Some general methodological considerations aimed to guarantee the necessary logical rigor to the present debate on quantum mechanics are presented. In particular some misunderstandings about the implications of the critical analysis put forward by Einstein Podolsky and Rosen (EPR) which can be found in the literature, are discussed. These misunderstanding are shown to arise from possible underestimates, overestimates and misinterpretations of the EPR argument. It is argued that the difficulties pointed out by EPR are, in a sense that will be defined precisely, unavoidable. A model which tries to solve the difficulties arising from quantum non separability effects when macroscopic systems are involved, is briefly sketched.