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20 Locke, Essay II.viii.7-26 Primary and
Secondary Qualities Over Essay II.viii.7-26 Locke considered the question of how our
simple ideas of sensation are related to the objects that produce them. Might
the qualities that appear in our ideas also be qualities of bodies that exist
outside of us? Might they at least
resemble qualities of bodies? Or might
there be nothing like the qualities of our ideas to be found in bodies? Alternatively might some qualities of our ideas
be qualities of bodies while others are not? In addressing these questions, Locke
divided our simple ideas of sensation into three different classes: i) ideas of solidity, extension or
bulk, and their various modifications, ii) ideas of sensible qualities like
colour, smell, taste, sound, heat and cold, iii) ideas of pleasure and pain. He proceeded to point out that people
have generally supposed that the qualities represented by our type (i)
and (ii) ideas are more or less exact replicas of properties existing in
external objects, and that we only have these ideas because external objects
have somehow managed to impress us with these qualities. In contrast, people have generally supposed
that type (iii) ideas of pleasure and pain do not resemble anything to
be found in external objects, even though they are also caused by these
objects. Type (iii) ideas are supposed to exist only in the mind, and
only when they are perceived. Locke’s main point over this part of
the Essay is that while the
tradition is right about type (i) and type (iii) ideas, it is wrong
about type (ii) ideas. The main reason Locke had to offer for
this position is given in Essay
II.viii.11. Locke there claimed that
the only way in which one body can be conceived to act upon another is by
impact. This requires us to ascribe
motion, solidity, and figure to bodies, since to impact one another bodies
have to be moving and solid, and to be solid they have to take up a space of
some figure. However, it also means
that we must consider all of our ideas to be products of the motion, solidity
and figure of bodies, rather than to be due to some quality in the bodies
that bleeds out of them and into our sense organs. For, if all action of one body on another
requires impact, then the action of bodies on our sense organs must also
require impact; and that means that bodies must be supposed to affect us
through being moving, solid and figured, and not through transmitting other
qualities. QUESTIONS
ON THE
1. Explain the
difference between qualities and ideas.
2. What features
must a quality have if it is to be considered primary?
3. How do the
secondary qualities differ from the primary, if at all?
4. How do the
tertiary qualities differ from the primary and the secondary, if at all?
5. How is it
possible for one body to act on another?
6. Given that
external objects are not only not united to our minds but even sometimes set
at some distance from us, by what means do we come to perceive their original
qualities?
7. When Locke
wrote in II.viii.15 that “the Ideas,
produced in us by these Secondary Qualities, have no resemblance
of them at all,” what were the ideas he was referring to, and what were the
secondary qualities that he had in mind?
8. What produces
the idea of the motion and shape of a piece of manna in us? What produces the ideas of sickness, acute
pains, and gripings in those who have eaten a piece of manna? What produces our ideas of the whiteness
and sweetness of the manna?
9. What is the
only effect that the pounding of an almond can produce in the almond? What effect does the pounding of an almond
produce in us when we perceive it? 10.
Under what conditions do we have an idea of the
thing as it is in itself? NOTES
ON THE The topic of Essay II.viii.7-26 does not fit very well with the idea of doing
a critique of the human knowing powers by means of the “historical, plain
method” of investigating the origin of our ideas, their nature, and the
conclusions that can be drawn from them.
Instead of starting from ideas and determining what can be inferred
from them, Locke here simply presupposed the existence of external objects,
presupposed that these objects affect us, and went on to inquire how our
ideas might be related to them. However, what Locke later described as
“this little excursion into natural philosophy” (II.viii.22) is not entirely
unjustified if we consider that, unlike Descartes, he did not think that he
first needed to prove the existence of bodies from absolutely certain first
principles. For him, it is enough that
it should be likely that there are bodies.
Granting that it is indeed likely, the question of the relation
between our ideas and bodies naturally arises, and Locke thought it would be
wise, right at the outset, to get clear about which features of our ideas
might even possibly be supposed to be resemblances of qualities in
bodies. This is especially the case
since, as he thought, people have generally taken things like colours, heat
and cold to be qualities in bodies when in fact they can be nothing more than
ideas in us. He began by drawing a distinction
between ideas in us and qualities in bodies. Whatsoever the Mind perceives
in it self, or is the immediate object of Perception, Thought, or Understanding,
that I call Idea; and the Power to
produce any Idea in our mind, I
call Quality of the Subject wherein
that power is. [II.viii.8] The inference seems solid enough. If there are ideas in us and we are not
ourselves responsible for producing them, then there must be something in
things other than us that is. Consider
whatever it is in a thing that does this to be a quality of that thing. But what might such qualities be? Locke needed to come up with some sort of
test for discriminating which, among the various things we find in our simple
ideas, might resemble qualities actually existing in bodies. He fixed on the same criteria Qualities
thus considered in Bodies are, First such as are utterly inseparable from the
Body, in whatever estate soever it be; such as in all the alterations and
changes it suffers, all the force can be used upon it, it constantly keeps;
and Such as sense constantly finds in every particle of Matter [that] has
bulk enough to be perceived, and the Mind finds inseparable from every
particle of Matter, though less than to make itself singly be perceived by
our Senses [II.viii.9] Compare We might wonder why Locke thought
these are useful criteria for identifying the “first” qualities of
bodies. After all, it is not as if we
see the bodies themselves and so can discern from experience that all bodies
in fact have certain qualities and that no process in nature ever destroys
those qualities. We can only see our
ideas. Unfortunately, Locke provided
us with no enlightenment on this score.
The most likely answer is that he may have thought that if any
features of our ideas could be ascribed to bodies, they would be those that
are present in all of our ideas of bodies. Applying this rule, Locke determined
that all bodies must be solid (for reasons already considered in the previous
chapter), and also that they must be extended. For, even though bodies may be divided,
division does not destroy their extension, but merely cuts it up into
separate pieces that can be moved apart from one another. Unlike Newton, however, Locke did not list
gravitational mass among the qualities that must be admitted among all bodies
(action at a distance seems to have been simply too much for him to accept,
though in later editions of the Essay
he silenced his objections to it in deference to Newton’s results), and he
speculated that inertial mass and hardness may be simply modifications of
solidity (II.iv.5). Insofar as bodies are admitted to be
solid and extended, they must also have all the qualities that arise from the
ways solidity and extension can be modified.
They must have inertia (which Locke took to be an effect of solidity
[II.iv.5]), hardness, figure, size, orientation, and mobility, and they must
be divisible into parts. These parts
in turn must have their own inertia, hardness, figures and sizes, and
depending on how they are ordered and interlinked in composite bodies, they
create different textures. There is another reason for concluding
that all bodies must have qualities of solidity and extension. Recall that Locke defined a quality as a
power in a body to produce an idea in us.
Locke also took it to be “manifest” that the only way that one thing
can act on another is by impulse, that is, communication of motion as a
result of impact or collision (Essay
II.viii.11). (Hence, his inability to
accept gravitational mass among the primary qualities.) It would have to follow that insofar as
bodies have powers to produce ideas in us, those powers must involve
impulse. But impulse presumes motion
and solidity, and motion presumes some number of things placed at different
locations over time, situated in some way with respect to one another to
constitute a shape of a certain size.
So all of the qualities that Locke identified as primary are necessary
if bodies are to exert a power to bring about ideas in us in the only way
Locke considered action to be possible, by impulse. Looking at things in this way led
Locke to conclude that people are in fact right to take their type (i) ideas
to be reflections or resemblances of qualities that are actually in
bodies. (Interestingly, Locke did not,
as was speculated in the previous chapter concerning solidity, take our type
(i) ideas to be direct perceptions of the primary qualities in bodies. Instead, he here took them to be images or
resemblances of such qualities. “The Ideas of primary Qualities of Bodies, are Resemblances of them, he
wrote, and their Patterns do really exist in the Bodies themselves,” he wrote
at II.viii.15, suggesting that the idea is one thing, the quality another,
even though they may resemble.
II.viii.7 similarly worries which of our ideas are “Images and Resemblances” of qualities in bodies,
not which are direct perceptions of those very qualities as they exist in
bodies.) However, Locke did not think
that the solidity, shape, and motion of bodies are directly communicated to
the mind, to produce our type (i) ideas.
Because he took it to be “manifest” that the only way bodies can bring
about ideas in us is by impulse he could not countenance any direct
connection between external objects and our minds, particularly in the case
of vision. Impulse requires contact,
and bodies are not in contact with our minds, or even with our brains.
Indeed, some of the bodies that we sense are set at quite some distance from
us. Reflecting on this fact, Locke
concluded that if we nonetheless get type (i) ideas from these bodies, it must
be because they emit or reflect a stream of insensibly small particles
towards our sense organs. But even the
objects of touch do not touch our brains, but only the exterior surface of
our sense organs, which produces alterations in the way the nerves or the
particles flowing through the nerves are moving. These motions are transmitted to the brain
and the result of this process, a motion of the parts of the brain, likely
bears only the most remote similarity to the body that originally caused
it. However, Locke supposed that the
particular ideas of extension and solidity that are produced in the mind when
particular motions occur in the brain do, happily or because of divine
providence, at least bear some degree of resemblance to the macroscopic shapes,
motions, and solidity of the bodies that originally affected us. Very often, the shapes we see are
distortions of the actual shapes of the objects, and the distortions are
mathematically related to the actual shapes and are distorted in the ways
that they are in accord with constant laws, the laws observed by painters
when depicting how the shapes and sizes of objects are changed as a
consequence of distance and perspective. Locke went on to claim that while our
type (i) ideas are at least “resemblances” of qualities in bodies, it is a
vulgar error to suppose that the type (ii) ideas also resemble qualities in
bodies. In fact, he claimed, we have
more reason to suppose that they are like the type (iii) ideas — that they
only exist in us and only exist when perceived, though they are caused by
something that endures in external objects independently of being perceived. It is important to understand the path
of Locke’s argument. Locke did not
claim that we can know that our
type (i) ideas are resemblances of qualities in bodies, but that our type
(ii) ideas are not. He rather argued
that we have a number of good reasons to doubt that our type (ii) ideas
resemble any qualities actually inhering in bodies. These same reasons do not, however, apply
to our type (i) ideas (Essay
II.viii.21 contrasts the different sensations of heat and cold that we can
get when we immerse a hot and a cold hand in the same bucket of water with
the sensations that we have of the figures of bodies, which according to
Locke never vary regardless of what state our hands are in). Therefore, while we have reason to doubt that our type (ii) ideas
resemble qualities in bodies, we have no reason to doubt that our type (i)
ideas do so. This does not mean that
we can claim to know or be certain that our type (i) ideas do resemble
qualities in bodies. At best it means
that we have no good reason to doubt this claim, and so can believe it is
probably true. Locke offered five main reasons for
doubting that type (ii) ideas resemble qualities in bodies. The first is to be found at
II.viii.16. Locke there observed that
type (ii) ideas can, as it were, shade off into type (iii) ideas. Warmth and cold, for example, are type (ii)
ideas that turn into pain as they are intensified. This is an indication that type (ii) ideas
cannot really be distinct from type (iii) ideas. They are simply lesser degrees of the same
phenomena that are present in more intense degrees in our type (iii)
ideas. But everyone is agreed that
type (iii) ideas exist only as ideas in us and are not qualities in
bodies. If the type (ii) ideas are
simply less intense degrees of the type (iii), then they ought to exist only
as ideas in us as well. Locke’s second argument is alluded to
in the last clause of II.viii.16 and laid out more fully in II.viii.18. (II.viii.17 does not offer an argument but
simply further describes the theory and is passed over here.) At the close of paragraph 16 he observed
that if the only way change can occur is by impulse (as was claimed in
II.viii.11), then the only way any ideas whatsoever, including our ideas of
sensible qualities, can be brought about in us is by motions of solid, shaped
parts. But if all that needs to exist
in order to cause our ideas of sensible qualities is the motion of shaped and
solid particles, then it would be extravagant to suppose that bodies must
also have qualities that resemble colours, smell, heat and cold, and other
sensible qualities. II.viii.18 argues
for this same point by means of an extended discussion of a piece of manna. (Manna was an 18th century medicinal
concoction used to induce nausea and vomiting. It was white and sweet and was baked up in
pans like cake and then cut up in squares.)
Locke’s point is that the type (i) ideas we get of the manna’s shape
and motion are supposed to be the result of the aggregate shape and motion of
its insensibly small parts. Similarly,
the type (iii) ideas we get of pain in the guts are supposed to be the result
of exactly the same cause: the motion of the insensibly small, shaped and
solid parts that go to make up the manna, acting on our intestines. Why, therefore, asked Locke, should we
suppose that the whiteness and sweetness must alone have some other, unique
cause, qualities actually resembling whiteness and sweetness? It is not as if it is any more mysterious
how colourless, tasteless particles could produce ideas of colour and taste
than it is how they could produce ideas of cramping and pain, yet we have no
problem accepting the latter consequence.
By parity of example we ought to accept the former. Locke’s third argument is given over
II.viii.19, and turns on the observation that our type (ii) ideas can
disappear even though the bodies remain and are not thought to have undergone
any alteration. Locke instanced the mineral, porphyry, which looks to be red
and white, but which does not have those qualities in the dark. Since the red and white disappear in the
dark, but we do not think that the porphyry is destroyed or altered by shutting
off the light, we must conclude that these colours are not really qualities
in the body, porphyry, but rather results of the way light affects our
senses. At the very least, they are
not qualities bodies have to have in order to be conceivable and that they
have to retain through all eventualities. Locke’s fourth argument is found at
II.viii.20. He there observed that
operations that can only plausibly be supposed to change the shapes,
arrangements, and motions of the insensibly small parts of bodies lead us to
have different type (ii) ideas.
Pounding, for instance, is an operation that can only be supposed to
break the extension of a body up into a number of separately movable parts,
and so make it softer. But pounding
also changes the colour and taste of an almond. Since all that pounding can really do is
alter the almond’s texture and hardness, the changed taste and colour must be
merely effects of the changes in the texture and hardness on our senses of
vision and taste, and not independently existing qualities in the bodies at
all. Locke’s final argument is found at
II.viii.21 and takes the form of an inference to the best explanation. He there observed that the same body can
simultaneously give us different, incompatible type (ii) ideas. The same
bucket of water, for instance, can simultaneously feel warm to a cold hand
and cold to a warm one. Locke pointed
out that it is difficult to account for this fact on the supposition that our
ideas of colour or heat and cold are caused by resembling qualities that
migrate into us from the bodies that affect us. Since the ideas are incompatible, both
cannot simultaneously exist in the object.
At least one of them must be merely an idea in us and not a quality in
the body. But which one is the real one and where does the unreal one come
from and how do we know that the real one does not come from the same sort of
causes that produce the unreal one rather than from a resembling quality in
the object? All of these difficult
questions are avoided, Locke claimed, if we accept an alternative
theory. If we take the colour and the
degree of temperature to be merely ideas produced in us as a result of bodies
hitting our sense organs, then we can take the previously existing state of
the sense organ to enhance or impede the motion and so alter the character of
the sensation that is communicated to the brain. And altered sensations can be expected to
produce different ideas in the mind. Thus, taking type (ii) ideas to be
produced in us by the impact of solid, moving parts provides a better
explanation of the phenomena of perceptual relativity than does the
supposition that they are caused by resembling qualities in the bodies. Summing up all of these considerations,
Locke claimed that there are three types of qualities in bodies, and three
types of ideas in us: First, there are primary qualities in
bodies. These qualities are solidity,
extension, and their modifications.
When bodies are aggregated together in large enough numbers to build
up composites of sufficient size to be visible or tangible, our type (i)
ideas can be considered to be resemblances of the macroscopic solidity, size,
shape, and motion of the composite bodies.
However, when the parts composing an object are too small for us to be
able to perceive, or when they lie below an opaque surface that has not been
anatomized, our ideas are less accurate. Locke considered that in addition to
the primary qualities of extension, solidity, and their modes, bodies also
have a further set of qualities. He
called these qualities powers. When we
consider what bodies can do to us, we get the idea that they have the power
to bring about ideas of sensation in us, and when we consider what they can
do to one another, we get the idea that they have the power to change one another. If all motion is due to impact, these
powers must ultimately arise from something solid, shaped, and moving hitting
something else. But when we cannot see
what it is in bodies that brings about these effects, our ideas of the powers
in things are only “relative.” The
power is really some arrangement of solid, shaped, moving, particles. But since this arrangement of particles is
invisible, we identify the power relative to its sensible effects. It is particularly important to
distinguish between secondary qualities as they are in bodies, and type (ii)
or non-resembling ideas as they are in us.
Colours, smells, tastes, and so on are not secondary qualities. They are type (ii) ideas brought about
by the secondary qualities of bodies.
As effects of the secondary qualities in objects, which are powers to
affect us arising from the insensibly small bulk, figure, number, situation,
and motion of particles, they may serve as “relative” ideas of those powers,
and this can lead to some confusion.
Since we can only think of the different powers by referring to their
effects, not by directly discerning the powers themselves, we tend to
substitute our ideas of the effects in the place of that of the powers, of
which we have no idea. This can happen
easily and inadvertently in language, where it is simply easier to talk about
the “redness” in a body than to employ a circumlocution like “the power in
the body to bring about the idea of red in us.” Locke warned us that he himself would often
speak this way, even though he knew better.
We need to keep in mind, therefore, that even though he may on many
occasions speak as though he takes colours, scents, tastes, and the like to
be secondary qualities in bodies, his considered position is that the
secondary qualities are powers due to the arrangement of solid, shaped, and
moving parts and do not resemble our type (ii) ideas in any way. If they resemble anything, it is our type
(i) ideas. To confuse colours, smells,
tastes and the rest with secondary qualities in bodies is to commit just the
error Locke was attempting to expose over II.viii.7-26. Essay II ix.1-4,8-9; x.1-2;
xi,1,4,6,8,9,15,17 Perception and
other Simple Ideas of Reflection For Locke, in addition to the ideas
that we get from sense, which refer to objects outside us, there are ideas we
get from reflection on the operations of our own minds. It is through these ideas that we first
become conscious of what our own minds do to the ideas they have previously
received. Through them, we learn how the mind processes ideas to generate
knowledge, belief, opinion, fantasy, and even experience itself. Essay II.ix-xi is devoted to an examination
of some of the main ideas of reflection and the operations they refer to. These main operations are perceiving,
remembering, discerning and comparing, compounding and repeating, naming, and
abstracting. QUESTIONS
ON THE
1. Can we have
ideas that go unnoticed by us?
2. What is the
idea immediately imprinted on the mind when we see a black or golden globe?
3. What makes it
“evident” that this is all there is to the immediate idea?
4. What was
Molyneux’s question and what was his reason for answering this question in
the negative?
5. What moral did
Locke draw from Molyneux’s negative answer to this question?
6. Explain
Locke’s distinction between the role played by “perception of sensation” and
“idea of judgment” in visual perception.
What is immediately perceived as a consequence of sensation and what
is judged?
7. What is wrong
with viewing memory as a storehouse for ideas we have had in the past? What is memory if not a storehouse?
8. How is it that
particular ideas can be made to become general? NOTES
ON THE Perceiving consists in attending to
the effects our senses convey from objects to the brain. Locke maintained that, unless the mind
actively attends to or “perceives” these effects, ideas will generally not
arise from sensation. There are
exceptions — bright lights, fast moving objects, cuts, burns, pinches, and
loud noises tend to intrude on the mind, draw its attention, and force it to
form corresponding ideas of colour, motion, pain, and sound. But objects can often have an influence on
our senses and brains that goes unnoticed and does not lead the mind to have
any perceptions. This is readily
exemplified by the case of our sensations of pressure and gravity. Up until this moment, you have likely not
been aware of the feeling of your chair or the ground pressing up on you from
below. Yet the chair and the ground
have all along been having an influence on your sense of touch, and your
sense of touch has all along been transmitting something to your brain as a
consequence of being so affected. But
until you chose to attend to them, those sensations did not produce any ideas
of solidity or pressure in your mind.
In this case, your ideas are not simply passively received as a result
of stimulation of your sense organs, but depend on a special effort of
attention. That act of attention,
whether forced upon us by the violence of the sensation of the product of an
effort, is what Locke called perceiving. Note that Locke did not define
perception as the operation of attending to ideas that already exist,
unnoticed, in the mind. The process of
perceiving or attending is required to bring ideas into being. If that process is not performed, the sense
organs can still transmit motions or impressions into the brain and those
motions and impressions will exist in the brain. But they will not cause ideas. They cause
ideas only with the cooperation of the perceptual faculty of the mind. This cooperation can sometimes be compelled
(as in the case of very strong sensations, as noted earlier), but if it is
not compelled, ideas will simply not be created, even though the appropriate
impressions and motions exist in the brain. There can be no unperceived
ideas, therefore. Ideas only exist
insofar as they are perceived. Locke went on to note that there is
much less happening in perception than many suppose. This is because acts of perception can be
overlaid with judgments from which they have not been properly distinguished. Usually, when we judge, the act of
judging is explicitly a two-stage process.
There is something that is given to us in perception as information or
premises, and then a conclusion is drawn from this information. We are perfectly aware that the information
is one thing and the conclusion drawn from the information something quite
different. However, in cases where we
have been called upon to make the same judgment over and over again, the
judgment can become so automatic that we are not aware of making it. We get the information by perception, make
the judgment, and then forget the information we based the judgment on, and
forget the act of judgment and just think of the conclusion, so that it seems
to us as if we are simply perceiving the conclusion, rather than perceiving
the original information and then judging that it entails the conclusion. Locke gave an example. A sensation is transmitted from the senses
to the brain. The mind attends to this
sensation. In very young children,
attention to this particular type of influence naturally and originally
produces the idea of a flat circle, variously coloured. However, children discover as they grow up
that their visual ideas of flat circles, variously coloured, are associated
with tangible ideas of globes, and these globes are seen, upon being turned
about, to actually be of a uniform colour.
As a result of this experience, an act of judgment intrudes to
influence our perception. In adults
the original idea of a flat circle variously coloured is taken to be a sign
of a uniformly coloured globe and the transition from the one idea to the
other is so easy and rapid that the initially received idea is transformed
into the associated idea. The
operation is quite extraordinary, when you think that it is quite difficult
to convince adults that they see anything other than a uniformly coloured
globe. They are so little aware of
really seeing something quite different and judging from that appearance that
they can hardly be convinced that they do not immediately see a uniformly
coloured globe. It is only when they
are forced to do something like paint a picture of the globe that they
suddenly discover, as they attempt to replicate the exact appearance in
coloured paint on canvas, that globes are not uniformly coloured and that
cubes are not seen to have three square faces (on the visible side, when
viewed from an oblique angle). In giving this example Locke supposed
that we originally see in just two dimensions. This is something that he took to have been
made evident by the practice of painters. Locke seems to have thought that
when we go to paint, we are forced to attend more closely to what we really
see than we normally do. Painters who
go to paint a golden or jet black globe actually see, upon close inspection
of this object, that it is not in fact of a uniform colour, but that the
colour shades from bright to dark over various parts. Then, when they go to replicate this actual
appearance on canvas, they discover that their painting, despite being made
of varying colours placed on a flat surface, actually looks rounded and
uniformly coloured, like a uniformly coloured globe, whereas if they had made
it all one colour, it would have looked flat and circular. Something similar happens with
cubes. We define cubes as three
dimensional figures enclosed by six squares set perpendicular to one
another. And this is what they feel
like to the touch. It is also what we
naively think they look like. But it
is impossible to make an accurate model of a three dimensional object on a
two dimensional surface, like a canvas.
So it ought to be impossible to draw or paint a cube. However painters discover, perhaps by
setting up a fine, wire grid before their eyes, drawing squares on canvas,
and then copying the appearance of a cube seen through the wire grid onto
canvas, that cubes are not actually seen to have the shapes they are felt to
have. They are seen in
perspective. And when this perspective
appearance is reproduced on canvas, the drawing on the two-dimensional
surface takes on an appearance of depth in three dimensions.
Woodcuts
by Albrecht Dürer, illustrating the use of
devices to assist us in drawing what we actually see so as to be able to
properly represent objects in perspective.
The spire in the top diagram is necessary for the draughtsman to keep
the eye constantly positioned at the same point while viewing through the grid. This experience convinces us that the
sensations we originally receive from vision must be like what the painter
paints onto canvas. Painters are forced by their craft to paint what they
really see. And we, who look
attentively at paintings and see how they lead us to, as we say, “perceive”
depth, discover that we are not really perceiving at all, but making
judgments based on what is really there, which is not in depth at all, but
flat. The features painters put into paintings
must be the very features of the original visual ideas that lead us to infer
depth. If Locke was right about this, then
those who have not yet had the relevant experiences should still see the
original visual ideas without the modifications our experience subsequently
leads us to impose on them. Thus, very
young children should see in only two dimensions. This is a controversial issue, and it
touches on a dispute between Locke and Descartes. Descartes shared Locke’s supposition that
we originally see in only two dimensions. But, when discussing the means
whereby we come to visually perceive depth in his Optics, he had declared that some of these means involve “as it
were an innate geometry.” That is,
Descartes had supposed that we are simply innately so constituted that, on
the occasion of experiencing certain two-dimensional visual ideas, we
automatically judge their three-dimensional significance. Locke’s rejection of innate knowledge
did not dispose him to accept Descartes’s account of depth perception. In opposition to Descartes, he wanted to
insist that it is only after we have discovered through experience that
certain visual ideas correspond to certain tangible ideas that we are enabled
to make judgments concerning visual depth. Unfortunately, Locke and Descartes
could not resolve their dispute by introspection. None of us is any longer in a position to
remember how things originally looked to us in the first weeks after birth,
or whether we had to learn to associate two-dimensional and chromatic
features of our infantile visual experiences with distances outwards along
the depth axis. Neither could the
dispute be resolved by approaching very young children and asking them
whether they are able to see depth. By
the time children have acquired the verbal and intellectual abilities to
understand the question, they are too old to remember what their original
visual experiences were like. The
Molyneux Question. This last
reflection led Locke into a fascinating digression on what adults, blind
since birth, but intellectually sophisticated, able to communicate, and
familiar with geometrical concepts learned from the sense of touch would tell
us upon acquiring the power of vision. One of his friends, William Molyneux,
had earlier posed a question on this topic — a question that has since become
one of the central topics of perceptual psychology. What would happen, Molyneux asked Locke, if
a blind person, who had learned by touch to distinguish between a cube and a
sphere were made to see and then shown a cube and a sphere? Would the blind person be able to tell
which was the cube and which the sphere just by looking at them, without
first touching them? Both Molyneux and Locke speculated
that the answer to this question would have to be no. They thought that the spatial features of
visual experience are not enough like those of tactile experience to lead a
previously blind person to be able to confidently declare what objects they
are seeing just based on the visual appearance of those objects. The previously blind person might see two
dimensionally extended coloured patches that are in fact circular or square
in the sense of having a circumference everywhere equidistant from the center
or having four equal sides and four equal angles. But Locke and Molyneux did not think that
this means that the previously blind person would understand their visual
experience in all the same ways that we do — that they would straightforwardly
take it to be an experience of the all the same objects that we do. This is because the objects of visual
experience are not simply seen but inferred from what is seen, and the
previously blind person has not yet learned how to draw those inferences from
what is seen to the nature of the objects responsible for that
appearance. The previously blind
person would not be able to identify distances of the parts of objects
outwards from one another in the direction of depth, and so would not see
three dimensional objects like cubes and spheres, much less infer that they
are uniformly coloured. Consequently,
when confronted by something like the variation in colour of a globe, the
previously blind person might draw distinctions between colour patches where we
see just one uniform colour. And vision
would present the previously blind person with nothing analogous to the
tactile sensation experienced when touching a cube. We can feel all six faces at once, but we
cannot see them, and the faces we do see may be seen in perspective, which
for anyone who accepts that we see in only two dimensions means that they may
not be seen as square or made of sides of equal lengths. As Molyneux put it, the previously blind
person is in no position to infer that, simply because something looks to have some shape it would also
be felt to have some shape —
particularly if the thing looks to
have a two-dimensional shape
but the question asks about a three-dimensional
shape it does not look to have, and if the two-dimensional shape that the
object looks to have is a function of where the previously blind person
understands the boundaries between differently coloured regions to be drawn. We have all had the experience that
things that feel a certain way do not always look the way they feel. For example, a straight pencil looks bent
when half inserted in a glass of water.
Solid objects cast different images on the eyes depending on how they
are turned. What appears smooth,
small, and round from a distance may look craggy, large, and square from
close up. Any object looks to have the
shape of a dot if viewed from a sufficient distance under sufficient
illumination. And so on. But even if the previously blind person
were to make the leap to suppose that because objects look to have a certain
shape that they would be felt to have that shape as well, the person might
well end up describing their visual experience in very different terms than
we do, because the two-dimensionality of visual experience is more apparent
to them than to us, and because the ways different colours can fall on same
surfaces and same colours on different surfaces might lead them to draw
figure/background distinctions in a different way than we do. Consequently, when asked “which is the cube
and which the sphere” when nothing they
see looks to them like either a cube or a sphere, they would quickly get the
idea that objects must look very different from the way they feel, and would
hesitate to answer the question with any confidence. We might ask what would happen if the
blind person were told in advance that objects seen from close up generally
look the way they feel, or that each point of the three dimensional objects
of touch projects onto the visual field by lines drawn from that point,
intersecting at the center of the eyeball, and hitting a concave surface of
the back of the eye behind that point, so that the sensory stimulus
originally produced by visual objects is a concave, two-dimensional
projection of those three-dimensional objects. Locke and Molyneux would probably answer
that in that case the experiment would be corrupted and nothing would be
learned from it. Molyneux’s question
was whether someone newly made to see would immediately perceive the same
objects we do or would see something so different from those objects that it
would take a guess or an inference to arrive at an answer. If you tell the blind person in advance
everything that they need to know in order to make a judgment about which
object is which, then you won’t be able to tell whether they are just
immediately seeing or instead drawing an inference from what they immediately
see. Those who have since considered
Molyneux’s question have often forgotten the context in which it was asked,
and the presuppositions about the nature of visual experience that Locke and
Molyneux carried to their study of that question. For instance, Leibniz, writing a bit later,
claimed that the blind person ought to be able to associate the prickly feel
of a cube with the existence of angles in the square colour patch experienced
in vision and so discriminate the visual cube from the visual sphere on first
sight. And Reid, a generation after
that, maintained that Nicholas Saunderson (a famous English mathematician and
geometer, who was blind, but understood the laws of geometrical projection
very well), would be able to tell which was which as long as he was told how
light rays are reflected from objects and refracted onto the retina by the
lens of the eye. Both Leibniz and Reid
missed the point that Molyneux was not asking whether the previously blind
person could make an educated guess or a correct judgment. Molyneux and Locke were trying to get an
answer to the question of what the previously blind person would immediately
see, not what they would be inclined to guess or judge about what they saw. Other philosophers and psychologists,
beginning with Berkeley and Condillac, have wondered whether the previously
blind person would at first be able to see any shapes, or even any spatial
order of colour points at all.
Molyneux might have welcomed that question as an even more compelling
way of making the point that there is so little affinity between visual and
tactile experience that a newly sighted person could not confidently claim to
be able to perceive objects by vision.
But Locke might also have seen it as a worrying challenge to his
position on primary qualities. If the
objects of vision are effectively not immediately seen to be in space at all,
then extension and motion cannot be assumed to be universal qualities of all
the objects of sensation. And since
solidity cannot be understood apart from motion and extension (since it has
to do with resistance to entry of a moving object into a space), nothing is
left that could be a primary quality. Locke’s purpose in raising the
Molyneux question was programmatic.
“This I have set down, and leave with my Reader[s],” he wrote towards
the close of Essay II.ix.8, “as an
occasion for [them] to consider, how much [they] may be beholding to
experience, improvement, and acquired notions, where [they] think, [they
have] not the least use of, or help from them.” Over subsequent parts of Essay II, Locke intended to argue that
a number of ideas that Descartes and others had supposed to be immediately
perceived by a direct inspection on the part of the understanding —
ideas like those of substance, infinity, intelligible extension, and
identity — are in fact built up by mental operations
(such as compounding, comparing, and abstracting) from more primitive ideas
that are originally given through sensation. The consideration of the Molyneux question
served as a sort of preparative for that argument. Locke’s thought was that if we could be led
by consideration of the Molyneux question to appreciate that a significant
number of the ideas that we think are directly and immediately perceived by
us are actually worked up by unnoticed mental operations performed upon more
primitive and simpler ideas, then we would be more receptive to what he had
to say in the remainder of Essay
II. But whatever opportunities the
question might have offered to Locke to make other points, it is also
troubling. It is not clear what
originally motivated Molyneux to ask his question, but the fact is that what
Locke said about visual perception in the first edition of Essay II.ix.8 does not sit well with
what he had said at Essay II.v
about ideas of space and extension coming from more than one sense, and at Essay II.viii.21 about the distinction
between primary and secondary qualities.
Locke seems not to have noticed this and to have viewed Molyneux’s
question as a further illustration of what he had to say at II.ix.8 rather
than as a challenge to his earlier claims.
But if the fact that the same bucket of water can appear warm to a cold
hand and hot to a cold hand entails that heat and cold must be merely type
(ii) ideas in us rather than primary qualities of bodies, then by parity of
example the fact that the same object can appear round to the touch and flat
to they eye should entail that round and flat must be merely type (ii) ideas
in us rather than primary qualities of objects. And the same object does appear round to
the touch and flat to the eye if we accept Molyneux’s claim that the visual
and tactile appearances of the same object are so different that a person newly
made to see could not, at first sight, apply the same names to both. If shape, size, and position are not
qualities that are common to both sight and touch, but visual shape is
distinct from tangible shape, visual size from tangible size, and visual position
different from tangible position, then with what right do we consider these
to be qualities of objects rather than features special to specifically
visual and tactile ideas? Had this
been what motivated Molyneux’s question, Locke might have had a harder time
endorsing Molyneux’s negative answer — or at least noticed a need to
reconcile a negative answer with his other views. There were no actual tests of the
Molyneux question made in Locke’s day, though a generation later an English
physician, William Chesselden, removed cataracts from a boy’s eyes and made
careful observations on the boy’s reactions — observations that appeared to
confirm Locke’s and Molyneux’s positions on the question. Subsequent work has been more ambiguous and
has tended, if anything, to establish Berkeley’s and Condillac’s conjecture
that visual experience is far more complex and multi-faceted than Locke and
Molyneux had imagined. Contemplation
and Memory. Locke noted
that we have a capacity to hold an idea we have once perceived in mind even
after the sensation that caused it is no longer occurring in the brain. Locke called this capacity contemplation. Memory, in contrast to contemplation,
is the capacity to have ideas that have been perceived in the past. Obviously, we do remember things, and we do
so all the time. But memory is an
extremely difficult operation to account for.
There is something almost paradoxical about it. We cannot remember something off in the
past the way we see something off in the distance, by just looking and seeing
it faint and obscure on the horizon.
For the past no longer exists.
Given this fact, it is tempting to say that what we do is contemplate
some left over trace or echo of the past object that continues to exist. Hobbes, insofar as he treated our
sensations as producing motions that continue to reverberate in the brain
after the time of their initial impression, took such a position. However, Locke was explicit that memory
cannot involve storing the echoes or traces of past ideas away in some filing
cabinet of the mind, like so many pictures or documents, and then pulling
them out again when needed. Were we to
accept that view, we would have to accept that ideas continue to exist when
not perceived and Locke did not want to make that supposition. Rather, he took memory to be a capacity to
recreate ideas we have had before and that have since disappeared, even
though the sensory stimulus that originally produced them is no longer
present. But then how do we distinguish these
ideas from ideas currently being produced in us? How do we know that we are
remembering? We cannot say that this
is because there are no motions or impressions currently being communicated
by our senses to our brains to cause the ideas, because all that we are ever
aware of is our ideas, not the activities in the brain that are supposed to
cause them. Neither can we say that it
is because we are aware of
deliberately producing them. While we
do deliberately produce memories, this does not suffice to distinguish memory
from imagination. Given that we have
no innate ideas, imagination is, like memory, confined to reproducing ideas
we have had before, in sensation or reflection. The only difference is that in memory we
reproduce ideas in the same sequence we have had them in the past, whereas in
imagination we are not bound to do this (though it is not impossible that we
might by accident). But since we are
now attempting to account for memory, we cannot say that memory is an ability
to reproduce ideas in the sequence they originally occurred in experience,
because how would we know what that sequence was? To presume that the order in which ideas
are produced is guided by knowledge of the sequence in which they originally
occurred is to presuppose the very thing we are trying to explain, a memory
of the order in which the ideas originally occurred. To suppose that we just have an ability to
reproduce ideas we have had in the past without being guided by any left-over
trace or impression of the original sequence is to admit that we are only
capable of imagination and leave it a problem how we ever manage to remember. To solve this problem Locke declared
that when we create an idea in memory we form the further idea that this idea
was sensed at some time before, and attach this idea of “beforeness” to the
idea we are currently creating. However, this position raises further
problems. To remember an idea, on this
account, is to attach to a currently existing idea the further idea that it
was had before. But what could make us
think such a thing, if the currently existing idea exists now, rather than
earlier? To answer that we remember that an idea just like it was
had earlier (or “before”) is unacceptable, because Locke is here supposed to
be explaining what memory is. To say
that to remember is to now have an
idea that you remember was had more
vividly in the past is not an explanation of what memory is because it
employs the very notion we are trying to explain as part of the explanation.
So it looks like Locke would have to say that we are simply innately so
constituted that when we perform the operation of remembering we
simultaneously produce an idea of beforeness, which we attach to what we
remember. One problem with this approach is that
beforeness is something that comes in degrees. How do we know how much before or how
earlier to consider a remembered idea to be? What gives us the capacity to
not merely reproduce the idea, but keep track of how much time has passed
since we had it so that we can attach the appropriate amount of “beforeness”
to it? It is not clear how these
questions could be answered without presupposing that we somehow remember how
long it has been since we last had the idea, though how we remember anything
is just what is supposed to be explained). Another problem concerns how Locke
would account for the origin of the idea of beforeness. He could not take it to be a simple idea of
sensation, like our idea of red, because the idea of beforeness is not simple. It is the idea of a relation that obtains
between two things, an earlier one and a later one. For Locke, ideas of relations arise as a
product of the operation of comparison.
We consider two ideas together and discover some relation to hold between
them. But in the case of the idea of
beforeness the two ideas we would need to consider together are an earlier
idea and a later idea. These are the
only ideas that are appropriate to give us an idea of beforeness. But if one of the two ideas is earlier then
at least it (if not also its later partner) no longer exists. (Alternatively, if it does, its later
partner does not exist, because what is future no more exists than what is
past.) But the whole problem is how we
manage to grab hold of an idea that no longer exists and contemplate it in
memory. Once again, it looks like we
would have to have solved this problem in order to account for the
acquisition of the idea of beforeness.
The idea of beforeness cannot, therefore, be invoked without circularity
in order to explain how we manage to remember. The only way out of the circle would
seem to be to accept that the idea is innate, but that is hardly an option
that Locke would be happy to countenance. Discerning
and Comparing. When we
perceive, it is typically the case that many different simple ideas are
perceived together. Some of these
simple ideas may follow one another in time; others may be disposed alongside
one another in space, and yet others may be bundled together, as figure and
colour are bundled together in a colour patch. Discerning is an operation of the mind that
works like a more acute perception.
When we discern we isolate the individual simple ideas that our perceptions
contain and contemplate them separately from one another. We may also compare various
perceptions, or even various simple ideas with one another. This operation leads us to form ideas of
the respects in which the ideas we are comparing resemble or are different
from one another. Our ideas of
relations arise in this way. These are
highly refined ideas that are not given in sensation, and are not parts or
aggregates of ideas of sensation, but are quite new ideas, though new ideas
that can only arise in us insofar as certain other ideas have first been
given in sensation and reflection and then compared in the right way. It is through discerning and comparing that
we come up with the idea of identity — the relation of being the same as — as
well as the idea of difference — the relation of being different from. The supposedly innate principles of the
identity of indiscernibles (if there is no discernible difference whatsoever
between one thing and another then they are the same), and the law of
non-contradiction (nothing is the same as what is different from it) are read
directly out of these relations. But
since the relations of identity and difference have to be learned by
comparing and contrasting sensations, these principles cannot in fact be
innate. Repeating
and Combining. The mind also has the ability to
imaginatively combine ideas that have originally been given separately from
one another in distinct perceptions.
This is what accounts for all our fantastic ideas as well as for all
our ideas of new inventions. It is
also what accounts for our mathematical and geometrical ideas of magnitudes
in time and space and number, which are generated by taking a unit and adding
it to itself. Locke sometimes
described combinations of multiple replicas of the same idea (like the idea
of a unit repeated twice, three times, etc., to give us our idea of number)
as “repeating.” “Combining,” in
contrast to repeating, involves combinations of different ideas. Naming. Naming is an operation whereby occurrences
of a given idea are associated with a particular word. A word is itself just a special kind of
auditory or visual idea (a spoken word or written symbol). Once we have named our ideas we can use
these names to later call them to mind. Abstracting. Abstracting is the operation whereby
the mind isolates some feature that a number of different ideas have in
common and forms an idea just of that common feature. (It is therefore importantly distinct from
discerning and separating.) Abstraction gives rise to our generic ideas
(i.e., our ideas of kinds of things or groups or classes, as opposed to our
ideas of particular things). All, or
most of our words are in fact names of general ideas. Very few are reserved to name particular
objects. ESSAY QUESTIONS AND RESEARCH PROJECTS
1. Critically
assess Locke’s argument for inferring that our type (i) ideas must be
resemblances of qualities in bodies.
2. Critically
assess Locke’s arguments for inferring that our type (ii) ideas are not
resemblances of any qualities actually inhering in bodies.
3. Locke’s claim
that there is a distinction to be drawn between type (i) and type (ii) ideas
was in part based on an appeal to the claim that type (ii) ideas are relative
(the same water can feel warm to one hand but cold to the other) whereas our
senses never give us conflicting information about the type (i) qualities of
objects (no object ever feels like a globe to one hand but a cube to
another — Essay
II.viii.21). However, this claim seems obviously false in a number of cases
(a pencil in a glass of water looks bent but feels straight, for example). This is a point that was made by Bayle in
note H of his Zeno article (to be read later in this class), by way of
criticism of the Cartesian claim that a “blind impulse” leads us to think
that material things are coloured, but a clear and distinct perception leads
us to think that they must be extended.
However, it works just as well as a criticism of Locke, and both
Berkeley (Principles 14-15) and
Hume (Enquiry XII) used it as
such. Survey Bayle’s,
4. Locke’s claim
that there is a distinction to be drawn between type (i) and type (ii) ideas
was also attacked by Berkeley (Principles
10, drawing on the argument of his Introduction to the Principles) on the grounds that it is impossible to form a type
(i) idea without making use of a type (ii) idea. This is because we cannot think of a figure
without a boundary, and we cannot think of a boundary without employing
contrasting qualities to mark its presence.
5. In his New essays on human understanding, Book II,
Chapter 9, Section 8, Leibniz rejected Locke’s and Molyneux’s answer to the
Molyneux question, writing that “the blind man whose sight is restored could
distinguish [the cube and the sphere] by applying rational principles to the
sensory knowledge he has already obtained by touch” (Remnant and Bennett,
eds. [Cambridge: Cambridge University Press, 1981], p.136). Outline the reasons Leibniz gave for his
view and the qualifications he applied to his positive answer. Assess whether Leibniz or Molyneux has the
stronger case.
6. It has
occasionally been charged that Locke’s negative answer to the Molyneux
question is inconsistent with his own position on the distinction between
type (i) and type (ii) ideas.
According to this objection, if type (i) are resemblances of qualities
in bodies, then the newly sighted person ought, on first seeing a globe or a
cube, to be able to suppose that the type (i) ideas they receive from vision
resemble qualities actually existing in bodies, and relate that information
to their tangible experience in order to be able to say which object is the
globe and which the cube. This objection is not supported by the
interpretation of Locke’s reasons for agreeing with Molyneux that was offered
in the reading notes. However, the
issue is not clear-cut. Accounts of
Locke’s position on the Molyneux question can be found both in works on Locke
(e.g., E.J. Lowe, Locke on human
understanding [
7. Locke was not
the only early modern philosopher to have problems accounting for the
phenomenon of memory. Do a comparative
and critical survey of attempts to account for the phenomenon of remembering
by major and minor figures in the seventeenth and eighteenth century. Particularly worthy of study are, in
addition to Locke, Condillac, Hume, Immanuel Kant, and Thomas Reid. |
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