  A discussion of the quantum mechanical use of superposition or entangled
states shows that descriptions containing only statements about state vectors
and experiments outputs are the most suitable for Quantum Mechanics. In
particular, it is shown that statements about the undefined values of physical
quantities before measurement can be dropped without changing the predictions
of the theory. If we apply these ideas to EPR issues, we find that the concept
of non-locality with its 'instantaneous action at a distance' evaporates.
Finally, it is argued that usual treatments of philosophical realist positions
end up in the construction of theories whose major role is that of being
disproved by experiment. This confutation proves simply that the theories are
wrong; no conclusion about realism (or any other philosophical position) can be
drawn, since experiments deal always with theories and these are never logical
consequences of philosophical positions.
