Tani

to answer godot's question: the names of the colour is not inherent properties of colours. blue is only the name we converse with each other, it merely confirms that i have an old sensation similar to the one i have now and i called it blue and you had an old sensation similar to the one you have now and you also called it blue, it however doesn't tell me if what i sense is like what you sense - we only agreed that what i see is what i saw before which i called blue and you have the same situation.

a colour-blinded person might agree with you on what is blue only to disagree with you on how red is not blue. in that case, you can't really tell if the colour blinded persons is actually seeing what you sense as blue or red, or anything else for that matter, when he sees blue and red. i mean does he see both blue and red as red? or does he see both blue and red as blue? all that you can infer is that they appear the same to him.

there is simply no way to know if what i sense is what you sense. we can have similar physio-chemical reaction in the brain to a particular wave length of light, but that does not translate to what we sense - there is nothing we call blue in the wave length itself or the physio-chemical reaction in the brain. how that translate into sensing blue is still a mystery.

copernicus

Since we all have the same physical equipment, and the mind is rooted in that physical equipment, there is no reason to believe that subjective experiences are different.

Tani

the only problem is that there is only exactly one sample you can reference from - your own mind, and that alone is insufficient even for using induction as a means to get a probable answer. this is one reason why consciousness is such a problem for science, sensing colour is only one minor example of it. basically, there is no reason to believe that subjective experiences are the same either.

Pyrrho

I don't mean to sound flippant, but what difference does it make? The function of language is to communicate, and as long as we more or less agree on which things are "blue", why would it matter if we experience "blue" the same or not?

Indeed, whenever two people are looking at the same thing at the same time, their view of the object MUST be different, as they are looking from different places, no matter how close to each other they are. And since their view is different, presumably what is going on in their mind is different. Yet we can still pretty much agree on which thing is a table, a chair, and so forth. No one need ever see the things you see from the perspective you are now seeing them, and it will not matter.

The blue object is, to speak commonly (as opposed to metaphysically), "out there", not in your mind, and when we speak of it, we are not speaking about the processes in your mind. When you speak of "blue", what you are speaking about MUST be "out there", or we would have no idea what you are talking about. For more on these ideas, you might find Wittgenstein's remarks about a "private language" interesting. It is in his Philosophical Investigations.

Tani

that, i'll say, is the reason why we can carry on out lives without much problems. it's because other's consciousness doesn't actually matter that much. this is no sarcasm. even if everyone but yourself is just some bots, as long as they respond as if they are intelligent, you'd be able to get by your life. the real reason to investigate it at all is really to satisfy your own curiosity.

flatland

I refer you to this page . Great resource for cognitive science and the philosophy of it. look around, search for color perception, etc. I'd reference some specific pages, but I've been up for 20 hours and it's time to wander off.

copernicus

It is true that we can only have direct experience of our own minds, but that is beside the point. We have as good a reason to believe that the experiences of others are the same as ours as we have reason to believe that other people exist. To the best of our knowledge, consciousness is grounded in the physical structures that make up human bodies. Since human bodies have the same physical equipment, we can assume that perceptual experiences grounded in that equipment is the same. To believe otherwise would be a violation of Occam's Razor. That is, we have no good reason to suspect that what I perceive as "blue" is what you perceive as "orange". Our physical similarities represent a good basis to suspect that what I perceive as "blue" is exactly what you perceive as "blue".

Godot's original question asked us to go beyond the physical issues, but that is just asking us to abandon the only evidence that we have for knowing anything that goes on outside of our own direct experiences. Why would we want to do that? There is no absolute knowledge, just degrees of (un)certainty about the nature of reality.

Torben

There are no colours that we cannot see. It is humans that defined colours, namely as being what we can see. There is no (in this context) qualitative difference between infrared, ultraviolet and visible light, except maybe that objects on this planet generally seem to absorb light of certain wavelengths in the visible spectrum.

Torben

Godot

I'm impressed with the number of comments generated by something I threw out there as a lark! From what I can tell, most people refused to consider any alternatives outside of their realist empirical box.
I know I'm quite happy with mine, thank you very much.

The point I was trying to get at (the colour analogy is something I came up with the first time I had thought about it) is that perception is completely subjective. We agree on the appearance of the natural environment because we assume that we all perceive it in the same manner given that we all use the same apparatus for doing so.
While our knowledge base can only encompass what we experience through our sensory organs, I just find it interesting on a purely philosophical level that we can agree on a meaning for something without knowing for certain if our perceptions of that something is consistent with how others see it.

Torben

So right you are!!:notworthy
It is mindtwisting!

Torben