The perceptual world we
create differs qualitatively
from the physicists'
descriptions because our
experience is mediated by our
senses and constructed
internally as a representation
of the world. Thus we perceive
colors, tones, tastes, and
smells—–perceptions that either
have no meaning in the world
of physical reality or have a
different meaning. What we
perceive as hues of red, blue, or
green the physicist describes as
surfaces reflecting
electromagnetic waves of
certain frequencies. What we
experience as tastes and smells
the physicist refers to as
chemical compounds. What we
experience as tones of varying
pitch the physicist describes as
objects vibrating at different
frequencies. Colors, tones,
tastes, and smells are mental
constructions, created out of
sensory stimulation. As such,
they do not exist outside of
living minds. The philosopher
asks, Does a sound exist when a
tree falls in the forest if no
creature is near enough to hear
it? We can assume that the fall
would cause vibrations in the
air. They would exist, to be
sure. But there would be no
sound because a sound, by
definition, implies the
sensation evoked in a living
being by such vibration.