[lit-ideas] Hume's Missing Shade of Blue

  • From: Jlsperanza@xxxxxxx
  • To: lit-ideas@xxxxxxxxxxxxx
  • Date: Tue, 30 Jun 2009 15:23:57 EDT

In a message dated 6/30/2009 2:57:28 P.M. Eastern Daylight Time,
rpaul@xxxxxxxx writes:
Dear Mr Trogge,
Let me congratulate you again on  your erudition. Contrary to what
Professor Speranza has suggested, the color  of your prize is Hume's
missing shade of blue.


Why, it is!
--- Prof. Speranza (on second viewing).
         *What does that logo read  at the umbilical level?

Nelson, J.O. “Hume’s Missing Shade of Blue Re-viewed”, Hume Studies Volume
 XV Number 2(November 1989) 353-364.

The Missing Shade of Blue is an example introduced by the Scottish
philosopher David Hume to show that it is at least conceivable that the mind can
generate an idea without first being exposed to the relevant sensory
experience.  It is regarded as a problem by philosophers because it appears to 
in  direct contradiction to what Hume had just written.

Contents [hide]
1 The Source of the Problem
2 Responses to the  Problem
3 Suggested Solutions
3.1 'There is no problem'
3.2 Mental  mixing
3.3 Colours as complex ideas
3.4 It doesn't undermine Hume's main  concern
3.5 The exception really is singular
3.6 Hume needs an exception
4 Conclusion
5 References
6 External links

[edit] The Source of the Problem
In both A Treatise of Human Nature  and An Enquiry Concerning Human
Understanding the Scottish philosopher David  Hume argues that all perceptions 
the mind can be classed as either  'Impressions' or 'Ideas'. He further
argues that

"We shall always find, that every idea which we examine is copied from a
similar impression. Those who would assert, that this position is not
universally true nor without exception, have only one, and that an easy method  
refuting it; by producing that idea, which, in their opinion, is not
derived  from this source."[1]
The problem of the missing shade of blue arises  because just two
paragraphs later Hume seems to provide just such an idea. He  says,

The Missing Shade of Blue"There is, however, one contradictory
phaenomenon, which may prove, that it is not absolutely impossible for ideas to 
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."

[edit] Responses to the Problem
Some philosophers take Hume to task for  presenting such a clear
counter-example and then dismissing it as insignificant.  Pritchard says,

“This is, of course, just the kind of fact which should have led Hume to
revise his whole theory. It is really effrontery on his part and not mere
naiveness to ignore an instance so dead against a fundamental doctrine of his
own…if he had considered the idea of cause as also to be ignored as being
an  isolated exceptional case, he would have had no reason to write the
Treatise at  all.” [2]
Other philosophers take a more generous view of Hume's position.  Jenkins

“It is not so much that it is hardly worth altering a general thesis for
one exception, which is very much the line Hume himself adopts. It is rather
that the character of the phenomenon itself does not clearly run counter to
the  essential emphasis of Hume's doctrine. That emphasis really consists
in the  claim that, ultimately, there can be no ideas without impressions.
His example  does not, strictly, disobey this principle since, presumably,
Hume would argue  that, without sensory experience of other colours and
particularly of other  shades of blue, the missing shade could not be 
envisaged. It
is not an admission  of innatism, nor is it a claim that the idea was, as
it were, produced out of a  hat. It is perhaps nothing more than the
concession that the natural powers of  the mind are a little more enterprising 
he had allowed for."[3]
In  their own ways both these views fail to address the problem of the
missing shade  of blue. The first fails to offer an explanation as to why Hume
has presented us  with the contradiction and the latter fails to deal with
the fact that Hume is  himself insistent that it really is a contradiction.

It is sometimes said that the problem is even more severe than Hume thinks.
 Hume claims that this instance is ‘singular' but Alexander Broadie writes

“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 
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.” [4]
However, as Williams points out, Hume’s own words  imply that he was fully
aware of this.[5] Hume begins the relevant paragraph by  talking about both
sounds and colours. In addition, when first introducing the  missing shade
of blue he says, “except one particular shade of blue, for  instance”. The
words “for instance” show that he could easily have chosen a  different
example. When he later says, “this instance is so singular, that it is  scarcely
worth our observing” he cannot be referring to this particular example  but
rather to the type of exception that it represents.

It is also said that when Hume says, “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”, he is assuming that colours are composed 
a set of  distinct independent hues when in reality they form a continuum.
In this matter  it does seem as if Hume is simply wrong. However, Fogelin
suggests, “Perhaps the  reason that Hume does not see this is that he is
thinking about the ideas of  objects and not about objects themselves. In
particular, he may hold that the  notion of an indistinguishable difference 
ideas make no sense. There is  nothing more to an idea than that which can
be discerned within it. If this is  Hume’s position, then the notion that
two ideas can be different without being  discernibly different would be a
contradiction in terms."[6]

[edit] Suggested Solutions
A fully adequate solution to the problem  will have the following features.
It will

Recognise that Hume believed that the problem to be a genuine
Recognise that Hume included the example for a purpose.
Provide an explanation that harmonizes well with other features of Hume’s
The problem has been tackled in various ways:

[edit] 'There is no problem'
It is sometimes claimed that the  problem can be removed by denying that
the problem exists. According to this  view Hume was wrong when he claimed
that it was possible to form an idea of the  missing shade. Perhaps it only
seems to us that such an idea can be formed  because we have already
experienced the whole range of colours. Indeed, even  after experiencing the 
range of colours a little experimentation will soon  show that it is much easier
for most people to recognise that there is a missing  shade than it is for
them to actually form a clear idea of that missing shade.  Be that as it
may, this dissolving of the problem fails to meet the second and  third
criteria listed above.

[edit] Mental mixing
Mental mixing is the solution proposed by  Morris.[7] The idea here is that
just as paints are mixed to produce the range  of colour swatches found in
a hardware store so it should be possible for  colours to be mixed in the
mind in some kind of analogous way. Unfortunately,  without further argument
it is not obvious that we are endowed with any such  ability and, if we were,
it is not clear why it would be limited to the mixing  of closely related
impressions, and yet, if this were not the case, then,  contrary to what
Morris says, it would open the floodgates to a range of  philosophically suspect

[edit] Colours as complex ideas
Another way of dissolving the  problem has been to suggest that colours
might also be regarded as complex  ideas. This is tempting since Hume has only
just talked of “the faculty of  compounding, transposing, augmenting, or
diminishing the materials afforded us  by the senses.” That ‘augmenting’ and ‘
diminishing’ does not just apply to  physical size is clear from the way
Hume suggests that our idea of God “arises  from reflecting on the operations
of our own mind, and augmenting, without  limit, those qualities of goodness
and wisdom.” Unfortunately, this fails our  third criterion for Hume
clearly distinguishes between complex ideas and simple  ideas in a way that
excludes the possibility of colours being complex. In the  treatise 
Section1) Hume writes,

“Simple perceptions or impressions and ideas are such as admit of no
distinction nor separation. The complex are the contrary to these, and may be
distinguished into parts. Though a particular colour, taste, and smell, are
qualities all united together in this apple, it is easy to perceive they are
not  the same, but are at least distinguishable from each other.”

[edit] It doesn't undermine Hume's main concern
Hume's lack of concern  might be explained by the fact that although it
contradicts the claim that all  simple ideas are preceded by simple impressions
this is not a problem because  this is not Hume’s main concern. This answer
draws attention to what Hume says  at the end of Section 2 of the Enquiries:

“When we entertain, therefore, any suspicion that a philosophical term is
employed without any meaning or idea (as is but too frequent), we need but
enquire, from what impression is that supposed idea derived? And if it be
impossible to assign any, this will serve to confirm our suspicion. By
bringing  ideas into so clear a light we may reasonably hope to remove all
dispute, which  may arise, concerning their nature and reality.”
In other words, Hume's  concern is that his principle can be used as a “
critical tool for clearing  discourse of metaphysical disputes, and not
necessarily that it provides an  exact account of the origin of our ideas.” The
fact that this contradicts Hume’s  explicitly stated purpose is explained by
arguing that the Treatise has to be  understood as a gradual unfolding of his
views. The problem is that Hume never  makes this clear and if this is the
way it is meant to be read then as Williams  says, “The narrative character
of the Treatise is…disguised…by the superficial  resemblance of the former
to Locke's Essay… Also, there is the fact that he  drops the problem in the
same way in the Enquiry, which arguably lacks the  narrative character of the

[edit] The exception really is singular
Fogelin argues[9] that the  reason this exception is a genuine exception
that can be safely ignored is  because despite being simple ideas, colours and
shades can be organised into a  highly organised colour space, (and that
sounds and tastes, etc., can be  similarly organised.) Hume allows that some
simple ideas can be seen to be  similar to one another without them sharing
anything in common. The proviso that  they do not share anything in common is
important because otherwise this feature  might be separated off and this
would show that the original idea was in fact  complex. In a note added to
the Treatise commenting on abstract ideas Hume  says,

“It is evident, that even different simple ideas may have a similarity or
resemblance to each other; nor is it necessary, that the point or
circumstance  of resemblance should be distinct or separable from that in which 
differ.  BLUE and GREEN are different simple ideas, but are more resembling
than BLUE and  SCARLET; though their perfect simplicity excludes all
possibility of separation  or distinction. It is the same case with particular
sounds, and tastes and  smells. These admit of infinite resemblances upon the
general appearance and  comparison, without having any common circumstance the
same. And of this we may  be certain, even from the very abstract terms
SIMPLE IDEA. They comprehend all  simple ideas under them. These resemble each
other in their simplicity. And yet  from their very nature, which excludes
all composition, this circumstance, in  which they resemble, is not
distinguishable nor separable from the rest. It is  the same case with all the 
in any quality. They are all resembling and  yet the quality, in any
individual, is not distinct from the degree.”
It is  this very ability to recognize similarity that enables us to arrange
the shades  of blue in order and to notice that two adjoining shades differ
more than any  two other adjoining shades. If it be allowed that the notion
of hue can arise  through abstraction even though it cannot in any instance
be separated from a  given example then it may be fairly argued that the
ability to fill a gap in the  colour space is quite a different matter to
coming up with an isolated idea  without any prior impression. It would
certainly still be the case that the  ability to conjure up the idea of the 
shade of blue is dependent on at  least some prior impressions.

The problem with this claim is that there needs to be some way of showing
that the exception really is limited and will not affect the important
general  claim that ideas depend on impressions. Suppose, therefore, a person to
have  enjoyed his sight for thirty years, and to have become perfectly
acquainted with  regular polygons of all kinds except the one having five sides…

[edit] Hume needs an exception
However the idea of the missing shade  is to be created there is still the
problem of why Hume takes such pains to  present the example to his readers.
Of course, it may just be that Hume was  aware of it as an exception and
was being open and honest. On the other hand,  Nelson[10] suggests the
intriguing possibility that far from being an oversight  or an embarrassment to 
wider project the missing shade of blue example turns  out to be crucial.
Later Hume will divide all objects of human reason into  ‘Relations of Ideas’
 and ‘Matters of Fact’. The former are certain and do not  necessarily say
anything about what actually exists in the world; the latter do  make
claims about the world but “the contrary of every matter of fact is still
possible”. With this in mind it can be asked what status holds for the claim  
“all our ideas or more feeble perceptions are copies of our impressions or
more lively ones”. If this is a Relation of Ideas then it does not
necessarily  say anything true about the world and this will not suit Hume’s 
at all;  if it is a Matter of Fact then the contrary must be possible. The
inconsequential hypothetical possibility that we are able to raise up to
ourselves the idea of the missing shade of blue even if in practice this doesn
’t  ever happen will ensure that Hume’s description of the origin of ideas
is  grounded in fact.

Unfortunately, what is required of matters of fact is the logical
possibility that they could be other than they are not the practical  
This being the case it is not necessary to construct an elaborately  worked
out example; it would be sufficient to say that we might have been
constituted differently.

[edit] Conclusion
None of the suggested solutions are without  difficulty, nor does it
necessarily follow that a historical judgment about what  Hume probably intended
will be the same as a philosophical judgment about which  solution fits in
most harmoniously with Hume's wider philosophy.

[edit] References
^ Enquiries, Section II. Of the Origin of Ideas
^ Pritchard, H.A. (1950) Knowledge and Perception, Oxford: Clarendon Press,
 page 177
^ Jenkins, J,J, (1992) Understanding Hume, Edinburgh University  Press,
page 22
^ Broadie, A. (1990) The Tradition of Scottish Philosophy: A  New
Perspective on the Enlightenment, Polygon, page 97
^ Williams, W.H. 'Is  Hume's Shade of Blue a Red Herring?', Synthese 92,
page 86
^ Fogelin, R.J.,  (1992) Philosophical Interpretations, Oxford University
Press, page 75
^  William Edward Morris (_http://plato.stanford.edu/entries/hume/_
(http://plato.stanford.edu/entries/hume/) )
^ Williams, W.H. page 96
^ Fogelin, R.J., (1992) Philosophical  Interpretations, Oxford University
Press, page 75
^ Nelson, J.O. “Hume’s  Missing Shade of Blue Re-viewed”, Hume Studies
Volume XV Number 2(November 1989)  353-364.

[edit] External links
Wikisource has original text related to this  article:
An Enquiry Concerning Human UnderstandingWikisource has original  text
related to this article:
Treatise_of_Human_NatureNelson, J.O. “Hume’s  Missing Shade of Blue
Re-viewed”, Hume Studies Volume XV Number 2(November 1989

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