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  • Created by: imyimss
  • Created on: 05-06-18 18:06
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      • our senses are subject to illusion
        • what we are immediately perceiving cannot be what is in the world as what we are perceiving is not that same as what's really there
          • bend straw example: direct realism would suggest the straw is bend when in actual fact it isn't
            • the direct realists response to the illusion objection is to say the straw only APPEARS to be bent (not turn the way it appears to the observer into a distinct thing)
        • we can point out / identify when we are hallucinating (Macbeth couldn't grab the dagger)
          • our other senses help detect deception
            • we can deny that hallucinations are really perceptions at all. We perceive sense data instead of a physical object
      • DESCARTES - dreams are sometimes distinguishable from real life - what we are immediately aware of is not the same as what is real
        • hallucination argument says it may be impossible to distinguish experience from genuine perception
          • what i'm immediately aware of, even when not hallucinating, must be an object of the mind or sense datum
      • RUSSELL notes that it takes time for light waves, or sound waves, or smells to get from the physical object to our senses
        • they can reply that this is a confusion between how we perceive and what we perceieve
          • we don't perceive light waves directly and physical objects indirectly
      • the time lag argument means we see the physical object as it was a moment before not as it is now
        • it takes 8 minutes for light from the sun to reach earth, so we see it as it was 8 minutes therefore you aren't seeing it directly
          • what we perceive is the physical medium by which we detect physical objects (light waves, sound waves, chemicals for smell)
            • so we don't perceive (ordinary) physical objects directly
      • what we perceive immediately isn't the same or directly isn't the physical object and its properties
      • RUSSELL - a table may appear to be different colours under different lightings
        • he says: the real colour is seen by the person standing next to it under normal conditions
          • difficult to determine which distance and under what lighting conditions to reveal reality
      • LOCKE - putting a hot hand and a cold hand in the same bucket of lukewarm water
        • it will feel hot to one hand and cold to the other hand - but the same bucket of water can't be both hot and cold
          • therefore it only appears hot and cold - they are not the real properties just effects such objects have on us
      • BERKELEY - when observing clouds they appear to be different colours to different observers
        • it makes no sense to say that they have a real colour
          • if we take a flower and put it under a microscope it will be a different colour from if we look at it with the naked eye
  • 1. we percieve somethiing having the property, F
    • 2. when we percieve something with property F, then there is something that has this property
      • 3. In an illusion, the physical object does not have the property F
        • 4. Therefore, what what has the property of F is something mental, a sense datum
          • 5. Therefore in an illusion we see sense data and not physical objects immediately
            • 6. Illusions can be 'subjectively indistinguishable' from veridical perception
              • 7. Therefore we see the same thing, sense data, in both illusions and veridical perception
                • 8. Therefore in all cases, we see sense data and not physical objects immediately
                  • 9. Therefore, direct realism is false
  • 1. There are variations in perception
    • 2. Our perception varies without corresponding changes in the physical object we perceive
      • 3. Therefore, the properties physical objects have and the properties they appear to have are not identical
        • 4. Therefore, what we are immediately aware of in perception is not exactly the same as what exists independently to our minds
          • 5. Therefore, we do not perceive physical objects directly
  • 1. In a hallucination, we perceive something having some property F
    • 2. When we perceive something having some property F, then there is something that has this property
      • 3. We don't perceive a physical object at all
        • 4. Therefore, what we perceive must be mental - sense data
          • 5. Hallucinations can be experience that are SUBJECTIVELY INDISTINGUISHABLE from veridical perception
            • 6. Therefore, we see the same thing, sense data, in both hallucinations and veridical perception
              • 7. Therefore, direct realism is false


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