has never seen) is asked to remove some set of pebbles from a jar and lay them down quietly, so that they cannot be counted by sound. The blind person can count even if he cannot see and he knows precisely how many pebbles from the jar he has exposed. A sighted person, who is at a distance tells the blind person how many pebbles were taken from the jar. This is done sufficiently many times to removes the possibility of coincidence. The blind person now has definite evidence that the other participant has a means of knowing with touch contact and from a distance how many pebbles were taken from a jar. Clearly another sense was at work.

Ba'al Chatzaf

[jordanz]

I'd be interested to listen to D.K.'s tape. Do you have the title or where I might find it?

It's part of the Evidence of the Senses series, but I don't remember which tape. Maybe it's in the book?

[kiaer.ts]

Oh, yeah, sure. And what about all the pebble sniffers out there?

The blind person has enough of an incentive on his own to figure out the reality or not of sight. The context of this thread among others bent on disproving such things as mysticism makes me wonder if the intent here isn't to ask is there some way to prove the validity of the senses to someone who wishes to assume they are not valid.

The proper answer is not to try to prove the validity of the senses or the validity of reason as opposed to unreason, but to let those who wish to challenge reason or the senses do so without using reason or the media of the senses.

You expect me to hear you say that the senses are invalid? To see your written arguments?

Metaphysician, cure thyself.

[BaalChatzaf]

I once saw a documentary which showed that in blind people, the sense of touch is processed by the visual cortex, the area in the back of the cerebrum. In people who once had sight, the processing of touch is taken over by the visual cortex. In people who never saw, the visual cortex (the area in the occipital lobe) manages the input from touch from the git-go. For people who learn Braille, their fine precision touch is handled in the visual cortex. Apparently the visual cortex is the repository of topological processing in the human brain. Touch and sight are the senses that deal specifically with shape and other spatial relations.

Ba'al Chatzaf

[Selene]

Ba'al:

Thanks. I was not aware of that, but it makes a lot of sense to me.

When I have been in a building wherein there are no lights, the hands and feet are amazing

"antennae" that do provide the brain with a "visual map" which with some knowledge as to how

rooms or buildings are made can actually allow me to "see" the room I am traversing.

Adam

[Christopher]

Ba'al,

I agree. Cool post on the processing of touch by the visual cortex.

Chris

[jeff]

You could just ask the blind man to touch a part of his body.

Then when he touches something tell him what he touched.

Then he will say "Wow, how did you know what I touched?"

You can say "Because I have eyes and I can see".

Then he says "But how do I know that what I touched is what you say it is"?

Then you say "Because you're Mom taught you where each part of your body is and what each part is called".

Then he says "How do I know you're not my Mom"?

The you say "Because I'm a guy and I don't even sound like a woman".

The he says "Maybe the person who claimed to be my Mom was also a guy. Maybe none of you are real. Maybe I'm not even real. Maybe existence doesn't exist".

[Christopher]

Yes, I'm noticing a common theme among responses. Basically, use sight to achieve some knowledge that the blind person can not explain as being accomplished through any other explainable means. I wonder if this is the only way...

[jordanz]

It's been years since I read it, but the book Flatland deals with this subject in a fun way. The main character, as I recall, lives in a two dimensional world and encounters a being that claims to be from a new third dimension. The three dimensional character describes the 2D character's insides because he can see inside of him, etc. and eventually convinces him of a 3rd dimension.

The main point here is that we have senses. Our senses react to the world as it is and give us objective information about reality. With our senses we can discover everything about reality. If some being claims to possess a previously unknown sense he should be able to prove it by the usual means of evidence, deduction and induction.

[BaalChatzaf]

The main point here is that we have senses. Our senses react to the world as it is and give us objective information about reality. With our senses we can discover everything about reality. If some being claims to possess a previously unknown sense he should be able to prove it by the usual means of evidence, deduction and induction.

Not so. There is a limit to how accurate our detection instruments are. In addition there is the Heisenberg Indeterminacy Principle which limits what we can measure by a pair of complementary observations such as position and momentum or time and energy. In any case it is highly unlikely we we ever measure down to Planck Length. With our best instruments we are 15 or 16 orders of magnitude shy. So there is a limit to what we can observe using our best instruments. And then there is the horizon to the cosmos. Our upper bound currently is about 300,000 light years from the singular point of sudden Cosmic Expansion (aka "the Big Bang"). That is just shy of two seconds.

Ba'al Chatzaf

[Selene]

Ba'al:

"Our upper bound currently is about 300,000 light years from the singular point of sudden Cosmic Expansion (aka "the Big Bang"). That is just shy of two seconds."

???? I am not clear as to the two seconds????

Adam

[BaalChatzaf]

Ba'al:

"Our upper bound currently is about 300,000 light years from the singular point of sudden Cosmic Expansion (aka "the Big Bang"). That is just shy of two seconds."

???? I am not clear as to the two seconds????

Adam

Error! Error! Will Robinson. Make that more like three minutes. It should have been 300,000,000 miles.

Our theories get to within 10^(-33) seconds of the expansion but the initial condition of the universe was such that light could not get out until the cosmos "thinned" a bit to around 300,000,000 miles in diameter which is a little under three light minutes , at the currently known speed of light. The theories break down at the singularity event and do not describe what it was like at that instant. By the time the cosmos thinned sufficiently for light to get out, the forces (or interactions) which are initially unified broke into the four known forces: electromagnetic, weak-nuclear, strong nuclear and gravitation.

In any case all of our cleverness and money will probably never get us to rock bottom. Besides which the initial expansion of the cosmos was at greater than light speed* so we haven't gotten all of the information from the horizon. Then we can only "see" a fraction of the matter in the cosmos (the rest is so called "dark matter") And the cosmos is now expanding at an increasing rate and the cause of that over-expansion is not really know. It goes by the name "dark energy" but that is just a place holder for our ignorance. There is no really workable theory to account for this pesky fact.

Ba'al Chatzaf

*the so called inflationary Big Bang hypothesis. Before the unified forces of nature broke up the cosmos expanded at greater than the currently known speed of light (but only for a short time). This hypothesis was put forth by Alan Guth (now at M.I.T.)

See http://en.wikipedia.org/wiki/Big_Bang

http://en.wikipedia.org/wiki/Inflationary_epoch

Edited May 19, 2009 by BaalChatzaf

[Selene]

Ba'al:

Thanks so much. I thought that some deep programing in my "hard drive" was really wrong. lol.

Adam

[jordanz]

Not so. There is a limit to how accurate our detection instruments are.

The limits to our senses are immaterial. Our senses react to reality in predictable way. There is no magic - the senses work according to their nature. Given a stimulus, a given sense will act accordingly. That's how we gain knowledge of objective reality. Anyway, David Kelley explains this much better than I can.

[BaalChatzaf]

Not so. There is a limit to how accurate our detection instruments are.

The limits to our senses are immaterial. Our senses react to reality in predictable way. There is no magic - the senses work according to their nature. Given a stimulus, a given sense will act accordingly. That's how we gain knowledge of objective reality. Anyway, David Kelley explains this much better than I can.

There is the Heisenberg Principle which limits what we can know (among other things). And the limits to our senses is highly material. Our eyes are sensitive to a very small portion of the electromagnetic spectrum and not all the Objectivists or their Men can change that. Our eyes evolved to be sensitive to the portion of the sun's spectrum which is most energetic. The human eye can resolve angles to about 2 seconds of arc (1/30 th of a degree). Eagles and Vultures can do five to ten times better which is why they can spot a squirrel carcass from 20,000 feet. Our ears work between 20 hz and 20,000 hz. That is narrow band compared to some other animals. We have to resort to various sonar devices to deal with that limitation.

We sense very little of the world directly and we must resort to indirect means, instrumentally supported to get a handle on the rest. Our inferences are theory laden and therefore subject to modification as our technology for observation improves. As I pointed out we are fifteen orders of magnitude away from Planck Length. How do you suppose we are going to bridge that gap?

With our best technology we can locate to with ten meters on the earth's surface. That is thirty feet or so. There things and places a lot smaller.

Our limitations are very material. They limit how good our science can get.

Ba'al Chatzaf

[jordanz]

There is the Heisenberg Principle which limits what we can know (among other things).

I don't believe that it does not limit what we can know - but that's another topic.

We sense very little of the world directly and we must resort to indirect means

This is incorrect. In fact, we experience the world directly. A photon of light enters the pupil makes its way to the optic nerve resulting in a stimulus in the brain. Where's the indirection? It's as direct as if I push a pencil and it moves.

Edited May 20, 2009 by jordanz

[BaalChatzaf]

There is the Heisenberg Principle which limits what we can know (among other things).

I don't believe that it does not limit what we can know - but that's another topic.

We sense very little of the world directly and we must resort to indirect means

This is incorrect. In fact, we experience the world directly. A photon of light enters the pupil makes its way to the optic nerve resulting in a stimulus in the brain. Where's the indirection? It's as direct as if I push a pencil and it moves.

Our eyes do not register ultra violet or infra red for example. Our senses respond to a very narrow pass band. The limitation is in the response range of the rhodopsin molecules in our rods and cones. They determine the bounds of the pass band to which we can respond.

As to the correctness of quantum physics, the standard model predicts good to twelve decimal places. I believe it.

The standard model of particles and fields, warts and all is the best physics theory ever developed.

We know it cannot be complete since it does not address the gravitational interaction but for the other three forces, it is right on the money in the energy ranges we can muster. It probably does not work in black holes but we will never know about that.

Ba'al Chatzaf

[tjohnson]

This is incorrect. In fact, we experience the world directly. A photon of light enters the pupil makes its way to the optic nerve resulting in a stimulus in the brain. Where's the indirection? It's as direct as if I push a pencil and it moves.

Yes, but you can't "see" a photon itself, you use it to manufacture images in your cortex. The photon is an inferred entity.

[BaalChatzaf]

We sense very little of the world directly and we must resort to indirect means

This is incorrect. In fact, we experience the world directly. A photon of light enters the pupil makes its way to the optic nerve resulting in a stimulus in the brain. Where's the indirection? It's as direct as if I push a pencil and it moves.

Really old chap? When was the last time you saw directly, with your own eyes and without instrumental mediation infra red or ultraviolet, not to say anything about X-rays and gamma rays. The instrumental mediation is theory laden. We rely on theory to interpret the dials. Suppose we find out one day, that the theory is wrong? We don't need theories for immediate perception. We see what we see and we hear what we hear.

By the way you cannot perceive sound at 35,000 Hz nor can you perceive sound at 5 Hz. To do that, instruments are required. One of the biologists studying elephants decided to speed up the recording of elephants and discovered they have nice conversations at 5 Hz which we cannot hear. This accidental discovery revealed how the female leaders of elephant herds control the rest. Apparently the herd-mothers issue orders to their followers at 5 Hz. Dolphins and porpoises have nice conversations at 30,000 to 40,000 Hz and even higher pitches than that. That is sound transmission way out of our pass band.

Ba'al Chatzaf

[jordanz]

When was the last time you saw directly, with your own eyes and without instrumental mediation infra red or ultraviolet

I didn't say our sense are perfect nor did I imply that our sense can perceive everything. But, what they do sense, they sense directly.