  A formulation of quantum mechanics based on an operational definition of
state is presented. This formulation, which includes explicitly the macroscopic
systems, assumes the probabilistic interpretation and is nevertheless
objective. The classical paradoxes of quantum mechanics are analyzed and their
origin is found to be the fictitious properties that are usually attributed to
quantum-mechanical states. The hypothesis that any mixed state can always be
considered as an incoherent superposition of pure states is found to contradict
quantum mechanics. A solution of EPR paradox is proposed. It is shown that
entanglement of quantum states is compatible with realism and locality of
events, but implies non-local encoding of information.
