  In this paper we discuss limitions appearing while using Boolean Logic in
Non-Constructive Mathematics (NCM) as a mathematical foundation for Quantum
Mechanics. These limitations naturally vanish using Constructive Mathematics
(CM) and Topos Theory which is one of its models. The line of reasoning is in
agreement with recent theoretical work on Quantum Logic, and focusses on the
pivotal role of the excluded middle law, and this will be addressed in more
detail in our discussion.
