抄録
An argument is presented that the consistent description of the evolution of a system is possible only with the statistical operator and not with the wave function. A reconstruction of the logic of quantum mechanics is proposed with the statistical operator as the basic quantity to describe the state in one-to-one correspondence. The problem of measurement is reconsidered in the light of this new logic. It is shown for the first time how the irreversible change in the measuring apparatus leads to the truncation of von Neumann’s chain between the object and the subject.