Perception as a source of knowledge Flashcards
what is empiricism
our fundamental knowledge comes from the sense+experience
and all knowledge is known posteriori
what is rationalism?
knowledge comes from reason
and all knowledge is known a priori
what is a priori?
knowledge doesnt depend on expereince
what is posteriori?
knowledge depends on expereince
definition of perception
expereince using our 5 senses
what is realism
(about the external world)
the view that the world outsid our minds is real.
we experience the world directly, unmediated by anything
definition of direct realism (DR)
the qualities we experince in objects are possessed by the objects themselves
so, appearence and reality should be idientical
what do realists claim
what we percieve are physical objects which exist independently of our minds
what is sense experinece
awareness of physical objects through senses
What is verdical perception
matching with reality
strengths of naive DR
common sense, simplicity, Ockams razor
what is Ockams razor
do not multiply entities beyond necessity
criticism of DR
illusions
- objectively, the world can only be one way at one time
- DR says that we percieve the world directly
- if so, we percieve the world as it is- nothing ‘gets in the way’ to stop it appearing as it is
- illusions show that the world is not percieved as it is
McGurk effect- facial expression clashes with what we hear therefore creating an auditory illusion
criticism of DR
perceptual variation
- what i see changes
- the object itself cant be supposed to change
- therefore what i see is not the object
Bertrand Russel’s table
properties physical objects have and the properties they appear to have are not always identical
criticism of DR
time lag
- all perception is a process which takes time (e.g the sun)
- therfore we see things as they were in the past
- but the past no longer exists- it isnt reality
- so we cannot percieve reality directly
- so we must percieve something else e.g sense data
criticism of DR
hallucinations
- some sense experinece is of hallucinations
- but in any experince something is being percieved
- therfore hallucinations dont exist in reality but in our heads
- hallucinations are perceptions of sense data
- some hallucinations are subjectively indistinguishable from verdical perceptions
- suggests all perception is sense data and not objects themselves
leads to indirect realism
what is sense data
a mental image
what is indirect realism (IDR)
we view the world through sense data, perception is indirect
we always directly perceve sense data
IDR
what is the phenomenal principle
- i must be seeing somehting in order to have an experinece
- it must be something mental that i see, if its not reality
- therefore im not perceiving a mental image
defintiion of subjectively indistinguishable
feels the same
qualities of sense data
5 points
- mental- mind dependent
- private to each person
- therefore seeing them slightly differently
- subjective
- temporary (transient)
qualities of physical objects
6 points
- material
- exists in the external world so mind-independent
- public to everyone
- an object in reality that possesses characteristics
- objective
- permanent
what are primary qualities
qualities that physical objects themselves have
an object must have these qualities to exist
examples of primary qualities
- mass
- solidity
- height
- density
- depth
- weight
- width
- figure
- mobility
Primary qualities are measureable
what are secondary qualities
qualities that are subjective
dependent on the person perceiving them
examples of secondary qualities
- colour
- taste
- texture
- smell
- sound
secondary qualities are not measurable
veil of perception criticism
weaker version
- if we only perceive sense data directly,how do we know what reality is like
response to veil of perception criticism (weaker version)
Primary+Secondary qualities:
1. we cna know we are experincing something so something exists in reality
2. we experince PQ via our sensedata
3. this resembles what the object is like in reality
4. so we can know about the nature of reality i.e. the PQ’s of the object
THIS IS LOCKE’S RESPONSE
veil of perception criticism
stronger version
if we only percieve sense data directly, how do we know there is an external world causing this. We dont know the exdternal world exists
leads to skeptism about the existence of mind independent objects
response to veil of perception criticism (stronger version)
involuntary nature of perception
- we have no choice over our perceptual experinces (unlike imagination)
- if i write on paper, i cant not see it
- this shows that there is a mind independent external world
response to veil of perception criticism (stronger version)
coherence of the senses
- our sense data is caused by mind-independent objects
- locke’s flame- if you see a bonfore, you shoukd be able to hear, feel it etc
Trotter-Cockburn develops this: - we learn which visual experinecs go with which auditory experinece e.g seeing a dog and hearing a dog bark
- we know what sound it will make
issue with responses to veil of perception criticism (stronger version)
involuntary nature of perception AND coherence of the senses
neither of these responses are decisive.
both of them could be explained by a demon, simulation etc
these are weaker responses
response to veil of perception criticism (stronger version)
best hypothesis
- the external world exists because its a simple and powerful explanation of our perceptual experinces (sense data)
- it is SIMPLE because it matches our instinctive belief in the existnec of the ext. world
- it is powerful because it can say why we experince things as bahvaing in regular+predictable ways
russell’s cat -moves from one place to another - it exists
this is the strongest response
who’s response is ‘involuntary experinces’
Locke
who’s response is ‘coherence of the senses’
locke + trotter-cockburn
who’s response is ‘the best hypothesis’
Bertrand Russell
what does berkeley say about sense data to criticise it
idealism
sense data and the ext. world are too different to give us knowledge
so sense-data cannot represent the external world
ideas cant be like material objects
explain.
- all sense data, including those of so called PQ’s, depend on the mind
- therefore we requre a perceiving mind to exist
- since matter is said to be unperceiving, it cant have such properties
what is the likeness principle
- the idea that ideas (or sense data) can only resemble other ideas and therefore we can make no sense of the claim that our ideas could be like or resemble the primary qualities of objects
what does berkeley say about PQ’S and SQ’s
both are perceiver dependent
berkeleys arg against locke
size arg
- size is supposed to be a primary quality
- but it appears to vary from perceiveer to perceiver
- so, size is perceiver dependent
berkeleys arg against locke
dependency
- perception of so-called PQ’s, like shape, depends on perceiving something on perceiving SQ’s like colour
- we need colour to distinguish shapes visually, or else where are the edges
- we need texture to distinguish shapes tactually
- therefore, the so-called PQ’s must also be perceiver dependnet
how successful is Berkeleys PQ/SQ arg?
does the fcat that PQ are subject to perceptual variation show that there is no real difference between PQ and SQ?
NO- berkely is wrong. Our ideas of PQ can vary, but remember that the ideas are not the same thing as the qualites
how successful is Berkeleys PQ/SQ arg?
does the fact that we cant access PQ except through SQ show that there is no real difference between them/
locke claimed that there were qualities objects had in themselves independent of us perceiving them- but if we can only perceive them through SQ, how can we know this? so is there really a distinction between PQ and SQ/
what is idealism
that the immediate objects of perception are physical objects, and all physical objects are mind dependent, so theres no external world
an anti-realist theory
the eorld is mind-dependent, the physical world is composed of ideas not matter
the basics of idealism
the world is physical, but mental not material
- we perceive physical objects directly
- but we only perceive ideas directly
- so physical objects are ideas (i.e sense data)
the basics of idealism
why are all qualities ideas
- because all qualities are perceiver dependent
- no such thing as the PQ/SQ distinction
the basics of idealism
the master arg. (simple)
- we cant even think of something existing unperceived (let alone experinence it)
- so there is no external world
what is sense data
in realtion to idealism
- sense data are the ideas that make up physical objects
- more vivid than other ideas, they seem to be outside the mind- very real
- no conscious control, sense data doesnt arrive or disappear because we will them too
what are concepts
in realtion to idealism
- concepts are the ideas that make up our thoughts e.g beliefs
- less vivid than sense-experince
- some conscious control, we can think of concepts when we want to
what are physical objects
in realtion to idealism
an object with properties such as shape,size,location,colour etc
these properties are sensible properties i.e. properties of sense data
what is berkeleys strongest arg.
idealism
all qualities are ideas—– arg from perceptual variation AND arg that PQ depends on SQ
issue with ‘all qualities are ideas’
- it isnt obvious that he has established the claim that mind-independdent objects do not exist (THE ANTI-REALISM PART)
- even if the PQ and SQ distinction does not hold, he hasnt distinguished betweehn our ideas of qualities (sense-data), and the qualities themselves (whichy are properties of the object itself)
- furthermore there could still be an underlying foundation that causes our perception of physical objects
what is Berkeleys master arg
- when we think of something, we think of it being percieved
- therefore no one can think of anything that exists unperce4ived
- what is perceived is in the mind
- therefore what is thought of is also in the mind
- therefore no one can think of anything existing outsude the mind (you cant think of an external world as this is defined as independnet of mind)
- therefore idealism is true- everything is ideas and there is no external world
difference between imagination and perceiving
master arg
we cant think of something without imagining perceiving it eg a room in your house
evaluating the master arg
- berkeley mixes up perception, conception and imagination
- only perception requires a picture from a perceivers perspective
- conception is a way of thinking about someting without a pciture- without seeing a perceivers perspective- e.g referring to it or reasoning with it
how can ID explain why hallucinations and illusions are not physical objects, if all of them are just ideas
issues with idealism
- according to ID, physical objects are ideas
- however, illusions and hallucinations are also ideas in expeerince but they arent physical objects
- ID fails to explain the difference between illusions and hallucinations and physical objects, so it implies that hallucinations and illusions are physical objects
response ONE to ‘how can ID explain why hallucinations and illusions are not physical objects, if all of them are just ideas’
vivid
illusions and hallucinations are less vivid than experince of real objects e.g the stick in the water looks bent but feels straight
compare to other experinces
response TWO to ‘how can ID explain why hallucinations and illusions are not physical objects, if all of them are just ideas’
I+H are inconsistnet with our other expereinces e.g elephants in the past looked grey and couldnt fly But now theyre pink and can fly
berkely argues reality is the ideas we percieve. what problem, in realtion to illusions, does this lead to?
leads to implying that illusions are physical objects and therefore that is how they truly exist in the physical world
what is berkely response to ‘berkely argues reality is the ideas we percieve. what problem, in realtion to illusions, does this lead to?’.
claims the issue is with language - pencil in water, he claims the pencil ‘looks’ bent instead of the pencil ‘is’ bent
how does berkely [IDEALISM] attempt to explain hallucinations
explains that hallucinations are not as vivid or clear compared to perception - and they’re not consistent with our past experinces
how can berkeley explain that objects continue to exist when no one percieves them
god
ideas we percive arent just caused by god, but exist as they are percieved by god
where do our ideas (i.e sense data or impressions) come from if not an external world?
idealism
god
simple crit.
critiscim of berkeley use of god
idealism
its ad hoc
meaning its used to solve a problem with no independnt justification for the solution
berkeleys response to his use of god being ad hoc
his theory is an arg. for the existnece of god
1. the only possible cause of the order, regularity, and predictability of our experinces is divine intelligence
2. god is divine intelligence (omniscient)
3. so, god exists
problem with the role of god
idealism
- idealism says that physical objects which i percieve exist as ideas in the mind of god
- but god cant have perceptual experinces like i have - e.g god doesnt feel sesnations such as pain
- the objects i perceive change and cease to exist, but gods mind is said to be unchanging
- therefore, what i percieve and feel cant be part of gods mind
- so idealism is incorrect
berkeleys response to the problem with the role of god
idealism
our experinces are copies of gods ideas
what is solipism
the claim that you only know youe own mind
why does idealism lead to solipism
everything we know is from experince, which is just sense data. and we have no experinces of other peoples minds
berkeleys response to why does idealism lead to solipism
idealism allos us to know that the mind of god exists as well as our own
progression of theories of perception
naive direct realism TO indirect realism TO idealism TO philosophical direct realism
how can illusiosn be accounted for by philosiphical direct realism
it turns out that ‘looking a particular way’ can be a property of an object, even when the way it looks doesnt reflect what the object truly looks like
e.g pen looks bent in water
defintion of intrinsic properties
philosiphical DR
belongs to the thing in-itslef
e.g im 5’4
these properties exist in the external world
definition of relational properties
philosiphical DR
belong to the thing but depends on its relationship to another thing
eg ‘im taller than a child’ OR ‘im smaller compared to somone who is 6’3
these properties exist in the external world
how do intrinsic and relational properties apply to the pen example
the pen looking bent in water is a relational property - due to reflection
response to perceptual variarion
philosiphical DR
appearances are relational properties
* e.g a property of a rectangular table is to appear rectangular but depending on their relation to the perceiver it’ll be different
sense data, verdical perception
response to hallucination crit
DR
only in hallucinations do we percive sense data, we dont in verdical pereption
* meaning DR should deny that experinces which cannot be told apart by the perceiver are the same kind of process
* despite hallucinations being able to be subjectively indistinguishable from verdical experinces, one is a direct perception of the external world and the other is direct perception of mental image
form of perception
response to hallucination crit
DR
deny that hallucinations are a form of perception at all
* perhaps when we hallucinate we do not have an experinces but rather we mistakenly imagine that we have an experince
* hallucinations are a kind of disorder or delusion where we think imagination is perception
response to time-lag
philosphical DR
- can are that this response confuses what we percive with how we perceive it
- what we are perceiving is still a mind-independnt object but we’re perceiving it as it was moments ago rather than how it is now
