Knowledge of the external world

Knowledge of the external world

1. Direct Realism

   • the world is exactly as we perceive it
   • objects exist as we perceive them - there are no primary and secondary qualities
   • Issues
     • illusions for NDR
     • hallucinations for PDR
     • relative sense experiences

2. Representative Realism

   • there is a physical world, external to our perception, that we indirectly experience through our direct experience of sense data
     • able to overcome problems of DR whilst still maintaining the existence of a real world
   • the primary qualities of an object, which are measurable and independent of the perceiver induces the secondary qualities which are subjective to the perceiver
     • primary qualities: shape, size, solidity
     • secondary qualities: colour, smell, taste
   • Issues
     • variability/solidity
     • causality
     • resemblance
     • inseparability
   • support comes from the existence of time lags and appeals to the science of light waves

3. Idealism

   • physical objects do not exist in themselves and that objects are just bundles of sensations
   • All of our experiences are subjective
     • therefore 'esse set percipi'
   • God feeds us with coherent, logical sensations, which are the basis of what we call 'rules of nature'
   • Issues
     • we cannot experience God, therefore empirically he does not exist
     • common sense
     • solipsism
     • lack of proof either way