AS Philosophy - Theory of Knowledge - Unit 3: Perception
AS Philosophy
Module 1
The
Theory
Of
Knowledge
Unit 4
Perception
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AS Philosophy - Theory of Knowledge - Unit 3: Perception
Introduction
We began TOK by looking at scepticism and problems related to acquiring
knowledge. Following that, we looked at Empiricism, Rationalism and how
knowledge is acquired. Now we are going to look at different theories of perception.
What you see is what you get
In his book, Ways of Seeing, John Berger states the problem of perception nicely:
Seeing comes before words. The child looks and recognises
before it can speak.
But there is also another sense in which seeing comes before
words. It is seeing which establishes our place in the surrounding
world; we explain that world with words, but the words can never
undo the fact that we are surrounded by it. The relation between
what we see and what we know is never settled. Each evening we
see the sun set. We know that the earth is turning away from it.
Yet the knowledge, the explanation, never quite fits the sight.
(From Ways of Seeing, p.7)
Many artists, writers and thinkers have been concerned with this problem. Berger
cites the Surrealist painter René Magritte’s work as illustrating this.
As you can see, what we see (a pipe) does not correspond to the meaning of the words
(“this is not a pipe”). Many philosophers have been intrigued by this problem: is what
we see, what we get? Does the world correspond to our experience of it?
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Empiricism and Perception
As we saw with Empiricism in the last unit, one of its main problems is how to check
which of our perceptions are true. This problem arises because, for the Empiricist,
only what is experienced is real. Therefore, our knowledge of objects comes not from
mathematical or logical principles – as it does for the Rationalist – but from direct
experience.
So, the fact that we know things about objects in the world is primarily because we
have experienced them. All knowledge of physical laws or scientific truths comes
through our observation of things that seem to correspond or validate such
knowledge. This view has given birth to 4 main theories of perception: Naïve
Realism, Representative Realism, Idealism and Phenomenalism.
We shall now look at each of these in turn.
Naïve Realism
First of all let’s look at naïve realism.
Exercise
Naïve Realism is the common sense, everyday viewpoint (also called Direct
Realism). Before we go on to look at exactly what it consists of, I want you to put
yourself in the shoes of “the person on the street”. Go through the following list of
questions and note down what sort of assumptions you think the average person has.
Bear in mind that you already have some philosophical training, so try not to be too
controversial – just go for what you think most people believe.
1.
2.
3.
4.
5.
6.
Does the world correspond to my perception of it?
Is there such a thing as matter and can we know it?
How certain are the laws of science and the natural world?
Do things that happen when human beings are not around?
Do other people see the world in the same way that I do?
Are smells, colours, tastes, etc., real? Can others share them?
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The Perceiver and the Perceived
You should now have a list of assumptions that most non-philosophers would agree
to. These things might include such things as: the world exists apart from our
perception of it; physical laws are certain and can be tested; objects continue to exist
when no one is there to perceive them; and so on.
This theory supposes that the process of perception has two main parts: the perceiver
and the thing perceived (the object).
So, when I look at an object – a table, for example – what I see is pretty much what
there is. The table is brown, shiny, has a certain shape, texture, etc. This seems quite
unproblematic. But what if a sceptical sort of person were to say, “You say that the
table is brown, but what about in different light – e.g. electric light as opposed to
daylight”. The sceptic has a point, I think. Can the table be both colours? Obviously
not. So, must we then assume that the table has no colour at all? Or that, what we
think of as real, isn’t so obvious after all?
The sceptic isn’t finished there, though. What about the shape of the table? It seems
square from one angle – straight above – but what about from the side, or some other
angle? Can we then say that the table is square at all? It seems here that we are in a
similar position to that of colour.
A further problem with this viewpoint is that there seems to be no way of
distinguishing between truth and illusion. In other words, whether I am looking at a
real person, or just an illusion (caused by sensory mistake, hallucination, etc.), there is
no way I can tell them apart.
You may notice a trend here: all these arguments have cropped up before in our
discussion of scepticism and the argument from illusion. However, in the case of the
naïve realist’s view of the world, what it actually means is that each of the “commonsense” perceptions that the person in the street holds about everyday objects can be
questioned. In other words, the break-down of the direct realist’s view has severe
consequences for each of the 6 questions we looked at earlier (“Does the world
correspond to my perception of it?” etc.). So, if we want to be a “naïve” or “direct”
realist, we have problems. Don’t we?
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Discussion
Imagine this situation: I am making a cup of tea; I go to the sink, fill the kettle, plug it
in and switch it on. I turn around to get some cups, but when I turn back I discover
that the kettle is gone. No one has come into the room – I am alone – and the kettle is
nowhere to be found. Is there any way that the direct theory of perception can help me
understand this situation?
Representative Realism
As you should by now begin to see, the direct or naïve realist has great difficulty in
differentiating between true and false perceptions. This is because the only appeal that
such a view can make is to perception itself. As we saw in the above situation,
perception alone could not help us: the kettle was there, and now it’s gone.
However, naïve realism is still defended by some philosophers on the grounds that the
way in which we see the world includes variation (size, shape, colour, etc.). So,
although a stick appears bent in water, that is how it actually should look. Whilst this
seems a good counter attack to the sceptical arguments, it arguably doesn’t save us
from the problem of telling false from true perceptions.
However, there is another version of realism that deserves some exploration. This is
called Representative or Indirect Realism. This view argues that we experience
reality indirectly by perceptions that represent the real world. So, if we see a brown
table, what we are actually seeing is not the table itself but a representation of it. In
this way, differences of perception which occur due to changes in light conditions,
position of viewer, etc., can be easily explained: it is not the object which is changing,
only the perception of it.
Whereas naïve or direct realism is a two-part theory (perceiver and perceiver),
representative realism has three parts: the perceiver, the perception of the object and
the object itself.
This view has been very popular among philosophers – we have already seen
Descartes, Locke and Hume use versions of it. But will it solve the problems faced by
naïve realism?
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Exercise
Imagine this situation: A man is standing on the corner of a busy road and witnesses
two cars collide. Neither driver is hurt, but both step out of their cars to inspect the
damage. Driver A is a young mother with a young child in the back of the car; driver
B is a business executive in a hurry; the witness is an old man wearing glasses. As the
two drivers argue about whose fault it was, the old man – let’s call him person C
approaches them and offers to confirm what happened. What does each one see?
Whose is the correct view?
Criticisms of Representative Realism
As you can see, it is difficult to clearly define what a real or objective experience
might consist of because every description is also another viewpoint. This is the same
with anything, from physical objects to ideas. The problem then seems to be that if we
can only ever experience perceptions of objects (what Locke would call secondary
qualities), who is to say that those objects actually exist?
Although this is an extreme point of view, there have been philosophers – such as
Berkeley – who have used this argument to point out the problems with the
representative theory. As you can see, what a representative realist actually sees is not
the object itself, but a representation of it. This representation has been called various
things, but the most usual term is “sense-data”. Representative realism therefore
reduces all knowledge of the world to knowledge of our perceptions.
We are next going to look at how the problems with representative realism gave birth
to something called Idealism.
Idealism
We have already looked at Idealism briefly in association with empiricism. As we saw
then, the Irish Philosopher George Berkeley has most famously advocated the theory.
The interesting thing about Berkeley’s theory is that it was initially intended as a
counter-argument to sceptical arguments about the existence of the soul.
The thing to remember here is that Berkeley himself was not a sceptic, the main
purpose of his arguments being to show how easily sceptical arguments could be
applied to the existence of physical matter. In this way, Berkeley’s scepticism is very
similar to Hume’s (although Hume’s target was the type of certainty that Rationalism
claimed for itself). Unfortunately, this point is usually forgotten when discussing the
theory.
If we refer back to the three-part theory of perception as proposed by such
philosophers as Locke, we can see what Berkeley has done.
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Exercise
As we saw in our earlier discussion of Berkeley, he takes the three-part model
proposed by Locke and points out that we can never actually experience the object
itself. Is this true? Look at the following arguments for the existence of physical
matter and identify the counter-arguments – if any – that Berkeley might use to
disprove them.
1.
2.
3.
4.
We can touch things
We can witness other people interacting with things
Things behave according to certain laws
We can agree with other people about the nature of things
Mental Events
As you can see, it is easy for idealists to argue that our only knowledge of the world
comes through sense experience. Berkeley also argued that it is impossible to think of
something that cannot be imagined, because to conceive of such a thing would be to
imagine it. Therefore, all arguments about the existence of objects can be reduced to
perceptions or assumptions based upon perceptions.
However, the main problem for idealist theories of perception is how to account for
the way in which the world seems to make sense. If we look, once again, at the four
things above which most people would agree with, we could see that idealists are left
with certain options:
1. Our perceptions are all individual and do not completely correspond
2. Our perceptions do correspond (somehow)
3. The world does not exist, only me (a view called Solipsism)
Since few idealists would wish to argue that only "I" exist (no. 3), we are left with
options 1 and 2. Option 1 would entail that our perceptions are all different, but that at
least we perceive something similar.
However, the problem with this is that if our perceptions differ too much from other
people’s we will not be able to interact with the world effectively. I call something
“red”, but actually see what someone else calls green. Unless this was very systematic
(i.e. they always saw green when I saw red, and so on), the world would be in chaos.
On the other hand, if the disagreement was systematic – aside from the question of
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whether this was possible – what would be the difference with saying that our
perceptions actually corresponded?
This leaves us with the final option (no. 2) that our perceptions do correspond to other
people’s. This is the main problem for idealists: if our perceptions correspond, what
to?
As you can see from the above diagram, a world that is full of perceptions is without a
foundation. Idealism does away with this foundation when it rejects the possibility of
experiencing the properties of physical objects.
Discussion
What further problems does the above diagram suggest about idealism?
Phenomenalism
We now come to the final theory of perception, that of Phenomenalism. Like
Idealism, Phenomenalism argues that our knowledge about the world comes through
our senses. Furthermore, it also shifts knowledge about the world away from any talk
of “the object itself” and replaces it with our experiences of it.
This is a little bit more difficult to grasp than the previous theories, mainly because it
is a theory of truth and not just an account of perception. We shall look at definitions
of truth, knowledge and belief in the next unit, so we shall only touch upon this theory
here.
Statements about the World
The Phenomenalist view argues that when we talk about a thing – such as a tree – we
are actually talking about our perceptions of it. So, when we say, “The leaves on the
tree are green,” what you are really saying is that you have a certain perception of
shape and colour that you call a tree. This might seem to be a trifling difference, but
notice that by doing so we are not saying anything about the tree, only our perception
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of it. In other words, the phemomenalist agrees with the representative realist that we
may only perceive sense-data; however, the obejcts which produce the impressions on
me exist as “permanent possibilities of sensation” (this last phrase is from the version
of phenomenalism put forward by J. S. Mill – we shall look at another one shortly).
But why would anyone want to do this? The main reason stems from the problems
with the naïve and representative realist theories of perception. As we have already
seen, naïve realism is inadequate - the world is simply not as it appears to be
(viewpoints change, people experience different things, light conditions alter the way
objects appear). However, the idea that all we see are representations of real objects is
equally problematic. As Berkeley pointed out, what is to stop us from simply saying
that the physical objects are not there at all (Idealism)?
So, phenomenalism tries to argue that this confusion stems from the fact that we talk
about things that are "beyond perception". What proof do we have for the existence of
these objects? Instead of thinking of objects as having a substance (which we cannot
see) which then interacts with our senses to give us representations of it, why not
simply assume that our perceptions are the main source of knowledge. In this way, by
talking only about our perception and experience of things, we are not led into saying
things that cannot be backed by the evidence of our senses. From the phenomenalist
point of view, although objects cannot be directly perceived, that is not to say that
they do not exist - rather, they exist as permanent possibilities of sensation.
Exercise
Which of the following statements would a phenomenalist say could be backed up by
experience?
Statement
The tree has green leaves
All swans are white
2+2=4
Maths is beautiful
Shakespeare is a great writer
Backed up by Experience?
Yes/No
Yes/No
Yes/No
Yes/No
Yes/No
Sense and Nonsense
What do you think? Can all of these statements be backed up by experience? If not,
what status do they then have? Phenomenalists, such as the 20th century English
philosopher A. J. Ayer, thought that if statements could not be confirmed by some
sense experience then they were literally non-sensical. We shall look at this view in
more detail in the next unit.
Phenomenalism and Scepticism
As well as attempting to limit what knowledge can be obtained and how,
phenomenalism has also been used against scepticism. Both realism and idealism
were open to sceptical attack - although in different ways. Realism was either seen as
not being able to account for errors (naïve realism) or being open to scepticism about
the existence of objects (representative realism). Idealism, in proposing that
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everything is immaterial, has the problem that our perceptions have nothing to refer to
(no physical objects) and therefore cannot be verified.
So how does phenomenalism solve these problems? First of all, phenomenalism does
not say that we experience objects directly (in this way, it is similar to indirect
realism). Rather, objects are "permanent possibilities of sensation". In other words, an
object does not exist unless it is possible to experience it in some way. In this way,
phenomenalism is a form of empiricism - it relies on experience for knowledge.
Problems With Phenomenalism
There are a number of problems with this theory.
First of all, unlike Berkeley, phenomenalists do not want to argue that we live in a
spiritual or mental universe. If you remember, Berkeley had to propose that God was
continously observing everything in the world so that it existed. However, to achieve
a similar thing - without invoking God - the phenomenalist must allow that an object
has the possibility of being perceived (otherwise, if an object is just defined as a
collection of sense-data, if it were not perceived it would not exist). This leaves the
door open for saying that there are possible perceptions of objects which are never
perceived - although they are capable of being so (this is the problem of the tree
which falls in the forest and no-one is around to hear it, so does it make a noise?).
Does this mean that we can't know about them? Would talk about them be nonsense?
Another problem is that talk about sense-data is not the same as the sense impressions
which we commonly refer to. We can say, for example, "I see a red car", but if I say,
"I see red sense-data", it could mean all sorts of things - a red hat, a red ball. This
implies that perceptual knowledge is not as easily categorised as the phenomenalists
think.
Finally, if we do not propose that something exists behind our perceptions, how can
we account for the way the world is? For instance, if physics proposed that the world
was made up of certain particles that were too small to observe, wouldn’t the
phenomenalists view this as non-sensical or metaphycsical? However, what if the
theory worked (it successfully predicted certain events)? It seems that the criteria that
something must be observable in order for us to be able to talk about it is a bit limited.
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Summary
In this unit we have looked at the 4 main theories of perception: naïve (direct) realism,
representative (indirect) realism, idealism and phenomenalism. Whereas realism sees
our perception of the world as basically reliable, indirect realism introduces the notion
of “sense-data” to account for the differences in those perceptions. Idealism
concentrates on the idea that we can only really be sure of our perceptions, and
Phenomenalism, whilst not supporting the anti-materialist aspects of idealism,
similarly emphasises experience over conjecture. From this last point of view, we
understand the world by analysing our own perceptions of it, and what this allows us
to say and not say.
Assignment
Answer the following essay question. Submissions may be via email
(g_southwell@hotmail.com), post (Gareth Southwell, Philosophy Lecturer,
Humanities Division, Swansea College, Tycoch, Swansea, SA2 9EB) or in person.
Essays may be handwritten or typed. There is an upper word limit of 2500 words and
a lower limit of 1000.
1) Answer all parts of the question (total marks available: 45):
a) Briefly explain the view that our senses only inform us about how things seem.
(6 marks)
b) Outline and illustrate two arguments which might be used to support a
representative theory of perception. (15 marks)
c) Assess the case for naïve realism. (24 marks)
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