A brood comb

….philosophical and other notes….

Green Looks Like Yellow-Under-Blue-Light

Posted by Tanas Gjorgoski on September 20, 2006

Does yellow ball under a blue light look like a green ball under white light? Or is it the case that green ball under white light looks like yellow ball under blue light?
One might be inclined to say that if one sees yellow ball under blue light, he will see the color of the ball “wrongly”, but why assume that the experience of looking at a green ball under white light is somehow right, and the experience of looking at a yellow ball under blue light somehow wrong? There is no reason I can see to give some kind of primacy to the experience of the green ball under white light over the experience of the yellow ball under blue light. We can say that yellow ball under blue light looks like a green ball under white light, but there is nothing wrong to say that in fact it is green ball under white light that looks the same as blue ball under yellow light.

But don’t we learn what “green” means based on our experience of green balls under white light? We probably do, but one can imagine learning what “green” means by ostensive teaching by showing yellow ball under blue light (things can be arranged so that effects of neural adaptation don’t enter the equation). After being taught green in that way, that person can join the linguistic community which has learned “green” based on looking at green things under white light, and there will be no problems. We can imagine even special case in which green color is taught to a student through after-images. And both those “nonstandard” teachings are possible, because learning the word “green” is based on looking somehow of the object; person is not learning word “green” by examining the reflectance properties of the object – and the green ball under white light and yellow ball under blue light look the same.

Saying “yellow ball under blue light” looks the same as “green ball under white light” (and vice versa) we acknowledge an identity. We use “looks the same“, so there is something identical in both situations. Some would say that it is some private mind-thing, i.e. qualia, but we don’t need to imagine existence of such things as qualia. It is the green ball under white light, and the yellow ball under blue light that look the same. So in that simple sentence we see where the identity lies, it is in the looking somehow of the things – Two things can look the same, and there is hardly anything problematic in that.

However some would insist to connect this looking somehow to an objective property, (e.g. reflectance properties of the surface of the objects). But why give primacy to the reflectance characteristics of the green ball over those of the yellow ball, when both, the first under white light, and the second under blue light, look the same? We don’t even need to change the light, we can look at both balls under white light, but take a look at the green ball first, and then look at the yellow ball wearing blue-glass sunglasses. Green ball under white light, and when one doesn’t wear glasses, looks same as yellow ball under white light when one wears blue glasses. And again, there is no reason to put “the way green ball looks under white light if you are not wearing sunglasses” in privileged position to “the way yellow ball looks under white light to one who is wearing blue eyeglasses”.

Thus the first thing that should be acknowledged, in my opinion, in order to clear up this confusion about colors, is that words for colors are based on things looking somehow. As said, nobody gets to analyze reflectance properties of the surface of the objects in order to learn colors. Through ostensive teaching things which look somehow are shown to the learner, and there is nothing but that looking somehow on base of which “the student” learns colors. And because there is nothing else, there isn’t any problem in learning “green” by showing a yellow ball under blue light.

But how are then sentences like “It looks green, but it is really yellow!”, possible?, or which is same – how come we can use colors in sentences like “green ball under white light looks the same as yellow ball under green light”, if the color concepts are learned based on looking somehow of the things ? I will put my thoughts on this issue in some next post…

For now, here is something very rare! A lime looking like a lemon under blue light:

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4 Responses to “Green Looks Like Yellow-Under-Blue-Light”

  1. Jasonnnnn said

    do you know how to make a liqid that looks invisable but when you put a blue light it turns green?

  2. naisioxerloro said

    Hi.
    Good design, who make it?

  3. WordPress.com host (which is free btw) has dozens of free designs or ‘themes’, as they call them. This is just one of them, and apparently it’s been made by Andreas Viklund.

  4. Great article, fascinating site by the way. I’ve been reading through some of your articles for the past 1 or so now, “Does Pain Have To Hurt?” was a great read as well.

    – Matt
    Paranoid Schizophrenia Symptoms

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