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KNOWLEDGE OF THE EXTERNAL WORLD
THEORIES OF PERCEPTION
Why an issue?
• Sensory perception a key source of our beliefs about the world.
• Empiricism – senses the basis of knowledge.
Key questions• What is the relationship between me (the subject) and
the world?
• What is the relationship between appearance and reality?
• When I perceive something, what is it that I am aware of?
• How are misperceptions and illusions to be explained?
• What happens when an object is not being perceived? What can we know of it?
The common sense approach to the questions…
• One’s awareness or perception is directly of the object.
• The object exists independently of us.
• The object is the cause of my perceptual experience.
• When unperceived the object retains (at least some of) its properties….
• Worries
The challenge of illusions
PARIS IN THE
THE SPRING
The challenge to direct realism
• The Time-Lag Argument.
• There is a time lag between my perception of an object and the object actually having the properties I perceive it to possess
• Well-known objection to direct realism but one that is easily answered. It trades on a confusion between two senses of immediate.
• Immediate #1: without delay
• Immediate #2: direct, without anything coming between.
A bigger worry… Misperception and Illusion
• a round coin can appear elliptical from certain angles, a straight stick bent when in water, parallel lines convergent as they move into the distance, a non-existent limb can feel painful to an amputee
• The basic problem is how to explain why an apparently direct relationship with the world can give rise to such errors.
• Also – think about how we can explain the phenomenal sameness of really seeing a small green man and having an hallucination of a small green man.
Physics and perceptual experience
• Physics tells us how the world really is.
• Yet we do not experience the world as it is described in our best physical theory, even though according to direct realism it is with the world as such that I have direct contact.
• Furthermore, at least some of the properties an object has seem to depend upon the perspective of the observer
The appeal to representative realism…