A Level Philosophy

Key Points

• Representative realism says it explains illusions and hallucinations. When we see a stick that looks bent, but actually isn’t, it’s the sense data that are bent. When we hallucinate, we just see sense data with no physical reality.
• Sense data are private, and exist only whilst being experienced, and are exactly as they seem to be. Physical objects are public, and continue to exist when not being perceived, but can be different from how they appear to be.
• Sense data mediate between the perceiver and the external world. They relate to real public objects.

Arguments For

• Argument from physics – Science describes objects as atoms, molecules and protons. We don’t experience them as such, merely as a collective, making them red, smelly, sweet or high pitched. This shows we don’t experience objects directly.
• Time lag – The image of the sun takes 8 mins to get to earth, so when we see the sun we see the sun as it was 8 mins ago. Direct realism seems to suggest we look into the past! You don’t see it directly.
• Causal dependency – Sight depends on light reflected from an object bouncing off the retina and sending an electric signal down the optic nerve to be decoded in the brain. All we are aware of is the final sensation. How can we prove there’s an external world at the other end of the chain?

Counter Arguments

• Argument from physics – gives us objective truths about the world, but demonstrates that the world is not as we immediately perceive it. We do not perceive the world as it really is given that we perceive taste, smell, and colour.
• Time lag – Direct realist just says that we directly experience the sun - but its past. We directly see the sun as it was eight minutes ago, and indeed we never see anything as it is now. We directly see things as they were at the time the light reaching our eyes reflected off the objects.
• Causal dependency – Physics tells us that perception is caused by something, and gives us objective truths. We are only aware of sense data at the end of the chain, so we have to doubt existence. These arguments use physical objects to get started and to conclude. Self contradiction?

Arguments Against

• The Ontological Question – If sense data has no physical existence, where is it? Russell argued that it’s purely a mental phenomena, but if sensation and sense data are only mental, how do they mediate between mental and physical realms?
• Representation – Sense data are completely private so I can’t have any help interpreting them, and I have no direct access to the objects they’re meant to represent. If its purely private, there is no sense in which you can be right or wrong in your sense data.
• If we can only ever experience perceptions of objects, how do we even know they exist in the first place?
• Massively contradictory - says we don't see the same thing as each other, which goes against common sense and how experience presents itself, in that we live in a world of, and perceive public objects. We naturally refer to things in the objective world because that's how experience presents itself.