Why does colour exist?

[povmcdov]

No its not. We have been through this. Wavelength is a physical property, colour is the way you perceive that property. "Redness" is the archetypal example of a quale.

 

[WouldBe]

No its not. We have been through this. Wavelength is a physical property, colour is the way you perceive that property. "Redness" is the archetypal example of a quale.

Short wave is still short wave even if no-one is listening to it. Red is a name given to a small band of the visible spectrum. It still exists even if we all go blind.

 

[paolo]

And as an aside... Does everyone see colour the same? Is 'my' red, the same as your blue? We both look at the bus, we both agree its red, but the picture in our mind is totally different.

 

[slainte]

Hmm I love reading threads like this as a photonics graduate...have to say good question as to why does colour exist..shows an enquiring mind. Point to note that it is generally accepted that individuals vary in measures to the range of spectrum which they see, some see more towards the red end ie 800 to 850 nm others see better towards the blue end 400 to 350nm edge.
Personally was told that blue in the sky occurs from total internal reflection occurring within the Oxygen molecules and due to the remainant being reflected at brewsters angle the intensity is less than 4% so we see the colour blue from the light entering the atomsphere from the sun.
Also taught human eye is most sensitive at 550 nm right in the middle of the yellow/green spectrum.
Finally photons are discrete wave packets emissible from an energy source.

Just taught I would clear that up...please continue

 

[slainte]

Oh and the graphs put in the thread are out of date the CIE curve has been updated

 

[Jonti]

And as an aside... Does everyone see colour the same? Is 'my' red, the same as your blue? We both look at the bus, we both agree its red, but the picture in our mind is totally different.

This is a very good point, and far deeper than it first appears. There is simply no way of telling whether the another's subjective sensation of "red" or any other colour is the same as one's own. All we can be sure of is that the relationships between the colours are the same. We are able to communicate with each other (well, y'know, always excepting astrologers) because the structure of our experience is similar, not because the sensations we experience are similar.

Colour is a simple and obvious example. But there's no need to stop there. There's an interesting result from geometry that is thought provoking in this context. It is that the terms for "point" and "line" are interchangeable, and geometric theories still work (two points define a straight line; two lines define a point) although the graphical representation of the theory (the sensation, if you will) will look entirely different. It's a spooky thought that not only colours may look different to you than they do to me -- everything may look different to you than it does to me!

'Course, there's no real way of knowing if this is true or not, but it's an entertaining notion all the same.

 

[paolo]

Thats a way better answer than i expected. The point about structure of experience is

 

[Kameron]

And as an aside... Does everyone see colour the same? Is 'my' red, the same as your blue? We both look at the bus, we both agree its red, but the picture in our mind is totally different.

How about just looking at it differently for a moment.

Colour is a hard one because it is impossible to know (as far as I know) but how about a potentially similar analysis of hearing. There are people with perfect pitch those people hear and then can reproduce a middle C.

I think that it could be argued that those people have the same hearing. obviously they might hear a sound that is in some way different but for all intent and measurable variables it is the same sound isn't it? I'd say that if you want to know whether it is exactly they same think then we are arguing over total imponderables and therefore wanking (or in mathematical parlance looking at a degenerate problem may be).

However, I would also say this. Acid makes you realise how fragile and open to interpretation the world is. The ego loss thing where you get the switches in perception and you see the world as you imagine that others see is an object lesson in how different our interpretation of the world can be from those around us and I for one am sure that that is a transferable lesson unlike many things discovered while enhanced.

 

[WouldBe]

There's an interesting result from geometry that is thought provoking in this context. It is that the terms for "point" and "line" are interchangeable, and geometric theories still work (two points define a straight line; two lines define a point) although the graphical representation of the theory (the sensation, if you will) will look entirely different.

What if they are parallel lines?

 

[Jonti]

Google is your friend.

Start here with the principle of duality, geometry.

Enjoy!

 

[invisibleplanet]

Does this mean I'm really blue-green?

 

[dash_two]

This is a very good point, and far deeper than it first appears. There is simply no way of telling whether the another's subjective sensation of "red" or any other colour is the same as one's own. All we can be sure of is that the relationships between the colours are the same. We are able to communicate with each other (well, y'know, always excepting astrologers) because the structure of our experience is similar, not because the sensations we experience are similar.

It's a spooky thought that not only colours may look different to you than they do to me -- everything may look different to you than it does to me!

'Course, there's no real way of knowing if this is true or not, but it's an entertaining notion all the same.

Some interesting points there, Jonti.

It is quite right the nature of what the visual brain constructs is quite arbitrary, all that matters is that it is related consistently to things 'out there', whatever they may be. The red part of the spectrum does not need to look red any more than your computer's waste basket icon needs to resemble a waste basket.

It is economical to assume though that different people's visual experiences of the same things are going to be very similar, due to things like the universality of many different optical illusions and the highly conserved evolutionary nature of the human visual system, not much different from that found in rhesus monkeys (from which a lot of experimental knowledge of the visual system is derived).

 

[Jonti]

Yeah, there's heaps of circumstantial evidence from science that different people's visual experiences of the same things are very similar in quality as well as structure.

I mentioned the principle of equivalence just as particularly dramatic way to make the philosophical (mathematical?) point that qualia are arbitrary and its the structure that matters. This is because another person's qualia cannot be directly observed; but as you say, that does not stop us being able to use scientific results to infer a great deal about their subjective aspect.