It is shown that a lack of knowledge about the measurements of a physical system gives rise
to a nonclassical probability calculus for this physical system. It is also shown that the
nonclassical probability calculus of quantum mechanics can be interpreted as being the
result of a lack of knowledge about the measurements. Examples are given of macroscopic
real systems that have a nonclassical probability calculus. A macroscopic real system that
has a quantum probability calculus is also given, and more specifically a model for the spin …

A possible explanation for the probabilities of quantum mechanics and a macroscopical
situation that violates Bell inequalities — Vrije Universiteit Brussel … Mittelstaedt and EW
Stachow (Eds.), Recent Developments in Quantum Logic, Grundlagen der Exacten
Naturwissenschaften, vol.6, Wissenschaftverlag (pp. 235-251). Mannheim:
Bibliographisches Institut, (1985). … Mittelstaedt and EW Stachow (Eds.), Recent
Developments in Quantum Logic, Grundlagen der Exacten Naturwissenschaften, vol.6 …