  It is shown that, although correct mathematically, the celebrated 1932
theorem of von Neumann which is often interpreted as proving the impossibility
of the existence of "hidden variables" in Quantum Mechanics, is in fact based
on an assumption which is physically not reasonable. Apart from that, the
alleged conclusion of von Neumann proving the impossibility of the existence of
"hidden variables" was already set aside in 1952 by the counterexample of the
possibility of a physical theory, such as given by what is usually called the
"Bohmian Mechanics". Similar arguments apply to other two well known
mathematical theorems, namely, of Gleason, and of Kochen and Specker, which
have often been seen as equally proving the impossibility of the existence of
"hidden variables" in Quantum Mechanics.
