Barbara asked:

Is it things, objects like shrubs, cars and houses, and people that I see out of my window? And an
armchair, a computer a pink mug, a white lamp and a dark green plan in my room? Or is all of that
just patches of colors? And what makes me think it is just patches of color? And if it is just patches of
color, what makes me take them for an armchair and a lamp?

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This is an excellent question because you have seen beyond the problem, How do I know there's a
armchair in front of me? to the deeper issue of why we are tempted to ask that question in the first
place.

The argument for the view that when I perceive a chair all I really see are patches of colour was put
forward by Descartes in the Meditationsand was revived in the twentieth century by philosophers
defending the sense datum theory of perception, such as H.H. Price. It is know as the Argument from
Illusion. It is possible to seemto see a chair, even though there is no chair there, for example, when I
am dreaming, or undergoing an hallucination. My subjective experience is exactly the same as if
there really were a chair there. Descartes used this point to argue that we cannot prove the existence
of an external world, simply on the basis of our experiences. The conclusion of the argument, whether
or not one accepts Descartes' sceptical conclusion, is that perceiving a chair involves having
chair-shaped sense data, and then interpreting those sense data as the perception of a chair.

The argument from illusion is sometimes combined with an argument based on the scientific account
of human perception. Seeing a chair involves a chain of causes and effects, the end product of which
are electrical impulses in the brain. So when I see a chair, it is argued, the immediate object of my
perception is not the chair, but changes in my brain. The final, dubious step in combining the two
arguments is to identify sense data with processes in the brain.

I am not going to try to say what is wrong with these arguments. Because even if I did give a
convincing critique, it would not answer your question. I don't think it is plausible to say that whenever
you or I are temptedto see the world around us as no longer 'out there' but 'in here', this convoluted
reasoning is going through our minds. If it were not for that priortemptation, the reasoning would not
appear so convincing.

What is so amazing about the experience of familiar things around us turning into patches of colour,
is that nothingactually changes:

The very objects themselves seem to dissolve away without a trace; nothing remains of what was
supposedly out there. The apple and the table lamp now appear to me as nothing other than images
floating in my own mind. As I look round, the same happens to every object I cast my eyes upon.
What caused this extraordinary event to occur? My whole world has completely changed; and yet, in
a strange way, everything remains the same as before. Nothing flickered or went fuzzy, no visible
sign testifies to the dramatic transformation I have just witnessed.

Geoffrey Klempner Naive Metaphysics Chapter 3.

It is a trick anyone can teach themselves to do. When you do the trick, you don't have to imagine that
the objects are anything other than what they are. You don't have to say to yourself, 'These are just
sensations in my mind.' All you have to do is see the chair as mychair, the apple as myapple, the
table lamp as mytable lamp. It is not even the changing into patches of colour that is the important
thing. You can mentally divide any object into bits without ceasing to think of it as 'out there'. What
happens when I do the trick is that the space which these objects are in ceases to be a space that
includes me as just another object in the world and becomes myspace, myworld. If I were not here,
then neither would there be theseobjects.

Once you have learned the trick, it is difficult to stop doing it. That is the real philosophical challenge.

Geoffrey Klempner

Second opinion:

Let's assume that we are not brains in jars, and that we are not dreaming, or the playthings of some
evil demon. For if any of these scenarios is the case, then none of the things we 'see' are really
objects in the world, in fact there is no world for objects to exist in. Let's pretend that we have solved
the problem of scepticism and that we knowthat there is a material world that exists and is full of
material objects. We are still left with a problem, namely, What is the nature of these material objects
and what is our relation to them?

Locke (1632—1704) said that physical objects possess two basic classes of qualities. His account fits
nicely with a modern scientific account. Primary qualities, such as solidity, extension and shape, are
aspects that are inseparable from the object because they belong to it intrinsically. Secondary
qualities, by contrast, are powers that objects have to produce experiences in us, including colour,
sounds, smells, taste.

On this account, a mug's pink colour is explained by the molecular structure of the mug and the way it
reflects light waves, the way our eyes convert the light waves into electro-chemical information, and
the rest.

However, colour is not a quality of a certain sort of wave length. Blind people can experience wave
lengths, yet not experience colour. And in fact a purely scientific description leaves the world
colourless: The mug is not pink, the light waves are not pink and no part of our brain has a pink patch
corresponding to the mug. On a fully objective description, pink does not enter the picture anywhere.

Nevertheless, we do have a sensation of the colour pink. Colour, then, appears to be a completely
subjective experience. If this is so, then perhaps all we are entitled to say is, not, 'I am seeing a pink
mug', but, 'I have an experience of a pink patch'.

In that case, what makes the patch look like a table or a mug? That's a tough one. Berkeley
(1685—1753) thought that physical objects were just mental events, a collection of ideas, that
continue to exist only so long as they are perceived. I'm not too keen on that theory myself. A better
answer would involve a reconciliation between the scientific, objective description of how the world is
and the subjective description of how the world is for me, or for you. Unfortunately, I do not know if
such a reconciliation is possible, certainly one has not yet been found.

A book that covers these issues is The Subjective Viewby Colin McGinn

Brian Tee
Dept of Philosophy
University of Sheffield.