THE PRINCIPLE OF SUPERPOSITION. The need for a quantum theory Classical mechanics has been developed continuously from the time of Newton and applied to an ...

It has been claimed that the Principle of the Identity of Indiscernibles (PII) is incompatible with quantum mechanics, considered as a complete theory. Van Fraassen has argued specifically that a conflict between the two arises due to the requirements of Bose-Einstein statistics when imposed on two-particle quantum states. It is shown here that this apparent contradiction of the PII with quantum mechanics can be removed by the introduction of a natural criterion of individuality.

This paper is concerned with the problem of the validity of Leibniz's principle of the identity of indiscernibles in physics. After briefly surveying how the question is currently discussed in recent literature and which is the actual meaning of the principle for what concerns physics, we address the question of the physical validity of Leibniz's principle in terms of the existence of a sufficient number of naming predicates in the formal language of physics. This approach allows us to obtain in (...) a formal way the result that a principle of the identity of indiscernibles can be justified in the domain of classical physics, while this is not the case in the domain of quantum physics. (shrink)