The secondary quality argument for
indirect realism
R1.
When I look at a rose, I see something that is
red.
R2. The red thing cannot be the rose itself (since
redness is a secondary quality which exists in
the mind of the perceiver rather than the objects we
perceive).
IC.
So it must be a mental image of the rose – a
sense datum.
C. But this means I see the rose indirectly, by
seeing its sense-datum- in which case direct
realism is false.
In a nutshell
• Indirect realism, through primary & secondary qualities,
develops a ‘two-world’ view of perception.
• World No. 1 = the world as it really is. Objects with
primary qualities obey the laws of physics here in a
sense-less world i.e. no colour, taste or smell.
• But it is this world, in conjunction with our perceptual
system, that causes us to perceive ‘World Number 2’.
• World No. 2, the world we directly perceive, is a
representation of World No. 1, the world as it is.
Written task:
Create an analogy to help explain the distinction between primary and
secondary qualities and how it explains how we perceive the external world.
How convincing is this distinction?
• Is it really possible to imagine an object with
no secondary qualities? Can you really
imagine an orange as colourless, odourless
and without texture?
Objections to indirect realism
Learning objectives:
1. To understand the objection that indirect
realism causes scepticism about the
existence of the external world
2. To begin to evaluate indirect realist replies to
it
Problem 1: How can we know there is
an external world?
• Indirect realists say that all we ever perceive is
sense-data.
• Sense-data is mind-dependent.
• So how can we know whether anything exists
beyond the mind?
Problem 1: How can we know there is
an external world?
• See Russell ch. 2, last para. on page 8 (to half
way down p.9)
Can you answer Problem 1 for indirect
realists? How can we know there is an
external world, even though it is
perceived via sense-data?
Can you answer Problem 1 for indirect
realists? How can we know there is an
external world, even though it is
perceived via sense-data?
• Similarity between different sense-data
suggests it comes from one thing.
• It makes more sense to say there is a stimulus.
• There are changes to physical matter when
we’re not perceiving it (e.g. decaying banana).
Makes more sense to say it changed whilst not
being perceived.
Russell’s first response
• Read the text from ch. 2, p.9 (2nd half)
Russell’s first response
• People perceive the same thing.
• What is his concern with this reason?
Russell’s preferred response
• Look at me.
• Close your eyes
• Look at me again.
• What’s the best explanation for our sensedata?
Physical objects existing or not existing?
Russell’s preferred response
• See last para. on p.10- half way down p.12
Russell’s preferred response
• Summary: Saying that there is an external
world (including other minds) is the best
hypothesis.
Locke’s two responses
Try not to think about a crocodile.
Locke’s two responses
See page 42 Lacewing.
Locke’s two responses
1) I can’t choose my sense-data.
2) My sense-data gives me a coherent picture.
To what extent are Locke and Russell’s
replies helpful in relieving us from
scepticism about the existence of the
external world?
Read 42-43 of Lacewing and write a
half page long answer to this question
Learning objectives
• To recap the distinction between primary and
secondary qualities.
• To evaluate the extent to which the distinction
answers the objection to indirect realism that
it leads to scepticism about the nature of the
external world.
Problem 2: How can we know the
NATURE of the external world?
• Summary on your work sheet
Response 1: Locke on primary and
secondary qualities
• Read through your sheet
Write down an example of a primary
quality of the apple.
Write down an example of a secondary
quality of the apple.
• How do you know the shape is a primary
quality?
Would the apple still roll off the desk if
no one was perceiving it?
What does this tell us about shape?
Would its colour still be having effects
if no one was looking at it?
Evaluation of Locke’s distinction
• How clear is he?
• Do you agree there is such a distinction?
How does the distinction help defend
indirect realism?
How does the distinction help defend
indirect realism?
• The subjective view of secondary qualities can
be used to defend indirect realism – we don’t
perceive the world directly.
How does it answer problem 2?
Problem 2: Indirect realism leads to scepticism
about the nature of the external world (what it
is like).
How does answer problem 2?
• Primary qualities are accurate reflections of
reality… so SOME of our perceptions
represent the world.
• The world of appearances (of secondary
qualities) is a representation of the world of
reality (of primary qualities).
• What’s the difference between representing
and resembling?
What would an indirect realist say?
• If a tree falls over in a forest, and no one is
there to hear it…
…does it make a noise?
Use primary and secondary qualities in your answer.
Explain why for Locke, extension is a primary
quality.
(5 marks)
Learning objectives
• To know Berkeley’s critique of the primary /
secondary quality distinction
• To know Russell’s response to issue 2
• To evaluate whether indirect realism does lead
to scepticism about the nature of the external
world.
Summary
• Criticism: On indirect realism, how can you
ever know the nature of the external world
when all there is is sense-data?
• Reply: We do have a true resemblence of the
world via our perception of primary qualities.
Bishop Berkeley (idealist)
• What does he say about the distinction
between p and s qualities?
Extension of arg. from perceptual
variation
• Different animals perceive time differently.
• https://www.youtube.com/watch?v=BcYpWBxsHU
• How could this be used to reply to the indirect
realist’s point about primary vs. secondary
qualities?
Extension of arg. from perceptual
variation
• Different distances affect our perception of
shape and size.
5 Mark Question
5
• Explain why, for Berkeley, there cannot be a
distinction between primary and secondary
qualities.
• 10 minutes. (3/4 minutes planning time).
• A full, clear and precise explanation.
The student makes logical links between precisely identified points, with
no significant redundancy.
4
A clear explanation, with logical links, but some imprecision, redundancy.
3
The substantive content of the explanation is present and there is an
attempt at logical linking. But the explanation is not full and/or precise.
Russell’s response to problem 2
• Sense-data tells us relations btwn objects.
Russell’s response to problem 2
• Find 2 objects of the same colour in this room.
• Can we know that they are the SAME colour?
What’s your conclusion?
• If indirect realism is true, I think you can /
can’t know the nature of the external world
because…
Do we perceive the physical world
directly?
Yes – perceive it directly
No – perceived indirectly
Do we perceive the physical world
directly?
Yes – perceive it directly
• Replies from direct realism
• Common-sense
• How can something mental
represent something
physical?
• Indirect realism results in
scepticism.
• Berkeley: Yes – redefines
‘physical object’ as bundles
of ideas.
No – perceived indirectly
• Args against direct realism,
e.g. time-lag
Demonstrate sense-data
• Distinction between
primary and secondary
properties shows that we
do know the nature of the
world, but not directly and
not entirely
representatively.