The Missing Shade of Blue in An Enquiry Concerning Human Understanding by Hume

While reading An Enquiry Concerning Human Understanding by Hume, I came upon a part where Hume draws a counterexample to his epistemological theory then dismisses it as insignificant.

"There is, however, one contradictory phenomenon, which may prove, that it is not absolutely impossible for ideas to arise, independent of their correspondent impressions. I believe it will readily be allowed, that the several distinct ideas of colour, which enter by the eye, or those of sound, which are conveyed by the ear, are really different from each other; though, at the same time, resembling. Now if this be true of different colours, it must be no less so of the different shades of the same colour; and each shade produces a distinct idea, independent of the rest. For if this should be denied, it is possible, by the continual gradation of shades, to run a colour insensibly into what is most remote from it; and if you will not allow any of the means to be different, you cannot, without absurdity, deny the extremes to be the same. Suppose, therefore, a person to have enjoyed his sight for thirty years, and to have become perfectly acquainted with colours of all kinds, except one particular shade of blue, for instance, which it never has been his fortune to meet with. Let all the different shades of that colour, except that single one, be placed before him, descending gradually from the deepest to the lightest; it is plain, that he will perceive a blank, where that shade is wanting, and will be sensible, that there is a greater distance in that place between the contiguous colours than in any other. Now I ask, whether it be possible for him, from his own imagination, to supply this deficiency, and raise up to himself the idea of that particular shade, though it had never been conveyed to him by his senses? I believe there are few but will be of opinion that he can: And this may serve as a proof, that the simple ideas are not always, in every instance, derived from the correspondent impressions; though this instance is so singular, that it is scarcely worth our observing, and does not merit, that for it alone we should alter our general maxim." -- Hume

Why does Hume dismiss the counterexample as insignificant. According to the philosopher Pritcahrd Hume should have revised his theory, but according to the philsoopher Jenkins since the surrounding colors need to be percieved before coming up with the intermediary shade, there is no significant contradiction with Hume's theory. I am incline to support Pritchard's position, but any insight into the reason for Hume's dismissal would be greatly appreciated!

As the philosopher Broadie states,
“The reason Hume’s instance is not singular, is this: if indeed a person can have an idea of a shade of blue, though he had not had a previous impression of that shade, then we have to allow that a person could have an idea of missing shades of every other colour also; and there is no reason why we should restrict ourselves here to a consideration of only the visual one of the five sensory modalities. We could also have an idea of a missing sound, or taste, or smell, or tactile quality.”

Just to summarize to see if I understand, Hume claims that ideas must come from some experience. If we have never experienced some shade of blue, then Hume claims we cannot have an idea of that shade of blue.

Suppose that shade of blue did not exist or were something false, could we have an idea of it? If not, because it cannot be traced to a perception, how could we reject that idea as false?

I don't know if I'm addressing your concern, but I find the ideas interesting.

Hi YesNo!

Your first paragraph is basically correct. In essence, Hume identifies ideas as combinations of copies of sensations, or impressions. Two of the examples provided in An Enquiry Concerning Human Understanding by Hume are a golden mountain and god. A golden mountain is the augmenting of the idea of gold, a reflection of seeing the color gold, and the idea of mountain, similarily derived from viewing a mountain. God, defined as an infinitely intelligent, wise, and good Being, is derived form extending indefintly the good qualities of our minds.

Your second paragraph is a bit off. Hume doesn't deny the existence of shades, far to the contrary he takes it as a given. Hume, rather, produces an example wherein a certain individual of good sight has experienced (seen) every shade of a particular color but one. If he orders all the shades of color which he has seen in a continuum, he will identify the blank where the missing shade should occupy. All so far is good. Yet here is the problem, which threatens Hume's epistemological theory, as explained above: can the man, by the powers purely of imagination, produce the idea of that shade of color without having before seen it. In plain terms, can the man visualize the missing shade of color, despite never having seen it. Hume implies that this is possible by stating that a few would believe it possible, but brushes the possibility aside as an insignficiant and singular case not sufficient to alter his theory (or as he calls it, his general maxim).

My question is how can such an example be deemed insignficant. As Broadie stated, it can be extended to all shades of colors, sounds, and other qualities detectable by the senses. Furthermore, any contradiction to a general theory of such extent surely begs for modification of the theory; if ideas can originate from places beyond impressions, then it is plain that Hume must be wrong. Yet Hume plainly implies that certain ideas can originate from regions detached from impressions. Jenkins claim that the surrounding shades need have been observed before creating the idea of the missing shade is unconvincing to me because his idea deviates from Humes, wherein ideas are copies of impressions, i.e. derived from impressions, not similar impressions. It seems that Pritchard is right in that Hume should have modified his epistemological theory, perhaps along the lines Jenkins mentioned.

Anyways, these are some clarifications on Hume's ideas and my quesiton.

An interesting article that relates... albeit loosely:

http://clarkesworldmagazine.com/hoffman_01_13/

Here's a quote from a link in Erin Hoffman's article that stlukesguild cited: http://faculty.washington.edu/chudler/eyecol.html

Many animals do not have color vision: the ability to discern different wavelengths evolved in animals that became diurnal, or active in the daytime. Among these, birds are especially color sensitive. Some have four or more cone pigments, allowing them to distinguish more accurately among colors than we do (probably seeing more shades), and to see into the ultraviolet range, which we cannot.

I take from this that the question of not seeing specific shades of blue is not theoretical. There are many shades of blue that we cannot see, but can only imagine to exist. Rather than seeing a blank for that shade of blue we see the same shade as those around it.

I suspect Hume's epistemology is incorrect, that is, we can know things that we cannot perceive or that cannot be the result of some construction of sense perceptions. There is more to knowledge than sense perceptions.

stlukesguild's link also introduces an additional complexity. We cannot have an idea of something, even if we can physically perceive it, unless we also have a word for it. Where does the word come from? So, epistemology cannot be separated from language.