AS Philosophy - Theory of Knowledge - Unit 3: Perception

AS Philosophy - Theory of Knowledge - Unit 3: Perception

AS Philosophy

Module 1

The

Theory

Of

Knowledge

Unit 4

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?

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. Does the world correspond to my perception of it?
2. Is there such a thing as matter and can we know it?
3. How certain are the laws of science and the natural world?
4. Do things that happen when human beings are not around?
5. Do other people see the world in the same way that I do?
6. Are smells, colours, tastes, etc., real? Can others share them?

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 thateach of the “common-sense” 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?

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?

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.

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. We can touch things
2. We can witness other people interacting with things
3. Things behave according to certain laws
4. 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 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 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 / Backed up by Experience?
The tree has green leaves / Yes/No
All swans are white / Yes/No
2 + 2 = 4 / Yes/No
Maths is beautiful / Yes/No
Shakespeare is a great writer / 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 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?