Direct Realism

Realist

Belief that objects exist independent from the mind

Anti-Realist

Belief that objects do not exist outside the mind

Direct Realism

The view that the external world exists independently from the mind (realism) and we perceive the external world directly

• Mind Independent

• Direct Perception Method

• Problems: Illusion, Hallucination, Perceptual variation, Timelag

Indirect Realism

The view that the external world exists independently of the mind (realism) but we perceive the external world indirectly via sense data

• Mind Independent

• Indirect perception (via sense data)

• Philosophers: Locke, Russel

• Problems: Sense data vs mind-independent objects, veil of perception

Idealism

• Mind dependant

• Direct perception method

• Philosopher: Berkeley

• Problems: Role of God, Hallucination, Illusion

Sense Data

• the content of perceptual experience.

• not a physical thing, so it exists in the mind

• caused by and represents mind-independent physical objects

• private, no one else can experience your sense data

• avoids the problem with direct realism

Primary Qualities

Properties inherent in the object itself. It’s objective so is reality. Ex:

• Size

• Shape

• Motion

• Number

Secondary Qualities

Powers of an object to cause sensations in humans. It’s subjective so is our perception of reality

• Colour

• Taste

• Smell

• Feel

Argument from Perceptual Variation

P1 There are variations in perception

P2 Our perception changes without corresponding changes in the physical object we perceive.

C1 The properties of the physical objects have and the properties they appear to have are not identical

C2 What we are immediately aware of in perception is not exactly the same as what exists independently of our minds

C3 We do not perceive physical objects directly

Hallucination

• Non-veridical perceptual experience that is not coherently connected with the rest of our perceptual experiences.

• The possibility of hallucinatory experiences that are subjectively indistinguishable from a veridical perception means that we don’t immediately perceive physical objects, but sense-data

Illusion

• A distortion of the sense such that we percieve is different from what exists

• Illusions can be subjectively indistinguishable from veridical perception, so we see sense-data (not physical objects) immediately.

Perceptual Variation

P1 Different people perceive the same object differently.

P2 What each person perceives is how the object appears to them

P3 This appearance is mind-dependant sense-data

C1 Physical objects aren’t perceived directly

Time Lag

There is a gap in time between the event and my perception of it

Mediated

Indirect Perception, via sense data

Russel’s Arguement from Perceptual Variation

1) Direct Realism claims that we directly perceive objects and their properties

2) When I perceive a table, what I am immediately aware of are the colour (brown) and shape (square)

3) However, when I view the table from another angle, it appears white and diamond shaped

4) Therefore my perceptions of the object are variable

5) The object itself has not changed

6) Therefore I do not perceive the object itself, but the sense-data representing the object

7) Direct Realism is False

Property

Something an object has (eg.colour, shape, size)

Relational Property

How an object appears in relation to other factors

Ex. A pencil looking bent in water

Criticism: what are normal properties or conditions to perceive an object?

Counter: Supported by science which shows all variation occurs in the object, mind-independently.

Criticisms of Hallucination Arguement

• Imagining, not perceiving so the arguement is irrelevant

• HOWEVER, we do use our senses so maybe we are percieving

• Hallucinations are subjectively distinguishable hence we have the word “hallucination” and discuss it

• HOWEVER, checking with other senses can be faulty as we don’t know which are reliable (Ex. John Nash)

Disjunctive Theory of Perception

Used as a defence by Direct Realists against Hallucination Argument

• Hallucination is very different from veridical perception as its spearated from reality

• Even though the two possibilities appear the same, it doesn’t mean they are… SO

• Even if hallucinations are of mind-dependant sense data it doesn’t follow that all perceptions are too.

Hallucination Arguement

1) In a hallucination we perceive something that doesn’t physically exist

2) THerefore what we perceive in a hallucination must be mind-dependant

3) Hallucinations can be subjectively indistinguishable from veridical perception

4) What we are immediately aware of in perception is not the same as what we suppose exists independently of our minds

5) It’s erroneous to argue that appearance and reality are the same

6) Direct Realism in it’s naive form is false

Direct Realism Response

Illusions and mirages exist as a result of scientific phenomena

Our perception is still unmediated and direct but dependent on other factors in the external world