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…