it is the average number of spider legs found in a candy bar multiplied by the naturally occurring ratio between leprechauns and unicorns in Sherwood forest
illusions - senses might be decieved E.g stick appears bent in water
dreams - might still be dreams E.g vivid dreams
Evil Demon - all our perceptions might be being decieved by a supreme power...
Empiricist notion (the prevailing modern view) that language is essentially an adventitious construct, taught by "conditioning" (as would be maintained, for example, by Skinner or Quine) or by drill...