A brood comb

….philosophical and other notes….

True Blue

Posted by Tanas Gjorgoski on November 6, 2007

Tye in his paper The puzzle of true blue presents to us the following puzzle:

Munsell chips of minimally different color are presented to John and Jane in standard conditions of visual observation. Both John and Jane have non-defective color vision, as measured by color tests.

Asked to pick-out a ‘pure-blue chip’, a chip that is blue, and is not tinged with any other color, John picks out Munsell chip 527. Jane, on other hand sees that chip as slightly greenish blue.

We are now presented with the following possibilities about John’s and Jane’s color experiences of the chip:

    (a) The color of the chip is both as it looks to John, and as it looks to Jane.
    (b) The color of the chip is as it looks to John, but not as it looks to Jane. (or other way around)
    (c) The color of the chip is neither as it looks to John, nor as it looks to Jane.

The puzzle is that none of those answers, on the face of it, seems plausible. Answer (a) is problematic, as it would mean that the chip is both true blue and blue tinged with green at same time. Answer (b) is problematic, as it is hard to see what would be the reason (positivist’ or metaphysical) to count John’s perception as “normal”, and not that of Jane. Answer (c) is problematic, as it would seem to require that nothing can be pure blue (or pure red, or pure green).

Attempts for solution of this puzzle range over views that nothing we see is really colored (something like Locke’s primary/secondary properties distinction), that we can in fact make sense of the idea that one of those perceivers is normal one, or view (like Tye’s) that the issue is one of precision. In that answer neither Jane nor John have been “designed” (by evolution) to get the color exactly right, but to pick out colors on course-grained level.


I want here to give an alternative solution to the puzzle, by picking out the choice (a). That is, I think that the color of the chip is (or can be) both as it looks to John, and as it looks to Jane.

First, it should be noted that it is not logically problematic that both A and B can be predicated to something, as long as A and B are not in contradiction. For example, there is nothing problematic in saying that something is both oval and green. So, the problem for the choice (a), is that the predicates ‘pure blue’ and ‘slightly greenish blue’ are apparently contradictory.

The proposal would be that objects have colors, but that we are seeing just an aspect of these colors due to the limits of our perception. John and Jane then when looking at the same color chip, are seeing different aspects of the color.

To make an analogy, it would be similar to a situation where we have a point on a plane, but we are limited to one dimensional projections. Usually such point, will be characterized by its projection on the x axis, in which we say that we get the x coordinate, and its projection on the y axis – y coordinate. But x and y axes are just one possible pair that covers the whole space – we can also imagine coordinate system rotated in the relation to that original one, with x’ and y’ axes. Given that there is nothing about the plane which gives primacy to certain coordinate system, there will be no reason to prefer the first over the second pair of axes.

So, staying with the analogy, we can use the following metaphor: the objects’ colors are two-dimensional (this has nothing to do with a usual categorizing of color along dimensions of hue, saturation and brightness, actually we are talking about hue solely here), but our perceptual systems are picking out just the coordinates in relation to a single axis (which axis would represent the linear space of all hues we can pick out). However relatively to this two-dimensional color space, there are infinity of possible hue axes, and there is no reason to give primacy to one over another. Applied to John’s/Jane’s case, it would look like this:

When John and Jane are looking at the same Munsell 527 chip, they are seeing two different aspects of the chip’s full-color. John is reporting true blue, and Jane is reporting slightly greenish blue. However John has never actually seen that ‘greenish blue’ that Jane sees, nor has Jane seen this ‘true blue’ color that John sees. So, even neither of them has better color sight than the other, the situation is not a contradiction. The property of John’s ‘true blue’ not to be tinged by any other color is a truth about this specific aspect of the color which John is picking out. The property of Jane’s aspect not to be true blue, is also truth about that specific aspect that Jane is picking out with her color vision. In such way, there is nothing problematic in the same Munsell chip being both John’s true blue, and Jane’s slightly greenish blue.

Even those aspects are different, if the hue-axes are not rotated much one to another, they will mostly overlap, and if we ignore those special cases, Jane and John will agree on the colors, especially as concepts like ‘blue’ cover not just a single coordinate, but a range of values.

Note:Of course this is a simplest aspect possible (projection from space to line), but the actual aspects that we pick out might not be so simple. For example we might pick out not one, but three aspects (relating to green, blue and red), which we would be able to relate easily to the known facts about eye, cones/pigments and functioning of opponent neurons. I just wanted to present how if we see the color that we see as an aspect of the richer color, it gives us a general way to solve the ‘true blue’ puzzle, while staying on color-realism side.

UPDATE: I first heard of the issue on Wo’s weblog, where Wo gave similar proposition with the one in this post.


11 Responses to “True Blue”

  1. John said

    Just to ask,

    Would it be true that where the greenish blue and true blue lines meet that that is where the true hue of blue would be?

  2. Hi John,

    No, “true blue” would be relative to which aspect of the objective color the individual’s color space pick out. That is, John and Jane would have different “true blue” color. I guess I should have explained more the picture, On it, only the “true blue” color of John is represented as a point(blue circle) in John’s line, a point which is an aspect of the Munsell chip 527. Different aspect of that chip is picked out by Jane, and is represented by slightly greenish blue on her line. The “true blue” point for Jane is not represented on the picture, but it would be solely on Jane’s line, same as John’s “true blue” is on his.

    The picture isn’t supposed to represent the relation exactly, just to give the idea of what is proposed.

  3. John said

    I understand a little better, thank you.

    But I have another question.

    After what you have said are you referring to the biology of the human eye? If not then what is the factor you are are refering too?

  4. The issue is analyzed on a more abstract level in the post.
    If we want to relate the post to the biology of human eye, it would be related to the ability of humans to pick out aspects of the color of objects, and connected to it, the limits of such access.

  5. John said

    So then how can the chip have color if it isn’t percieved through John’s and Jane’s sense of sight?

  6. John, the answer to that question I guess depends on the general stance one takes about color. Is one a color realist, and thinks that colors are properties of the objects, or thinks that colors in our experiences are something which comes from our minds.
    I think that color realism is true, and that objects have color even when we don’t look at them, and while I didn’t give much of an argument for this position, it is assumed in the post.

  7. Hi Tanasije,

    You say that you ar etrying to defend option (a) which says that the object is both blue and blueish green at the same time, but it looks to me like what you are actually trying to defend is option (c) which say that the object is some other color than the ones that Jane and John experience. What else could it mean to say that they are both just seeing one aspect of teh (real)color if not to say that the actual color of the chip differs from each experience. You can’t really be saying that in reality the chip is both blue and not blue?????

  8. Hey Richard!

    The analogy would be with Jane seeing just the form of the ball (e.g. oval), and John seeing the size (e.g. 30cm). I guess nothing is problematic in the case, and we can say that the ball is both as Jane and as John sees it.

    As long there is no contradiction in two predicates, there is no problem. So, what I say, is that both “true blue” by John, and “slightly greenish blue” by Jane are two aspects of the objective color, in the way that ‘oval’ and ’30 cm radius’ are aspects of the ball.

    They are not contradictory in this picture, as John’s “true blue” is incompatible as predicate with *John’s* “slightly greenish blue”. But, as John and Jane pick out slightly different aspect (through not orthogonally different), it is not incompatible with Jane’s “slightly greenish blue”.

    In fact, neither John can experience exactly the same hue that Jane experiences, nor she can experience exactly the aspect John experiences. So, it is NOT the problem “I can’t imagine a color that is both slightly greenish, and also not greenish at all”. That is true, in case if we are limited to the aspect of one person. But here we have two aspects, and “true” in “true blue”, and “slightly greenish” in “slightly greenish blue” are relative to the aspect.

  9. […] 7, 2007 Via Tanasije I found Michael Tye’s paper The Puzzle of True Blue where he considers the problem posed by […]

  10. Aki said

    “The proposal would be that objects have colors, but that we are seeing just an aspect of these colors due to the limits of our perception. John and Jane then when looking at the same color chip, are seeing different aspects of the color.”

    This sounds like great explanation to me.

    I really like the whole color thing since it can be used as great example when you are talking about sign, reference, perception and meaning, and how really important reference is to knowledge, and everyday speech.

  11. Hey Aki,

    I agree with you that colors are fascinating philosophically. Besides the things you mentioned… there is that thing about them… that they are so simple, and yet so concrete.

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