KOCHEN-SPECKER THEOREM IN THE MODAL INTERPRETATION OF QUANTUM-MECHANICS

According to the modal interpretation of quantum mechanics, subsystems of a quantum mechanical system have definite properties, the set of d efinite properties forming a partial Boolean algebra. It is shown that these partial Boolean algebras have no common extension (as a partial Boolean subalgebra of the properties of the total system) that is emb eddable in a Boolean algebra. One has thus either to restrict the rule s to preferred subsystems (Healey), or to advocate a shift in metaphys ics (Dieks).