Other ‘truth tests’
Authority
Consensus
Pragmatic
…and there are more
http://en.wikipedia.org/wiki/Criteria_of_truth
http://www.brentcunningham.org/?p=584
What are we going to talk about today?
Theory of Knowledge Diagram
Mathematics
Ways of
Knowing
Ethics
Natural
Sciences
Sense
Perception
Reason
Knower(s)
Emotion
Areas of
Knowledge
Arts
Language
History
Human
Sciences
TaK - Perception
ToK Prescribed Essay Title: 2008
“When should we trust our
senses to give us truth?”
Theory of Knowledge Diagram
Mathematics
Ways of Knowing
Sense
Perception
Natural
Sciences
Ethics
Emotion
Knower(s)
Language
Areas of Knowledge
Reason
Human
Sciences
Arts
History
What role do the different senses play
in the different Areas of Knowledge?
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Empiricism
starting point for all knowledge is experience
Rationalism
starting point for all knowledge is reason
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Sense Perception and Knowledge
Our senses connect us with
the world around us …
… but how connected are we?
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Cosmic Rays
UV Light
X Rays
Radar
Infra Red
TV & Radio
10 22 10 20 10 18 10 16 10 14 10 12 10 10 10 8
10 6
Frequency (Hz)
Visual Window
Our senses are limited: Light Waves
10 4
10 2
10 0
Common Buzzard
Can spot a meal (rodent) from 15,000ft (4,500m)
Fields - taken at 10,000ft
Brasilia - taken from 15,000ft
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Highest
Voice
10 22 10 20 10 18 10 16 10 14 10 12 10 10 10 8
10 6
Lowest
Voice
10 4
10 2
10 0
Frequency (Hz)
Audio Window
Our senses are limited: Sound Waves
McGurk Effect – Video
http://www.youtube.com/watch?v=G-lN8vWm3m0
TaK - Perception
Bloodhound:
“A nose with a dog attached”
• 230 million olfactory cells
compared to 5 million in
humans
• 1000 times better sense of
smell than humans
• Have been known to be
able to track a scent for over
100 miles
Our senses are limited: Smell
TaK - Perception
So perhaps we don’t see, hear, smell,
taste and touch everything…
… but what we do sense, we sense
accurately – don’t we?
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What is in the mind and
what is in the world?
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Esref Armagan
– born blind
TaK - Perception
Sensation
which is provided by the world
Interpretation
which is provided by the mind
(external stimuli + mental processes)
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In our everyday life, we are not
usually aware of our minds
interpreting the sensations that
flood into our senses ....
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Awareness test – Video
http://www.youtube.com/watch?v=oSQJP40PcGI
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“It’s not what you look at that
matters, it’s what you see.”
H.D. Thoreau
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Sensory Perception is selective: What the eye saw….
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Sensory Perception is selective: What the camera saw….
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Interpretation: Understanding what we see - Coherence
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Interpretation
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Interpretation – finding meaning in what we see
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Expectation
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What is this?
Organising Principles – the Law of Simplicity
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What is this?
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Imagination,
Context,
Expectation and
Sense Perception
affect the way we interpret sense data
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You are walking down a dark alley ...
there are footsteps behind you …
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Context
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The mental construction of reality
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“The eyes see only what the
mind is prepared to
comprehend”
Bergson
Who are you?
http://www.youtube.com/watch?v=dgbs2ZP_qSk @52.21
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“Who you are decides what you see”
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Take the following and explain how education
and training can affect what we perceive:
•
•
•
•
A biologist looking down a microscope
A professional wine taster
A lifeguard
An artist
TaK - Perception
Think about the following and describe how
they might be seen through the eyes of the
different people:
1. A child dying in poverty as seen by a
doctor, an economist, a social worker,
the child’s father
2. A sunset as seen by a religious figure,
a physicist, a painter, a farmer
3. A tree as seen by a biologist, a logger,
an environmentalist, a carpenter
TaK - Perception
Sense Perception is an important
source of knowledge but there are
reasons for treating it with caution:
TaK - Perception
• We may misinterpret what we perceive
• We may fail to notice something
• We may misremember what we have
perceived
• Sensory perception is selective
• Our senses have limitations
• Experience creates expectations
• Subjective factors – interests, moods –
affect sensory perception
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Eye-witness testimony
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Person Swap – Video
http://www.youtube.com/watch?v=vBPG_OBgTWg
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Some key points:
• Sense perception consists of Sensation
and Interpretation
• If we accept that pain and taste are
subjective, we might conclude that color
and sound are also subjective
• Senses are an important source of
knowledge but rather than passively reflect
reality, they actively structure it
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Some more key points:
• Sense perception is selective
• Sense perception has limitations
• Although sense perception cannot give
us certainty, if the evidence of our senses
is consistent with what reason and
intuition tell us, it can still provide a good
foundation for reliable knowledge
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Some safeguards:
• Confirmation by another sense
• Coherence
• Independent testimony
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Language
How does the
way we describe
something affect
the way we see
it?
Religion
What role does
perception play in
religious
experience?
Ethics
Do good people
see the world
differently from
bad people?
Perception
Does perception
play any role in
Mathematics?
Natural
Sciences
Do expectations
influence
observations?
Human
Sciences
Arts
To what extent do
the arts help us to
see the world with
new eyes?
Maths
History
Should we trust
eyewitness
testimony?
Does observation
influence what is
observed?
TaK - Perception
Some Knowledge Questions
• What factors affect our ability to gain
knowledge through the senses?
• How do our senses hinder us in our attempts to
gain knowledge?
• How is sensory perception affected by
emotion/reason/faith/language?
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• How do context and culture affect our
perceptions?
• When you are told that ‘you should be
more objective’ – what does that mean?
Extras
TaK - Perception
Common sense realism: the way we perceive the
world mirrors the way the world is
Scientific realism: the world exists as an
independent reality but it is different from the way
we perceive it
Phenomenalism: it makes no sense to say that the
world exists independent of our experience of it.
“To be is to be perceived” (Are the chairs in the
classroom when you aren’t there?)
See ‘Theory of Knowledge for the IB Diploma’ Richard van der Lagemaat,
p 99-101
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Think about physical sensation (Touch)….
• You plunge your hand into a bucket of hot
water – is the pain in your hand, or in your
mind?
• You plunge your hand into a bucket of ice cold
water – for a moment you aren’t sure if it is hot
or cold …