Direct realism issues and replies

Illusions

Sometimes our illusions can be deceptive or illusory

Illusion argument

p1-We perceive something having some property F(e.g a stick that is bent)
P2-When we perceive something having some property F, then there is something that has this property
P3-In an illusion, the physical object does not have the F(the stick is not crooked in reality)
C1-Therefore, what has the property F is something mental, a sense-datum
C2-Therefore, in illusions, we see sense-data, and not physical objects immediately
P4-Illusions can be 'subjectively indistinguishable' from veridical perception
C3-Therefore, we see the same thing, namely sense-data, in both illusions and veridical perception
C4-Therefore, in all cases, we see sense-data, and not physical objects immediately
C5-Therefore, direct realism is false

Illusion reply

Austin- just because something appears to us differently than it is does not allow us to infer that there is something extra involved
There are not two things involved here, but rather one stick which has the property of looking bent
e.g a barn that looks like a church, there is not immaterial barn or church.

Perceptual variation

The appearance of something can be different to how it is in reality e.g a tables shape or colour

Perceptual variation argument

P1-There are variations in perception
P2-Our perception varies without corresponding changes in the physical objects we perceive(e.g a table remaining rectangular as its shape is different in certain angles)
C1-Therefore, the properties physical objects have and the properties they appear to have are not identical
C2-Therefore, what we are immediately aware of in perception is not exactly the same as what exists independently of our minds
C3-Therefore, we do not perceive physical objects directly

Perceptual variation reply

Strawson- there is no 'real' colour, taste, smell etc for every object but you have to have the optimum conditions for experience e.g the lighting, angle, health of the perceiver
BUT how can we determine what optimum conditions actually are

Hallucinations

You are perceiving something, but not an object. Could we be in a continual hallucination?

Hallucination argument

P1-In a hallucination, we perceive something having some Property F
P2-When we perceive something having some property F, then there is something that has this property
P3-We don't perceive a physical object at all (unlike the case of illusion)]
C1-Therefore, what we perceive must be mental-sense data
P4-Hallucinations can be experiences that are 'subjectively indistinguishable' from veridical perceptions
C2-Therefore, we see the same thing, namely sense-data, in both hallucinations and veridical perception
C3-Therefore, in all cases, we see sense-data, and not physical objects, immediately
C4-Therefore, direct realism is false

Hallucination reply

Austin-hallucinations are a rare occurrence that most people do not have, so we do not need to concern ourselves much.
Hallucinations are distinct from veridical perceptions or we would not be able to recognise they are hallucinations in the first place

Time-lag argument

-Light takes time to reach our eyes so I cannot directly perceive the object itself, what I perceive is a delayed image of the object
-Light takes a long time to travel from the star to Earth, by the time the light hits your retina and you experience the star, the star may not even exist anymore
-How are you perceiving the object directly if it's the past

Time-lag reply

Perceiving directly and immediately are not the same thing, my perception may be delayed but it is still direct