How do we know that places like Narnia do not exist?

[69dodge]

How do you define seeing, then?

The eye is a photosensor. It is built to see things. That much is obvious.

The CCD in a digital camera is a photosensor too. But it doesn't consciously see. It's not obvious just by looking at an eye that it does see.

Space is three-dimensional. It's very simple.

A force travelling in one-dimension will not diminish, because it has nowhere to diminish into.
An omnidirectional force travelling in two dimensions wil disperse into the second dimension, falling off proportionally with distance.
And such a force travelling in three dimensions will fall off with the square of distance.

In Newtonian mechanics, the force of gravity doesn't travel; it simply exists everywhere at once. A constant force could exist everywhere at once just as easily as a force that decreases with distance.

 

[Interesting Ian]

The pink exists in the real world. It is directly measurable by lab equipment.

Yer wha . .???

You cannot measure qualia. The world as described by science is entirely absent of any colours, any sounds, any smells, indeed it is entirely absent of anthing we ever perceptually experience.

The experience of greenness is constructed entirely inside the brain.

Materialists hold that all colours are constructed entirely inside the brain. Well, at least they do if they know what they're talking about.

There is no green in the real world to be measured. There is an experience of green, but it's an illusion.

Nor indeed is ther any pink, blue, red, orange, or any smell, or any sound, or anything else we have ever experienced to be measured either.

Constitutive?

Pink is not part of reality. Not according to non-idealists anyway.

There really are pink dots in the example. There really isn't a green dot in the example. The illusion of the green dot is generated by the brain.
[/font][/color]

What's it an illusion of?

 

[Paul C. Anagnostopoulos]

Apart from colour blindness, is there good evidence that people see green differently?

I think so. My wife and I argue all the time about whether something is green or blue. Apropos to that, some women are tetrachromatic, and I think that allows them subtler distinctions in the blue-green range.

Remember, all that is required for coherent conversation is that I correlate my experience of color with the color names in a way that is consistent with you. Up to a point, it doesn't matter whether we actually experience the colors the same way.

~~ Paul

 

[Interesting Ian]

That doesn't even approach the level of a meaningful statement on the subject.

There are colours in the real world.

There are experiences of colour in the brain.

Some of these experiences directly represent real-world colours.

Some of these experiences are illusory.

But you're supposed to hold that there are only certain wavelengths of light in the world. There is nothing corresponding to colours in reality itself .. they are a creation of the brain.

Some colours are created by the brain as a result of a wavelength of light entering the brain, some are entirely a fabrication of the brain. But they are both creations of the brain.

You have to acknowledge this before we can proceed with the argument.

 

[Paul C. Anagnostopoulos]

What I mean by this is that colours don't really constitute reality -- colours are something whcih the brain creates.

Ian, come on, man. Explain how your model of perception distinquishes between these two cases. Clearly the perception of the pink is different from the perception of the green, whether the pink is external or not, whether there is such a thing as external color or not, whether my senses are being played on by the Metamind or not.

A machine can sense the wavelength of light corresponding to the pink, but not to the green. They are different. How do you describe and explain the difference?

~~ Paul

 

[Paul C. Anagnostopoulos]

Some colours are created by the brain as a result of a wavelength of light entering the brain, some are entirely a fabrication of the brain. But they are both creations of the brain.

You have to acknowledge this before we can proceed with the argument.

Yes, acknowledged. Now can we continue?

~~ Paul

 

[Interesting Ian]

Consider it this way, Ian. If you took the individual dots, apart from the rest of the illusion, and looked only at the dots or photographed them, or ran them through a photospectrometer, they would be pink.

You mean they would look pink.

The green that you imagine is situational,

So is the pink. You have to not look directly at the centre.

However, they are both part of reality, its just that the "green" part of reality is only in your brain, not in the objects themselves.

Not in the objects themselves?? But everything we ever perceptually perceive is moulded by the brain. If we really saw colours as in the objects themselves, then the colours of objects would change throughout the day.

Look, you say you know your car is a nice bright red and it remains red around the clock. But the light is not constant throughout the day. In the morning and evening, the light is considerably redder than at midday. When the sun is low in the sky, lots of blue light gets scattered away, because the sunlight has to penetrate a greater quantity of air when it passes through the atmosphere at an angle.

Yet your car appears to everyone to be equally red all day. This is despite the fact that the light our eyes receive from this car is not the same.

In other words the red colour you perceive is illusionary.

 

[Z]

I think we can agree that what we call 'colour' refers to certain brain processes which, ordinarily, occur when our photorecepters detect certain wavelengths of light; which can, also, be fooled by various means into occuring in the absence of those wavelengths of light. That being said, I personally think we are not incorrect to also apply the term 'colour' to objects which reflect/refract/absorb certain wavelengths of light. For example, a sphere which absorbs all wavelengths except for those of the 650-nm wavelength, which it reflects, could reasonably said to be 'red'. Simply enough, my reasoning for this is that this object will be detected as 'red' to anyone with the vision capacity to discern light at this wavelength and who has been educated that the label for this wavelength is 'red'.

As such, we can safely say that there is pink on that example, but no green; within the observing mind, there is pink and green; therefore revealing that the green within the observing mind is an illusion, and warranting sufficient justification to investigate why green exists within the subjective perception, where it does not exist on the image itself.

Of course, we know why the green exists, pretty much, but that's the subject of another discussion, isn't it?

But it would not be incorrect to say that the pink exists moreso than the green - that the pink exists in the objective and observable sense, while the green does not.

 

[Interesting Ian]

Ian, come on, man. Explain how your model of perception distinquishes between these two cases. Clearly the perception of the pink is different from the perception of the green, whether the pink is external or not, whether there is such a thing as external color or not, whether my senses are being played on by the Metamind or not.

A machine can sense the wavelength of light corresponding to the pink, but not to the green. They are different. How do you describe and explain the difference?

~~ Paul

You said it yourself.

A machine can sense the wavelength of light corresponding to the pink but not the green.

Now when we declare that something is a certain colour, do we go by what a machine says, or do we go by what everybody actually experiences??

 

[Z]

Not in the objects themselves?? But everything we ever perceptually perceive is moulded by the brain. If we really saw colours as in the objects themselves, then the colours of objects would change throughout the day.

Wha---?

Look, you say you know your car is a nice bright red and it remains red around the clock. But the light is not constant throughout the day. In the morning and evening, the light is considerably redder than at midday. When the sun is low in the sky, lots of blue light gets scattered away, because the sunlight has to penetrate a greater quantity of air when it passes through the atmosphere at an angle.

Yet your car appears to everyone to be equally red all day. This is despite the fact that the light our eyes receive from this car is not the same.

Ah. I see - WRONG. A 'bright red' car DOES change apparent colour throughout the day, as a matter of fact. EVERYTHING changes colour as the atmosphere changes colour with it. Chances are, you've been too wrapped up in your own 'magnificence' to notice.

Look at a 'bright red' object at night - is it still bright red? Nope. Therefore, your example is bullsh!t.

In other words the red colour you perceive is illusionary.

In other words, you've never paid any attention to the world around you, Ignorant Ian.

 

[Z]

On the other hand, the object still absorbs the same frequencies of light, provided those frequencies are present, and reflects the same frequencies, under the same conditions. Therefore, the object may still be said to be 'bright red' with the unspoken understanding that this means 'when exposed to white light'.

That should help clarify the issue.

 

[69dodge]

There are colours in the real world.

There are experiences of colour in the brain.

Some of these experiences directly represent real-world colours.

Some of these experiences are illusory.

I do not understand your view of things.

Is white a colour in the real world? Is pink? Neither is a pure spectral colour. Is every experience of seeing white or pink illusory, then?

If my computer screen lights up some tiny red and green dots, I see yellow. Is that experience illusory? Who says? Maybe it's real, and my identical experience when I look at monochromatic spectral yellow is the illusory one.

Bees can see ultraviolet light. Is ultraviolet a colour in the real world?

Two flowers that look the same to me might look different to a bee. Does my experience when looking at each flower directly represent its real-world colour?

It makes much more sense to me to say that there are no colours in the real world; there are only photons of light with various frequencies. When light enters my eye, I see a colour that depends on the frequency spectrum of the light. I can't always distinguish between different spectra; some spectra look the same as others. Sometimes, the colour I see depends on other factors as well, e.g., not only what I'm looking at right now, but also what I've been looking at recently, as in the case of afterimages.

 

[Paul C. Anagnostopoulos]

Now when we declare that something is a certain colour, do we go by what a machine says, or do we go by what everybody actually experiences??

I don't care! I'm happy to use "wavelength of light" and "color," respectively. Can we move on?

How do you describe and explain the difference between the perception of the pink and green colors?

~~ Paul

 

[Paul C. Anagnostopoulos]

It makes much more sense to me to say that there are no colours in the real world; there are only photons of light with various frequencies. When light enters my eye, I see a colour that depends on the frequency spectrum of the light. I can't always distinguish between different spectra; some spectra look the same as others. Sometimes, the colour I see depends on other factors as well, e.g., not only what I'm looking at right now, but also what I've been looking at recently, as in the case of afterimages.

This is fine technically, but you're not seriously suggesting that we stop talking about "the color of an object," are you? That would be a practical nightmare.

Also, I'm not sure what is wrong with giving a name to 510 nm light: green light.

~~ Paul

 

[aggle-rithm]

I think so. My wife and I argue all the time about whether something is green or blue. Apropos to that, some women are tetrachromatic, and I think that allows them subtler distinctions in the blue-green range.

Remember, all that is required for coherent conversation is that I correlate my experience of color with the color names in a way that is consistent with you. Up to a point, it doesn't matter whether we actually experience the colors the same way.

~~ Paul

My wife is always telling me that the shirt I am wearing does not match the pants I am wearing. I just don't see it. Besides, her claim is demonstrably untrue, since the two items of clothing are in the process of going together even as we speak.

I think it's safe to say that no two people experience ANY sensation in exactly the same way. For instance, the man who discovered and named the grapefruit gave it that name because, to him, it tasted exactly like a grape. Not to most other people, however.

 

[Interesting Ian]

Wha---?



Ah. I see - WRONG. A 'bright red' car DOES change apparent colour throughout the day, as a matter of fact. EVERYTHING changes colour as the atmosphere changes colour with it. Chances are, you've been too wrapped up in your own 'magnificence' to notice.

People don't notice because the colour of objects appear to be constant throughout the day. But obviously, since they do appear to be the same colour, then the colour we see is an illusion.

Look at a 'bright red' object at night - is it still bright red? Nope. Therefore, your example is bullsh!t.

We need to be able to receive a certain minimum threshold amount of light.

 

[Tricky]

You mean they would look pink.

They would correspond to a wavelength agreed upon as "pink" even to an inanimate object.

So is the pink. You have to not look directly at the centre.

No. The pink corresponds to an agreed upon wavelength of "pinkness". What you perceive may not, but objectively, it is.

In my job, I do a lot of graphics work and when I show my work, there is, for the most part, objective agreement upon what the colors are. Even the color tables have color names next to them, so even a computer can recognize certain wavelengths as being certain colors.

Not in the objects themselves?? But everything we ever perceptually perceive is moulded by the brain. If we really saw colours as in the objects themselves, then the colours of objects would change throughout the day.

Colors do change throughout the day based on light conditions because color is based on reflected and absorbed light. A photo spectrometer would record this too. So you are correct that we don't see colors as in the objects themselves, but as the light that they absorb and reflect, based on several factors. But we can still objectively agree upon those colors.

Look, you say you know your car is a nice bright red and it remains red around the clock. But the light is not constant throughout the day. In the morning and evening, the light is considerably redder than at midday. When the sun is low in the sky, lots of blue light gets scattered away, because the sunlight has to penetrate a greater quantity of air when it passes through the atmosphere at an angle.

Um. Yes. I am aware of this. Also that the sky is not always blue. But at any given instant, it has a measurable color.

Yet your car appears to everyone to be equally red all day. This is despite the fact that the light our eyes receive from this car is not the same.

No, this is just the reverse of what you said. It appears to be (with some variation) the same color of red at the same time of day to most people who are observing it from the same point of reference. Also to a photo spectrometer or a camera.

In other words the red colour you perceive is illusionary.

Yes, in that the car is not physically in my brain. It's properties must be detected by my sensory apparatus and converted to nerve signals which are interpreted by my brain. We can agree to call that "illusory" if you like. Of course, my sensory apparatus are not perfect recorders and my brain is not a perfect translator, hence, we can fool them with things like optical illusions.

But for the most part, people agree on what colors are what. That certain wavelengths are being transmitted to your eyes is not illusory. It is measurable and quantifiable. That we, more often than not, can recognize those wavelengths and agree on what colors they are is also not illusory. If it were, the game of "Twister" would be impossible to play, and that would be a great loss.

 

[Interesting Ian]

On the other hand, the object still absorbs the same frequencies of light, provided those frequencies are present, and reflects the same frequencies, under the same conditions. Therefore, the object may still be said to be 'bright red' with the unspoken understanding that this means 'when exposed to white light'.

That should help clarify the issue.

Look at this picture.

http://www.michaelbach.de/ot/lum_adelson_check_shadow/index.html

It is extremely clear that all the lighter shaded squares are the same colour, and all the darker shaded squares are the same colour. Right?

 

[Paul C. Anagnostopoulos]

Ian, please, I'm asking you politely:

How do you describe and explain the difference between the perception of the pink and green colors?

~~ Paul

 

[Tricky]

Look at this picture.

http://www.michaelbach.de/ot/lum_adelson_check_shadow/index.html

It is extremely clear that all the lighter shaded squares are the same colour, and all the darker shaded squares are the same colour. Right?

That's perhaps my favorite optical illusion. I keep it on my wall to show people how their eyes brains can be fooled. But to the computer, there is no confusion about the shades. If you made it into a bitmap and selectively replaced specific colors, you would see that. Of course, you can also see it with your eyes if the surrounding colors eyes are removed.